diff options
Diffstat (limited to 'fs/fdos/fat.c')
| -rw-r--r-- | fs/fdos/fat.c | 85 |
1 files changed, 41 insertions, 44 deletions
diff --git a/fs/fdos/fat.c b/fs/fdos/fat.c index 42df755..2ef2371 100644 --- a/fs/fdos/fat.c +++ b/fs/fdos/fat.c @@ -33,24 +33,24 @@ /*----------------------------------------------------------------------------- - * fat_decode -- + * 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; - + return 1; + if (num & 1) - return ((address [1] & 0xff) << 4) | ((address [0] & 0xf0 ) >> 4); + return ((address [1] & 0xff) << 4) | ((address [0] & 0xf0 ) >> 4); else - return ((address [1] & 0xf) << 8) | (address [0] & 0xff ); + return ((address [1] & 0xf) << 8) | (address [0] & 0xff ); } /*----------------------------------------------------------------------------- - * check_fat -- + * check_fat -- *----------------------------------------------------------------------------- */ static int check_fat (Fs_t *fs) @@ -59,48 +59,48 @@ static int check_fat (Fs_t *fs) /* 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); - } + f = fat_decode (fs, i); + if (f < FAT12_LAST && f > fs -> num_clus){ + /* Wrong cluster number detected */ + return (-1); + } } return (0); } /*----------------------------------------------------------------------------- - * read_one_fat -- + * 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); + (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 -> 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); + /* Too much clusters */ + return (-1); } return check_fat (fs); } /*----------------------------------------------------------------------------- - * read_fat -- + * read_fat -- *----------------------------------------------------------------------------- */ int read_fat (BootSector_t *boot, Fs_t *fs) @@ -111,35 +111,32 @@ int read_fat (BootSector_t *boot, Fs_t *fs) /* Allocate Fat Buffer */ buflen = fs -> fat_len * SZ_STD_SECTOR; if (fs -> fat_buf) { - free (fs -> fat_buf); + free (fs -> fat_buf); } if ((fs -> fat_buf = malloc (buflen)) == NULL) { - return (-1); + 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 (read_one_fat (boot, fs, i) == 0) { + /* Fat is OK */ + fs -> num_fat = i; + break; + } } if (i == fs -> nb_fat){ - return (-1); + return (-1); } - + if (fs -> fat_len > (((fs -> num_clus + 2) * - (FAT_BITS / 4) -1 ) / 2 / - SZ_STD_SECTOR + 1)) { - return (-1); + (FAT_BITS / 4) -1 ) / 2 / + SZ_STD_SECTOR + 1)) { + return (-1); } return (0); } - - - #endif |