utils/AMS/hacking/extract_fw.c

   1 /*
   2
   3 extract_fw.c - extract the main firmware image from a Sansa V2 (AMS) firmware
   4                file
   5
   6 Copyright (C) Dave Chapman 2008
   7
   8 This program is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2 of the License, or
  11 (at your option) any later version.
  12
  13 This program is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with this program; if not, write to the Free Software
  20 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
  21
  22 */
  23
  24
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <stdint.h>
  28 #include <sys/types.h>
  29 #include <sys/stat.h>
  30 #include <fcntl.h>
  31 #include <unistd.h>
  32 #include <string.h>
  33
  34
  35 /* Win32 compatibility */
  36 #ifndef O_BINARY
  37 #define O_BINARY 0
  38 #endif
  39
  40
  41 static off_t filesize(int fd) {
  42     struct stat buf;
  43
  44     if (fstat(fd,&buf) < 0) {
  45         perror("[ERR]  Checking filesize of input file");
  46         return -1;
  47     } else {
  48         return(buf.st_size);
  49     }
  50 }
  51
  52 static uint32_t get_uint32le(unsigned char* p)
  53 {
  54     return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
  55 }
  56
  57 void usage(void)
  58 {
  59     printf("Usage: extract_fw <firmware file> <output file>\n");
  60
  61     exit(1);
  62 }
  63
  64 int main(int argc, char* argv[])
  65 {
  66     char *infile, *outfile;
  67     int fdin, fdout;
  68     off_t len;
  69     uint32_t n;
  70     unsigned char* buf;
  71     uint32_t firmware_size;
  72
  73     if(argc != 3) {
  74         usage();
  75     }
  76
  77     infile = argv[1];
  78     outfile = argv[2];
  79
  80     /* Open the firmware file */
  81     fdin = open(infile,O_RDONLY|O_BINARY);
  82
  83     if (fdin < 0) {
  84         fprintf(stderr,"[ERR]  Could not open %s for reading\n",infile);
  85         return 1;
  86     }
  87
  88     if ((len = filesize(fdin)) < 0)
  89         return 1;
  90
  91     /* We will need no more memory than the total size plus the bootloader size
  92        padded to a boundary */
  93     if ((buf = malloc(len)) == NULL) {
  94         fprintf(stderr,"[ERR]  Could not allocate buffer for input file (%d bytes)\n",(int)len);
  95         return 1;
  96     }
  97
  98     n = read(fdin, buf, len);
  99
 100     if (n != (uint32_t)len) {
 101         fprintf(stderr,"[ERR] Could not read firmware file\n");
 102         return 1;
 103     }
 104
 105     close(fdin);
 106
 107     /* Get the firmware size */
 108     if (get_uint32le(&buf[0x04])==0x0000f000)
 109         firmware_size = get_uint32le(&buf[0x10]);   /* v2 format */
 110     else
 111         firmware_size = get_uint32le(&buf[0x0c]);   /* v1 format */
 112
 113     fdout = open(outfile, O_CREAT|O_TRUNC|O_WRONLY|O_BINARY,0666);
 114
 115     if (fdout < 0) {
 116         fprintf(stderr,"[ERR]  Could not open %s for writing\n",outfile);
 117         return 1;
 118     }
 119
 120     n = write(fdout, buf + 0x400, firmware_size);
 121
 122     if (n != (uint32_t)firmware_size) {
 123         fprintf(stderr,"[ERR] Could not write firmware block\n");
 124         return 1;
 125     }
 126
 127     /* Clean up */
 128     close(fdout);
 129     free(buf);
 130
 131     return 0;
 132 }