package/system/mtd/src/linksys_bootcount_fix.c

   1 /*
   2  * Linksys boot counter reset code for mtd
   3  *
   4  * Copyright (C) 2013 Jonas Gorski <jogo@openwrt.org>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License v2
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18  *
  19  */
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <stddef.h>
  24 #include <unistd.h>
  25 #include <fcntl.h>
  26 #include <sys/mman.h>
  27 #include <sys/stat.h>
  28 #include <endian.h>
  29 #include <string.h>
  30 #include <errno.h>
  31 #include <stdint.h>
  32
  33 #include <sys/ioctl.h>
  34 #include <mtd/mtd-user.h>
  35
  36 #include "mtd.h"
  37
  38 #define BOOTCOUNT_MAGIC 0x20110811
  39
  40 struct bootcounter {
  41         uint32_t magic;
  42         uint32_t count;
  43         uint32_t checksum;
  44 };
  45
  46 static char page[2048];
  47
  48 int mtd_resetbc(const char *mtd)
  49 {
  50         struct mtd_info_user mtd_info;
  51         struct bootcounter *curr = (struct bootcounter *)page;
  52         unsigned int i;
  53         int last_count = 0;
  54         int num_bc;
  55         int fd;
  56         int ret;
  57
  58         fd = mtd_check_open(mtd);
  59
  60         if (ioctl(fd, MEMGETINFO, &mtd_info) < 0) {
  61                 fprintf(stderr, "failed to get mtd info!\n");
  62                 return -1;
  63         }
  64
  65         num_bc = mtd_info.size / 16;
  66
  67         for (i = 0; i < num_bc; i++) {
  68                 pread(fd, curr, sizeof(*curr), i * 16);
  69
  70                 if (curr->magic != (BOOTCOUNT_MAGIC) && curr->magic != 0xffffffff) {
  71                         fprintf(stderr, "unexpected magic %08x, bailing out\n", curr->magic);
  72                         goto out;
  73                 }
  74
  75                 if (curr->magic == 0xffffffff)
  76                         break;
  77
  78                 last_count = curr->count;
  79         }
  80
  81         /* no need to do writes when last boot count is already 0 */
  82         if (last_count == 0)
  83                 goto out;
  84
  85
  86         if (i == num_bc) {
  87                 struct erase_info_user erase_info;
  88                 erase_info.start = 0;
  89                 erase_info.length = mtd_info.size;
  90
  91                 /* erase block */
  92                 ret = ioctl(fd, MEMERASE, &erase_info);
  93                 if (ret < 0) {
  94                         fprintf(stderr, "failed to erase block: %i\n", ret);
  95                         return -1;
  96                 }
  97
  98                 i = 0;
  99         }
 100
 101         memset(curr, 0xff, 16);
 102
 103         curr->magic = BOOTCOUNT_MAGIC;
 104         curr->count = 0;
 105         curr->checksum = BOOTCOUNT_MAGIC;
 106
 107         ret = pwrite(fd, curr, 16, i * 16);
 108         if (ret < 0)
 109                 fprintf(stderr, "failed to write: %i\n", ret);
 110         sync();
 111 out:
 112         close(fd);
 113
 114         return 0;
 115 }