/* * (C) Copyright 2002 * St�ubli Faverges - <www.staubli.com> * Pierre AUBERT p.aubert@staubli.com * * See file CREDITS for list of people who contributed to this * project. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. * * 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 */ #include <common.h> #include <config.h> #include <malloc.h> #if (CONFIG_COMMANDS & CFG_CMD_FDOS) #include "dos.h" #include "fdos.h" /*----------------------------------------------------------------------------- * fat_decode -- *----------------------------------------------------------------------------- */ unsigned int fat_decode (Fs_t *fs, unsigned int num) { unsigned int start = num * 3 / 2; unsigned char *address = fs -> fat_buf + start; if (num < 2 || start + 1 > (fs -> fat_len * SZ_STD_SECTOR)) return 1; if (num & 1) return ((address [1] & 0xff) << 4) | ((address [0] & 0xf0 ) >> 4); else return ((address [1] & 0xf) << 8) | (address [0] & 0xff ); } /*----------------------------------------------------------------------------- * check_fat -- *----------------------------------------------------------------------------- */ static int check_fat (Fs_t *fs) { int i, f; /* Cluster verification */ for (i = 3 ; i < fs -> num_clus; i++){ f = fat_decode (fs, i); if (f < FAT12_LAST && f > fs -> num_clus){ /* Wrong cluster number detected */ return (-1); } } return (0); } /*----------------------------------------------------------------------------- * read_one_fat -- *----------------------------------------------------------------------------- */ static int read_one_fat (BootSector_t *boot, Fs_t *fs, int nfat) { if (dev_read (fs -> fat_buf, (fs -> fat_start + nfat * fs -> fat_len), fs -> fat_len) < 0) { return (-1); } if (fs -> fat_buf [0] || fs -> fat_buf [1] || fs -> fat_buf [2]) { if ((fs -> fat_buf [0] != boot -> descr && (fs -> fat_buf [0] != 0xf9 || boot -> descr != MEDIA_STD)) || fs -> fat_buf [0] < MEDIA_STD){ /* Unknown Media */ return (-1); } if (fs -> fat_buf [1] != 0xff || fs -> fat_buf [2] != 0xff){ /* FAT doesn't start with good values */ return (-1); } } if (fs -> num_clus >= FAT12_MAX_NB) { /* Too much clusters */ return (-1); } return check_fat (fs); } /*----------------------------------------------------------------------------- * read_fat -- *----------------------------------------------------------------------------- */ int read_fat (BootSector_t *boot, Fs_t *fs) { unsigned int buflen; int i; /* Allocate Fat Buffer */ buflen = fs -> fat_len * SZ_STD_SECTOR; if (fs -> fat_buf) { free (fs -> fat_buf); } if ((fs -> fat_buf = malloc (buflen)) == NULL) { return (-1); } /* Try to read each Fat */ for (i = 0; i< fs -> nb_fat; i++){ if (read_one_fat (boot, fs, i) == 0) { /* Fat is OK */ fs -> num_fat = i; break; } } if (i == fs -> nb_fat){ return (-1); } if (fs -> fat_len > (((fs -> num_clus + 2) * (FAT_BITS / 4) -1 ) / 2 / SZ_STD_SECTOR + 1)) { return (-1); } return (0); } #endif