HDF5 History
============

This file contains development history of the HDF5 1.14 branch

04.      Release Information for hdf5-1.14.3
03.      Release Information for hdf5-1.14.2
02.      Release Information for hdf5-1.14.1
01.      Release Information for hdf5-1.14.0

[Search on the string '%%%%' for section breaks of each release.]

%%%%1.14.3%%%%

HDF5 version 1.14.3 released on 2023-10-27
================================================================================


INTRODUCTION
============

This document describes the differences between this release and the previous
HDF5 release. It contains information on the platforms tested and known
problems in this release. For more details check the HISTORY*.txt files in the
HDF5 source.

Note that documentation in the links below will be updated at the time of each
final release.

Links to HDF5 documentation can be found on The HDF5 web page:

     https://portal.hdfgroup.org/display/HDF5/HDF5

The official HDF5 releases can be obtained from:

     https://www.hdfgroup.org/downloads/hdf5/

Changes from release to release and new features in the HDF5-1.14.x release series
can be found at:

     https://portal.hdfgroup.org/display/HDF5/Release+Specific+Information

If you have any questions or comments, please send them to the HDF Help Desk:

     help@hdfgroup.org


CONTENTS
========

- New Features
- Support for new platforms and languages
- Bug Fixes since HDF5-1.14.2
- Platforms Tested
- Known Problems
- CMake vs. Autotools installations


New Features
============

    Configuration:
    -------------
    - Improved support for Intel oneAPI

      * Separates the old 'classic' Intel compiler settings and warnings
        from the oneAPI settings
      * Uses `-check nouninit` in debug builds to avoid false positives
        when building H5_buildiface with `-check all`
      * Both Autotools and CMake

    - Added new options for CMake and Autotools to control the Doxygen
      warnings as errors setting.

        * HDF5_ENABLE_DOXY_WARNINGS: ON/OFF (Default: ON)
        * --enable-doxygen-errors: enable/disable (Default: enable)

      The default will fail to compile if the doxygen parsing generates warnings.
      The option can be disabled for certain versions of doxygen with parsing
      issues. i.e. 1.9.5, 1.9.8.

      Addresses GitHub issue #3398

    - Added support for AOCC and classic Flang w/ the Autotools

      * Adds a config/clang-fflags options file to support Flang
      * Corrects missing "-Wl," from linker options in the libtool wrappers
        when using Flang, the MPI Fortran compiler wrappers, and building
        the shared library. This would often result in unrecognized options
        like -soname.
      * Enable -nomp w/ Flang to avoid linking to the OpenMPI library.

      CMake can build the parallel, shared library w/ Fortran using AOCC
      and Flang, so no changes were needed for that build system.

      Fixes GitHub issues #3439, #1588, #366, #280

    - Converted the build of libaec and zlib to use FETCH_CONTENT with CMake.

      Using the CMake FetchContent module, the external filters can populate
      content at configure time via any method supported by the ExternalProject
      module. Whereas ExternalProject_Add() downloads at build time, the
      FetchContent module makes content available immediately, allowing the
      configure step to use the content in commands like add_subdirectory(),
      include() or file() operations.

      Removed HDF options for using FETCH_CONTENT explicitly:
          BUILD_SZIP_WITH_FETCHCONTENT:BOOL
          BUILD_ZLIB_WITH_FETCHCONTENT:BOOL

    - Thread-safety + static library disabled on Windows w/ CMake

      The thread-safety feature requires hooks in DllMain(), which is only
      present in the shared library.

      We previously just warned about this, but now any CMake configuration
      that tries to build thread-safety and the static library will fail.
      This cannot be overridden with ALLOW_UNSUPPORTED.

      Fixes GitHub issue #3613

    - Autotools builds now build the szip filter by default when an appropriate
      library is found

      Since libaec is prevalent and BSD-licensed for both encoding and
      decoding, we build the szip filter by default now.

      Both autotools and CMake build systems will process the szip filter the same as
      the zlib filter is processed.

    - Removed CMake cross-compiling variables

      * HDF5_USE_PREGEN
      * HDF5_BATCH_H5DETECT

      These were used to work around H5detect and H5make_libsettings and
      are no longer required.

    - Running H5make_libsettings is no longer required for cross-compiling

      The functionality of H5make_libsettings is now handled via template files,
      so H5make_libsettings has been removed.

    - Running H5detect is no longer required for cross-compiling

      The functionality of H5detect is now exercised at library startup,
      so H5detect has been removed.


    Library:
    --------
    - Added a simple cache to the read-only S3 (ros3) VFD

      The read-only S3 VFD now caches the first N bytes of a file stored
      in S3 to avoid a lot of small I/O operations when opening files.
      This cache is per-file and created when the file is opened.

      N is currently 16 MiB or the size of the file, whichever is smaller.

      Addresses GitHub issue #3381

    - Added new API function H5Pget_actual_selection_io_mode()

      This function allows the user to determine if the library performed
      selection I/O, vector I/O, or scalar (legacy) I/O during the last HDF5
      operation performed with the provided DXPL.


    Parallel Library:
    -----------------
    - Added optimized support for the parallel compression feature when
      using the multi-dataset I/O API routines collectively

      Previously, calling H5Dwrite_multi/H5Dread_multi collectively in parallel
      with a list containing one or more filtered datasets would cause HDF5 to
      break out of the optimized multi-dataset I/O mode and instead perform I/O
      by looping over each dataset in the I/O request. The library has now been
      updated to perform I/O in a more optimized manner in this case by first
      performing I/O on all the filtered datasets at once and then performing
      I/O on all the unfiltered datasets at once.

    - Changed H5Pset_evict_on_close so that it can be called with a parallel
      build of HDF5

      Previously, H5Pset_evict_on_close would always fail when called from a
      parallel build of HDF5, stating that the feature is not supported with
      parallel HDF5. This failure would occur even if a parallel build of HDF5
      was used with a serial HDF5 application. H5Pset_evict_on_close can now
      be called regardless of the library build type and the library will
      instead fail during H5Fcreate/H5Fopen if the "evict on close" property
      has been set to true and the file is being opened for parallel access
      with more than 1 MPI process.


    Fortran Library:
    ----------------
    - Fixed an uninitialized error return value for hdferr
      to return the error state of the h5aopen_by_idx_f API.

    - Added h5pget_vol_cap_flags_f and related Fortran VOL
      capability definitions.

    - Fortran async APIs H5A, H5D, H5ES, H5G, H5F, H5L and H5O were added.

    - Added Fortran APIs:
      h5pset_selection_io_f, h5pget_selection_io_f,
      h5pget_actual_selection_io_mode_f,
      h5pset_modify_write_buf_f, h5pget_modify_write_buf_f

    - Added Fortran APIs:
      h5get_free_list_sizes_f, h5dwrite_chunk_f, h5dread_chunk_f,
      h5fget_info_f, h5lvisit_f, h5lvisit_by_name_f,
      h5pget_no_selection_io_cause_f, h5pget_mpio_no_collective_cause_f,
      h5sselect_shape_same_f, h5sselect_intersect_block_f,
      h5pget_file_space_page_size_f, h5pset_file_space_page_size_f,
      h5pget_file_space_strategy_f, h5pset_file_space_strategy_f

    - Removed "-commons" linking option on Darwin, as COMMON and EQUIVALENCE
      are no longer used in the Fortran source.

      Fixes GitHub issue #3571

    C++ Library:
    ------------
    -


    Java Library:
    -------------
    -


    Tools:
    ------
    -


    High-Level APIs:
    ----------------
    - Added Fortran HL API: h5doappend_f


    C Packet Table API:
    -------------------
    -


    Internal header file:
    ---------------------
    -


    Documentation:
    --------------
    -


Support for new platforms, languages and compilers
==================================================
    -


Bug Fixes since HDF5-1.14.2 release
===================================
    Library
    -------
    - Fixed some issues with chunk index metadata not getting read
      collectively when collective metadata reads are enabled

      When looking up dataset chunks during I/O, the parallel library
      temporarily disables collective metadata reads since it's generally
      unlikely that the application will read the same chunks from all
      MPI ranks. Leaving collective metadata reads enabled during
      chunk lookups can lead to hangs or other bad behavior depending
      on the chunk indexing structure used for the dataset in question.
      However, due to the way that dataset chunk index metadata was
      previously loaded in a deferred manner, this could mean that
      the metadata for the main chunk index structure or its
      accompanying pieces of metadata (e.g., fixed array data blocks)
      could end up being read independently if these chunk lookup
      operations are the first chunk index-related operation that
      occurs on a dataset. This behavior is generally observed when
      opening a dataset for which the metadata isn't in the metadata
      cache yet and then immediately performing I/O on that dataset.
      This behavior is not generally observed when creating a dataset
      and then performing I/O on it, as the relevant metadata will
      usually be in the metadata cache as a side effect of creating
      the chunk index structures during dataset creation. 

      This issue has been fixed by adding callbacks to the different
      chunk indexing structure classes that allow more explicit control
      over when chunk index metadata gets loaded. When collective
      metadata reads are enabled, the necessary index metadata will now
      get loaded collectively by all MPI ranks at the start of dataset
      I/O to ensure that the ranks don't unintentionally read this
      metadata independently further on. These changes fix collective
      loading of the main chunk index structure, as well as v2 B-tree
      root nodes, extensible array index blocks and fixed array data
      blocks. There are still pieces of metadata that cannot currently
      be loaded collectively, however, such as extensible array data
      blocks, data block pages and super blocks, as well as fixed array
      data block pages. These pieces of metadata are not necessarily
      read in by all MPI ranks since this depends on which chunks the
      ranks have selected in the dataset. Therefore, reading of these
      pieces of metadata remains an independent operation.

    - Fixed potential hangs in parallel library during collective I/O with
      independent metadata writes

      When performing collective parallel writes to a dataset where metadata
      writes are requested as (or left as the default setting of) independent,
      hangs could potentially occur during metadata cache sync points. This
      was due to incorrect management of the internal state tracking whether
      an I/O operation should be collective or not, causing the library to
      attempt collective writes of metadata when they were meant to be
      independent writes. During the metadata cache sync points, if the number
      of cache entries being flushed was a multiple of the number of MPI ranks
      in the MPI communicator used to access the HDF5 file, an equal amount of
      collective MPI I/O calls were made and the dataset write call would be
      successful. However, when the number of cache entries being flushed was
      NOT a multiple of the number of MPI ranks, the ranks with more entries
      than others would get stuck in an MPI_File_set_view call, while other
      ranks would get stuck in a post-write MPI_Barrier call. This issue has
      been fixed by correctly switching to independent I/O temporarily when
      writing metadata independently during collective dataset I/O.

    - Fixed a bug with the way the Subfiling VFD assigns I/O concentrators

      During a file open operation, the Subfiling VFD determines the topology
      of the application and uses that to select a subset of MPI ranks that
      I/O will be forwarded to, called I/O concentrators. The code for this
      had previously assumed that the parallel job launcher application (e.g.,
      mpirun, srun, etc.) would distribute MPI ranks sequentially to a node's
      processors until all processors on that node have been assigned before
      going on to the next node. When the launcher application mapped MPI ranks
      to nodes in a different fashion, such as round-robin, this could cause 
      the Subfiling VFD to incorrectly map MPI ranks as I/O concentrators,
      leading to missing subfiles.

    - Fixed a file space allocation bug in the parallel library for chunked
      datasets

      With the addition of support for incremental file space allocation for
      chunked datasets with filters applied to them that are created/accessed
      in parallel, a bug was introduced to the library's parallel file space
      allocation code. This could cause file space to not be allocated correctly
      for datasets without filters applied to them that are created with serial
      file access and later opened with parallel file access. In turn, this could
      cause parallel writes to those datasets to place incorrect data in the file.

    - Fixed an assertion failure in Parallel HDF5 when a file can't be created
      due to an invalid library version bounds setting

      An assertion failure could occur in H5MF_settle_raw_data_fsm when a file
      can't be created with Parallel HDF5 due to specifying the use of a paged,
      persistent file free space manager
      (H5Pset_file_space_strategy(..., H5F_FSPACE_STRATEGY_PAGE, 1, ...)) with
      an invalid library version bounds combination
      (H5Pset_libver_bounds(..., H5F_LIBVER_EARLIEST, H5F_LIBVER_V18)). This
      has now been fixed.

    - Fixed an assertion in a previous fix for CVE-2016-4332

      An assert could fail when processing corrupt files that have invalid
      shared message flags (as in CVE-2016-4332).

      The assert statement in question has been replaced with pointer checks
      that don't raise errors. Since the function is in cleanup code, we do
      our best to close and free things, even when presented with partially
      initialized structs.

      Fixes CVE-2016-4332 and HDFFV-9950 (confirmed via the cve_hdf5 repo)

    - Fixed performance regression with some compound type conversions

      In-place type conversion was introduced for most use cases in 1.14.2.
      While being able to use the read buffer for type conversion potentially
      improves performance by performing the entire I/O at once, it also
      disables the optimized compound type conversion used when the destination
      is a subset of the source. Disabled in-place type conversion when using
      this optimized conversion and there is no benefit in terms of the I/O
      size.

    - Reading a H5std_string (std::string) via a C++ DataSet previously
      truncated the string at the first null byte as if reading a C string.
      Fixed length datasets are now read into H5std_string as a fixed length
      string of the appropriate size. Variable length datasets will still be
      truncated at the first null byte.

      Fixes Github issue #3034

    - Fixed write buffer overflow in H5O__alloc_chunk

      The overflow was found by OSS-Fuzz https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=58658

    Java Library
    ------------
    -


    Configuration
    -------------
    - Fixes the ordering of INCLUDES when building with CMake

      Include directories in the source or build tree should come before other
      directories to prioritize headers in the sources over installed ones.

      Fixes GitHub #1027

    - The accum test now passes on macOS 12+ (Monterey) w/ CMake

      Due to changes in the way macOS handles LD_LIBRARY_PATH, the accum test
      started failing on macOS 12+ when building with CMake. CMake has been
      updated to set DYLD_LIBRARY_PATH on macOS and the test now passes.

      Fixes GitHub #2994, #2261, and #1289

    - Changed the default settings used by CMake for the GZIP filter

      The default for the option HDF5_ENABLE_Z_LIB_SUPPORT was OFF. Now the default is ON.
      This was done to match the defaults used by the autotools configure.ac.
      In addition, the CMake message level for not finding a suitable filter library was
      changed from FATAL_ERROR (which would halt the build process) to WARNING (which
      will print a message to stderr). Associated files and documentation were changed to match.

      In addition, the default settings in the config/cmake/cacheinit.cmake file were changed to
      allow CMake to disable building the filters if the tgz file could not be found. The option
      to allow CMake to download the file from the original Github location requires setting
      the ZLIB_USE_LOCALCONTENT option to OFF for gzip. And setting the LIBAEC_USE_LOCALCONTENT
      option to OFF for libaec (szip).

      Fixes GitHub issue #2926


    Tools
    -----
    - Fixed an issue with unmatched MPI messages in ph5diff

      The "manager" MPI rank in ph5diff was unintentionally sending "program end"
      messages to its workers twice, leading to an error from MPICH similar to the
      following:

      Abort(810645519) on node 1 (rank 1 in comm 0): Fatal error in internal_Finalize: Other MPI error, error stack:
      internal_Finalize(50)...........: MPI_Finalize failed
      MPII_Finalize(394)..............:
      MPIR_Comm_delete_internal(1224).: Communicator (handle=44000000) being freed has 1 unmatched message(s)
      MPIR_Comm_release_always(1250)..:
      MPIR_finalize_builtin_comms(154):


    Performance
    -------------
    -


    Fortran API
    -----------
    -


    High-Level Library
    ------------------
    -


    Fortran High-Level APIs
    -----------------------
    -


    Documentation
    -------------
    -


    F90 APIs
    --------
    -


    C++ APIs
    --------
    - 


    Testing
    -------
    - Disabled running of MPI Atomicity tests for OpenMPI major versions < 5

      Support for MPI atomicity operations is not implemented for major
      versions of OpenMPI less than version 5. This would cause the MPI
      atomicity tests for parallel HDF5 to sporadically fail when run
      with OpenMPI. Testphdf5 now checks if OpenMPI is being used and will
      skip running the atomicity tests if the major version of OpenMPI is
      < 5.

    - Fixed Fortran 2003 test with gfortran-v13, optimization levels O2,O3

      Fixes failing Fortran 2003 test with gfortran, optimization level O2,O3
      with -fdefault-real-16. Fixes GH #2928.


Platforms Tested
===================

    Linux 5.19.0-1023-aws            GNU gcc, gfortran, g++
    #24-Ubuntu SMP x86_64 GNU/Linux  (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0
    Ubuntu 22.04                     Ubuntu clang version 14.0.0-1ubuntu1
                                     Intel(R) oneAPI DPC++/C++ Compiler 2023.1.0
                                     ifort (IFORT) 2021.9.0 20230302
                                     (cmake and autotools)

    Linux 5.16.14-200.fc35           GNU gcc (GCC) 11.2.1 20220127 (Red Hat 11.2.1-9)
    #1 SMP x86_64  GNU/Linux         GNU Fortran (GCC) 11.2.1 20220127 (Red Hat 11.2.1-9)
    Fedora35                         clang version 13.0.0 (Fedora 13.0.0-3.fc35)
                                     (cmake and autotools)

    Linux 5.14.21-cray_shasta_c      cray-mpich/8.1.27
    #1 SMP x86_64 GNU/Linux              cce/15.0.0
    (frontier)                           gcc/12.2.0
                                     (cmake)

    Linux 5.11.0-34-generic          GNU gcc (GCC) 9.4.0-1ubuntu1
    #36-Ubuntu SMP x86_64 GNU/Linux  GNU Fortran (GCC) 9.4.0-1ubuntu1
    Ubuntu 20.04                     Ubuntu clang version 10.0.0-4ubuntu1
                                     Intel(R) oneAPI DPC++/C++ Compiler 2023.1.0
                                     ifort (IFORT) 2021.9.0 20230302
                                     (cmake and autotools)

    Linux 4.14.0-115.35.1.1chaos     aue/openmpi/4.1.4-arm-22.1.0.12
    #1 SMP aarch64 GNU/Linux             Arm C/C++/Fortran Compiler version 22.1
    (stria)                              (based on LLVM 13.0.1)
                                     (cmake)

    Linux 4.14.0-115.35.1.3chaos     spectrum-mpi/rolling-release
    #1 SMP ppc64le GNU/Linux             clang 12.0.1
    (vortex)                             GCC 8.3.1
                                         XL 2021.09.22
                                     (cmake)

    Linux-4.14.0-115.21.2            spectrum-mpi/rolling-release
    #1 SMP ppc64le GNU/Linux             clang 12.0.1, 14.0.5
    (lassen)                             GCC 8.3.1
                                         XL 16.1.1.2, 2021.09.22, 2022.08.05
                                     (cmake)

    Linux-4.12.14-197.99-default     cray-mpich/7.7.14
    #1 SMP x86_64 GNU/Linux              cce 12.0.3
    (theta)                              GCC 11.2.0
                                         llvm 9.0
                                         Intel 19.1.2

    Linux 3.10.0-1160.36.2.el7.ppc64 gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)
    #1 SMP ppc64be GNU/Linux         g++ (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)
    Power8 (echidna)                 GNU Fortran (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)

    Linux 3.10.0-1160.24.1.el7       GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux          compilers:
    Centos7                              Version 4.8.5 20150623 (Red Hat 4.8.5-4)
    (jelly/kituo/moohan)                 Version 4.9.3, Version 7.2.0, Version 8.3.0,
                                         Version 9.1.0, Version 10.2.0
                                     Intel(R) C (icc), C++ (icpc), Fortran (icc)
                                     compilers:
                                         Version 17.0.0.098 Build 20160721
                                     GNU C (gcc) and C++ (g++) 4.8.5 compilers
                                         with NAG Fortran Compiler Release 7.1(Hanzomon)
                                     Intel(R) C (icc) and C++ (icpc) 17.0.0.098 compilers
                                         with NAG Fortran Compiler Release 7.1(Hanzomon)
                                     MPICH 3.1.4 compiled with GCC 4.9.3
                                     MPICH 3.3 compiled with GCC 7.2.0
                                     OpenMPI 3.1.3 compiled with GCC 7.2.0 and 4.1.2
                                         compiled with GCC 9.1.0
                                     PGI C, Fortran, C++ for 64-bit target on
                                     x86_64;
                                         Versions 18.4.0 and 19.10-0
                                     NVIDIA nvc, nvfortran and nvc++ version 22.5-0
                                     (autotools and cmake)


    Linux-3.10.0-1160.0.0.1chaos     openmpi-4.1.2
    #1 SMP x86_64 GNU/Linux              clang 6.0.0, 11.0.1
    (quartz)                             GCC 7.3.0, 8.1.0
                                         Intel 19.0.4, 2022.2, oneapi.2022.2

    Linux-3.10.0-1160.90.1.1chaos    openmpi/4.1
    #1 SMP x86_64 GNU/Linux              GCC 7.2.0
    (skybridge)                          Intel/19.1
                                     (cmake)

    Linux-3.10.0-1160.90.1.1chaos    openmpi/4.1
    #1 SMP x86_64 GNU/Linux              GCC 7.2.0
    (attaway)                            Intel/19.1
                                     (cmake)

    Linux-3.10.0-1160.90.1.1chaos    openmpi-intel/4.1
    #1 SMP x86_64 GNU/Linux              Intel/19.1.2, 21.3.0 and 22.2.0
    (chama)                          (cmake)

    macOS Apple M1 11.6              Apple clang version 12.0.5 (clang-1205.0.22.11)
    Darwin 20.6.0 arm64              gfortran GNU Fortran (Homebrew GCC 11.2.0) 11.1.0
    (macmini-m1)                     Intel icc/icpc/ifort version 2021.3.0 202106092021.3.0 20210609

    macOS Big Sur 11.3.1             Apple clang version 12.0.5 (clang-1205.0.22.9)
    Darwin 20.4.0 x86_64             gfortran GNU Fortran (Homebrew GCC 10.2.0_3) 10.2.0
    (bigsur-1)                       Intel icc/icpc/ifort version 2021.2.0 20210228

    Mac OS X El Capitan 10.11.6      Apple clang version 7.3.0 from Xcode 7.3
    64-bit                           gfortran GNU Fortran (GCC) 5.2.0
    (osx1011test)                    Intel icc/icpc/ifort version 16.0.2

    Linux 2.6.32-573.22.1.el6        GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux          compilers:
    Centos6                              Version 4.4.7 20120313
    (platypus)                           Version 4.9.3, 5.3.0, 6.2.0
                                     MPICH 3.1.4 compiled with GCC 4.9.3
                                     PGI C, Fortran, C++ for 64-bit target on
                                     x86_64;
                                         Version 19.10-0

    Windows 10 x64                  Visual Studio 2019 w/ clang 12.0.0
                                        with MSVC-like command-line (C/C++ only - cmake)
                                    Visual Studio 2019 w/ Intel oneAPI 2023.2 C/C++ only - cmake)
                                    Visual Studio 2022 w/ clang 16.0.5
                                        with MSVC-like command-line (C/C++ only - cmake)
                                    Visual Studio 2022 w/ Intel oneAPI 2023.2 (C/C++ only - cmake)
                                    Visual Studio 2019 w/ MSMPI 10.1 (C only - cmake)


Known Problems
==============

    Building HDF5 Fortran on Windows with Intel oneAPI 2023.2 currently fails for
    this release with link errors. As a result, Windows binaries for this release
    will not include Fortran.  The problem will be addressed in HDF5 1.14.4.

    IEEE standard arithmetic enables software to raise exceptions such as overflow,
    division by zero, and other illegal operations without interrupting or halting
    the program flow. The HDF5 C library intentionally performs these exceptions.
    Therefore, the "-ieee=full" nagfor switch is necessary when compiling a program
    to avoid stopping on an exception.

    CMake files do not behave correctly with paths containing spaces.
    Do not use spaces in paths because the required escaping for handling spaces
    results in very complex and fragile build files.
    ADB - 2019/05/07

    At present, metadata cache images may not be generated by parallel
    applications.  Parallel applications can read files with metadata cache
    images, but since this is a collective operation, a deadlock is possible
    if one or more processes do not participate.

    CPP ptable test fails on both VS2017 and VS2019 with Intel compiler, JIRA
    issue: HDFFV-10628.  This test will pass with VS2015 with Intel compiler.

    The subsetting option in ph5diff currently will fail and should be avoided.
    The subsetting option works correctly in serial h5diff.

    Several tests currently fail on certain platforms:
        MPI_TEST-t_bigio fails with spectrum-mpi on ppc64le platforms.

        MPI_TEST-t_subfiling_vfd and MPI_TEST_EXAMPLES-ph5_subfiling fail with
        cray-mpich on theta and with XL compilers on ppc64le platforms.

        MPI_TEST_testphdf5_tldsc fails with cray-mpich 7.7 on cori and theta.

    Known problems in previous releases can be found in the HISTORY*.txt files
    in the HDF5 source. Please report any new problems found to
    help@hdfgroup.org.


CMake vs. Autotools installations
=================================
While both build systems produce similar results, there are differences.
Each system produces the same set of folders on linux (only CMake works
on standard Windows); bin, include, lib and share. Autotools places the
COPYING and RELEASE.txt file in the root folder, CMake places them in
the share folder.

The bin folder contains the tools and the build scripts. Additionally, CMake
creates dynamic versions of the tools with the suffix "-shared". Autotools
installs one set of tools depending on the "--enable-shared" configuration
option.
  build scripts
  -------------
  Autotools: h5c++, h5cc, h5fc
  CMake: h5c++, h5cc, h5hlc++, h5hlcc

The include folder holds the header files and the fortran mod files. CMake
places the fortran mod files into separate shared and static subfolders,
while Autotools places one set of mod files into the include folder. Because
CMake produces a tools library, the header files for tools will appear in
the include folder.

The lib folder contains the library files, and CMake adds the pkgconfig
subfolder with the hdf5*.pc files used by the bin/build scripts created by
the CMake build. CMake separates the C interface code from the fortran code by
creating C-stub libraries for each Fortran library. In addition, only CMake
installs the tools library. The names of the szip libraries are different
between the build systems.

The share folder will have the most differences because CMake builds include
a number of CMake specific files for support of CMake's find_package and support
for the HDF5 Examples CMake project.

The issues with the gif tool are:
    HDFFV-10592 CVE-2018-17433
    HDFFV-10593 CVE-2018-17436
    HDFFV-11048 CVE-2020-10809
These CVE issues have not yet been addressed and are avoided by not building
the gif tool by default. Enable building the High-Level tools with these options:
    autotools:   --enable-hlgiftools
    cmake:       HDF5_BUILD_HL_GIF_TOOLS=ON


%%%%1.14.2%%%%

HDF5 version 1.14.2 released on 2023-08-11
================================================================================


INTRODUCTION
============

This document describes the differences between this release and the previous
HDF5 release. It contains information on the platforms tested and known
problems in this release. For more details check the HISTORY*.txt files in the
HDF5 source.

Note that documentation in the links below will be updated at the time of each
final release.

Links to HDF5 documentation can be found on The HDF5 web page:

     https://portal.hdfgroup.org/display/HDF5/HDF5

The official HDF5 releases can be obtained from:

     https://www.hdfgroup.org/downloads/hdf5/

Changes from release to release and new features in the HDF5-1.14.x release series
can be found at:

     https://portal.hdfgroup.org/display/HDF5/Release+Specific+Information

If you have any questions or comments, please send them to the HDF Help Desk:

     help@hdfgroup.org


CONTENTS
========

- New Features
- Support for new platforms and languages
- Bug Fixes since HDF5-1.14.1
- Platforms Tested
- Known Problems
- CMake vs. Autotools installations


New Features
============

    Configuration:
    -------------
    - Updated HDF5 API tests CMake code to support VOL connectors

      * Implemented support for fetching, building and testing HDF5
        VOL connectors during the library build process and documented
        the feature under doc/cmake-vols-fetchcontent.md

      * Implemented the HDF5_TEST_API_INSTALL option that enables
        installation of the HDF5 API tests on the system


    Library:
    --------
    - Added support for in-place type conversion in most cases

      In-place type conversion allows the library to perform type conversion
      without an intermediate type conversion buffer.  This can improve
      performance by allowing I/O in a single operation over the entire
      selection instead of being limited by the size of the intermediate buffer.
      Implemented for I/O on contiguous and chunked datasets when the selection
      is contiguous in memory and when the memory datatype is not smaller than
      the file datatype.

    - Changed selection I/O to be on by default when using the MPIO file driver

    - Added support for selection I/O in the MPIO file driver

      Previously, only vector I/O operations were supported.  Support for
      selection I/O should improve performance and reduce memory uses in some
      cases.

    - Change the error handling for a not found path in the find plugin process.

      While attempting to load a plugin the HDF5 library will fail if one of the
      directories in the plugin paths does not exist, even if there are more paths
      to check. Instead of exiting the function with an error, just log the error
      and continue processing the list of paths to check.


    Parallel Library:
    -----------------
    -


    Fortran Library:
    ----------------
    -


    C++ Library:
    ------------
    -


    Java Library:
    -------------
    -


    Tools:
    ------
    -


    High-Level APIs:
    ----------------
    -


    C Packet Table API:
    -------------------
    -


    Internal header file:
    ---------------------
    -


    Documentation:
    --------------
    -


Support for new platforms, languages and compilers
==================================================
    - Linux 5.14.21-cray_shasta_c     
      #1 SMP x86_64 GNU/Linux
      (frontier)


Bug Fixes since HDF5-1.14.1 release
===================================
    Library
    -------
    - Fixed bugs in selection I/O

      Previously, the library could fail in some cases when performing selection
      I/O with type conversion.

    - Fixed CVE-2018-13867

      A corrupt file containing an invalid local heap datablock address
      could trigger an assert failure when the metadata cache attempted
      to load the datablock from storage.

      The local heap now verifies that the datablock address is valid
      when the local heap header information is parsed.

    - Fixed CVE-2018-11202

      A malformed file could result in chunk index memory leaks. Under most
      conditions (i.e., when the --enable-using-memchecker option is NOT
      used), this would result in a small memory leak and and infinite loop
      and abort when shutting down the library. The infinite loop would be
      due to the "free list" package not being able to clear its resources
      so the library couldn't shut down. When the "using a memory checker"
      option is used, the free lists are disabled so there is just a memory
      leak with no abort on library shutdown.

      The chunk index resources are now correctly cleaned up when reading
      misparsed files and valgrind confirms no memory leaks.

    - Fixed an issue where an assert statement was converted to an
      incorrect error check statement

      An assert statement in the library dealing with undefined dataset data
      fill values was converted to an improper error check that would always
      trigger when a dataset's fill value was set to NULL (undefined). This
      has now been fixed.

    - Fixed an assertion failure when attempting to use the Subfiling IOC
      VFD directly

      The Subfiling feature makes use of two Virtual File Drivers, the
      Subfiling VFD and the IOC (I/O Concentrator) VFD. The two VFDs are
      intended to be stacked together such that the Subfiling VFD sits
      "on top" of the IOC VFD and routes I/O requests through it; using the
      IOC VFD alone is currently unsupported. The IOC VFD has been fixed so
      that an error message is displayed in this situation rather than causing
      an assertion failure.

    - Fixed a potential bug when copying empty enum datatypes

      Copying an empty enum datatype (including implicitly, as when an enum
      is a part of a compound datatype) would fail in an assert in debug
      mode and could fail in release mode depending on how the platform
      handles undefined behavior regarding size 0 memory allocations and
      using memcpy with a NULL src pointer.

      The library is now more careful about using memory operations when
      copying empty enum datatypes and will not error or raise an assert.

    - Added an AAPL check to H5Acreate

      A check was added to H5Acreate to ensure that a failure is correctly
      returned when an invalid Attribute Access Property List is passed
      in to the function. The HDF5 API tests were failing for certain
      build types due to this condition not being checked previously.


    Java Library
    ------------
    - Fixed switch case 'L' block missing a break statement.

      The HDF5Array.arrayify method is missing a break statement in the case 'L': section
      which causes it to fall through and throw an HDF5JavaException when attempting to
      read an Array[Array[Long]].

      The error was fixed by inserting a break statement at the end of the case 'L': sections.

      Fixes GitHub issue #3056


    Configuration
    -------------
    - Fixed a configuration issue that prevented building of the Subfiling VFD on macOS

      Checks were added to the CMake and Autotools code to verify that CLOCK_MONOTONIC_COARSE,
      PTHREAD_MUTEX_ADAPTIVE_NP and pthread_condattr_setclock() are available before attempting
      to use them in Subfiling VFD-related utility code. Without these checks, attempting
      to build the Subfiling VFD on macOS would fail. 


    Tools
    -----
    - Fixed an issue in h5repack for variable-length typed datasets

      When repacking datasets into a new file, h5repack tries to determines whether
      it can use H5Ocopy to copy each dataset into the new file, or if it needs to
      manually re-create the dataset, then read data from the old dataset and write
      it to the new dataset. H5repack was previously using H5Ocopy for datasets with
      variable-length datatypes, but this can be problematic if the global heap
      addresses involved do not match exactly between the old and new files. These
      addresses could change for a variety of reasons, such as the command-line options
      provided to h5repack, how h5repack allocates space in the repacked file, etc.      
      Since H5Ocopy does not currently perform any translation when these addresses
      change, datasets that were repacked with H5Ocopy could become unreadable in the
      new file. H5repack has been fixed to repack variable-length typed datasets without
      using H5Ocopy to ensure that the new datasets always have the correct global heap
      addresses.


    Performance
    -------------
    -


    Fortran API
    -----------
    -

    High-Level Library
    ------------------
    -


    Fortran High-Level APIs
    -----------------------
    -


    Documentation
    -------------
    -


    F90 APIs
    --------
    -


    C++ APIs
    --------
    - 


    Testing
    -------
    - Fixed a testing failure in testphdf5 on Cray machines

      On some Cray machines, what appears to be a bug in Cray MPICH was causing
      calls to H5Fis_accessible to create a 0-byte file with strange Unix
      permissions. This was causing an H5Fdelete file deletion test in the
      testphdf5 program to fail due to a just-deleted HDF5 file appearing to
      still be accessible on the file system. The issue in Cray MPICH has been
      worked around for the time being by resetting the MPI_Info object on the
      File Access Property List used to MPI_INFO_NULL before passing it to the
      H5Fis_accessible call.

    - A bug was fixed in the HDF5 API test random datatype generation code

      A bug in the random datatype generation code could cause test failures
      when trying to generate an enumeration datatype that has duplicated
      name/value pairs in it. This has now been fixed.

    - A bug was fixed in the HDF5 API test VOL connector registration checking code

      The HDF5 API test code checks to see if the VOL connector specified by the
      HDF5_VOL_CONNECTOR environment variable (if any) is registered with the library
      before attempting to run tests with it so that testing can be skipped and an
      error can be returned when a VOL connector fails to register successfully.
      Previously, this code didn't account for VOL connectors that specify extra
      configuration information in the HDF5_VOL_CONNECTOR environment variable and
      would incorrectly report that the specified VOL connector isn't registered
      due to including the configuration information as part of the VOL connector
      name being checked for registration status. This has now been fixed. 


Platforms Tested
===================

    Linux 5.19.0-1023-aws            GNU gcc, gfortran, g++
    #24-Ubuntu SMP x86_64 GNU/Linux  (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0
    Ubuntu 22.04                     Ubuntu clang version 14.0.0-1ubuntu1
                                     Intel(R) oneAPI DPC++/C++ Compiler 2023.1.0
                                     ifort (IFORT) 2021.9.0 20230302
                                     (cmake and autotools)

    Linux 5.16.14-200.fc35           GNU gcc (GCC) 11.2.1 20220127 (Red Hat 11.2.1-9)
    #1 SMP x86_64  GNU/Linux         GNU Fortran (GCC) 11.2.1 20220127 (Red Hat 11.2.1-9)
    Fedora35                         clang version 13.0.0 (Fedora 13.0.0-3.fc35)
                                     (cmake and autotools)

    Linux 5.14.21-cray_shasta_c      cray-mpich/8.1.23
    #1 SMP x86_64 GNU/Linux              cce/15.0.0
    (frontier)                           gcc/12.2.0
                                     (cmake)

    Linux 5.11.0-34-generic          GNU gcc (GCC) 9.4.0-1ubuntu1
    #36-Ubuntu SMP x86_64 GNU/Linux  GNU Fortran (GCC) 9.4.0-1ubuntu1
    Ubuntu 20.04                     Ubuntu clang version 10.0.0-4ubuntu1
                                     Intel(R) oneAPI DPC++/C++ Compiler 2023.1.0
                                     ifort (IFORT) 2021.9.0 20230302
                                     (cmake and autotools)

    Linux 4.14.0-115.35.1.1chaos     aue/openmpi/4.1.4-arm-22.1.0.12
    #1 SMP aarch64 GNU/Linux             Arm C/C++/Fortran Compiler version 22.1 
    (stria)                              (based on LLVM 13.0.1)
                                     (cmake)

    Linux 4.14.0-115.35.1.3chaos     spectrum-mpi/rolling-release
    #1 SMP ppc64le GNU/Linux             clang 12.0.1
    (vortex)                             GCC 8.3.1
                                         XL 2021.09.22
                                     (cmake)

    Linux-4.14.0-115.21.2            spectrum-mpi/rolling-release
    #1 SMP ppc64le GNU/Linux             clang 12.0.1, 14.0.5
    (lassen)                             GCC 8.3.1
                                         XL 16.1.1.2, 2021.09.22, 2022.08.05
                                     (cmake)

    Linux-4.12.14-197.99-default     cray-mpich/7.7.14
    #1 SMP x86_64 GNU/Linux              cce 12.0.3
    (theta)                              GCC 11.2.0
                                         llvm 9.0
                                         Intel 19.1.2

    Linux 3.10.0-1160.36.2.el7.ppc64 gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)
    #1 SMP ppc64be GNU/Linux         g++ (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)
    Power8 (echidna)                 GNU Fortran (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)

    Linux 3.10.0-1160.24.1.el7       GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux          compilers:
    Centos7                              Version 4.8.5 20150623 (Red Hat 4.8.5-4)
    (jelly/kituo/moohan)                 Version 4.9.3, Version 7.2.0, Version 8.3.0, 
                                         Version 9.1.0, Version 10.2.0
                                     Intel(R) C (icc), C++ (icpc), Fortran (icc)
                                     compilers:
                                         Version 17.0.0.098 Build 20160721
                                     GNU C (gcc) and C++ (g++) 4.8.5 compilers
                                         with NAG Fortran Compiler Release 7.1(Hanzomon)
                                     Intel(R) C (icc) and C++ (icpc) 17.0.0.098 compilers
                                         with NAG Fortran Compiler Release 7.1(Hanzomon)
                                     MPICH 3.1.4 compiled with GCC 4.9.3
                                     MPICH 3.3 compiled with GCC 7.2.0
                                     OpenMPI 3.1.3 compiled with GCC 7.2.0 and 4.1.2 
                                         compiled with GCC 9.1.0
                                     PGI C, Fortran, C++ for 64-bit target on
                                     x86_64;
                                         Versions 18.4.0 and 19.10-0
                                     NVIDIA nvc, nvfortran and nvc++ version 22.5-0
                                     (autotools and cmake)


    Linux-3.10.0-1160.0.0.1chaos     openmpi-4.1.2
    #1 SMP x86_64 GNU/Linux              clang 6.0.0, 11.0.1
    (quartz)                             GCC 7.3.0, 8.1.0
                                         Intel 19.0.4, 2022.2, oneapi.2022.2

    Linux-3.10.0-1160.90.1.1chaos    openmpi/4.1
    #1 SMP x86_64 GNU/Linux              GCC 7.2.0
    (skybridge)                          Intel/19.1
                                     (cmake)

    Linux-3.10.0-1160.90.1.1chaos    openmpi/4.1
    #1 SMP x86_64 GNU/Linux              GCC 7.2.0
    (attaway)                            Intel/19.1
                                     (cmake)

    Linux-3.10.0-1160.90.1.1chaos    openmpi-intel/4.1
    #1 SMP x86_64 GNU/Linux              Intel/19.1.2, 21.3.0 and 22.2.0
    (chama)                          (cmake)

    macOS Apple M1 11.6              Apple clang version 12.0.5 (clang-1205.0.22.11)
    Darwin 20.6.0 arm64              gfortran GNU Fortran (Homebrew GCC 11.2.0) 11.1.0
    (macmini-m1)                     Intel icc/icpc/ifort version 2021.3.0 202106092021.3.0 20210609

    macOS Big Sur 11.3.1             Apple clang version 12.0.5 (clang-1205.0.22.9)
    Darwin 20.4.0 x86_64             gfortran GNU Fortran (Homebrew GCC 10.2.0_3) 10.2.0
    (bigsur-1)                       Intel icc/icpc/ifort version 2021.2.0 20210228

    Mac OS X El Capitan 10.11.6      Apple clang version 7.3.0 from Xcode 7.3
    64-bit                           gfortran GNU Fortran (GCC) 5.2.0
    (osx1011test)                    Intel icc/icpc/ifort version 16.0.2


    Linux 2.6.32-573.22.1.el6        GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux          compilers:
    Centos6                              Version 4.4.7 20120313
    (platypus)                           Version 4.9.3, 5.3.0, 6.2.0
                                     MPICH 3.1.4 compiled with GCC 4.9.3
                                     PGI C, Fortran, C++ for 64-bit target on
                                     x86_64;
                                         Version 19.10-0

    Windows 10 x64                  Visual Studio 2019 w/ clang 12.0.0
                                        with MSVC-like command-line (C/C++ only - cmake)
                                    Visual Studio 2019 w/ Intel C/C++ only cmake)
                                    Visual Studio 2022 w/ clang 15.0.1
                                        with MSVC-like command-line (C/C++ only - cmake)
                                    Visual Studio 2022 w/ Intel C/C++/Fortran oneAPI 2023 (cmake)
                                    Visual Studio 2019 w/ MSMPI 10.1 (C only - cmake)


Known Problems
==============

    CMake files do not behave correctly with paths containing spaces.
    Do not use spaces in paths because the required escaping for handling spaces
    results in very complex and fragile build files.
    ADB - 2019/05/07

    At present, metadata cache images may not be generated by parallel
    applications.  Parallel applications can read files with metadata cache
    images, but since this is a collective operation, a deadlock is possible
    if one or more processes do not participate.

    CPP ptable test fails on both VS2017 and VS2019 with Intel compiler, JIRA
    issue: HDFFV-10628.  This test will pass with VS2015 with Intel compiler.

    The subsetting option in ph5diff currently will fail and should be avoided.
    The subsetting option works correctly in serial h5diff.

    Several tests currently fail on certain platforms:
        MPI_TEST-t_bigio fails with spectrum-mpi on ppc64le platforms.

        MPI_TEST-t_subfiling_vfd and MPI_TEST_EXAMPLES-ph5_subfiling fail with
        cray-mpich on theta and with XL compilers on ppc64le platforms.

        MPI_TEST_testphdf5_tldsc fails with cray-mpich 7.7 on theta.

    Known problems in previous releases can be found in the HISTORY*.txt files
    in the HDF5 source. Please report any new problems found to
    help@hdfgroup.org.


CMake vs. Autotools installations
=================================
While both build systems produce similar results, there are differences.
Each system produces the same set of folders on linux (only CMake works
on standard Windows); bin, include, lib and share. Autotools places the
COPYING and RELEASE.txt file in the root folder, CMake places them in
the share folder.

The bin folder contains the tools and the build scripts. Additionally, CMake
creates dynamic versions of the tools with the suffix "-shared". Autotools
installs one set of tools depending on the "--enable-shared" configuration
option.
  build scripts
  -------------
  Autotools: h5c++, h5cc, h5fc
  CMake: h5c++, h5cc, h5hlc++, h5hlcc

The include folder holds the header files and the fortran mod files. CMake
places the fortran mod files into separate shared and static subfolders,
while Autotools places one set of mod files into the include folder. Because
CMake produces a tools library, the header files for tools will appear in
the include folder.

The lib folder contains the library files, and CMake adds the pkgconfig
subfolder with the hdf5*.pc files used by the bin/build scripts created by
the CMake build. CMake separates the C interface code from the fortran code by
creating C-stub libraries for each Fortran library. In addition, only CMake
installs the tools library. The names of the szip libraries are different
between the build systems.

The share folder will have the most differences because CMake builds include
a number of CMake specific files for support of CMake's find_package and support
for the HDF5 Examples CMake project.

The issues with the gif tool are:
    HDFFV-10592 CVE-2018-17433
    HDFFV-10593 CVE-2018-17436
    HDFFV-11048 CVE-2020-10809
These CVE issues have not yet been addressed and are avoided by not building
the gif tool by default. Enable building the High-Level tools with these options:
    autotools:   --enable-hlgiftools
    cmake:       HDF5_BUILD_HL_GIF_TOOLS=ON

    
%%%%1.14.1%%%%

HDF5 version 1.14.1-2 released on 2023-05-11
================================================================================
HDF5 1.14.1-2 is a patch release for HDF5 1.14.1. The only change in the patch
release is that Autoconf 2.71 was used to generate the Autotools build files,
which allows building with Intel's oneAPI.


INTRODUCTION
============

This document describes the differences between this release and the previous
HDF5 release. It contains information on the platforms tested and known
problems in this release. For more details check the HISTORY*.txt files in the
HDF5 source.

Note that documentation in the links below will be updated at the time of each
final release.

Links to HDF5 documentation can be found on The HDF5 web page:

     https://portal.hdfgroup.org/display/HDF5/HDF5

The official HDF5 releases can be obtained from:

     https://www.hdfgroup.org/downloads/hdf5/

Changes from release to release and new features in the HDF5-1.14.x release series
can be found at:

     https://portal.hdfgroup.org/display/HDF5/Release+Specific+Information

If you have any questions or comments, please send them to the HDF Help Desk:

     help@hdfgroup.org


CONTENTS
========

- New Features
- Support for new platforms and languages
- Bug Fixes since HDF5-1.14.0
- Platforms Tested
- Known Problems
- CMake vs. Autotools installations


New Features
============

    Configuration:
    -------------
    - Added new CMake options for building and running HDF5 API tests
      (Experimental)

      HDF5 API tests are an experimental feature, primarily targeted
      toward HDF5 VOL connector authors, that is currently being developed.
      These tests exercise the HDF5 API and are being integrated back
      into the HDF5 library from the HDF5 VOL tests repository
      (https://github.com/HDFGroup/vol-tests). To support this feature,
      the following new options have been added to CMake:

        * HDF5_TEST_API: ON/OFF (Default: OFF)

          Controls whether the HDF5 API tests will be built. These tests
          will only be run during testing of HDF5 if the HDF5_TEST_SERIAL
          (for serial tests) and HDF5_TEST_PARALLEL (for parallel tests)
          options are enabled.

        * HDF5_TEST_API_INSTALL: ON/OFF (Default: OFF)

          Controls whether the HDF5 API test executables will be installed
          on the system alongside the HDF5 library. This option is currently
          not functional.

        * HDF5_TEST_API_ENABLE_ASYNC: ON/OFF (Default: OFF)

          Controls whether the HDF5 Async API tests will be built. These
          tests will only be run if the VOL connector used supports Async
          operations.

        * HDF5_TEST_API_ENABLE_DRIVER: ON/OFF (Default: OFF)

          Controls whether to build the HDF5 API test driver program. This
          test driver program is useful for VOL connectors that use a
          client/server model where the server needs to be up and running
          before the VOL connector can function. This option is currently
          not functional.

        * HDF5_TEST_API_SERVER: String (Default: "")

          Used to specify a path to the server executable that the test
          driver program should execute.

    - Added support for CMake presets file.

      CMake supports two main files, CMakePresets.json and CMakeUserPresets.json,
      that allow users to specify common configure options and share them with others.
      HDF added a CMakePresets.json file of a typical configuration and support
      file, config/cmake-presets/hidden-presets.json. 
      Also added a section to INSTALL_CMake.txt with very basic explanation of the
      process to use CMakePresets.

    - Deprecated and removed old SZIP library in favor of LIBAEC library

      LIBAEC library has been used in HDF5 binaries as the szip library of choice
      for a few years. We are removing the options for using the old SZIP library.

      Also removed the config/cmake/FindSZIP.cmake file.

    - Enabled instrumentation of the library by default in CMake for parallel
      debug builds

      HDF5 can be configured to instrument portions of the parallel library to
      aid in debugging. Autotools builds of HDF5 turn this capability on by
      default for parallel debug builds and off by default for other build types.
      CMake has been updated to match this behavior.

    - Added new option to build libaec and zlib inline with CMake.

      Using the CMake FetchContent module, the external filters can populate
      content at configure time via any method supported by the ExternalProject
      module. Whereas ExternalProject_Add() downloads at build time, the
      FetchContent module makes content available immediately, allowing the
      configure step to use the content in commands like add_subdirectory(),
      include() or file() operations.

      The HDF options (and defaults) for using this are:
          BUILD_SZIP_WITH_FETCHCONTENT:BOOL=OFF
          LIBAEC_USE_LOCALCONTENT:BOOL=OFF
          BUILD_ZLIB_WITH_FETCHCONTENT:BOOL=OFF
          ZLIB_USE_LOCALCONTENT:BOOL=OFF

      The CMake variables to control the path and file names:
          LIBAEC_TGZ_ORIGPATH:STRING
          LIBAEC_TGZ_ORIGNAME:STRING
          ZLIB_TGZ_ORIGPATH:STRING
          ZLIB_TGZ_ORIGNAME:STRING

      See the CMakeFilters.cmake and config/cmake/cacheinit.cmake files for usage.


    Library:
    --------
    - Added a Subfiling VFD configuration file prefix environment variable

      The Subfiling VFD now checks for values set in a new environment
      variable "H5FD_SUBFILING_CONFIG_FILE_PREFIX" to determine if the
      application has specified a pathname prefix to apply to the file
      path for its configuration file. For example, this can be useful
      for cases where the application wishes to write subfiles to a
      machine's node-local storage while placing the subfiling configuration
      file on a file system readable by all machine nodes.

    - Added H5Pset_selection_io(), H5Pget_selection_io(), and
      H5Pget_no_selection_io_cause() API functions to manage the selection I/O
      feature.  This can be used to enable collective I/O with type conversion,
      or it can be used with custom VFDs that support vector or selection I/O.

    - Added H5Pset_modify_write_buf() and H5Pget_modify_write_buf() API
      functions to allow the library to modify the contents of write buffers, in
      order to avoid malloc/memcpy.  Currently only used for type conversion
      with selection I/O.


    Parallel Library:
    -----------------
    -


    Fortran Library:
    ----------------
    - Fortran async APIs H5A, H5D, H5ES, H5G, H5F, H5L and H5O were added.

    - Added Fortran APIs:
      h5pset_selection_io_f, h5pget_selection_io_f
      h5pset_modify_write_buf_f, h5pget_modify_write_buf_f

    C++ Library:
    ------------
    -


    Java Library:
    -------------
    -


    Tools:
    ------
    -


    High-Level APIs:
    ----------------
    -


    C Packet Table API:
    -------------------
    -


    Internal header file:
    ---------------------
    -


    Documentation:
    --------------
    - Ported the existing VOL Connector Author Guide document to doxygen.

      Added new dox file, VOLConnGuide.dox.


Support for new platforms, languages and compilers
==================================================
    -


Bug Fixes since HDF5-1.14.0 release
===================================
    Library
    -------
    - Fixed a bug in H5Ocopy that could generate invalid HDF5 files

      H5Ocopy was missing a check to determine whether the new object's
      object header version is greater than version 1. Without this check,
      copying of objects with object headers that are smaller than a
      certain size would cause H5Ocopy to create an object header for the
      new object that has a gap in the header data. According to the
      HDF5 File Format Specification, this is not allowed for version
      1 of the object header format.

      Fixes GitHub issue #2653

    - Fixed H5Pget_vol_cap_flags and H5Pget_vol_id to accept H5P_DEFAULT

      H5Pget_vol_cap_flags and H5Pget_vol_id were updated to correctly
      accept H5P_DEFAULT for the 'plist_id' FAPL parameter. Previously,
      they would fail if provided with H5P_DEFAULT as the FAPL.

    - Fixed ROS3 VFD anonymous credential usage with h5dump and h5ls

      ROS3 VFD anonymous credential functionality became broken in h5dump
      and h5ls in the HDF5 1.14.0 release with the added support for VFD
      plugins, which changed the way that the tools handled setting of
      credential information that the VFD uses. The tools could be
      provided the command-line option of "--s3-cred=(,,)" as a workaround
      for anonymous credential usage, but the documentation for this
      option stated that anonymous credentials could be used by simply
      omitting the option. The latter functionality has been restored.

      Fixes GitHub issue #2406

    - Fixed memory leaks when processing malformed object header continuation messages

      Malformed object header continuation messages can result in a too-small
      buffer being passed to the decode function, which could lead to reading
      past the end of the buffer. Additionally, errors in processing these
      malformed messages can lead to allocated memory not being cleaned up.

      This fix adds bounds checking and cleanup code to the object header
      continuation message processing.

      Fixes GitHub issue #2604

    - Fixed memory leaks, aborts, and overflows in H5O EFL decode

      The external file list code could call assert(), read past buffer
      boundaries, and not properly clean up resources when parsing malformed
      external data files messages.

      This fix cleans up allocated memory, adds buffer bounds checks, and
      converts asserts to HDF5 error checking.

      Fixes GitHub issue #2605

    - Fixed potential heap buffer overflow in decoding of link info message

      Detections of buffer overflow were added for decoding version, index
      flags, link creation order value, and the next three addresses.  The
      checkings will remove the potential invalid read of any of these
      values that could be triggered by a malformed file.

      Fixes GitHub issue #2603

    - Memory leak

      Memory leak was detected when running h5dump with "pov".  The memory was allocated
      via H5FL__malloc() in hdf5/src/H5FL.c

      The fuzzed file "pov" was an HDF5 file containing an illegal continuation message.
      When deserializing the object header chunks for the file, memory is allocated for the
      array of continuation messages (cont_msg_info->msgs) in continuation message info struct.
      As error is encountered in loading the illegal message, the memory allocated for
      cont_msg_info->msgs needs to be freed.

      Fixes GitHub issue #2599

    - Fixed memory leaks that could occur when reading a dataset from a
      malformed file

      When attempting to read layout, pline, and efl information for a
      dataset, memory leaks could occur if attempting to read pline/efl
      information threw an error, which is due to the memory that was 
      allocated for pline and efl not being properly cleaned up on error.  

      Fixes GitHub issue #2602

    - Fixed potential heap buffer overrun in group info header decoding from malformed file

      H5O__ginfo_decode could sometimes read past allocated memory when parsing a
      group info message from the header of a malformed file.
  
      It now checks buffer size before each read to properly throw an error in these cases.
  
      Fixes GitHub issue #2601
      
    - Fixed potential buffer overrun issues in some object header decode routines

      Several checks were added to H5O__layout_decode and H5O__sdspace_decode to
      ensure that memory buffers don't get overrun when decoding buffers read from
      a (possibly corrupted) HDF5 file.

    - Fixed issues in the Subfiling VFD when using the SELECT_IOC_EVERY_NTH_RANK
      or SELECT_IOC_TOTAL I/O concentrator selection strategies

      Multiple bugs involving these I/O concentrator selection strategies
      were fixed, including:

        * A bug that caused the selection strategy to be altered when
          criteria for the strategy was specified in the
          H5FD_SUBFILING_IOC_SELECTION_CRITERIA environment variable as
          a single value, rather than in the old and undocumented
          'integer:integer' format
        * Two bugs which caused a request for 'N' I/O concentrators to
          result in 'N - 1' I/O concentrators being assigned, which also
          lead to issues if only 1 I/O concentrator was requested

      Also added a regression test for these two I/O concentrator selection
      strategies to prevent future issues. 

    - Fixed a heap buffer overflow that occurs when reading from
      a dataset with a compact layout within a malformed HDF5 file

      During opening of a dataset that has a compact layout, the
      library allocates a buffer that stores the dataset's raw data.
      The dataset's object header that gets written to the file
      contains information about how large of a buffer the library
      should allocate. If this object header is malformed such that
      it causes the library to allocate a buffer that is too small
      to hold the dataset's raw data, future I/O to the dataset can
      result in heap buffer overflows. To fix this issue, an extra
      check is now performed for compact datasets to ensure that
      the size of the allocated buffer matches the expected size
      of the dataset's raw data (as calculated from the dataset's
      dataspace and datatype information). If the two sizes do not
      match, opening of the dataset will fail.

      Fixes GitHub issue #2606

    - Fixed a memory corruption issue that can occur when reading
      from a dataset using a hyperslab selection in the file
      dataspace and a point selection in the memory dataspace

      When reading from a dataset using a hyperslab selection in
      the dataset's file dataspace and a point selection in the
      dataset's memory dataspace where the file dataspace's "rank"
      is greater than the memory dataspace's "rank", memory corruption
      could occur due to an incorrect number of selection points
      being copied when projecting the point selection onto the
      hyperslab selection's dataspace.

    - Fixed an issue with collective metadata writes of global heap data

      New test failures in parallel netCDF started occurring with debug
      builds of HDF5 due to an assertion failure and this was reported in
      GitHub issue #2433. The assertion failure began happening after the
      collective metadata write pathway in the library was updated to use
      vector I/O so that parallel-enabled HDF5 Virtual File Drivers (other
      than the existing MPI I/O VFD) can support collective metadata writes.

      The assertion failure was fixed by updating collective metadata writes
      to treat global heap metadata as raw data, as done elsewhere in the
      library. 

      Fixes GitHub issue #2433

    - Fix CVE-2021-37501 / GHSA-rfgw-5vq3-wrjf

      Check for overflow when calculating on-disk attribute data size.

      A bogus hdf5 file may contain dataspace messages with sizes
      which lead to the on-disk data sizes to exceed what is addressable.
      When calculating the size, make sure, the multiplication does not
      overflow.
      The test case was crafted in a way that the overflow caused the
      size to be 0.

      Fixes GitHub issue #2458

    - Fixed buffer overflow error in image decoding function.

      The error occurred in the function for decoding address from the specified
      buffer, which is called many times from the function responsible for image
      decoding. The length of the buffer is known in the image decoding function,
      but no checks are produced, so the buffer overflow can occur in many places,
      including callee functions for address decoding. 

      The error was fixed by inserting corresponding checks for buffer overflow.

      Fixes GitHub issue #2432


    Java Library
    ------------
    -


    Configuration
    -------------
    - Fixed syntax of generator expressions used by CMake

      Add quotes around the generator expression should allow CMake to
      correctly parse the expression. Generator expressions are typically
      parsed after command arguments. If a generator expression contains
      spaces, new lines, semicolons or other characters that may be
      interpreted as command argument separators, the whole expression
      should be surrounded by quotes when passed to a command. Failure to
      do so may result in the expression being split and it may no longer
      be recognized as a generator expression.

      Fixes GitHub issue #2906

    - Fixed improper include of Subfiling VFD build directory

      With the release of the Subfiling Virtual File Driver feature, compiler
      flags were added to the Autotools build's CPPFLAGS and AM_CPPFLAGS
      variables to always include the Subfiling VFD source code directory,
      regardless of whether the VFD is enabled and built or not. These flags
      are needed because the header files for the VFD contain macros that are
      assumed to always be available, such as H5FD_SUBFILING_NAME, so the
      header files are unconditionally included in the HDF5 library. However,
      these flags are only needed when building HDF5, so they belong in the
      H5_CPPFLAGS variable instead. Inclusion in the CPPFLAGS and AM_CPPFLAGS
      variables would export these flags to the h5cc and h5c++ wrapper scripts,
      as well as the libhdf5.settings file, which would break builds of software
      that use HDF5 and try to use or parse information out of these files after
      deleting temporary HDF5 build directories.

      Fixes GitHub issues #2422 and #2621

    - Correct the CMake generated pkg-config file

      The pkg-config file generated by CMake had the order and placement of the
      libraries wrong. Also added support for debug library names.

      Changed the order of Libs.private libraries so that dependencies come after
      dependents. Did not move the compression libraries into Requires.private
      because there was not a way to determine if the compression libraries had
      supported pkconfig files. Still recommend that the CMake config file method
      be used for building projects with CMake.

      Fixes GitHub issues #1546 and #2259

    - Force lowercase Fortran module file names

      The Cray Fortran compiler  uses  uppercase Fortran module file names, which
      caused CMake installs to fail. A compiler option was added to use lowercase
      instead.


    Tools
    -----
    - Names of objects with square brackets will have trouble without the
      special argument, --no-compact-subset, on the h5dump command line.

      h5diff did not have this option and now it has been added.

      Fixes GitHub issue #2682

    - In the tools traverse function - an error in either visit call
      will bypass the cleanup of the local data variables.

      Replaced the H5TOOLS_GOTO_ERROR with just H5TOOLS_ERROR.

      Fixes GitHub issue #2598


    Performance
    -------------
    -


    Fortran API
    -----------
    -

    High-Level Library
    ------------------
    -


    Fortran High-Level APIs
    -----------------------
    -


    Documentation
    -------------
    -


    F90 APIs
    --------
    -


    C++ APIs
    --------
    - 


    Testing
    -------
    -


Platforms Tested
===================

    Linux 5.16.14-200.fc35           GNU gcc (GCC) 11.2.1 20220127 (Red Hat 11.2.1-9)
    #1 SMP x86_64  GNU/Linux         GNU Fortran (GCC) 11.2.1 20220127 (Red Hat 11.2.1-9)
    Fedora35                         clang version 13.0.0 (Fedora 13.0.0-3.fc35)
                                     (cmake and autotools)

    Linux 5.11.0-34-generic          GNU gcc (GCC) 9.3.0-17ubuntu1
    #36-Ubuntu SMP x86_64 GNU/Linux  GNU Fortran (GCC) 9.3.0-17ubuntu1
    Ubuntu 20.04                     Ubuntu clang version 10.0.0-4
                                     (cmake and autotools)

    Linux 5.3.18-150300-cray_shasta_c cray-mpich/8.1.16
    #1 SMP x86_64 GNU/Linux              Cray clang 14.0.0
    (crusher)                            GCC 11.2.0
                                     (cmake)

    Linux 4.14.0-115.35.1.1chaos     openmpi 4.0.5
    #1 SMP aarch64 GNU/Linux             GCC 9.2.0 (ARM-build-5)
    (stria)                              GCC 7.2.0 (Spack GCC)
                                     (cmake)

    Linux 4.14.0-115.35.1.3chaos     spectrum-mpi/rolling-release
    #1 SMP ppc64le GNU/Linux             clang 12.0.1
    (vortex)                             GCC 8.3.1
                                         XL 16.1.1
                                     (cmake)

    Linux-4.14.0-115.21.2            spectrum-mpi/rolling-release
    #1 SMP ppc64le GNU/Linux             clang 12.0.1, 14.0.5
    (lassen)                             GCC 8.3.1
                                         XL 16.1.1.2, 2021,09.22, 2022.08.05
                                     (cmake)

    Linux-4.12.14-197.99-default     cray-mpich/7.7.14
    #1 SMP x86_64 GNU/Linux              cce 12.0.3
    (theta)                              GCC 11.2.0
                                         llvm 9.0
                                         Intel 19.1.2

    Linux 3.10.0-1160.36.2.el7.ppc64 gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)
    #1 SMP ppc64be GNU/Linux         g++ (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)
    Power8 (echidna)                 GNU Fortran (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)

    Linux 3.10.0-1160.24.1.el7       GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux          compilers:
    Centos7                              Version 4.8.5 20150623 (Red Hat 4.8.5-4)
    (jelly/kituo/moohan)                 Version 4.9.3, Version 5.3.0, Version 6.3.0,
                                         Version 7.2.0, Version 8.3.0, Version 9.1.0
                                     Intel(R) C (icc), C++ (icpc), Fortran (icc)
                                     compilers:
                                         Version 17.0.0.098 Build 20160721
                                     GNU C (gcc) and C++ (g++) 4.8.5 compilers
                                         with NAG Fortran Compiler Release 6.1(Tozai)
                                     Intel(R) C (icc) and C++ (icpc) 17.0.0.098 compilers
                                         with NAG Fortran Compiler Release 6.1(Tozai)
                                     MPICH 3.1.4 compiled with GCC 4.9.3
                                     MPICH 3.3 compiled with GCC 7.2.0
                                     OpenMPI 2.1.6 compiled with icc 18.0.1
                                     OpenMPI 3.1.3 and 4.0.0 compiled with GCC 7.2.0
                                     PGI C, Fortran, C++ for 64-bit target on
                                     x86_64;
                                         Version 19.10-0
                                     (autotools and cmake)

    Linux-3.10.0-1160.0.0.1chaos     openmpi-4.1.2
    #1 SMP x86_64 GNU/Linux              clang 6.0.0, 11.0.1
    (quartz)                             GCC 7.3.0, 8.1.0
                                         Intel 19.0.4, 2022.2, oneapi.2022.2

    Linux-3.10.0-1160.71.1.1chaos    openmpi/4.1
    #1 SMP x86_64 GNU/Linux              GCC 7.2.0
    (skybridge)                          Intel/19.1
                                     (cmake)

    Linux-3.10.0-1160.66.1.1chaos    openmpi/4.1
    #1 SMP x86_64 GNU/Linux              GCC 7.2.0
    (attaway)                            Intel/19.1
                                     (cmake)

    Linux-3.10.0-1160.59.1.1chaos    openmpi/4.1
    #1 SMP x86_64 GNU/Linux              Intel/19.1
    (chama)                          (cmake)

    macOS Apple M1 11.6              Apple clang version 12.0.5 (clang-1205.0.22.11)
    Darwin 20.6.0 arm64              gfortran GNU Fortran (Homebrew GCC 11.2.0) 11.1.0
    (macmini-m1)                     Intel icc/icpc/ifort version 2021.3.0 202106092021.3.0 20210609

    macOS Big Sur 11.3.1             Apple clang version 12.0.5 (clang-1205.0.22.9)
    Darwin 20.4.0 x86_64             gfortran GNU Fortran (Homebrew GCC 10.2.0_3) 10.2.0
    (bigsur-1)                       Intel icc/icpc/ifort version 2021.2.0 20210228

    macOS High Sierra 10.13.6        Apple LLVM version 10.0.0 (clang-1000.10.44.4)
    64-bit                           gfortran GNU Fortran (GCC) 6.3.0
    (bear)                           Intel icc/icpc/ifort version 19.0.4.233 20190416

    macOS Sierra 10.12.6             Apple LLVM version 9.0.0 (clang-900.39.2)
    64-bit                           gfortran GNU Fortran (GCC) 7.4.0
    (kite)                           Intel icc/icpc/ifort version 17.0.2

    Mac OS X El Capitan 10.11.6      Apple clang version 7.3.0 from Xcode 7.3
    64-bit                           gfortran GNU Fortran (GCC) 5.2.0
    (osx1011test)                    Intel icc/icpc/ifort version 16.0.2


    Linux 2.6.32-573.22.1.el6        GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux          compilers:
    Centos6                              Version 4.4.7 20120313
    (platypus)                           Version 4.9.3, 5.3.0, 6.2.0
                                     MPICH 3.1.4 compiled with GCC 4.9.3
                                     PGI C, Fortran, C++ for 64-bit target on
                                     x86_64;
                                         Version 19.10-0

    Windows 10 x64                  Visual Studio 2015 w/ Intel C/C++/Fortran 18 (cmake)
                                    Visual Studio 2017 w/ Intel C/C++/Fortran 19 (cmake)
                                    Visual Studio 2019 w/ clang 12.0.0
                                        with MSVC-like command-line (C/C++ only - cmake)
                                    Visual Studio 2019 w/ Intel C/C++/Fortran oneAPI 2022 (cmake)
                                    Visual Studio 2022 w/ clang 15.0.1
                                        with MSVC-like command-line (C/C++ only - cmake)
                                    Visual Studio 2022 w/ Intel C/C++/Fortran oneAPI 2022 (cmake)
                                    Visual Studio 2019 w/ MSMPI 10.1 (C only - cmake)


Known Problems
==============

    CMake files do not behave correctly with paths containing spaces.
    Do not use spaces in paths because the required escaping for handling spaces
    results in very complex and fragile build files.
    ADB - 2019/05/07

    At present, metadata cache images may not be generated by parallel
    applications.  Parallel applications can read files with metadata cache
    images, but since this is a collective operation, a deadlock is possible
    if one or more processes do not participate.

    CPP ptable test fails on both VS2017 and VS2019 with Intel compiler, JIRA
    issue: HDFFV-10628.  This test will pass with VS2015 with Intel compiler.

    The subsetting option in ph5diff currently will fail and should be avoided.
    The subsetting option works correctly in serial h5diff.

    Several tests currently fail on certain platforms:
        MPI_TEST-t_bigio fails with spectrum-mpi on ppc64le platforms.

        MPI_TEST-t_subfiling_vfd and MPI_TEST_EXAMPLES-ph5_subfiling fail with
        cray-mpich on theta and with XL compilers on ppc64le platforms.

        MPI_TEST_testphdf5_tldsc fails with cray-mpich 7.7 on cori and theta.

    Known problems in previous releases can be found in the HISTORY*.txt files
    in the HDF5 source. Please report any new problems found to
    help@hdfgroup.org.


CMake vs. Autotools installations
=================================
While both build systems produce similar results, there are differences.
Each system produces the same set of folders on linux (only CMake works
on standard Windows); bin, include, lib and share. Autotools places the
COPYING and RELEASE.txt file in the root folder, CMake places them in
the share folder.

The bin folder contains the tools and the build scripts. Additionally, CMake
creates dynamic versions of the tools with the suffix "-shared". Autotools
installs one set of tools depending on the "--enable-shared" configuration
option.
  build scripts
  -------------
  Autotools: h5c++, h5cc, h5fc
  CMake: h5c++, h5cc, h5hlc++, h5hlcc

The include folder holds the header files and the fortran mod files. CMake
places the fortran mod files into separate shared and static subfolders,
while Autotools places one set of mod files into the include folder. Because
CMake produces a tools library, the header files for tools will appear in
the include folder.

The lib folder contains the library files, and CMake adds the pkgconfig
subfolder with the hdf5*.pc files used by the bin/build scripts created by
the CMake build. CMake separates the C interface code from the fortran code by
creating C-stub libraries for each Fortran library. In addition, only CMake
installs the tools library. The names of the szip libraries are different
between the build systems.

The share folder will have the most differences because CMake builds include
a number of CMake specific files for support of CMake's find_package and support
for the HDF5 Examples CMake project.

The issues with the gif tool are:
    HDFFV-10592 CVE-2018-17433
    HDFFV-10593 CVE-2018-17436
    HDFFV-11048 CVE-2020-10809
These CVE issues have not yet been addressed and are avoided by not building
the gif tool by default. Enable building the High-Level tools with these options:
    autotools:   --enable-hlgiftools
    cmake:       HDF5_BUILD_HL_GIF_TOOLS=ON

    
%%%%1.14.0%%%%

HDF5 version 1.14.0 released on 2022-12-28
================================================================================


INTRODUCTION
============

This document describes the differences between this release and the previous
HDF5 release. It contains information on the platforms tested and known
problems in this release. For more details check the HISTORY*.txt files in the
HDF5 source.

Note that documentation in the links below will be updated at the time of each
final release.

Links to HDF5 documentation can be found on The HDF5 web page:

     https://portal.hdfgroup.org/display/HDF5/HDF5

The official HDF5 releases can be obtained from:

     https://www.hdfgroup.org/downloads/hdf5/

Changes from Release to Release and New Features in the HDF5-1.13.x release series
can be found at:

     https://portal.hdfgroup.org/display/HDF5/Release+Specific+Information

If you have any questions or comments, please send them to the HDF Help Desk:

     help@hdfgroup.org


CONTENTS
========

- New Features
- Support for new platforms and languages
- Bug Fixes since HDF5-1.12.0
- Platforms Tested
- Known Problems
- CMake vs. Autotools installations


New Features
============

    Configuration:
    -------------
    - Removal of MPE support

      The ability to build with MPE instrumentation has been removed along with
      the following configure options:

      Autotools:
          --with-mpe=

      CMake has never supported building with MPE support.

      (DER - 2022/11/08)

     - Removal of dmalloc support

      The ability to build with dmalloc support has been removed along with
      the following configure options:

      Autotools:
          --with-dmalloc=

      CMake:
          HDF5_ENABLE_USING_DMALLOC

      (DER - 2022/11/08)
      
    - Removal of memory allocation sanity checks configure options

      With the removal of the memory allocation sanity checks feature, the
      following configure options are no longer necessary and have been
      removed:

      Autotools:
          --enable-memory-alloc-sanity-check

      CMake:
          HDF5_MEMORY_ALLOC_SANITY_CHECK
          HDF5_ENABLE_MEMORY_STATS

      (DER - 2022/11/03)

    - Add new CMake configuration variable HDF5_USE_GNU_DIRS

      HDF5_USE_GNU_DIRS (default OFF) selects the use of GNU Coding Standard install
      directory variables by including the CMake module, GNUInstallDirs(see CMake
      documentation for details). The HDF_DIR_PATHS macro in the HDFMacros.cmake file
      sets various PATH variables for use during the build, test and install processes.
      By default, the historical settings for these variables will be used.

      (ADB - 2022/10/21, GH-2175, GH-1716)

    - Update CMake minimum version to 3.18

      Updated CMake minimum version from 3.12 to 3.18 and removed version checks
      which were added for Windows features not yet available in version 3.12. Also
      removed configure macros and code checks for old style code compile checks.

      (ADB - 2022/08/29, HDFFV-11329)

    - Correct the usage of CMAKE_Fortran_MODULE_DIRECTORY and where to
      install Fortran mod files.

      The Fortran modules files, ending in .mod are files describing a
      Fortran 90 (and above) module API and ABI. These are not like C
      header files describing an API, they are compiler dependent and
      arch dependent, and not easily readable by a human being. They are
      nevertheless searched for in the includes directories by gfortran
      (in directories specified with -I).

      Autotools configure uses the -fmoddir option to specify the folder.
      CMake will use "mod" folder by default unless overridden by the CMake
      variable; HDF5_INSTALL_MODULE_DIR.

      (ADB - 2022/07/21)

    - HDF5 memory allocation sanity checking is now off by default for
      Autotools debug builds

      HDF5 can be configured to perform sanity checking on internal memory
      allocations by adding heap canaries to these allocations. However,
      enabling this option can cause issues with external filter plugins
      when working with (reallocating/freeing/allocating and passing back)
      buffers.

      Previously, this option was off by default for all CMake build types,
      but only off by default for non-debug Autotools builds. Since debug
      is the default build mode for HDF5 when built from source with
      Autotools, this can result in surprising segfaults that don't occur
      when an application is built against a release version of HDF5.
      Therefore, this option is now off by default for all build types
      across both CMake and Autotools.

      (JTH - 2022/03/01)

    - Reworked corrected path searched by CMake find_package command

      The install path for cmake find_package files had been changed to use
        "share/cmake"
      for all platforms. However setting the HDF5_ROOT variable failed to locate
      the configuration files. The build variable HDF5_INSTALL_CMAKE_DIR is now
      set to the <INSTALL_DIR>/cmake folder. The location of the configuration 
      files can still be specified by the "HDF5_DIR" variable.

      (ADB - 2022/02/02)

    - CPack will now generate RPM/DEB packages.

      Enabled the RPM and DEB CPack generators on linux. In addition to
      generating STGZ and TGZ packages, CPack will try to package the 
      library for RPM and DEB packages. This is the initial attempt and
      may change as issues are resolved.

      (ADB - 2022/01/27)

    - Added new option to the h5cc scripts produced by CMake.

      Add -showconfig option to h5cc scripts to cat the 
      libhdf5.settings file to the standard output.

      (ADB - 2022/01/25)

    - CMake will now run the PowerShell script tests in test/ by default
      on Windows.

      The test directory includes several shell script tests that previously
      were not run by CMake on Windows. These are now run by default.
      If TEST_SHELL_SCRIPTS is ON and PWSH is found, the PowerShell scripts
      will execute. Similar to the bash scripts on unix platforms.

      (ADB - 2021/11/23)

    - Added new configure option to support building parallel tools.
      See Tools below (autotools - CMake):
            --enable-parallel-tools      HDF5_BUILD_PARALLEL_TOOLS

      (RAW - 2021/10/25)

    - Added new configure options to enable dimension scales APIs (H5DS*) to
      use new object references with the native VOL connector (aka native HDF5
      library). New references are always used for non-native terminal VOL
      connectors (e.g., DAOS).

      Autotools   --enable-dimension-scales-with-new-ref
      CMake       HDF5_DIMENSION_SCALES_NEW_REF=ON

      (EIP - 2021/10/25, HDFFV-11180)

    - Refactored the utils folder.

      Added subfolder test and moved the 'swmr_check_compat_vfd.c file'
      from test into utils/test. Deleted the duplicate swmr_check_compat_vfd.c
      file in hl/tools/h5watch folder. Also fixed vfd check options.

      (ADB - 2021/10/18)

    - Changed autotools and CMake configurations to derive both
      compilation warnings-as-errors and warnings-only-warn configurations
      from the same files, 'config/*/*error*'.  Removed redundant files
      'config/*/*noerror*'.

      (DCY - 2021/09/29)

    - Adds C++ Autotools configuration file for Intel

      * Checks for icpc as the compiler
      * Sets std=c++11
      * Copies most non-warning flags from intel-flags

      (DER - 2021/06/02)

    - Adds C++ Autotools configuration file for PGI

      * Checks for pgc++ as the compiler name (was: pgCC)
      * Sets -std=c++11
      * Other options basically match new C options (below)

      (DER - 2021/06/02)

    - Updates PGI C options

      * -Minform set to warn (was: inform) to suppress spurious messages
      * Sets -gopt -O2 as debug options
      * Sets -O4 as 'high optimization' option
      * Sets -O0 as 'no optimization' option
      * Removes specific settings for PGI 9 and 10

      (DER - 2021/06/02)

    - A C++11-compliant compiler is now required to build the C++ wrappers

      CMAKE_CXX_STANDARD is now set to 11 when building with CMake and
      -std=c++11 is added when building with clang/gcc via the Autotools.

      (DER - 2021/05/27)

    - CMake will now run the shell script tests in test/ by default

      The test directory includes several shell script tests that previously
      were not run by CMake. These are now run by default. TEST_SHELL_SCRIPTS
      has been set to ON and SH_PROGRAM has been set to bash (some test
      scripts use bash-isms). Platforms without bash (e.g., Windows) will
      ignore the script tests.

      (DER - 2021/05/23)

    - Removed unused HDF5_ENABLE_HSIZET option from CMake

      This has been unused for some time and has no effect.

      (DER - 2021/05/23)

    - CMake no longer builds the C++ library by default

      HDF5_BUILD_CPP_LIB now defaults to OFF, which is in line with the
      Autotools build defaults.

      (DER - 2021/04/20)

    - Removal of pre-VS2015 work-arounds

      HDF5 now requires Visual Studio 2015 or greater, so old work-around
      code and definitions have been removed, including:

      * <inttypes.h>
      * snprintf and vsnprintf
      * llround, llroundf, lround, lroundf, round, roundf
      * strtoll and strtoull
      * va_copy
      * struct timespec

      (DER - 2021/03/22)

    - Add CMake variable HDF5_LIB_INFIX

      This infix is added to all library names after 'hdf5'.
      e.g. the infix '_openmpi' results in the library name 'libhdf5_openmpi.so'
      This name is used in packages on debian based systems.
      (see https://packages.debian.org/jessie/amd64/libhdf5-openmpi-8/filelist)

      (barcode - 2021/03/22)

    - On macOS, Universal Binaries can now be built, allowing native execution on
      both Intel and Apple Silicon (ARM) based Macs.

      To do so, set CMAKE_OSX_ARCHITECTURES="x86_64;arm64"

      (SAM - 2021/02/07, github-311)

    - Added a configure-time option to control certain compiler warnings
      diagnostics

      A new configure-time option was added that allows some compiler warnings
      diagnostics to have the default operation. This is mainly intended for
      library developers and currently only works for gcc 10 and above. The
      diagnostics flags apply to C, C++ and Fortran compilers and will appear
      in "H5 C Flags", H5 C++ Flags" and H5 Fortran Flags, respectively. They
      will NOT be exported to h5cc, etc.

      The default is OFF, which will disable the warnings URL and color attributes
      for the warnings output. ON will not add the flags and allow default behavior.

      Autotools:    --enable-diags

      CMake:        HDF5_ENABLE_BUILD_DIAGS

      (ADB - 2021/02/05, HDFFV-11213)

    - CMake option to build the HDF filter plugins project as an external project

      The HDF filter plugins project is a collection of registered compression
      filters that can be dynamically loaded when needed to access data stored
      in a hdf5 file. This CMake-only option allows the plugins to be built and
      distributed with the hdf5 library and tools. Like the options for szip and
      zlib, either a tgz file or a git repository can be specified for the source.

      The option was refactored to use the CMake FetchContent process. This allows
      more control over the filter targets, but required external project command
      options to be moved to a CMake include file, HDF5PluginCache.cmake. Also
      enabled the filter examples to be used as tests for operation of the
      filter plugins.

      (ADB - 2020/12/10, OESS-98)

    - FreeBSD Autotools configuration now defaults to 'cc' and 'c++' compilers

      On FreeBSD, the autotools defaulted to 'gcc' as the C compiler and did
      not process C++ options. Since FreeBSD 10, the default compiler has
      been clang (via 'cc').

      The default compilers have been set to 'cc' for C and 'c++' for C++,
      which will pick up clang and clang++ respectively on FreeBSD 10+.
      Additionally, clang options are now set correctly for both C and C++
      and g++ options will now be set if that compiler is being used (an
      omission from the former functionality).

      (DER - 2020/11/28, HDFFV-11193)

    - Fixed POSIX problems when building w/ gcc on Solaris

      When building on Solaris using gcc, the POSIX symbols were not
      being set correctly, which could lead to issues like clock_gettime()
      not being found.

      The standard is now set to gnu99 when building with gcc on Solaris,
      which allows POSIX things to be #defined and linked correctly. This
      differs slightly from the gcc norm, where we set the standard to c99
      and manually set POSIX #define symbols.

      (DER - 2020/11/25, HDFFV-11191)

    - Added a configure-time option to consider certain compiler warnings
      as errors

      A new configure-time option was added that converts some compiler warnings
      to errors. This is mainly intended for library developers and currently
      only works for gcc and clang. The warnings that are considered errors
      will appear in the generated libhdf5.settings file. These warnings apply
      to C and C++ code and will appear in "H5 C Flags" and H5 C++ Flags",
      respectively. They will NOT be exported to h5cc, etc.

      The default is OFF. Building with this option may fail when compiling
      on operating systems and with compiler versions not commonly used by
      the library developers. Compilation may also fail when headers not
      under the control of the library developers (e.g., mpi.h, hdfs.h) raise
      warnings.

      Autotools:    --enable-warnings-as-errors

      CMake:        HDF5_ENABLE_WARNINGS_AS_ERRORS

      (DER - 2020/11/23, HDFFV-11189)

    - Autotools and CMake target added to produce doxygen generated documentation

      The default is OFF or disabled.
      Autoconf option is '--enable-doxygen'
        autotools make target is 'doxygen' and will build all doxygen targets
      CMake configure option is 'HDF5_BUILD_DOC'.
        CMake target is 'doxygen' for all available doxygen targets
        CMake target is 'hdf5lib_doc' for the src subdirectory

      (ADB - 2020/11/03)

    - CMake option to use MSVC naming conventions with MinGW

      HDF5_MSVC_NAMING_CONVENTION option enable to use MSVC naming conventions
      when using a MinGW toolchain

      (xan - 2020/10/30)

    - CMake option to statically link gcc libs with MinGW

      HDF5_MINGW_STATIC_GCC_LIBS allows to statically link libg/libstdc++
      with the MinGW toolchain

      (xan - 2020/10/30)

    - CMake option to build the HDF filter plugins project as an external project

      The HDF filter plugins project is a collection of registered compression
      filters that can be dynamically loaded when needed to access data stored
      in a hdf5 file. This CMake-only option allows the plugins to be built and
      distributed with the hdf5 library and tools. Like the options for szip and
      zlib, either a tgz file or a git repository can be specified for the source.

      The necessary options are (see the INSTALL_CMake.txt file):
        HDF5_ENABLE_PLUGIN_SUPPORT
        PLUGIN_TGZ_NAME or PLUGIN_GIT_URL
      There are more options necessary for various filters and the plugin project
      documents should be referenced.

      (ADB - 2020/09/27, OESS-98)

    - Added CMake option to format source files

      HDF5_ENABLE_FORMATTERS option will enable creation of targets using the
      pattern - HDF5_*_SRC_FORMAT - where * corresponds to the source folder
      or tool folder. All sources can be formatted by executing the format target;
      make format

      (ADB - 2020/08/24)

    - Add file locking configure and CMake options

      HDF5 1.10.0 introduced a file locking scheme, primarily to help
      enforce SWMR setup. Formerly, the only user-level control of the scheme
      was via the HDF5_USE_FILE_LOCKING environment variable.

      This change introduces configure-time options that control whether
      or not file locking will be used and whether or not the library
      ignores errors when locking has been disabled on the file system
      (useful on some HPC Lustre installations).

      In both the Autotools and CMake, the settings have the effect of changing
      the default property list settings (see the H5Pset/get_file_locking()
      entry, below).

      The yes/no/best-effort file locking configure setting has also been
      added to the libhdf5.settings file.

      Autotools:

        An --enable-file-locking=(yes|no|best-effort) option has been added.

        yes:          Use file locking.
        no:           Do not use file locking.
        best-effort:  Use file locking and ignore "disabled" errors.

      CMake:

        Two self-explanatory options have been added:

        HDF5_USE_FILE_LOCKING
        HDF5_IGNORE_DISABLED_FILE_LOCKS

        Setting both of these to ON is the equivalent to the Autotools'
        best-effort setting.

      NOTE:
      The precedence order of the various file locking control mechanisms is:

        1) HDF5_USE_FILE_LOCKING environment variable (highest)

        2) H5Pset_file_locking()

        3) configure/CMake options (which set the property list defaults)

        4) library defaults (currently best-effort)

      (DER - 2020/07/30, HDFFV-11092)

    - CMake option to link the generated Fortran MOD files into the include
      directory.

      The Fortran generation of MOD files by a Fortran compile can produce
      different binary files between SHARED and STATIC compiles with different
      compilers and/or different platforms. Note that it has been found that
      different versions of Fortran compilers will produce incompatible MOD
      files. Currently, CMake will locate these MOD files in subfolders of
      the include directory and add that path to the Fortran library target
      in the CMake config file, which can be used by the CMake find library
      process. For other build systems using the binary from a CMake install,
      a new CMake configuration can be used to copy the pre-chosen version
      of the Fortran MOD files into the install include directory.

      The default will depend on the configuration of
      BUILD_STATIC_LIBS and BUILD_SHARED_LIBS:
          YES                   YES         Default to SHARED
          YES                   NO          Default to STATIC
          NO                    YES         Default to SHARED
          NO                    NO          Default to SHARED
      The defaults can be overridden by setting the config option
          HDF5_INSTALL_MOD_FORTRAN to one of NO, SHARED, or STATIC

      (ADB - 2020/07/09, HDFFV-11116)

    - CMake option to use AEC (open source SZip) library instead of SZip

      The open source AEC library is a replacement library for SZip. In
      order to use it for hdf5 the libaec CMake source was changed to add
      "-fPIC" and exclude test files. Autotools does not build the
      compression libraries within hdf5 builds. New option USE_LIBAEC is
      required to compensate for the different files produced by AEC build.

      (ADB - 2020/04/22, OESS-65)

    - CMake ConfigureChecks.cmake file now uses CHECK_STRUCT_HAS_MEMBER

      Some handcrafted tests in HDFTests.c has been removed and the CMake
      CHECK_STRUCT_HAS_MEMBER module has been used.

      (ADB - 2020/03/24, TRILAB-24)

    - Both build systems use same set of warnings flags

      GNU C, C++ and gfortran warnings flags were moved to files in a config
      sub-folder named gnu-warnings. Flags that only are available for a specific
      version of the compiler are in files named with that version.
      Clang C warnings flags were moved to files in a config sub-folder
      named clang-warnings.
      Intel C, Fortran warnings flags were moved to files in a config sub-folder
      named intel-warnings.

      There are flags in named "error-xxx" files with warnings that may
      be promoted to errors. Some source files may still need fixes.

      There are also pairs of files named "developer-xxx" and "no-developer-xxx"
      that are chosen by the CMake option:HDF5_ENABLE_DEV_WARNINGS or the
      configure option:--enable-developer-warnings.

      In addition, CMake no longer applies these warnings for examples.

      (ADB - 2020/03/24, TRILAB-192)


    Library:
    --------
    - Overhauled the Virtual Object Layer (VOL)

      The virtual object layer (VOL) was added in HDF5 1.12.0 but the initial
      implementation required API-breaking changes to better support optional
      operations and pass-through VOL connectors. The original VOL API is
      now considered deprecated and VOL users and connector authors should
      target the 1.14 VOL API.

      The specific changes are too extensive to document in a release note, so
      VOL users and connector authors should consult the updated VOL connector
      author's guide and the 1.12-1.14 VOL migration guide.

      (DER - 2022/12/28)

    - H5VLquery_optional() signature change

      The last parameter of this API call has changed from a pointer to hbool_t
      to a pointer to uint64_t. Due to the changes in how optional operations
      are handled in the 1.14 VOL API, we cannot make the old API call work
      with the new scheme, so there is no API compatibility macro for it.

      (DER - 2022/12/28)

    - H5I_free_t callback signature change

      In order to support asynchronous operations and future IDs, the signature
      of the H5I_free_t callback has been modified to take a second 'request'
      parameter. Due to the nature of the internal library changes, no API
      compatibility macro is available for this change.

      (DER - 2022/12/28)

    - Fix for CVE-2019-8396

      Malformed HDF5 files may have truncated content which does not match
      the expected size. When H5O__pline_decode() attempts to decode these it
      may read past the end of the allocated space leading to heap overflows
      as bounds checking is incomplete.

      The fix ensures each element is within bounds before reading.

      (2022/11/09 - HDFFV-10712, CVE-2019-8396, GitHub #2209)

    - Removal of memory allocation sanity checks feature

      This feature added heap canaries and statistics tracking for internal
      library memory operations. Unfortunately, the heap canaries caused
      problems when library memory operations were mixed with standard C
      library memory operations (such as in the filter pipeline, where
      buffers may have to be reallocated). Since any platform with a C
      compiler also usually has much more sophisticated memory sanity
      checking tools than the HDF5 library provided (e.g., valgrind), we
      have decided to to remove the feature entirely.

      In addition to the configure changes described above, this also removes
      the following from the public API:
          H5get_alloc_stats()
          H5_alloc_stats_t

      (DER - 2022/11/03)

    - Added multi dataset I/O feature

      Added H5Dread_multi, H5Dread_multi_async, H5Dwrite_multi, and
      H5Dwrite_multi_async API routines to allow I/O on multiple datasets with a
      single API call. Added H5Dread_multi_f and H5Dwrite_multi_f Fortran
      wrappers. Updated VOL callbacks for dataset I/O to support multi dataset
      I/O.

      (NAF - 2022/10/19)

    - Onion VFD

      The onion VFD allows creating "versioned" HDF5 files. File open/close
      operations after initial file creation will add changes to an external
      "onion" file (.onion extension by default) instead of the original file.
      Each written revision can be opened independently.

      To open a file with the onion VFD, use the H5Pset_fapl_onion() API call
      (does not need to be used for the initial creation of the file). The
      options for the H5FD_onion_fapl_info_t struct are described in H5FDonion.h.

      The H5FDonion_get_revision_count() API call can be used to query a file
      to find out how many revisions have been created.

      (DER - 2022/08/02)

    - Subfiling VFD

      The HDF5 Subfiling VFD is a new MPI-based file driver that allows an
      HDF5 application to distribute an HDF5 file across a collection of
      "sub-files" in equal-sized data segment "stripes". I/O to the logical
      HDF5 file is then directed to the appropriate "sub-file" according to
      the Subfiling configuration and a system of I/O concentrators, which
      are MPI ranks operating worker threads.

      By allowing a configurable stripe size, number of I/O concentrators and
      method for selecting MPI ranks as I/O concentrators, the Subfiling VFD
      aims to enable an HDF5 application to find a middle ground between the
      single shared file and file-per-process approaches to parallel file I/O
      for the particular machine the application is running on. In general, the
      goal is to avoid some of the complexity of the file-per-process approach
      while also minimizing the locking issues of the single shared file approach
      on a parallel file system.

      Also included with the Subfiling VFD is a new h5fuse.sh script which
      reads a Subfiling configuration file and then combines the various
      sub-files back into a single HDF5 file. By default, the h5fuse.sh script
      looks in the current directory for the Subfiling configuration file,
      but can also be pointed to the configuration file with a command-line
      option.

      The Subfiling VFD can be used by calling H5Pset_fapl_subfiling() on a
      File Access Property List and using that FAPL for file operations. Note
      that the Subfiling VFD currently has the following limitations:

      * Does not currently support HDF5 collective I/O, other than collective
        metadata writes and reads as set by H5Pset_coll_metadata_write() and
        H5Pset_all_coll_metadata_ops()

      * The Subfiling VFD should not currently be used with an HDF5 library
        that has been built with thread-safety enabled. This can cause deadlocks
        when failures occur due to interactions between the VFD's internal
        threads and HDF5's global lock. 

      (JTH - 2022/07/22)

    - Add a new public function, H5ESget_requests()

      This function allows the user to retrieve request pointers from an event
      set. It is intended for use primarily by VOL plugin developers.

      (NAF - 2022/01/11)

    - Adds new file driver-level memory copy operation for
      "ctl" callback and updates compact dataset I/O routines
      to utilize it

      When accessing an HDF5 file with a file driver that uses
      memory allocated in special ways (e.g., without standard
      library's `malloc`), a crash could be observed when HDF5
      tries to perform `memcpy` operations on such a memory
      region.

      These changes add a new H5FD_FEAT_MEMMANAGE VFD feature
      flag, which, if specified as supported by a VFD, will
      inform HDF5 that the VFD either uses special memory
      management routines or wishes to perform memory management
      in a specific way. Therefore, this flag instructs HDF5 to
      ask the file driver to perform memory management for
      certain operations.

      These changes also introduce a new "ctl" callback
      operation identified by the H5FD_CTL__MEM_COPY op code.
      This operation simply asks a VFD to perform a memory copy.
      The arguments to this operation are passed to the "ctl"
      callback's "input" parameter as a pointer to a struct
      defined as:

        struct H5FD_ctl_memcpy_args_t {
          void *      dstbuf;  /**< Destination buffer */
          hsize_t     dst_off; /**< Offset within destination buffer */
          const void *srcbuf;  /**< Source buffer */
          hsize_t     src_off; /**< Offset within source buffer */
          size_t      len;     /**< Length of data to copy from source buffer */
        } H5FD_ctl_memcpy_args_t;

      Further, HDF5's compact dataset I/O routines were
      identified as a problematic area that could cause a crash
      for VFDs that make use of special memory management. Those
      I/O routines were therefore updated to make use of this new
      "ctl" callback operation in order to ask the underlying
      file driver to correctly handle memory copies.

      (JTH - 2021/09/28)

    - Adds new "ctl" callback to VFD H5FD_class_t structure
      with the following prototype:

        herr_t (*ctl)(H5FD_t *file, uint64_t op_code,
                      uint64_t flags, const void *input,
                      void **output);

      This newly-added "ctl" callback allows Virtual File
      Drivers to intercept and handle arbitrary operations
      identified by an operation code. Its parameters are
      as follows:

        `file` [in] - A pointer to the file to be operated on
        `op_code` [in] - The operation code identifying the
                         operation to be performed
        `flags` [in] - Flags governing the behavior of the
                       operation performed (see H5FDpublic.h
                       for a list of valid flags)
        `input` [in] - A pointer to arguments passed to the
                       VFD performing the operation
        `output` [out] - A pointer for the receiving VFD to
                         use for output from the operation

      (JRM - 2021/08/16)

    - Change how the release part of version, in major.minor.release is checked
      for compatibility

      The HDF5 library uses a function, H5check_version, to check that
      the version defined in the header files, which is used to compile an
      application is compatible with the version codified in the library, which
      the application loads at runtime. This previously required an exact match
      or the library would print a warning, dump the build settings and then
      abort or continue. An environment variable controlled the logic.

      Now the function first checks that the library release version, in
      major.minor.release, is not older than the version in the headers.
      Secondly, if the release version is different, it checks if either
      the library version or the header version is in the exception list, in
      which case the release part of version, in major.minor.release, must
      be exact. An environment variable still controls the logic.

      (ADB - 2021/07/27)

    - gcc warning suppression macros were moved out of H5public.h

      The HDF5 library uses a set of macros to suppress warnings on gcc.
      These warnings were originally located in H5public.h so that the
      multi VFD (which only uses public headers) could also make use of them
      but internal macros should not be publicly exposed like this.

      These macros have now been moved to H5private.h. Pending future multi
      VFD refactoring, the macros have been duplicated in H5FDmulti.c to
      suppress the format string warnings there.

      (DER - 2021/06/03)

    - H5Gcreate1() now rejects size_hint parameters larger than UINT32_MAX

      The size_hint value is ultimately stored in a uint32_t struct field,
      so specifying a value larger than this on a 64-bit machine can cause
      undefined behavior including crashing the system.

      The documentation for this API call was also incorrect, stating that
      passing a negative value would cause the library to use a default
      value. Instead, passing a "negative" value actually passes a very large
      value, which is probably not what the user intends and can cause
      crashes on 64-bit systems.

      The Doxygen documentation has been updated and passing values larger
      than UINT32_MAX for size_hint will now produce a normal HDF5 error.

      (DER - 2021/04/29, HDFFV-11241)


    - H5Pset_fapl_log() no longer crashes when passed an invalid fapl ID

      When passed an invalid fapl ID, H5Pset_fapl_log() would usually
      segfault when attempting to free an uninitialized pointer in the error
      handling code. This behavior is more common in release builds or
      when the memory sanitization checks were not selected as a build
      option.

      The pointer is now correctly initialized and the API call now
      produces a normal HDF5 error when fed an invalid fapl ID.

      (DER - 2021/04/28, HDFFV-11240)

    - Fixes a segfault when H5Pset_mdc_log_options() is called multiple times

      The call incorrectly attempts to free an internal copy of the previous
      log location string, which causes a segfault. This only happens
      when the call is invoked multiple times on the same property list.
      On the first call to a given fapl, the log location is set to NULL so
      the segfault does not occur.

      The string is now handled properly and the segfault no longer occurs.

      (DER - 2021/04/27, HDFFV-11239)

    - HSYS_GOTO_ERROR now emits the results of GetLastError() on Windows

      HSYS_GOTO_ERROR is an internal macro that is used to produce error
      messages when system calls fail. These strings include errno and the
      the associated strerror() value, which are not particularly useful
      when a Win32 API call fails.

      On Windows, this macro has been updated to include the result of
      GetLastError(). When a system call fails on Windows, usually only
      one of errno and GetLastError() will be useful, however we emit both
      for the user to parse. The Windows error message is not emitted as
      it would be awkward to free the FormatMessage() buffer given the
      existing HDF5 error framework. Users will have to look up the error
      codes in MSDN.

      The format string on Windows has been changed from:

        "%s, errno = %d, error message = '%s'"

      to:

        "%s, errno = %d, error message = '%s', Win32 GetLastError() = %"PRIu32""

      for those inclined to parse it for error values.

      (DER - 2021/03/21)

    - File locking now works on Windows

      Since version 1.10.0, the HDF5 library has used a file locking scheme
      to help enforce one reader at a time accessing an HDF5 file, which can
      be helpful when setting up readers and writers to use the single-
      writer/multiple-readers (SWMR) access pattern.

      In the past, this was only functional on POSIX systems where flock() or
      fcntl() were present. Windows used a no-op stub that always succeeded.

      HDF5 now uses LockFileEx() and UnlockFileEx() to lock the file using the
      same scheme as POSIX systems. We lock the entire file when we set up the
      locks (by passing DWORDMAX as both size parameters to LockFileEx()).

      (DER - 2021/03/19, HDFFV-10191)

    - H5Epush_ret() now requires a trailing semicolon

      H5Epush_ret() is a function-like macro that has been changed to
      contain a `do {} while(0)` loop. Consequently, a trailing semicolon
      is now required to end the `while` statement. Previously, a trailing
      semi would work, but was not mandatory. This change was made to allow
      clang-format to correctly format the source code.

      (SAM - 2021/03/03)

    - Improved performance of H5Sget_select_elem_pointlist

      Modified library to cache the point after the last block of points
      retrieved by H5Sget_select_elem_pointlist, so a subsequent call to the
      same function to retrieve the next block of points from the list can
      proceed immediately without needing to iterate over the point list.

      (NAF - 2021/01/19)

    - Replaced H5E_ATOM with H5E_ID in H5Epubgen.h

      The term "atom" is archaic and not in line with current HDF5 library
      terminology, which uses "ID" instead. "Atom" has mostly been purged
      from the library internals and this change removes H5E_ATOM from
      the H5Epubgen.h (exposed via H5Epublic.h) and replaces it with
      H5E_ID.

      (DER - 2020/11/24, HDFFV-11190)

    - Add a new public function H5Ssel_iter_reset

      This function resets a dataspace selection iterator back to an
      initial state so that it may be used for iteration once more.
      This can be useful when needing to iterate over a selection
      multiple times without having to repeatedly create/destroy
      a selection iterator for that dataspace selection.

      (JTH - 2020/09/18)

    - Remove HDFS VFD stubs

      The original implementation of the HDFS VFD included non-functional
      versions of the following public API calls when the HDFS VFD is
      not built as a part of the HDF5 library:

      * H5FD_hdfs_init()
      * H5Pget_fapl_hdfs()
      * H5Pset_fapl_hdfs()

      They will remain present in HDF5 1.10 and HDF5 1.12 releases
      for binary compatibility purposes but have been removed as of 1.14.0.

      Note that this has nothing to do with the real HDFS VFD API calls
      that are fully functional when the HDFS VFD is configured and built.

      We simply changed:

        #ifdef LIBHDFS
          <real API call>
        #else
          <useless stub>
        #endif

      to:

        #ifdef LIBHDFS
          <real API call>
        #endif

      Which is how the other optional VFDs are handled.

      (DER - 2020/08/27)

    - Add Mirror VFD

      Use TCP/IP sockets to perform write-only (W/O) file I/O on a remote
      machine. Must be used in conjunction with the Splitter VFD.

      (JOS - 2020/03/13, TBD)

    - Add Splitter VFD

      Maintain separate R/W and W/O channels for "concurrent" file writes
      to two files using a single HDF5 file handle.

      (JOS - 2020/03/13, TBD)


    Parallel Library:
    -----------------
    - Several improvements to parallel compression feature, including:

      * Improved support for collective I/O (for both writes and reads)

      * Significant reduction of memory usage for the feature as a whole

      * Reduction of copying of application data buffers passed to H5Dwrite

      * Addition of support for incremental file space allocation for filtered
        datasets created in parallel. Incremental file space allocation is the
        default for these types of datasets (early file space allocation is
        also still supported), while early file space allocation is still the
        default (and only supported at allocation time) for unfiltered datasets
        created in parallel. Incremental file space allocation should help with
        parallel HDF5 applications that wish to use fill values on filtered
        datasets, but would typically avoid doing so since dataset creation in
        parallel would often take an excessive amount of time. Since these
        datasets previously used early file space allocation, HDF5 would
        allocate space for and write fill values to every chunk in the dataset
        at creation time, leading to noticeable overhead. Instead, with
        incremental file space allocation, allocation of file space for chunks
        and writing of fill values to those chunks will be delayed until each
        individual chunk is initially written to.

      * Addition of support for HDF5's "don't filter partial edge chunks" flag
        (https://portal.hdfgroup.org/display/HDF5/H5P_SET_CHUNK_OPTS)

      * Addition of proper support for HDF5 fill values with the feature

      * Addition of 'H5_HAVE_PARALLEL_FILTERED_WRITES' macro to H5pubconf.h
        so HDF5 applications can determine at compile-time whether the feature
        is available

      * Addition of simple examples (ph5_filtered_writes.c and
        ph5_filtered_writes_no_sel.c) under examples directory to demonstrate
        usage of the feature

      * Improved coverage of regression testing for the feature

      (JTH - 2022/2/23)


    Fortran Library:
    ----------------
    - Added pointer based H5Dfill_f API

      Added Fortran H5Dfill_f, which is fully equivalent to the C API. It accepts pointers,
      fill value datatype and datatype of dataspace elements.

      (MSB - 2022/10/10, HDFFV-10734.)

    - H5Fget_name_f fixed to handle correctly trailing whitespaces and
      newly allocated buffers.

      (MSB - 2021/08/30, github-826,972)

    - Add wrappers for H5Pset/get_file_locking() API calls

        h5pget_file_locking_f()
        h5pset_file_locking_f()

      See the configure option discussion for HDFFV-11092 (above) for more
      information on the file locking feature and how it's controlled.

      (DER - 2020/07/30, HDFFV-11092)


    C++ Library:
    ------------
    - Added two new constructors to H5::H5File class

      Two new constructors were added to allow opening a file with non-default
      access property list.

    - Add wrappers for H5Pset/get_file_locking() API calls

        FileAccPropList::setFileLocking()
        FileAccPropList::getFileLocking()

      See the configure option discussion for HDFFV-11092 (above) for more
      information on the file locking feature and how it's controlled.

      (DER - 2020/07/30, HDFFV-11092)


    Java Library:
    -------------
    - Added version of H5Rget_name to return the name as a Java string.

      Other functions that get_name process the get_size then get the name
      within the JNI implementation. Now H5Rget_name has a H5Rget_name_string.

      (ADB - 2022/07/12)

    - Added reference support to H5A and H5D read write vlen JNI functions.

      Added the implementation to handle VL references as an Array of Lists
      of byte arrays.

      The JNI wrappers translate the Array of Lists to/from the hvl_t vlen
      structures. The wrappers use the specified datatype arguments for the
      List type translation, it is expected that the Java type is correct.

      (ADB - 2022/07/11, HDFFV-11318)

    - H5A and H5D read write vlen JNI functions were incorrect.

      Corrected the vlen function implementations for the basic primitive types.
      The VLStrings functions now correctly use the implementation that had been
      the VL functions. (VLStrings functions did not have an implementation.)
      The new VL functions implementation now expect an Array of Lists between
      Java and the JNI wrapper. 

      The JNI wrappers translate the Array of Lists to/from the hvl_t vlen
      structures. The wrappers use the specified datatype arguments for the
      List type translation, it is expected that the Java type is correct.

      (ADB - 2022/07/07, HDFFV-11310)

    - H5A and H5D read write JNI functions had flawed vlen datatype check.

      Adapted tools function for JNI utils file. This reduced multiple calls
      to a single check and variable. The variable can then be used to call 
      the H5Treclaim function. Adjusted existing test and added new test.

      (ADB - 2022/06/22)

    - Replaced HDF5AtomException with HDF5IdException

      Since H5E_ATOM changed to H5E_ID in the C library, the Java exception
      that wraps the error category was also renamed. Its functionality
      remains unchanged aside from the name.

      (See also the HDFFV-11190 note in the C library section)

      (DER - 2020/11/24, HDFFV-11190)

    - Added new H5S functions.

      H5Sselect_copy, H5Sselect_shape_same, H5Sselect_adjust,
      H5Sselect_intersect_block, H5Sselect_project_intersection,
      H5Scombine_hyperslab, H5Smodify_select, H5Scombine_select
      wrapper functions added.

      (ADB - 2020/10/27, HDFFV-10868)

    - Add wrappers for H5Pset/get_file_locking() API calls

        H5Pset_file_locking()
        H5Pget_use_file_locking()
        H5Pget_ignore_disabled_file_locking()

      Unlike the C++ and Fortran wrappers, there are separate getters for the
      two file locking settings, each of which returns a boolean value.

      See the configure option discussion for HDFFV-11092 (above) for more
      information on the file locking feature and how it's controlled.

      (DER - 2020/07/30, HDFFV-11092)


    Tools:
    ------
    - Building h5perf/h5perf_serial in "standalone mode" has been removed

      Building h5perf separately from the library was added circa 2008
      in HDF5 1.6.8. It's unclear what purpose this serves and the current
      implementation is currently broken. The existing files require
      H5private.h and the symbols we use to determine how the copied
      platform-independence scheme should be used come from H5pubconf.h,
      which may not match the compiler being used to build standalone h5perf.

      Due to the maintenance overhead and lack of a clear use case, support
      for building h5perf and h5perf_serial separately from the HDF5 library
      has been removed.

      (DER - 2022/07/15)

    - The perf tool has been removed

      The small `perf` tool didn't really do anything special and the name
      conflicts with gnu's perf tool.

      (DER - 2022/07/15, GitHub #1787)

    - 1.10 References in containers were not displayed properly by h5dump.

      Ported 1.10 tools display function to provide ability to inspect and
      display 1.10 reference data. 

      (ADB - 2022/06/22)

    - h5repack added an optional verbose value for reporting R/W timing.

      In addition to adding timing capture around the read/write calls in
      h5repack, added help text to indicate how to show timing for read/write;
           -v N, --verbose=N       Verbose mode, print object information.
              N - is an integer greater than 1, 2 displays read/write timing
      (ADB - 2021/11/08)

    - Added a new (unix ONLY) parallel meta tool 'h5dwalk', which utilizes the
      mpifileutils (https://hpc.github.io/mpifileutils) open source utility
      library to enable parallel execution of other HDF5 tools.
      This approach can greatly enhance the serial hdf5 tool performance over large
      collections of files by utilizing MPI parallelism to distribute an application
      load over many independent MPI ranks and files.

      An introduction to the mpifileutils library and initial 'User Guide' for
      the new 'h5dwalk" tool can be found at:
      https://github.com/HDFGroup/hdf5doc/tree/master/RFCs/HDF5/tools/parallel_tools

      (RAW - 2021/10/25)

    - Refactored the perform tools and removed depends on test library.

      Moved the perf and h5perf tools from tools/test/perform to
      tools/src/h5perf so that they can be installed. This required
      that the test library dependency be removed by copying the
      needed functions from h5test.c.
      The standalone scripts and other perform tools remain in the
      tools/test/perform folder.

      (ADB - 2021/08/10)

    - Removed partial long exceptions

      Some of the tools accepted shortened versions of the long options
      (ex: --datas instead of --dataset). These were implemented inconsistently,
      are difficult to maintain, and occasionally block useful long option
      names. These partial long options have been removed from all the tools.

      (DER - 2021/08/03)

    - h5repack added help text for user-defined filters.

      Added help text line that states the valid values of the filter flag
      for user-defined filters;
          filter_flag: 1 is OPTIONAL or 0 is MANDATORY

      (ADB - 2021/01/14, HDFFV-11099)

    - Added h5delete tool

      Deleting HDF5 storage when using the VOL can be tricky when the VOL
      does not create files. The h5delete tool is a simple wrapper around
      the H5Fdelete() API call that uses the VOL specified in the
      HDF5_VOL_CONNECTOR environment variable to delete a "file". If
      the call to H5Fdelete() fails, the tool will attempt to use
      the POSIX remove(3) call to remove the file.

      Note that the HDF5 library does currently have support for
      H5Fdelete() in the native VOL connector.

      (DER - 2020/12/16)

    - h5repack added options to control how external links are handled.

      Currently h5repack preserves external links and cannot copy and merge
      data from the external files. Two options, merge and prune, were added to
      control how to merge data from an external link into the resulting file.
          --merge             Follow external soft link recursively and merge data.
          --prune             Do not follow external soft links and remove link.
          --merge --prune     Follow external link, merge data and remove dangling link.

      (ADB - 2020/08/05, HDFFV-9984)

    - h5repack was fixed to repack the reference attributes properly.
      The code line that checks if the update of reference inside a compound
      datatype is misplaced outside the code block loop that carries out the
      check. In consequence, the next attribute that is not the reference
      type was repacked again as the reference type and caused the failure of
      repacking. The fix is to move the corresponding code line to the correct
      code block.

       (KY -2020/02/07, HDFFV-11014)


    High-Level APIs:
    ----------------
    - added set/get for unsigned long long attributes

      The attribute writing high-level API has been expanded to include
      public set/get functions for ULL attributes, analogously to the
      existing set/get for other types.

      (AF - 2021/09/08)


    C Packet Table API:
    -------------------
    -


    Internal header file:
    ---------------------
    - All the #defines named H5FD_CTL__* were renamed to H5FD_CTL_*, i.e. the double underscore was reduced to a single underscore.


    Documentation:
    --------------
    - Doxygen User Guide documentation is available when configured and generated.
      The resulting documentation files will be in the share/html subdirectory
      of the HDF5 install directory.

      (ADB - 2022/08/09)


Support for new platforms, languages and compilers
==================================================
    -

    
Bug Fixes since HDF5-1.12.0 release
===================================
    Library
    -------
    - Seg fault on file close

      h5debug fails at file close with core dump on a file that has an
      illegal file size in its cache image.  In H5F_dest(), the library
      performs all the closing operations for the file and keeps track of
      the error encountered when reading the file cache image.  
      At the end of the routine, it frees the file's file structure and 
      returns error.  Due to the error return, the file object is not removed 
      from the ID node table.  This eventually causes assertion failure in 
      H5VL__native_file_close() when the library finally exits and tries to 
      access that file object in the table for closing.

      The closing routine, H5F_dest(), will not free the file structure if
      there is error, keeping a valid file structure in the ID node table.
      It will be freed later in H5VL__native_file_close() when the
      library exits and terminates the file package.

      (VC - 2022/12/14, HDFFV-11052, CVE-2020-10812)

    - Fix CVE-2018-13867 / GHSA-j8jr-chrh-qfrf
 
      Validate location (offset) of the accumulated metadata when comparing.

      Initially, the accumulated metadata location is initialized to HADDR_UNDEF
      - the highest available address. Bogus input files may provide a location
      or size matching this value. Comparing this address against such bogus
      values may provide false positives. Thus make sure, the value has been
      initialized or fail the comparison early and let other parts of the
      code deal with the bogus address/size.
      Note: To avoid unnecessary checks, it is assumed that if the 'dirty'
      member in the same structure is true the location is valid.

      (EFE - 2022/10/10 GH-2230)
      
    - Fix CVE-2018-16438 / GHSA-9xmm-cpf8-rgmx

      Make sure info block for external links has at least 3 bytes.
    
      According to the specification, the information block for external links
      contains 1 byte of version/flag information and two 0 terminated strings
      for the object linked to and the full path.
      Although not very useful, the minimum string length for each (with
      terminating 0) would be one byte.
      Checking this helps to avoid SEGVs triggered by bogus files.

      (EFE - 2022/10/09 GH-2233)

    - CVE-2021-46244 / GHSA-vrxh-5gxg-rmhm

      Compound datatypes may not have members of size 0
 
      A member size of 0 may lead to an FPE later on as reported in
      CVE-2021-46244. To avoid this, check for this as soon as the
      member is decoded.

      (EFE - 2022/10/05 GEH-2242)


    - Fix CVE-2021-45830 / GHSA-5h2h-fjjr-x9m2

      Make H5O__fsinfo_decode() more resilient to out-of-bound reads.

      When decoding a file space info message in H5O__fsinfo_decode()  make
      sure each element to be decoded is still within the message. Malformed
      hdf5 files may have trunkated content which does not match the
      expected size. Checking this will prevent attempting to decode
      unrelated data and heap overflows. So far, only free space manager
      address data was checked before decoding.

      (EFE - 2022/10/05 GH-2228)

    - Fix CVE-2021-46242 / GHSA-x9pw-hh7v-wjpf

      When evicting driver info block, NULL the corresponding entry.

      Since H5C_expunge_entry() called (from H5AC_expunge_entry()) sets the  flag
      H5C__FLUSH_INVALIDATE_FLAG, the driver info block will be freed. NULLing
      the pointer in f->shared->drvinfo will prevent use-after-free  when it is
      used in other functions (like  H5F__dest()) - as other places will check
      whether the pointer is initialized before using its value.

      (EFE - 2022/09/29 GH-2254)

    - Fix CVE-2021-45833 / GHSA-x57p-jwp6-4v79

      Report error if dimensions of chunked storage in data layout < 2
    
      For Data Layout Messages version 1 & 2 the specification state
      that the value stored in the data field is 1 greater than the
      number of dimensions in the dataspace. For version 3 this is
      not explicitly stated but the implementation suggests it to be
      the case.
      Thus the set value needs to be at least 2. For dimensionality
      < 2 an out-of-bounds access occurs.
 
      (EFE - 2022/09/28 GH-2240)
      
    - Fix CVE-2018-14031 / GHSA-2xc7-724c-r36j

      Parent of enum datatype message must have the same size as the
      enum datatype message itself.
      Functions accessing the enumeration values use the size of the
      enumeration datatype to determine the size of each element and
      how much data to copy.
      Thus the size of the enumeration and its parent need to match.
      Check in H5O_dtype_decode_helper()  to avoid unpleasant surprises
      later.

      (EFE - 2022/09/28 GH-2236)

    - Fix CVE-2018-17439 / GHSA-vcxv-vp43-rch7

      H5IMget_image_info(): Make sure to not exceed local array size

      Malformed hdf5 files may provide more dimensions than the array dim[] in
      H5IMget_image_info() is able to hold. Check number of elements first by calling
      H5Sget_simple_extent_dims() with NULL for both 'dims' and 'maxdims' arguments.
      This will cause the function to return only the number of dimensions.
      The fix addresses a stack overflow on write.

      (EFE - 2022/09/27 HDFFV-10589, GH-2226)

    - Fixed an issue with variable length attributes

      Previously, if a variable length attribute was held open while its file
      was opened through another handle, the same attribute was opened through
      the second file handle, and the second file and attribute handles were
      closed, attempting to write to the attribute through the first handle
      would cause an error.

      (NAF - 2022/10/24)

    - Memory leak 
    
      A memory leak was observed with variable-length fill value in 
      H5O_fill_convert() function in H5Ofill.c. The leak is
      manifested by running valgrind on test/set_extent.c.

      Previously, fill->buf is used for datatype conversion 
      if it is large enough and the variable-length information 
      is therefore lost.  A buffer is now allocated regardless 
      so that the element in fill->buf can later be reclaimed.

      (VC - 2022/10/10, HDFFV-10840)
 
    - Fixed an issue with hyperslab selections

      Previously, when combining hyperslab selections, it was possible for the
      library to produce an incorrect combined selection.

      (NAF - 2022/09/25)

    - Fixed an issue with attribute type conversion with compound datatypes

      Previously, when performing type conversion for attribute I/O with a
      compound datatype, the library would not fill the background buffer with
      the contents of the destination, potentially causing data to be lost when
      only writing to a subset of the compound fields.

      (NAF - 2022/08/22, GitHub #2016)

    - The offset parameter in H5Dchunk_iter() is now scaled properly

      In earlier HDF5 1.13.x versions, the chunk offset was not scaled by the
      chunk dimensions. This offset parameter in the callback now matches
      that of H5Dget_chunk_info().

      (@mkitti - 2022/08/06, GitHub #1419)

    - Converted an assertion on (possibly corrupt) file contents to a normal
      error check

      Previously, the library contained an assertion check that a read superblock
      doesn't contain a superblock extension message when the superblock
      version < 2. When a corrupt HDF5 file is read, this assertion can be triggered
      in debug builds of HDF5. In production builds, this situation could cause
      either a library error or a crash, depending on the platform.

      (JTH - 2022/07/08, HDFFV-11316/HDFFV-11317)

    - Fixed a metadata cache bug when resizing a pinned/protected cache entry

      When resizing a pinned/protected cache entry, the metadata
      cache code previously would wait until after resizing the
      entry to attempt to log the newly-dirtied entry. This 
      caused H5C_resize_entry to mark the entry as dirty and made
      H5AC_resize_entry think that it didn't need to add the
      newly-dirtied entry to the dirty entries skiplist.

      Thus, a subsequent H5AC__log_moved_entry would think it
      needed to allocate a new entry for insertion into the dirty
      entry skip list, since the entry didGn't exist on that list.
      This caused an assertion failure, as the code to allocate a
      new entry assumes that the entry is not dirty.

      (JRM - 2022/02/28)

    - Issue #1436 identified a problem with the H5_VERS_RELEASE check in the
      H5check_version function.

      Investigating the original fix, #812, we discovered some inconsistencies
      with a new block added to check H5_VERS_RELEASE for incompatibilities.
      This new block was not using the new warning text dealing with the
      H5_VERS_RELEASE check and would cause the warning to be duplicated.
      
      By removing the H5_VERS_RELEASE argument in the first check for 
      H5_VERS_MAJOR and H5_VERS_MINOR, the second check would only check
      the H5_VERS_RELEASE for incompatible release versions. This adheres
      to the statement that except for the develop branch, all release versions
      in a major.minor maintenance branch should be compatible. The prerequisite
      is that an application will not use any APIs not present in all release versions.

      (ADB - 2022/02/24, #1438)

    - Unified handling of collective metadata reads to correctly fix old bugs

      Due to MPI-related issues occurring in HDF5 from mismanagement of the
      status of collective metadata reads, they were forced to be disabled
      during chunked dataset raw data I/O in the HDF5 1.10.5 release. This
      wouldn't generally have affected application performance because HDF5
      already disables collective metadata reads during chunk lookup, since
      it is generally unlikely that the same chunks will be read by all MPI
      ranks in the I/O operation. However, this was only a partial solution
      that wasn't granular enough.

      This change now unifies the handling of the file-global flag and the
      API context-level flag for collective metadata reads in order to
      simplify querying of the true status of collective metadata reads. Thus,
      collective metadata reads are once again enabled for chunked dataset
      raw data I/O, but manually controlled at places where some processing
      occurs on MPI rank 0 only and would cause issues when collective
      metadata reads are enabled.

      (JTH - 2021/11/16, HDFFV-10501/HDFFV-10562)

    - Fixed several potential MPI deadlocks in library failure conditions

      In the parallel library, there were several places where MPI rank 0
      could end up skipping past collective MPI operations when some failure
      occurs in rank 0-specific processing. This would lead to deadlocks
      where rank 0 completes an operation while other ranks wait in the
      collective operation. These places have been rewritten to have rank 0
      push an error and try to cleanup after the failure, then continue to
      participate in the collective operation to the best of its ability.

      (JTH - 2021/11/09)

    - Fixed an H5Pget_filter_by_id1/2() assert w/ out of range filter IDs

      Both H5Pget_filter_by_id1 and 2 did not range check the filter ID, which
      could trip as assert in debug versions of the library. The library now
      returns a normal HDF5 error when the filter ID is out of range.

      (DER - 2021/11/23, HDFFV-11286)

    - Fixed an issue with collective metadata reads being permanently disabled
      after a dataset chunk lookup operation. This would usually cause a
      mismatched MPI_Bcast and MPI_ERR_TRUNCATE issue in the library for
      simple cases of H5Dcreate() -> H5Dwrite() -> H5Dcreate().

      (JTH - 2021/11/08, HDFFV-11090)

    - Fixed cross platform incompatibility of references within variable length
      types

      Reference types within variable length types previously could not be
      read on a platform with different endianness from where they were
      written. Fixed so cross platform portability is restored.

      (NAF - 2021/09/30)

    - Detection of simple data transform function "x"

      In the case of the simple data transform function "x" the (parallel)
      library recognizes this is the same as not applying this data transform
      function. This improves the I/O performance. In the case of the parallel
      library, it also avoids breaking to independent I/O, which makes it
      possible to apply a filter when writing or reading data to or from
      the HDF5 file.

      (JWSB - 2021/09/13)

    - Fixed an invalid read and memory leak when parsing corrupt file space
      info messages

      When the corrupt file from CVE-2020-10810 was parsed by the library,
      the code that imports the version 0 file space info object header
      message to the version 1 struct could read past the buffer read from
      the disk, causing an invalid memory read. Not catching this error would
      cause downstream errors that eventually resulted in a previously
      allocated buffer to be unfreed when the library shut down. In builds
      where the free lists are in use, this could result in an infinite loop
      and SIGABRT when the library shuts down.

      We now track the buffer size and raise an error on attempts to read
      past the end of it.

      (DER - 2021/08/12, HDFFV-11053)


    - Fixed CVE-2018-14460

      The tool h5repack produced a segfault when the rank in dataspace
      message was corrupted, causing invalid read while decoding the
      dimension sizes.

      The problem was fixed by ensuring that decoding the dimension sizes
      and max values will not go beyond the end of the buffer.

      (BMR - 2021/05/12, HDFFV-11223)

    - Fixed CVE-2018-11206

      The tool h5dump produced a segfault when the size of a fill value
      message was corrupted and caused a buffer overflow.

      The problem was fixed by verifying the fill value's size
      against the buffer size before attempting to access the buffer.

      (BMR - 2021/03/15, HDFFV-10480)

    - Fixed CVE-2018-14033 (same issue as CVE-2020-10811)

      The tool h5dump produced a segfault when the storage size message
      was corrupted and caused a buffer overflow.

      The problem was fixed by verifying the storage size against the
      buffer size before attempting to access the buffer.

      (BMR - 2021/03/15, HDFFV-11159/HDFFV-11049)

    - Remove underscores on header file guards

      Header file guards used a variety of underscores at the beginning of the define.

      Removed all leading (some trailing) underscores from header file guards.

      (ADB - 2021/03/03, #361)

    - Fixed a segmentation fault

      A segmentation fault occurred with a Mathworks corrupted file.

      A detection of accessing a null pointer was added to prevent the problem.

      (BMR - 2021/02/19, HDFFV-11150)

    - Fixed issue with MPI communicator and info object not being
      copied into new FAPL retrieved from H5F_get_access_plist

      Added logic to copy the MPI communicator and info object into
      the output FAPL. MPI communicator is retrieved from the VFD, while
      the MPI info object is retrieved from the file's original FAPL.

      (JTH - 2021/02/15, HDFFV-11109)

    - Fixed problems with vlens and refs inside compound using
      H5VLget_file_type()

      Modified library to properly ref count H5VL_object_t structs and only
      consider file vlen and reference types to be equal if their files are
      the same.

      (NAF - 2021/01/22)

    - Fixed CVE-2018-17432

      The tool h5repack produced a segfault on a corrupted file which had
      invalid rank for scalar or NULL datatype.

      The problem was fixed by modifying the dataspace encode and decode
      functions to detect and report invalid rank. h5repack now fails
      with an error message for the corrupted file.

      (BMR - 2020/10/26, HDFFV-10590)

    - Creation of dataset with optional filter

      When the combination of type, space, etc doesn't work for filter
      and the filter is optional, it was supposed to be skipped but it was
      not skipped and the creation failed.

      Allowed the creation of the dataset in such a situation.

      (BMR - 2020/08/13, HDFFV-10933)

    - Explicitly declared dlopen to use RTLD_LOCAL

      dlopen documentation states that if neither RTLD_GLOBAL nor
      RTLD_LOCAL are specified, then the default behavior is unspecified.
      The default on linux is usually RTLD_LOCAL while macos will default
      to RTLD_GLOBAL.

      (ADB - 2020/08/12, HDFFV-11127)

    - H5Sset_extent_none() sets the dataspace class to H5S_NO_CLASS which
      causes asserts/errors when passed to other dataspace API calls.

      H5S_NO_CLASS is an internal class value that should not have been
      exposed via a public API call.

      In debug builds of the library, this can cause assert() function to
      trip. In non-debug builds, it will produce normal library errors.

      The new library behavior is for H5Sset_extent_none() to convert
      the dataspace into one of type H5S_NULL, which is better handled
      by the library and easier for developers to reason about.

      (DER - 2020/07/27, HDFFV-11027)

    - Fixed issues CVE-2018-13870 and CVE-2018-13869

      When a buffer overflow occurred because a name length was corrupted
      and became very large, h5dump crashed on memory access violation.

      A check for reading pass the end of the buffer was added to multiple
      locations to prevent the crashes and h5dump now simply fails with an
      error message when this error condition occurs.

      (BMR - 2020/07/22, HDFFV-11120 and HDFFV-11121)

    - Fixed the segmentation fault when reading attributes with multiple threads

      It was reported that the reading of attributes with variable length string
      datatype will crash with segmentation fault particularly when the number of
      threads is high (>16 threads).  The problem was due to the file pointer that
      was set in the variable length string datatype for the attribute.  That file
      pointer was already closed when the attribute was accessed.

      The problem was fixed by setting the file pointer to the current opened file pointer
      when the attribute was accessed.  Similar patch up was done before when reading
      dataset with variable length string datatype.

      (VC - 2020/07/13, HDFFV-11080)

    - Fixed CVE-2020-10810

      The tool h5clear produced a segfault during an error recovery in
      the superblock decoding.  An internal pointer was reset to prevent
      further accessing when it is not assigned with a value.

      (BMR - 2020/06/29, HDFFV-11053)

    - Fixed CVE-2018-17435

      The tool h52gif produced a segfault when the size of an attribute
      message was corrupted and caused a buffer overflow.

      The problem was fixed by verifying the attribute message's size
      against the buffer size before accessing the buffer.  h52gif was
      also fixed to display the failure instead of silently exiting
      after the segfault was eliminated.

      (BMR - 2020/06/19, HDFFV-10591)


    Java Library
    ------------
    - Improve variable-length datatype handling in JNI.

      The existing JNI read-write functions could handle variable-length datatypes
      that were simple variable-length datatype with an atomic sub-datatype. More
      complex combinations could not be handled. Reworked the JNI read-write functions
      to recursively inspect datatypes for variable-length sub-datatypes.

      (ADB - 2022/10/12, HDFFV-8701,10375)

    - JNI utility function does not handle new references.

      The JNI utility function for converting reference data to string did
      not use the new APIs. In addition to fixing that function, added new
      java tests for using the new APIs.

      (ADB - 2021/02/16, HDFFV-11212)

    - The H5FArray.java class, in which virtually the entire execution time
      is spent using the HDFNativeData method that converts from an array
      of bytes to an array of the destination Java type.

        1. Convert the entire byte array into a 1-d array of the desired type,
           rather than performing 1 conversion per row;
        2. Use the Java Arrays method copyOfRange to grab the section of the
           array from (1) that is desired to be inserted into the destination array.

      (PGT,ADB - 2020/12/13, HDFFV-10865)


    Configuration
    -------------
    - Remove Javadoc generation

      The use of doxygen now supersedes the requirement to build javadocs. We do not
      have the resources to continue to support two documentation methods and have
      chosen doxygen as our standard.

      (ADB - 2022/12/19)

    - Change the default for building the high-level GIF tools

      The gif2h5 and h52gif high-level tools are deprecated and will be removed
      in a future release. The default build setting for them has been changed
      from enabled to disabled. A user can enable the build of these tools if
      needed.

          autotools:   --enable-hlgiftools
          cmake:       HDF5_BUILD_HL_GIF_TOOLS=ON

      Disabling the GIF tools eliminates the following CVEs:

          HDFFV-10592 CVE-2018-17433
          HDFFV-10593 CVE-2018-17436
          HDFFV-11048 CVE-2020-10809

      (ADB - 2022/12/16)

    - Change the settings of the *pc files to use the correct format

      The pkg-config files generated by CMake uses incorrect syntax for the 'Requires'
      settings. Changing the set to use 'lib-name = version' instead 'lib-name-version'
      fixes the issue

      (ADB - 2022/12/06 HDFFV-11355)

    - Move MPI libraries link from PRIVATE to PUBLIC

      The install dependencies were not including the need for MPI libraries when
      an application or library was built with the C library. Also updated the
      CMake target link command to use the newer style MPI::MPI_C link variable.

      (ADB - 2022/10/27)

    - Corrected path searched by CMake find_package command

      The install path for cmake find_package files had been changed to use
        "share/cmake"
      for all platforms. However the trailing "hdf5" directory was not removed.
      This "hdf5" additional directory has been removed.

      (ADB - 2021/09/27)

    - Corrected pkg-config compile script

      It was discovered that the position of the "$@" argument for the command
      in the compile script may fail on some platforms and configurations. The
      position of the "$@"command argument was moved before the pkg-config sub command.

      (ADB - 2021/08/30)

    - Fixed CMake C++ compiler flags

      A recent refactoring of the C++ configure files accidentally removed the
      file that executed the enable_language command for C++ needed by the
      HDFCXXCompilerFlags.cmake file. Also updated the intel warnings files,
      including adding support for windows platforms.

      (ADB - 2021/08/10)

    - Better support for libaec (open-source Szip library) in CMake

      Implemented better support for libaec 1.0.5 (or later) library. This version
      of libaec contains improvements for better integration with HDF5. Furthermore,
      the variable USE_LIBAEC_STATIC has been introduced to allow to make use of
      static version of libaec library. Use libaec_DIR or libaec_ROOT to set
      the location in which libaec can be found.

      Be aware, the Szip library of libaec 1.0.4 depends on another library within
      libaec library. This dependency is not specified in the current CMake
      configuration which means that one can not use the static Szip library of
      libaec 1.0.4 when building HDF5. This has been resolved in libaec 1.0.5.

      (JWSB - 2021/06/22)

    - Refactor CMake configure for Fortran

      The Fortran configure tests for KINDs reused a single output file that was
      read to form the Integer and Real Kinds defines. However, if config was run
      more then once, the CMake completed variable prevented the tests from executing
      again and the last value saved in the file was used to create the define.
      Creating separate files for each KIND solved the issue.

      In addition the test for H5_PAC_C_MAX_REAL_PRECISION was not pulling in
      defines for proper operation and did not define H5_PAC_C_MAX_REAL_PRECISION
      correctly for a zero value. This was fixed by supplying the required defines.
      In addition it was moved from the Fortran specific HDF5UseFortran.camke file
      to the C centric ConfigureChecks.cmake file.

      (ADB - 2021/06/03)

    - Move emscripten flag to compile flags

      The emscripten flag, -O0, was removed from target_link_libraries command
      to the correct target_compile_options command.

      (ADB - 2021/04/26 HDFFV-11083)

    - Remove arbitrary warning flag groups from CMake builds

      The arbitrary groups were created to reduce the quantity of warnings being
      reported that overwhelmed testing report systems. Considerable work has
      been accomplished to reduce the warning count and these arbitrary groups
      are no longer needed.
      Also the default for all warnings, HDF5_ENABLE_ALL_WARNINGS, is now ON.

      Visual Studio warnings C4100, C4706, and C4127 have been moved to
      developer warnings, HDF5_ENABLE_DEV_WARNINGS, and are disabled for normal builds.

      (ADB - 2021/03/22, HDFFV-11228)

    - Reclassify CMake messages, to allow new modes and --log-level option

      CMake message commands have a mode argument. By default, STATUS mode
      was chosen for any non-error message. CMake version 3.15 added additional
      modes, NOTICE, VERBOSE, DEBUG and TRACE. All message commands with a mode
      of STATUS were reviewed and most were reclassified as VERBOSE. The new
      mode was protected by a check for a CMake version of at least 3.15. If CMake
      version 3.17 or above is used, the user can use the command line option
      of "--log-level" to further restrict which message commands are displayed.

      (ADB - 2021/01/11, HDFFV-11144)

    - Fixes Autotools determination of the stat struct having an st_blocks field

      A missing parenthesis in an autoconf macro prevented building the test
      code used to determine if the stat struct contains the st_blocks field.
      Now that the test functions correctly, the H5_HAVE_STAT_ST_BLOCKS #define
      found in H5pubconf.h will be defined correctly on both the Autotools and
      CMake. This #define is only used in the tests and does not affect the
      HDF5 C library.

      (DER - 2021/01/07, HDFFV-11201)

    - Add missing ENV variable line to hdfoptions.cmake file

      Using the build options to use system SZIP/ZLIB libraries need to also
      specify the library root directory. Setting the {library}_ROOT ENV
      variable was added to the hdfoptions.cmake file.

      (ADB - 2020/10/19 HDFFV-11108)


    Tools
    -----
    - Fix h5repack to only print output when verbose option is selected

      When timing option was added to h5repack, the check for verbose was
      incorrectly implemented.

      (ADB -  2022/12/02, GH #2270)

    - Changed how h5dump and h5ls identify long double.

      Long double support is not consistent across platforms. Tools will always
      identify long double as 128-bit [little/big]-endian float nn-bit precision.
      New test file created for datasets with attributes for float, double and
      long double. In addition any unknown integer or float datatype will now
      also show the number of bits for precision.
      These files are also used in the java tests.

      (ADB - 2021/03/24, HDFFV-11229,HDFFV-11113)

    - Fixed tools argument parsing.

      Tools parsing used the length of the option from the long array to match
      the option from the command line. This incorrectly matched a shorter long
      name option that happened to be a subset of another long option.
      Changed to match whole names.

      (ADB - 2021/01/19, HDFFV-11106)

    - The tools library was updated by standardizing the error stack process.

      General sequence is:
        h5tools_setprogname(PROGRAMNAME);
        h5tools_setstatus(EXIT_SUCCESS);
        h5tools_init();
        ... process the command-line (check for error-stack enable) ...
        h5tools_error_report();
        ... (do work) ...
        h5diff_exit(ret);

      (ADB - 2020/07/20, HDFFV-11066)

    - h5diff fixed a command line parsing error.

      h5diff would ignore the argument to -d (delta) if it is smaller than DBL_EPSILON.
      The macro H5_DBL_ABS_EQUAL was removed and a direct value comparison was used.

      (ADB - 2020/07/20, HDFFV-10897)

    - h5diff added a command line option to ignore attributes.

      h5diff would ignore all objects with a supplied path if the exclude-path argument is used.
      Adding the exclude-attribute argument will only exclude attributes, with the supplied path,
      from comparison.

      (ADB - 2020/07/20, HDFFV-5935)

    - h5diff added another level to the verbose argument to print filenames.

      Added verbose level 3 that is level 2 plus the filenames. The levels are:
        0 : Identical to '-v' or '--verbose'
        1 : All level 0 information plus one-line attribute status summary
        2 : All level 1 information plus extended attribute status report
        3 : All level 2 information plus file names

      (ADB - 2020/07/20, HDFFV-1005)


    Performance
    -------------
    -


    Fortran API
    -----------
    - h5open_f and h5close_f fixes
     * Fixed it so both h5open_f and h5close_f can be called multiple times.
     * Fixed an issue with open objects remaining after h5close_f was called.
     * Added additional tests.
       (MSB, 2022/04/19, HDFFV-11306)


    High-Level Library
    ------------------
    - Fixed HL_test_packet, test for packet table vlen of vlen.

      Incorrect length assignment.

      (ADB - 2021/10/14)


    Fortran High-Level APIs
    -----------------------
    -


    Documentation
    -------------
    -


    F90 APIs
    --------
    -


    C++ APIs
    --------
    - Added DataSet::operator=

      Some compilers complain if the copy constructor is given explicitly
      but the assignment operator is implicitly set to default.

      (2021/05/19)


    Testing
    -------
    - Stopped java/test/junit.sh.in installing libs for testing under ${prefix}

      Lib files needed are now copied to a subdirectory in the java/test
      directory, and on Macs the loader path for libhdf5.xxxs.so is changed
      in the temporary copy of libhdf5_java.dylib.

      (LRK, 2020/07/02, HDFFV-11063)


Platforms Tested
===================

    Linux 5.16.14-200.fc35            GNU gcc (GCC) 11.2.1 20220127 (Red Hat 11.2.1-9)
    #1 SMP x86_64  GNU/Linux          GNU Fortran (GCC) 11.2.1 20220127 (Red Hat 11.2.1-9)
    Fedora35                          clang version 13.0.0 (Fedora 13.0.0-3.fc35)
                                      (cmake and autotools)

    Linux 5.15.0-1026-aws             gcc (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0
    #30-Ubuntu SMP x86_64 GNU/Linux   GNU Fortran (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0
    Ubuntu 22.04                      Ubuntu clang version 14.0.0-1ubuntu1
                                      (cmake and autotools)

    Linux 5.13.0-1031-aws             GNU gcc (GCC) 9.4.0-1ubuntu1
    #35-Ubuntu SMP x86_64 GNU/Linux   GNU Fortran (GCC) 9.4.0-1ubuntu1
    Ubuntu 20.04                      clang version 10.0.0-4ubuntu1
                                      (cmake and autotools)

    Linux 5.3.18-150300-cray_shasta_c cray-mpich/8.3.3
    #1 SMP x86_64 GNU/Linux           Cray clang 14.0.2, 15.0.0
    (crusher)                         GCC 11.2.0, 12.1.0
                                      (cmake)

    Linux 4.18.0-348.7.1.el8_5        gcc (GCC) 8.5.0 20210514 (Red Hat 8.5.0-4)
    #1 SMP x86_64 GNU/Linux           GNU Fortran (GCC) 8.5.0 20210514 (Red Hat 8.5.0-4) 
    CentOS8                           clang version 12.0.1 (Red Hat 12.0.1)
                                      (cmake and autotools)

    Linux 4.14.0-115.35.1.1chaos      openmpi 4.0.5
    #1 SMP aarch64 GNU/Linux             GCC 9.3.0 (ARM-build-5)
    (stria)                              GCC 7.2.0 (Spack GCC)
                                         arm/20.1
                                         arm/22.1
                                      (cmake)

    Linux 4.14.0-115.35.1.3chaos      spectrum-mpi/rolling-release
    #1 SMP ppc64le GNU/Linux             clang 12.0.1
    (vortex)                             GCC 8.3.1
                                         XL 16.1.1
                                      (cmake)

    Linux-4.14.0-115.21.2             spectrum-mpi/rolling-release
    #1 SMP ppc64le GNU/Linux             clang 12.0.1, 14.0.5
    (lassen)                             GCC 8.3.1
                                         XL 16.1.1.2, 2021,09.22, 2022.08.05
                                      (cmake)

    Linux-4.12.14-197.99-default      cray-mpich/7.7.14
    #1 SMP x86_64 GNU/Linux              cce 12.0.3
    (theta)                              GCC 11.2.0
                                         llvm 9.0
                                         Intel 19.1.2

    Linux 3.10.0-1160.36.2.el7.ppc64  gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)
    #1 SMP ppc64be GNU/Linux          g++ (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)
    Power8 (echidna)                  GNU Fortran (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)

    Linux 3.10.0-1160.24.1.el7        GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux           compilers:
    Centos7                              Version 4.8.5 20150623 (Red Hat 4.8.5-4)
    (jelly/kituo/moohan)                 Version 4.9.3, Version 5.3.0, Version 6.3.0,
                                         Version 7.2.0, Version 8.3.0, Version 9.1.0
                                      Intel(R) C (icc), C++ (icpc), Fortran (icc)
                                      compilers:
                                         Version 17.0.0.098 Build 20160721
                                      GNU C (gcc) and C++ (g++) 4.8.5 compilers
                                         with NAG Fortran Compiler Release 6.1(Tozai)
                                      Intel(R) C (icc) and C++ (icpc) 17.0.0.098 compilers
                                         with NAG Fortran Compiler Release 6.1(Tozai)
                                      MPICH 3.1.4 compiled with GCC 4.9.3
                                      MPICH 3.3 compiled with GCC 7.2.0
                                      OpenMPI 2.1.6 compiled with icc 18.0.1
                                      OpenMPI 3.1.3 and 4.0.0 compiled with GCC 7.2.0
                                      PGI C, Fortran, C++ for 64-bit target on
                                      x86_64;
                                         Version 19.10-0
                                      (autotools and cmake)

    Linux-3.10.0-1160.0.0.1chaos      openmpi-4.1.2
    #1 SMP x86_64 GNU/Linux              clang 6.0.0, 11.0.1
    (quartz)                             GCC 7.3.0, 8.1.0
                                         Intel 19.0.4, 2022.2, oneapi.2022.2

    Linux-3.10.0-1160.71.1.1chaos     openmpi/4.1
    #1 SMP x86_64 GNU/Linux              GCC 7.2.0
    (skybridge)                          Intel/19.1
                                      (cmake)

    Linux-3.10.0-1160.66.1.1chaos     openmpi/4.1
    #1 SMP x86_64 GNU/Linux              GCC 7.2.0
    (attaway)                            Intel/19.1
                                      (cmake)

    Linux-3.10.0-1160.59.1.1chaos     openmpi/4.1
    #1 SMP x86_64 GNU/Linux              Intel/19.1
    (chama)                           (cmake)

    macOS Apple M1 11.6               Apple clang version 12.0.5 (clang-1205.0.22.11)
    Darwin 20.6.0 arm64               gfortran GNU Fortran (Homebrew GCC 11.2.0) 11.1.0
    (macmini-m1)                      Intel icc/icpc/ifort version 2021.3.0 202106092021.3.0 20210609

    macOS Big Sur 11.3.1              Apple clang version 12.0.5 (clang-1205.0.22.9)
    Darwin 20.4.0 x86_64              gfortran GNU Fortran (Homebrew GCC 10.2.0_3) 10.2.0
    (bigsur-1)                        Intel icc/icpc/ifort version 2021.2.0 20210228

    macOS High Sierra 10.13.6         Apple LLVM version 10.0.0 (clang-1000.10.44.4)
    64-bit                            gfortran GNU Fortran (GCC) 6.3.0
    (bear)                            Intel icc/icpc/ifort version 19.0.4.233 20190416

    macOS Sierra 10.12.6              Apple LLVM version 9.0.0 (clang-900.39.2)
    64-bit                            gfortran GNU Fortran (GCC) 7.4.0
    (kite)                            Intel icc/icpc/ifort version 17.0.2

    Mac OS X El Capitan 10.11.6       Apple clang version 7.3.0 from Xcode 7.3
    64-bit                            gfortran GNU Fortran (GCC) 5.2.0
    (osx1011test)                     Intel icc/icpc/ifort version 16.0.2


    Linux 2.6.32-573.22.1.el6         GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux           compilers:
    Centos6                              Version 4.4.7 20120313
    (platypus)                           Version 4.9.3, 5.3.0, 6.2.0
                                      MPICH 3.1.4 compiled with GCC 4.9.3
                                      PGI C, Fortran, C++ for 64-bit target on
                                      x86_64;
                                         Version 19.10-0

    Windows 10 x64                   Visual Studio 2015 w/ Intel C/C++/Fortran 18 (cmake)
                                     Visual Studio 2017 w/ Intel C/C++/Fortran 19 (cmake)
                                     Visual Studio 2019 w/ clang 12.0.0
                                        with MSVC-like command-line (C/C++ only - cmake)
                                     Visual Studio 2019 w/ Intel C/C++/Fortran oneAPI 2022 (cmake)
                                     Visual Studio 2022 w/ clang 15.0.1
                                        with MSVC-like command-line (C/C++ only - cmake)
                                     Visual Studio 2022 w/ Intel C/C++/Fortran oneAPI 2022 (cmake)
                                     Visual Studio 2019 w/ MSMPI 10.1 (C only - cmake)


Known Problems
==============

       ************************************************************
       *                                  _                       *
       *                                 (_)                      *
       *        __      ____ _ _ __ _ __  _ _ __   __ _           *
       *        \ \ /\ / / _` | '__| '_ \| | '_ \ / _` |          *
       *         \ V  V / (_| | |  | | | | | | | | (_| |          *
       *          \_/\_/ \__,_|_|  |_| |_|_|_| |_|\__, |          *
       *                                           __/ |          *
       *                                          |___/           *
       *                                                          *
       *  Please refrain from running any program (including      *
       *  HDF5 tests) which uses the subfiling VFD on Perlmutter  *
       *  at the National Energy Research Scientific Computing    *
       *  Center, NERSC.                                          *
       *  Doing so may cause a system disruption due to subfiling *
       *  crashing Lustre. The system's Lustre bug is expected    *
       *  to be resolved by 2023.                                 *
       *                                                          *
       ************************************************************

    There is a bug in OpenMPI 4.1.0-4.1.4 that can result in incorrect
    results from MPI I/O requests unless one of the following parameters
    is passed to mpirun:

        --mca io ^ompio

        --mca fbtl_posix_read_data_sieving 0

    This bug has been fixed in later versions of OpenMPI.

    Further discussion can be found here:

    https://www.hdfgroup.org/2022/11/workarounds-for-openmpi-bug-exposed-by-make-check-in-hdf5-1-13-3/

    When using the subfiling feature with OpenMPI it is often necessary to
    increase the maximum number of threads:

    --mca common_pami_max_threads 4096

    There is a bug in MPICH 4.0.0-4.0.3 where using device=ch4:ofi (the default)
    can cause failures in the testphdf5 test program. Using ch4:ucx or ch3
    allows the test to pass. The bug appears to be fixed in the upcoming 4.1
    release.

    These MPI implementation bugs may also be present in implementations derived
    from OpenMPI or MPICH. The workarounds listed above may need to be adjusted
    to match the derived implementation, or in some cases, there may be no
    workaround.

    The accum test fails on MacOS 12.6.2 (Monterey) with clang 14.0.0. The
    reason for this failure and its impact are unknown.

    The onion test has failures on Windows when built using Intel OneAPI
    2022.3. The cause of these failures is under investigation.

    CMake files do not behave correctly with paths containing spaces.
    Do not use spaces in paths because the required escaping for handling spaces
    results in very complex and fragile build files.
    ADB - 2019/05/07

    At present, metadata cache images may not be generated by parallel
    applications.  Parallel applications can read files with metadata cache
    images, but since this is a collective operation, a deadlock is possible
    if one or more processes do not participate.

    CPP ptable test fails on both VS2017 and VS2019 with Intel compiler, JIRA
    issue: HDFFV-10628.  This test will pass with VS2015 with Intel compiler.

    The subsetting option in ph5diff currently will fail and should be avoided.
    The subsetting option works correctly in serial h5diff.

    Several tests currently fail on certain platforms:
        MPI_TEST-t_bigio fails with spectrum-mpi on ppc64le platforms.

        MPI_TEST-t_subfiling_vfd and MPI_TEST_EXAMPLES-ph5_subfiling fail with
        cray-mpich on theta and with XL compilers on ppc64le platforms.

        MPI_TEST_testphdf5_tldsc fails with cray-mpich 7.7 on cori and theta.

    Known problems in previous releases can be found in the HISTORY*.txt files
    in the HDF5 source. Please report any new problems found to
    help@hdfgroup.org.


CMake vs. Autotools installations
=================================
While both build systems produce similar results, there are differences.
Each system produces the same set of folders on linux (only CMake works
on standard Windows); bin, include, lib and share. Autotools places the
COPYING and RELEASE.txt file in the root folder, CMake places them in
the share folder.

The bin folder contains the tools and the build scripts. Additionally, CMake
creates dynamic versions of the tools with the suffix "-shared". Autotools
installs one set of tools depending on the "--enable-shared" configuration
option.
  build scripts
  -------------
  Autotools: h5c++, h5cc, h5fc
  CMake: h5c++, h5cc, h5hlc++, h5hlcc

The include folder holds the header files and the fortran mod files. CMake
places the fortran mod files into separate shared and static subfolders,
while Autotools places one set of mod files into the include folder. Because
CMake produces a tools library, the header files for tools will appear in
the include folder.

The lib folder contains the library files, and CMake adds the pkgconfig
subfolder with the hdf5*.pc files used by the bin/build scripts created by
the CMake build. CMake separates the C interface code from the fortran code by
creating C-stub libraries for each Fortran library. In addition, only CMake
installs the tools library. The names of the szip libraries are different
between the build systems.

The share folder will have the most differences because CMake builds include
a number of CMake specific files for support of CMake's find_package and support
for the HDF5 Examples CMake project.

The issues with the gif tool are:
    HDFFV-10592 CVE-2018-17433
    HDFFV-10593 CVE-2018-17436
    HDFFV-11048 CVE-2020-10809
These CVE issues have not yet been addressed and are avoided by not building
the gif tool by default. Enable building the High-Level tools with these options:
    autotools:   --enable-hltools
    cmake:       HDF5_BUILD_HL_TOOLS=ON
