package/system/mtd/src/seama.c

   1 /*
   2  * seama.c
   3  *
   4  * Copyright (C) 2011-2012 Gabor Juhos <juhosg@openwrt.org>
   5  *
   6  * Based on the trx fixup code:
   7  *   Copyright (C) 2005 Mike Baker
   8  *   Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  23  */
  24
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <stddef.h>
  28 #include <unistd.h>
  29 #include <fcntl.h>
  30 #include <sys/mman.h>
  31 #include <sys/stat.h>
  32 #include <string.h>
  33 #include <errno.h>
  34 #include <arpa/inet.h>
  35
  36 #include <sys/ioctl.h>
  37 #include <mtd/mtd-user.h>
  38 #include "mtd.h"
  39 #include "seama.h"
  40 #include "md5.h"
  41
  42 #if __BYTE_ORDER == __BIG_ENDIAN
  43 #define STORE32_LE(X)           ((((X) & 0x000000FF) << 24) | (((X) & 0x0000FF00) << 8) | (((X) & 0x00FF0000) >> 8) | (((X) & 0xFF000000) >> 24))
  44 #elif __BYTE_ORDER == __LITTLE_ENDIAN
  45 #define STORE32_LE(X)           (X)
  46 #else
  47 #error unknown endianness!
  48 #endif
  49
  50 ssize_t pread(int fd, void *buf, size_t count, off_t offset);
  51 ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset);
  52
  53 int
  54 seama_fix_md5(struct seama_entity_header *shdr, char *buf, size_t len)
  55 {
  56         char *data;
  57         size_t msize;
  58         size_t isize;
  59         MD5_CTX ctx;
  60         unsigned char digest[16];
  61         int i;
  62
  63         if (len < sizeof(struct seama_entity_header))
  64                 return -1;
  65
  66         isize = ntohl(shdr->size);
  67         msize = ntohs(shdr->metasize);
  68         if (isize == 0) {
  69                 /* the image contains no checksum */
  70                 return -1;
  71         }
  72
  73         len -= sizeof(struct seama_entity_header) + msize;
  74         if (isize > len)
  75                 isize = len;
  76
  77         data = buf + sizeof(struct seama_entity_header) + msize;
  78
  79         MD5_Init(&ctx);
  80         MD5_Update(&ctx, data, isize);
  81         MD5_Final(digest, &ctx);
  82
  83         if (!memcmp(digest, shdr->md5, sizeof(digest))) {
  84                 if (quiet < 2)
  85                         fprintf(stderr, "the header is fixed already\n");
  86                 return -1;
  87         }
  88
  89         if (quiet < 2) {
  90                 fprintf(stderr, "new size:%u, new MD5: ", isize);
  91                 for (i = 0; i < sizeof(digest); i++)
  92                         fprintf(stderr, "%02x", digest[i]);
  93
  94                 fprintf(stderr, "\n");
  95         }
  96
  97         /* update the size in the image */
  98         shdr->size = htonl(isize);
  99
 100         /* update the checksum in the image */
 101         memcpy(shdr->md5, digest, sizeof(digest));
 102
 103         return 0;
 104 }
 105
 106 int
 107 mtd_fixseama(const char *mtd, size_t offset)
 108 {
 109         int fd;
 110         char *first_block;
 111         char *buf;
 112         ssize_t res;
 113         size_t block_offset;
 114         struct seama_entity_header *shdr;
 115
 116         if (quiet < 2)
 117                 fprintf(stderr, "Trying to fix SEAMA header in %s at 0x%x...\n",
 118                         mtd, offset);
 119
 120         block_offset = offset & ~(erasesize - 1);
 121         offset -= block_offset;
 122
 123         fd = mtd_check_open(mtd);
 124         if(fd < 0) {
 125                 fprintf(stderr, "Could not open mtd device: %s\n", mtd);
 126                 exit(1);
 127         }
 128
 129         if (block_offset + erasesize > mtdsize) {
 130                 fprintf(stderr, "Offset too large, device size 0x%x\n",
 131                         mtdsize);
 132                 exit(1);
 133         }
 134
 135         first_block = malloc(erasesize);
 136         if (!first_block) {
 137                 perror("malloc");
 138                 exit(1);
 139         }
 140
 141         res = pread(fd, first_block, erasesize, block_offset);
 142         if (res != erasesize) {
 143                 perror("pread");
 144                 exit(1);
 145         }
 146
 147         shdr = (struct seama_entity_header *)first_block;
 148         if (shdr->magic != htonl(SEAMA_MAGIC)) {
 149                 fprintf(stderr, "No SEAMA header found\n");
 150                 return -1;
 151         }
 152
 153         buf = malloc(mtdsize);
 154         if (!buf) {
 155                 perror("malloc");
 156                 exit(1);
 157         }
 158
 159         res = pread(fd, buf, mtdsize, block_offset);
 160         if (res != mtdsize) {
 161                 perror("pread");
 162                 exit(1);
 163         }
 164
 165         if (seama_fix_md5(shdr, buf, mtdsize))
 166                 goto out;
 167
 168         if (mtd_erase_block(fd, block_offset)) {
 169                 fprintf(stderr, "Can't erease block at 0x%x (%s)\n",
 170                         block_offset, strerror(errno));
 171                 exit(1);
 172         }
 173
 174         if (quiet < 2)
 175                 fprintf(stderr, "Rewriting block at 0x%x\n", block_offset);
 176
 177         if (pwrite(fd, first_block, erasesize, block_offset) != erasesize) {
 178                 fprintf(stderr, "Error writing block (%s)\n", strerror(errno));
 179                 exit(1);
 180         }
 181
 182         if (quiet < 2)
 183                 fprintf(stderr, "Done.\n");
 184
 185 out:
 186         close (fd);
 187         sync();
 188
 189         return 0;
 190 }
 191