/*
 * Copyright (C) 2004  Manuel Novoa III  <mjn3@codepoet.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/* July 29, 2004
 *
 * This is a hacked replacement for the 'trx' utility used to create
 * wrt54g .trx firmware files.  It isn't pretty, but it does the job
 * for me.
 *
 * As an extension, you can specify a larger maximum length for the
 * .trx file using '-m'.  It will be rounded up to be a multiple of 4K.
 * NOTE: This space will be malloc()'d.
 *
 * August 16, 2004
 *
 * Sigh... Make it endian-neutral.
 *
 * TODO: Support '-b' option to specify offsets for each file.
 *
 * February 19, 2005 - mbm
 *
 * Add -a (align offset) and -b (absolute offset)
 *
 * March 24, 2010 - markus
 *
 * extend trx header struct for new version
 * assume v1 for as default
 * Add option -2 to allow v2 header
 */

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>

#if __BYTE_ORDER == __BIG_ENDIAN
#define STORE32_LE(X)		bswap_32(X)
#define LOAD32_LE(X)		bswap_32(X)
#elif __BYTE_ORDER == __LITTLE_ENDIAN
#define STORE32_LE(X)		(X)
#define LOAD32_LE(X)		(X)
#else
#error unkown endianness!
#endif

uint32_t crc32buf(char *buf, size_t len);

/**********************************************************************/
/* from trxhdr.h */

#define TRX_MAGIC	0x30524448	/* "HDR0" */
#define TRX_MAX_LEN	0x720000
#define TRX_NO_HEADER	1		/* Do not write TRX header */

struct trx_header {
	uint32_t magic;			/* "HDR0" */
	uint32_t len;			/* Length of file including header */
	uint32_t crc32;			/* 32-bit CRC from flag_version to end of file */
	uint32_t flag_version;	/* 0:15 flags, 16:31 version */
	uint32_t offsets[4];	/* Offsets of partitions from start of header */
};

/**********************************************************************/

void usage(void) __attribute__ (( __noreturn__ ));

void usage(void)
{
	fprintf(stderr, "Usage:\n");
	fprintf(stderr, " trx [-2] [-o outfile] [-m maxlen] [-a align] [-b absolute offset] [-x relative offset]\n");
	fprintf(stderr, "     [-f file] [-f file [-f file [-f file (v2 only)]]]\n");
	exit(EXIT_FAILURE);
}

int main(int argc, char **argv)
{
	FILE *out = stdout;
	FILE *in;
	char *ofn = NULL;
	char *buf;
	char *e;
	int c, i, append = 0;
	size_t n;
	ssize_t n2;
	uint32_t cur_len, fsmark=0;
	unsigned long maxlen = TRX_MAX_LEN;
	struct trx_header *p;
	char trx_version = 1;
	unsigned char binheader[32];

	fprintf(stderr, "mjn3's trx replacement - v0.81.1\n");

	if (!(buf = malloc(maxlen))) {
		fprintf(stderr, "malloc failed\n");
		return EXIT_FAILURE;
	}

	p = (struct trx_header *) buf;

	p->magic = STORE32_LE(TRX_MAGIC);
	cur_len = sizeof(struct trx_header) - 4; /* assume v1 header */

	in = NULL;
	i = 0;

	while ((c = getopt(argc, argv, "-:2o:m:a:x:b:f:A:F:")) != -1) {
		switch (c) {
			case '2':
				/* take care that nothing was written to buf so far */
				if (cur_len != sizeof(struct trx_header) - 4) {
					fprintf(stderr, "-2 has to be used before any other argument!\n");
				}
				else {
					trx_version = 2;
					cur_len += 4;
				}
				break;
			case 'F':
				fsmark = cur_len;
			case 'A':
				append = 1;
				/* fall through */
			case 'f':
			case 1:
				if (!append)
					p->offsets[i++] = STORE32_LE(cur_len);

				if (!(in = fopen(optarg, "r"))) {
					fprintf(stderr, "can not open \"%s\" for reading\n", optarg);
					usage();
				}
				n = fread(buf + cur_len, 1, maxlen - cur_len, in);
				if (!feof(in)) {
					fprintf(stderr, "fread failure or file \"%s\" too large\n",optarg);
					fclose(in);
					return EXIT_FAILURE;
				}
				fclose(in);
#undef  ROUND
#define ROUND 4
				if (n & (ROUND-1)) {
					memset(buf + cur_len + n, 0, ROUND - (n & (ROUND-1)));
					n += ROUND - (n & (ROUND-1));
				}
				cur_len += n;
				append = 0;

				break;
			case 'o':
				ofn = optarg;
				if (ofn && !(out = fopen(ofn, "w"))) {
					fprintf(stderr, "can not open \"%s\" for writing\n", ofn);
					usage();
				}

				break;
			case 'm':
				errno = 0;
				maxlen = strtoul(optarg, &e, 0);
				if (errno || (e == optarg) || *e) {
					fprintf(stderr, "illegal numeric string\n");
					usage();
				}
#undef  ROUND
#define ROUND 0x1000
				if (maxlen & (ROUND-1)) {
					maxlen += (ROUND - (maxlen & (ROUND-1)));
				}
				if (maxlen < ROUND) {
					fprintf(stderr, "maxlen too small (or wrapped)\n");
					usage();
				}
				if (maxlen > TRX_MAX_LEN) {
					fprintf(stderr, "WARNING: maxlen exceeds default maximum!  Beware of overwriting nvram!\n");
				}
				if (!(buf = realloc(buf,maxlen))) {
					fprintf(stderr, "realloc failed");
					return EXIT_FAILURE;
				}
				p = (struct trx_header *) buf;
				break;
			case 'a':
				errno = 0;
				n = strtoul(optarg, &e, 0);
				if (errno || (e == optarg) || *e) {
					fprintf(stderr, "illegal numeric string\n");
					usage();
				}
				if (cur_len & (n-1)) {
					n = n - (cur_len & (n-1));
					memset(buf + cur_len, 0, n);
					cur_len += n;
				}
				break;
			case 'b':
				errno = 0;
				n = strtoul(optarg, &e, 0);
				if (errno || (e == optarg) || *e) {
					fprintf(stderr, "illegal numeric string\n");
					usage();
				}
				if (n < cur_len) {
					fprintf(stderr, "WARNING: current length exceeds -b %d offset\n",(int) n);
				} else {
					memset(buf + cur_len, 0, n - cur_len);
					cur_len = n;
				}
				break;
			case 'x':
				errno = 0;
				n2 = strtol(optarg, &e, 0);
				if (errno || (e == optarg) || *e) {
					fprintf(stderr, "illegal numeric string\n");
					usage();
				}
				if (n2 < 0) {
					if (-n2 > cur_len) {
						fprintf(stderr, "WARNING: current length smaller then -x %d offset\n",(int) n2);
						cur_len = 0;
					} else
						cur_len += n2;
				} else {
					memset(buf + cur_len, 0, n2);
					cur_len += n2;
				}

				break;
			default:
				usage();
		}
	}
	p->flag_version = STORE32_LE((trx_version << 16));

	if (!in) {
		fprintf(stderr, "we require atleast one filename\n");
		usage();
	}

#undef  ROUND
#define ROUND 0x1000
	n = cur_len & (ROUND-1);
	if (n) {
		memset(buf + cur_len, 0, ROUND - n);
		cur_len += ROUND - n;
	}

	/* for TRXv2 set bin-header Flags to 0xFF for CRC calculation like CFE does */
	if (trx_version == 2) {
		if(cur_len - LOAD32_LE(p->offsets[3]) < sizeof(binheader)) {
			fprintf(stderr, "TRXv2 binheader too small!\n");
			return EXIT_FAILURE;
		}
		memcpy(binheader, buf + LOAD32_LE(p->offsets[3]), sizeof(binheader)); /* save header */
		memset(buf + LOAD32_LE(p->offsets[3]) + 22, 0xFF, 8); /* set stable and try1-3 to 0xFF */
	}

	p->crc32 = crc32buf((char *) &p->flag_version,
						((fsmark)?fsmark:cur_len) - offsetof(struct trx_header, flag_version));
	p->crc32 = STORE32_LE(p->crc32);

	p->len = STORE32_LE((fsmark) ? fsmark : cur_len);

	/* restore TRXv2 bin-header */
	if (trx_version == 2) {
		memcpy(buf + LOAD32_LE(p->offsets[3]), binheader, sizeof(binheader));
	}

	if (!fwrite(buf, cur_len, 1, out) || fflush(out)) {
		fprintf(stderr, "fwrite failed\n");
		return EXIT_FAILURE;
	}

	fclose(out);

	return EXIT_SUCCESS;
}

/**********************************************************************/
/* The following was grabbed and tweaked from the old snippets collection
 * of public domain C code. */

/**********************************************************************\
|* Demonstration program to compute the 32-bit CRC used as the frame  *|
|* check sequence in ADCCP (ANSI X3.66, also known as FIPS PUB 71     *|
|* and FED-STD-1003, the U.S. versions of CCITT's X.25 link-level     *|
|* protocol).  The 32-bit FCS was added via the Federal Register,     *|
|* 1 June 1982, p.23798.  I presume but don't know for certain that   *|
|* this polynomial is or will be included in CCITT V.41, which        *|
|* defines the 16-bit CRC (often called CRC-CCITT) polynomial.  FIPS  *|
|* PUB 78 says that the 32-bit FCS reduces otherwise undetected       *|
|* errors by a factor of 10^-5 over 16-bit FCS.                       *|
\**********************************************************************/

/* Copyright (C) 1986 Gary S. Brown.  You may use this program, or
   code or tables extracted from it, as desired without restriction.*/

/* First, the polynomial itself and its table of feedback terms.  The  */
/* polynomial is                                                       */
/* X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0 */
/* Note that we take it "backwards" and put the highest-order term in  */
/* the lowest-order bit.  The X^32 term is "implied"; the LSB is the   */
/* X^31 term, etc.  The X^0 term (usually shown as "+1") results in    */
/* the MSB being 1.                                                    */

/* Note that the usual hardware shift register implementation, which   */
/* is what we're using (we're merely optimizing it by doing eight-bit  */
/* chunks at a time) shifts bits into the lowest-order term.  In our   */
/* implementation, that means shifting towards the right.  Why do we   */
/* do it this way?  Because the calculated CRC must be transmitted in  */
/* order from highest-order term to lowest-order term.  UARTs transmit */
/* characters in order from LSB to MSB.  By storing the CRC this way,  */
/* we hand it to the UART in the order low-byte to high-byte; the UART */
/* sends each low-bit to hight-bit; and the result is transmission bit */
/* by bit from highest- to lowest-order term without requiring any bit */
/* shuffling on our part.  Reception works similarly.                  */

/* The feedback terms table consists of 256, 32-bit entries.  Notes:   */
/*                                                                     */
/*  1. The table can be generated at runtime if desired; code to do so */
/*     is shown later.  It might not be obvious, but the feedback      */
/*     terms simply represent the results of eight shift/xor opera-    */
/*     tions for all combinations of data and CRC register values.     */
/*                                                                     */
/*  2. The CRC accumulation logic is the same for all CRC polynomials, */
/*     be they sixteen or thirty-two bits wide.  You simply choose the */
/*     appropriate table.  Alternatively, because the table can be     */
/*     generated at runtime, you can start by generating the table for */
/*     the polynomial in question and use exactly the same "updcrc",   */
/*     if your application needn't simultaneously handle two CRC       */
/*     polynomials.  (Note, however, that XMODEM is strange.)          */
/*                                                                     */
/*  3. For 16-bit CRCs, the table entries need be only 16 bits wide;   */
/*     of course, 32-bit entries work OK if the high 16 bits are zero. */
/*                                                                     */
/*  4. The values must be right-shifted by eight bits by the "updcrc"  */
/*     logic; the shift must be unsigned (bring in zeroes).  On some   */
/*     hardware you could probably optimize the shift in assembler by  */
/*     using byte-swap instructions.                                   */

static const uint32_t crc_32_tab[] = { /* CRC polynomial 0xedb88320 */
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};

#define UPDC32(octet,crc) (crc_32_tab[((crc) ^ (octet)) & 0xff] ^ ((crc) >> 8))

uint32_t crc32buf(char *buf, size_t len)
{
      uint32_t crc;

      crc = 0xFFFFFFFF;

      for ( ; len; --len, ++buf)
      {
            crc = UPDC32(*buf, crc);
      }

      return crc;
}
