// SPDX-FileCopyrightText: 2013-2017 pancake <pancake@nopcode.org>
// SPDX-FileCopyrightText: 2013-2017 fenugrec <fenugrec@users.sourceforge.net>
// SPDX-License-Identifier: LGPL-3.0-only

/*
*** .hex format description : every line follows this pattern
:SSAAAARR<xx*SS>KK
SS: num of "xx" bytes
AAAA lower 16bits of address for resulting data (==0 for 01, 02, 04 and 05 records)
RR: rec type:
	00 data
	01 EOF (always SS=0, AAAA=0)
	02 extended segment addr reg: (always SS=02, AAAA=0); data = 0x<xxyy> => bits 4..19 of following addresses
	04 extended linear addr reg: (always SS=02, AAAA=0); data = 0x<xxyy> => bits 16..31 of following addresses
	05 non-standard; could be "start linear address" AKA "entry point".
KK = 0 - (sum of all bytes)

//sauce : http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka9903.html

**** example records
:02000002fffffe		#rec 02 : new seg = 0xffff, so next addresses will be (seg<<4)+AAAA
:02000000556643		#rec 00 : load 2 bytes [0x000f fff0]=0x55; [0x000f fff1]=0x66
:020000040800f2		#rec 04 : new linear addr = 0x0800, so next addresses will be (0x0800 <<16) + AAAA
:10000000480F0020F948000811480008134800086C	#rec 00 : load 16 bytes @ 0x0800 0000
:04000005080049099D	#rec 05 : entry point = 0x0800 4909 (ignored)
:00000001FF		#rec 01 : EOF

*/

#include "rz_io.h"
#include "rz_lib.h"
#include "rz_util.h"
#include <limits.h> //for INT_MAX
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>

// struct Rihex : holds sparse buffer + its own fd, for internal management
typedef struct {
	int fd;
	RzBuffer *rbuf;
} Rihex;

static bool ihex_write(RzIODesc *desc, Rihex *rih);

static int __write(RzIO *io, RzIODesc *fd, const ut8 *buf, size_t count) {
	if (!fd || !fd->data || (fd->perm & RZ_PERM_W) == 0 || count <= 0) {
		return -1;
	}
	Rihex *rih = fd->data;
	/* mem write */
	if (rz_buf_write_at(rih->rbuf, io->off, buf, count) != count) {
		eprintf("ihex:write(): sparse write failed\n");
		return -1;
	}
	rz_buf_seek(rih->rbuf, count, RZ_BUF_CUR);
	if (!ihex_write(fd, rih)) {
		return -1;
	}
	return count;
}

// fw04b : write 04 record (extended address); ret <0 if error
static int fw04b(FILE *fd, ut16 eaddr) {
	ut8 cks = 0 - (6 + (eaddr >> 8) + (eaddr & 0xff));
	return fprintf(fd, ":02000004%04X%02X\n", eaddr, cks);
}

// write contiguous block of data to file; ret 0 if ok
// max 65535 bytes; assumes a 04 rec was written before
static int fwblock(FILE *fd, ut8 *b, ut32 start_addr, ut32 size) {
	ut8 cks;
	char linebuf[80];
	ut16 last_addr;
	int j;
	ut32 i; // has to be bigger than size !

	if (size < 1 || size > 0x10000 || !fd || !b) {
		return -1;
	}

	for (i = 0; (i + 0x10) < size; i += 0x10) {
		cks = 0x10;
		cks += (i + start_addr) >> 8;
		cks += (i + start_addr);
		for (j = 0; j < 0x10; j++) {
			cks += b[j];
		}
		cks = 0 - cks;
		if (fprintf(fd, ":10%04x00%02x%02x%02x%02x%02x%02x%02x"
				"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n",
			    (i + start_addr) & 0xffff, b[0], b[1], b[2], b[3], b[4], b[5], b[6],
			    b[7], b[8], b[9], b[10], b[11], b[12], b[13],
			    b[14], b[15], cks) < 0) {
			return -1;
		}
		b += 0x10;
		if (((i + start_addr) & 0xffff) < 0x10) {
			// addr rollover: write ext address record
			if (fw04b(fd, (i + start_addr) >> 16) < 0) {
				return -1;
			}
		}
	}
	if (i == size) {
		return 0;
	}
	// write crumbs
	last_addr = i + start_addr;
	cks = -last_addr;
	cks -= last_addr >> 8;
	for (j = 0; i < size; i++, j++) {
		cks -= b[j];
		sprintf(linebuf + (2 * j), "%02X", b[j]);
	}
	cks -= j;

	if (fprintf(fd, ":%02X%04X00%.*s%02X\n", j, last_addr, 2 * j, linebuf, cks) < 0) {
		return -1;
	}
	return 0;
}

static int __read(RzIO *io, RzIODesc *fd, ut8 *buf, size_t count) {
	if (!fd || !fd->data || (count <= 0)) {
		return -1;
	}
	Rihex *rih = fd->data;
	memset(buf, io->Oxff, count);
	int r = rz_buf_read_at(rih->rbuf, io->off, buf, count);
	if (r >= 0) {
		rz_buf_seek(rih->rbuf, r, RZ_BUF_CUR);
	}
	// sparse read return >= 0 but < count still means everything was read successfully,
	// just maybe not entirely populated by chunks:
	return r < 0 ? -1 : count;
}

static int __close(RzIODesc *fd) {
	if (!fd || !fd->data) {
		return -1;
	}
	Rihex *rih = fd->data;
	rz_buf_free(rih->rbuf);
	free(rih);
	fd->data = NULL;
	return 0;
}

static ut64 __lseek(struct rz_io_t *io, RzIODesc *fd, ut64 offset, int whence) {
	Rihex *rih;
	if (!fd || !fd->data) {
		return -1;
	}
	rih = fd->data;
	io->off = rz_buf_seek(rih->rbuf, offset, whence);
	return io->off;
}

static bool __plugin_open(RzIO *io, const char *pathname, bool many) {
	return (!strncmp(pathname, "ihex://", 7));
}

// ihex_parse : parse ihex file loaded at *str, fill sparse buffer "rbuf"
// supported rec types : 00, 01, 02, 04
// ret 0 if ok
static bool ihex_parse(RzBuffer *rbuf, char *str) {
	ut8 *sec_tmp;
	ut32 sec_start = 0; // addr for next section write
	ut32 segreg = 0; // basis for addr fields
	ut32 addr_tmp = 0; // addr for record
	ut16 next_addr = 0; // for checking if records are sequential
	char *eol;
	ut8 cksum;
	int extH, extL;
	int bc = 0, type, byte, i, l;
	// fugly macro to prevent an overflow of rz_buf_write_at() len
#define SEC_MAX (sec_size < INT_MAX) ? sec_size : INT_MAX
	ut32 sec_size = 0;
	const int sec_count = UT16_MAX;
	sec_tmp = calloc(1, sec_count);
	if (!sec_tmp) {
		goto fail;
	}
	do {
		l = sscanf(str, ":%02x%04x%02x", &bc, &addr_tmp, &type);
		if (l != 3) {
			eprintf("Invalid data in ihex file (%.*s)\n", 80, str);
			goto fail;
		}
		bc &= 0xff;
		addr_tmp &= 0xffff;
		type &= 0xff;

		switch (type) {
		case 0: // DATA
			eol = strchr(str + 1, ':');
			if (eol) {
				*eol = 0;
			}
			cksum = bc;
			cksum += addr_tmp >> 8;
			cksum += addr_tmp;
			cksum += type;

			if ((next_addr != addr_tmp) || ((sec_size + bc) > SEC_MAX)) {
				// previous block is not contiguous, or
				// section buffer is full => write a sparse chunk
				if (sec_size && sec_size < UT16_MAX) {
					if (rz_buf_write_at(rbuf, sec_start, sec_tmp, (int)sec_size) != sec_size) {
						eprintf("sparse buffer problem, giving up\n");
						goto fail;
					}
				}
				// advance cursor, reset section
				sec_start = segreg + addr_tmp;
				next_addr = addr_tmp;
				sec_size = 0;
			}

			for (i = 0; i < bc; i++) {
				if (sscanf(str + 9 + (i * 2), "%02x", &byte) != 1) {
					eprintf("unparsable data !\n");
					goto fail;
				}
				if (sec_size + i < sec_count) {
					sec_tmp[sec_size + i] = (ut8)byte & 0xff;
				}
				cksum += byte;
			}
			sec_size += bc;
			next_addr += bc;
			if (eol) {
				// checksum
				if (sscanf(str + 9 + (i * 2), "%02x", &byte) != 1) {
					eprintf("unparsable data !\n");
					goto fail;
				}
				cksum += byte;
				if (cksum != 0) {
					ut8 fixedcksum = 0 - (cksum - byte);
					eprintf("Checksum failed %02x (got %02x expected %02x)\n",
						cksum, byte, fixedcksum);
					goto fail;
				}
				*eol = ':';
			}
			str = eol;
			break;
		case 1: // EOF. we don't validate checksum here
			if (sec_size) {
				if (rz_buf_write_at(rbuf, sec_start, sec_tmp, sec_size) != sec_size) {
					eprintf("sparse buffer problem, giving up. ssiz=%X, sstart=%X\n", sec_size, sec_start);
					goto fail;
				}
			}
			str = NULL;
			break;
		case 2: // extended segment record
		case 4: // extended linear address rec
			// both rec types are handled the same except :
			//	new address = seg_reg <<4 for type 02; new address = lin_addr <<16 for type 04.
			// write current section
			if (sec_size) {
				if (rz_buf_write_at(rbuf, sec_start, sec_tmp, sec_size) != sec_size) {
					eprintf("sparse buffer problem, giving up\n");
					goto fail;
				}
			}
			sec_size = 0;

			eol = strchr(str + 1, ':');
			if (eol) {
				*eol = 0;
			}
			cksum = bc;
			cksum += addr_tmp >> 8;
			cksum += addr_tmp;
			cksum += type;
			if ((bc != 2) || (addr_tmp != 0)) {
				eprintf("invalid type 02/04 record!\n");
				goto fail;
			}
			if ((sscanf(str + 9 + 0, "%02x", &extH) != 1) ||
				(sscanf(str + 9 + 2, "%02x", &extL) != 1)) {
				eprintf("unparsable data !\n");
				goto fail;
			}
			extH &= 0xff;
			extL &= 0xff;
			cksum += extH + extL;

			segreg = extH << 8 | extL;

			// segment rec(02) gives bits 4..19; linear rec(04) is bits 16..31
			segreg = segreg << ((type == 2) ? 4 : 16);
			next_addr = 0;
			sec_start = segreg;

			if (eol) {
				// checksum
				byte = 0; // break checksum if sscanf failed
				if (sscanf(str + 9 + 4, "%02x", &byte) != 1) {
					cksum = 1;
				}
				cksum += byte;
				if (cksum != 0) {
					ut8 fixedcksum = 0 - (cksum - byte);
					eprintf("Checksum failed %02x (got %02x expected %02x)\n",
						cksum, byte, fixedcksum);
					goto fail;
				}
				*eol = ':';
			}
			str = eol;
			break;
		case 3: // undefined rec. Just skip.
		case 5: // non-standard, sometimes "start linear address"
			str = strchr(str + 1, ':');
			break;
		}
	} while (str);
	free(sec_tmp);
	return true;
fail:
	free(sec_tmp);
	return false;
}

static bool ihex_write(RzIODesc *desc, Rihex *rih) {
	const char *pathname = desc->name + 7;
	FILE *out = rz_sys_fopen(pathname, "w");
	if (!out) {
		eprintf("Cannot open '%s' for writing\n", pathname);
		return false;
	}
	// disk write : process each sparse chunk
	size_t chunks_count;
	const RzBufferSparseChunk *chunks = rz_buf_sparse_get_chunks(rih->rbuf, &chunks_count);
	ut64 addh_cur = 0;
	for (size_t i = 0; i < chunks_count; i++) {
		const RzBufferSparseChunk *rbs = &chunks[i];
		ut64 from = rbs->from;
		while (from >> 16 != rbs->to >> 16) {
			// we cross a 64k boundary, so write in multiple steps
			ut16 addl = from & 0xffff;
			ut16 addh = from >> 16;
			if (addh != addh_cur) {
				addh_cur = addh;
				// 04 record (ext address)
				if (fw04b(out, addh) < 0) {
					eprintf("ihex:write: file error\n");
					fclose(out);
					return false;
				}
			}
			// 00 records (data)
			ut32 tsiz = (ut32)0x10000 - (ut32)addl;
			if (fwblock(out, rbs->data + (from - rbs->from), from, tsiz)) {
				eprintf("ihex:fwblock error\n");
				fclose(out);
				return false;
			}
			from = ((from >> 16) + 1) << 16;
		}
		ut16 addh = from >> 16;
		if (addh != addh_cur) {
			addh_cur = addh;
			// 04 record (ext address)
			if (fw04b(out, addh) < 0) {
				eprintf("ihex:write: file error\n");
				fclose(out);
				return false;
			}
		}
		// 00 records (remaining data)
		if (fwblock(out, rbs->data + (from - rbs->from), from, rbs->to - from + 1)) {
			eprintf("ihex:fwblock error 2\n");
			fclose(out);
			return false;
		}
	}

	fprintf(out, ":00000001FF\n");
	fclose(out);
	return true;
}

static RzIODesc *__open(RzIO *io, const char *pathname, int rw, int mode) {
	Rihex *mal = NULL;
	char *str = NULL;
	if (__plugin_open(io, pathname, 0)) {
		str = rz_file_slurp(pathname + 7, NULL);
		if (!str) {
			return NULL;
		}
		mal = RZ_NEW0(Rihex);
		if (!mal) {
			free(str);
			return NULL;
		}
		mal->rbuf = rz_buf_new_sparse(io->Oxff);
		if (!mal->rbuf) {
			free(str);
			free(mal);
			return NULL;
		}
		if (!ihex_parse(mal->rbuf, str)) {
			eprintf("ihex: failed to parse file\n");
			free(str);
			rz_buf_free(mal->rbuf);
			free(mal);
			return NULL;
		}
		free(str);
		return rz_io_desc_new(io, &rz_io_plugin_ihex,
			pathname, rw, mode, mal);
	}
	return NULL;
}

static bool __resize(RzIO *io, RzIODesc *fd, ut64 size) {
	if (!fd) {
		return false;
	}
	Rihex *rih = fd->data;
	if (!rih) {
		return false;
	}
	if (!rz_buf_resize(rih->rbuf, size)) {
		return false;
	}
	return ihex_write(fd, rih);
}

RzIOPlugin rz_io_plugin_ihex = {
	.name = "ihex",
	.desc = "Open intel HEX file",
	.uris = "ihex://",
	.license = "LGPL",
	.open = __open,
	.close = __close,
	.read = __read,
	.check = __plugin_open,
	.lseek = __lseek,
	.write = __write,
	.resize = __resize
};

#ifndef RZ_PLUGIN_INCORE
RZ_API RzLibStruct rizin_plugin = {
	.type = RZ_LIB_TYPE_IO,
	.data = &rz_io_plugin_ihex,
	.version = RZ_VERSION
};
#endif
