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- /*
- * add_header.c - partially based on OpenWrt's motorola-bin.c
- *
- * Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
- * Gabor Juhos <juhosg@openwrt.org>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License,
- * version 2 as published by the Free Software Foundation.
- *
- * 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.
- */
- /*
- * The add_header utility used by various vendors preprends the buf
- * image with a header containing a CRC32 value which is generated for the
- * model id + reserved space for CRC32 + buf, then replaces the reserved
- * area with the actual CRC32. This replacement tool mimics this behavior.
- */
- #include <stdio.h>
- #include <stdlib.h>
- #include <stddef.h>
- #include <unistd.h>
- #include <errno.h>
- #include <fcntl.h>
- #include <sys/mman.h>
- #include <string.h>
- #include <netinet/in.h>
- #include <inttypes.h>
- #define BPB 8 /* bits/byte */
- static uint32_t crc32[1<<BPB];
- static void init_crc32()
- {
- const uint32_t poly = ntohl(0x2083b8ed);
- int n;
- for (n = 0; n < 1<<BPB; n++) {
- uint32_t crc = n;
- int bit;
- for (bit = 0; bit < BPB; bit++)
- crc = (crc & 1) ? (poly ^ (crc >> 1)) : (crc >> 1);
- crc32[n] = crc;
- }
- }
- static uint32_t crc32buf(unsigned char *buf, size_t len)
- {
- uint32_t crc = 0xFFFFFFFF;
- for (; len; len--, buf++)
- crc = crc32[(uint8_t)crc ^ *buf] ^ (crc >> BPB);
- return ~crc;
- }
- struct header {
- unsigned char model[16];
- uint32_t crc;
- };
- static void usage(const char *) __attribute__ (( __noreturn__ ));
- static void usage(const char *mess)
- {
- fprintf(stderr, "Error: %s\n", mess);
- fprintf(stderr, "Usage: add_header model_id input_file output_file\n");
- fprintf(stderr, "\n");
- exit(1);
- }
- int main(int argc, char **argv)
- {
- off_t len; // of original buf
- off_t buflen; // of the output file
- int fd;
- void *input_file; // pointer to the input file (mmmapped)
- struct header header;
- unsigned char *buf; // pointer to prefix + copy of original buf
- // verify parameters
- if (argc != 4)
- usage("wrong number of arguments");
- // mmap input_file
- if ((fd = open(argv[2], O_RDONLY)) < 0
- || (len = lseek(fd, 0, SEEK_END)) < 0
- || (input_file = mmap(0, len, PROT_READ, MAP_SHARED, fd, 0)) == (void *) (-1)
- || close(fd) < 0)
- {
- fprintf(stderr, "Error loading file %s: %s\n", argv[2], strerror(errno));
- exit(1);
- }
- buflen = len + sizeof(header);
- init_crc32();
- // copy model name into header
- strncpy(header.model, argv[1], sizeof(header.model));
- header.crc = 0;
- // create a firmware image in memory and copy the input_file to it
- buf = malloc(buflen);
- memcpy(buf, &header, sizeof(header));
- memcpy(&buf[sizeof(header)], input_file, len);
- // CRC of temporary header + buf
- header.crc = htonl(crc32buf(buf, buflen));
- memcpy(buf, &header, sizeof(header));
- // write the buf
- if ((fd = open(argv[3], O_CREAT|O_WRONLY|O_TRUNC,0644)) < 0
- || write(fd, buf, buflen) != buflen
- || close(fd) < 0)
- {
- fprintf(stderr, "Error storing file %s: %s\n", argv[3], strerror(errno));
- exit(2);
- }
- free(buf);
- munmap(input_file,len);
- return 0;
- }
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