openwrt/package/openwrt/jffs2root.c

   1 /*
   2  * jffs2root.c
   3  *
   4  * Copyright (C) 2005 Mike Baker
   5  *
   6  * $Id$
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version 2
  11  * of the License, or (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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21  *
  22  */
  23
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <stddef.h>
  27 #include <unistd.h>
  28 #include <fcntl.h>
  29 #include <sys/mman.h>
  30 #include <sys/stat.h>
  31 #include <string.h>
  32
  33
  34 #define FILENAME "/dev/mtdblock/1"
  35
  36 struct trx_header {
  37     unsigned magic;             /* "HDR0" */
  38     unsigned len;               /* Length of file including header */
  39     unsigned crc32;             /* 32-bit CRC from flag_version to end of file */
  40     unsigned flag_version;      /* 0:15 flags, 16:31 version */
  41     unsigned offsets[3];        /* Offsets of partitions from start of header */
  42 };
  43
  44 unsigned long *crc32;
  45
  46 void init_crc32()
  47 {
  48     unsigned long crc;
  49     unsigned long poly = 0xEDB88320L;
  50     int n, bit;
  51     crc32 = (unsigned long *) malloc(256 * sizeof(unsigned long));
  52     for (n = 0; n < 256; n++) {
  53         crc = (unsigned long) n;
  54         for (bit = 0; bit < 8; bit++)
  55             crc = (crc & 1) ? (poly ^ (crc >> 1)) : (crc >> 1);
  56         crc32[n] = crc;
  57     }
  58 }
  59
  60 unsigned int crc32buf(char *buf, size_t len)
  61 {
  62     unsigned int crc = 0xFFFFFFFF;
  63     for (; len; len--, buf++)
  64         crc = crc32[(crc ^ *buf) & 0xff] ^ (crc >> 8);
  65     return crc;
  66 }
  67
  68 int main(int argc, char **argv)
  69 {
  70     int fd;
  71     unsigned long len;
  72     struct trx_header *ptr;
  73     if (((fd = open(FILENAME, O_RDWR))  < 0)
  74     || ((len = lseek(fd, 0, SEEK_END)) < 0)
  75     || ((ptr = (struct trx_header *) mmap(0, len, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0)) == (void *) (-1))
  76     || (ptr->magic != 0x30524448)) {
  77         printf("Error reading trx info\n");
  78         exit(-1);
  79     }
  80
  81     if (argc > 1 && !strcmp(argv[1],"--move")) {
  82       if (ptr->offsets[1] >= ptr->len) {
  83         printf("Partition already moved outside trx\n");
  84       } else if (ptr->offsets[1] & 0x0001ffff) {
  85         printf("Partition does not start on a block boundary\n");
  86       } else {
  87         init_crc32();
  88         bzero((void *)((int)ptr + ptr->len), (size_t)(len - ptr->len));
  89         ptr->len = ptr->offsets[1];
  90         ptr->crc32 = crc32buf((void *) &(ptr->flag_version), ptr->len - offsetof(struct trx_header, flag_version));
  91         msync(ptr,len,MS_SYNC|MS_INVALIDATE);
  92         printf("Partition moved; please reboot\n");
  93       }
  94     } else {
  95       int x;
  96       printf("=== trx ===\n");
  97       printf("mapped: 0x%08x\n", (unsigned)ptr);
  98       printf(" magic: 0x%08x\n", ptr->magic);
  99       printf("   len: 0x%08x\n", ptr->len);
 100       printf("   crc: 0x%08x\n", ptr->crc32);
 101       for (x = 0; x < 3; x++)
 102         printf(" offset[%d]: 0x%08x\n", x, ptr->offsets[x]);
 103     }
 104
 105
 106     munmap((void *) ptr, sizeof(struct trx_header));
 107     return 0;
 108 }