## libhfsp

This library can be used to prorammatically acces HFS+ volumes. The library in turn is used by utilities allowing user access to the volume.

### objects exposed

The library has some top level objects that are to be used by other programs:

- volume identifies the volume as a whole.
The btree is used a cache for the records used later (this object will eventually be included in the volume later on).
- The record represent a file or folder.

### Design principles

In contrast to the original library by Robert Leslie this libray rarely uses malloc/free. This impoes, that all memory is contained in the objects shown above. As of now only the current two blocks are "cached". Performance may be poor when doing large transactions. function returning int return 0 on success and any other value (normally -1) on failure unless stated otherwise. functions returning pointers return NULL on error. In most cases `hfsp_error` and `errno` should be set. Byte swapping happens when reading structure from raw memory, this avoids any alignment problems. (In contrast to Brad Boyers aproach wich needs to swap (and assemble) the bytes on every acces.) The contentes of the raw HFS+ structures is usually not copied to other structures and remains embedded in the high level strcutures. In case you need such a value acces it directly (e.G. volume->vol.create_date - HFSPTIMEDIFF )

### volume

Call `volume_open()` to open a volume. You must call `volume_close()` to close the volume. all other `volume_` functions are used internally only use them when you really know what you are doing.

### btree

The btree as of now is the catalog-file btree, althoug there are other btrees like the extends-file btree. I intend to make the btree a (more or less) private member of the volume. This will be done together with implementing a catalog-node cache superseeding the simple block cache at the volume.

### record

The record is used whenever a file or folder is needed. There is a sufficient set of methods to navigate around with records. Folders and FolderThreads can both be used when acces to the files of a folder is needed. File Threads are supported, althoug Apple does not use them. (The utility functions like hpls however suppress then since I dont know what to do with them.) As of now there is no concept of "opening" a record, for readonlny acces just take one of the forks and use the fork functkions found at the volume to acces the raw data. See hpcopy for examples how to do that.

This is work in progress, either be patient or provide help.

$Id: libhfsp.html,v 1.1.1.1 2002/03/05 19:50:28 klaus Exp $