diff options
Diffstat (limited to 'shlibs/blkid/src/probers/vfat.c')
-rw-r--r-- | shlibs/blkid/src/probers/vfat.c | 364 |
1 files changed, 364 insertions, 0 deletions
diff --git a/shlibs/blkid/src/probers/vfat.c b/shlibs/blkid/src/probers/vfat.c new file mode 100644 index 000000000..a83175c0b --- /dev/null +++ b/shlibs/blkid/src/probers/vfat.c @@ -0,0 +1,364 @@ +/* + * Copyright (C) 1999 by Andries Brouwer + * Copyright (C) 1999, 2000, 2003 by Theodore Ts'o + * Copyright (C) 2001 by Andreas Dilger + * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org> + * Copyright (C) 2008 Karel Zak <kzak@redhat.com> + * + * This file may be redistributed under the terms of the + * GNU Lesser General Public License. + */ +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <errno.h> +#include <ctype.h> +#include <stdint.h> + +#include "blkidP.h" + +/* Yucky misaligned values */ +struct vfat_super_block { +/* 00*/ unsigned char vs_ignored[3]; +/* 03*/ unsigned char vs_sysid[8]; +/* 0b*/ unsigned char vs_sector_size[2]; +/* 0d*/ uint8_t vs_cluster_size; +/* 0e*/ uint16_t vs_reserved; +/* 10*/ uint8_t vs_fats; +/* 11*/ unsigned char vs_dir_entries[2]; +/* 13*/ unsigned char vs_sectors[2]; +/* 15*/ unsigned char vs_media; +/* 16*/ uint16_t vs_fat_length; +/* 18*/ uint16_t vs_secs_track; +/* 1a*/ uint16_t vs_heads; +/* 1c*/ uint32_t vs_hidden; +/* 20*/ uint32_t vs_total_sect; +/* 24*/ uint32_t vs_fat32_length; +/* 28*/ uint16_t vs_flags; +/* 2a*/ uint8_t vs_version[2]; +/* 2c*/ uint32_t vs_root_cluster; +/* 30*/ uint16_t vs_fsinfo_sector; +/* 32*/ uint16_t vs_backup_boot; +/* 34*/ uint16_t vs_reserved2[6]; +/* 40*/ unsigned char vs_unknown[3]; +/* 43*/ unsigned char vs_serno[4]; +/* 47*/ unsigned char vs_label[11]; +/* 52*/ unsigned char vs_magic[8]; +/* 5a*/ unsigned char vs_dummy2[164]; +/*1fe*/ unsigned char vs_pmagic[2]; +}; + +/* Yucky misaligned values */ +struct msdos_super_block { +/* 00*/ unsigned char ms_ignored[3]; +/* 03*/ unsigned char ms_sysid[8]; +/* 0b*/ unsigned char ms_sector_size[2]; +/* 0d*/ uint8_t ms_cluster_size; +/* 0e*/ uint16_t ms_reserved; +/* 10*/ uint8_t ms_fats; +/* 11*/ unsigned char ms_dir_entries[2]; +/* 13*/ unsigned char ms_sectors[2]; +/* 15*/ unsigned char ms_media; +/* 16*/ uint16_t ms_fat_length; +/* 18*/ uint16_t ms_secs_track; +/* 1a*/ uint16_t ms_heads; +/* 1c*/ uint32_t ms_hidden; +/* 20*/ uint32_t ms_total_sect; +/* 24*/ unsigned char ms_unknown[3]; +/* 27*/ unsigned char ms_serno[4]; +/* 2b*/ unsigned char ms_label[11]; +/* 36*/ unsigned char ms_magic[8]; +/* 3d*/ unsigned char ms_dummy2[192]; +/*1fe*/ unsigned char ms_pmagic[2]; +}; + +struct vfat_dir_entry { + uint8_t name[11]; + uint8_t attr; + uint16_t time_creat; + uint16_t date_creat; + uint16_t time_acc; + uint16_t date_acc; + uint16_t cluster_high; + uint16_t time_write; + uint16_t date_write; + uint16_t cluster_low; + uint32_t size; +}; + +struct fat32_fsinfo { + uint8_t signature1[4]; + uint32_t reserved1[120]; + uint8_t signature2[4]; + uint32_t free_clusters; + uint32_t next_cluster; + uint32_t reserved2[4]; +}; + +/* maximum number of clusters */ +#define FAT12_MAX 0xFF4 +#define FAT16_MAX 0xFFF4 +#define FAT32_MAX 0x0FFFFFF6 + +#define FAT_ATTR_VOLUME_ID 0x08 +#define FAT_ATTR_DIR 0x10 +#define FAT_ATTR_LONG_NAME 0x0f +#define FAT_ATTR_MASK 0x3f +#define FAT_ENTRY_FREE 0xe5 + +static const char *no_name = "NO NAME "; + +static unsigned char *search_fat_label(struct vfat_dir_entry *dir, int count) +{ + int i; + + for (i = 0; i < count; i++) { + if (dir[i].name[0] == 0x00) + break; + + if ((dir[i].name[0] == FAT_ENTRY_FREE) || + (dir[i].cluster_high != 0 || dir[i].cluster_low != 0) || + ((dir[i].attr & FAT_ATTR_MASK) == FAT_ATTR_LONG_NAME)) + continue; + + if ((dir[i].attr & (FAT_ATTR_VOLUME_ID | FAT_ATTR_DIR)) == + FAT_ATTR_VOLUME_ID) { + return dir[i].name; + } + } + return 0; +} + +/* + * The FAT filesystem could be without a magic string in superblock + * (e.g. old floppies). This heuristic for FAT detection is inspired + * by libvolume_id and the Linux kernel. + */ +static int probe_fat_nomagic(blkid_probe pr, const struct blkid_idmag *mag) +{ + struct msdos_super_block *ms; + + ms = blkid_probe_get_sb(pr, mag, struct msdos_super_block); + if (!ms) + return -1; + + /* heads check */ + if (ms->ms_heads == 0) + return 1; + + /* cluster size check*/ + if (ms->ms_cluster_size == 0 || + (ms->ms_cluster_size & (ms->ms_cluster_size-1))) + return 1; + + /* media check */ + if (ms->ms_media < 0xf8 && ms->ms_media != 0xf0) + return 1; + + /* fat counts(Linux kernel expects at least 1 FAT table) */ + if (!ms->ms_fats) + return 1; + + /* + * OS/2 and apparently DFSee will place a FAT12/16-like + * pseudo-superblock in the first 512 bytes of non-FAT + * filesystems --- at least JFS and HPFS, and possibly others. + * So we explicitly check for those filesystems at the + * FAT12/16 filesystem magic field identifier, and if they are + * present, we rule this out as a FAT filesystem, despite the + * FAT-like pseudo-header. + */ + if ((memcmp(ms->ms_magic, "JFS ", 8) == 0) || + (memcmp(ms->ms_magic, "HPFS ", 8) == 0)) + return 1; + + return 0; +} + +/* FAT label extraction from the root directory taken from Kay + * Sievers's volume_id library */ +static int probe_vfat(blkid_probe pr, const struct blkid_idmag *mag) +{ + struct vfat_super_block *vs; + struct msdos_super_block *ms; + struct vfat_dir_entry *dir; + const unsigned char *vol_label = 0, *tmp; + unsigned char *vol_serno; + int maxloop = 100; + uint16_t sector_size, dir_entries, reserved; + uint32_t sect_count, fat_size, dir_size, cluster_count, fat_length; + uint32_t buf_size, start_data_sect, next, root_start, root_dir_entries; + const char *version = NULL; + + + /* non-standard magic strings */ + if (mag->len <= 2 && probe_fat_nomagic(pr, mag) != 0) + return 1; + + vs = blkid_probe_get_sb(pr, mag, struct vfat_super_block); + if (!vs) + return -1; + + ms = blkid_probe_get_sb(pr, mag, struct msdos_super_block); + if (!ms) + return -1; + + /* sector size check */ + tmp = (unsigned char *) &ms->ms_sector_size; + sector_size = tmp[0] + (tmp[1] << 8); + if (sector_size != 0x200 && sector_size != 0x400 && + sector_size != 0x800 && sector_size != 0x1000) + return 1; + + tmp = (unsigned char *) &ms->ms_dir_entries; + dir_entries = tmp[0] + (tmp[1] << 8); + reserved = le16_to_cpu(ms->ms_reserved); + tmp = (unsigned char *) &ms->ms_sectors; + sect_count = tmp[0] + (tmp[1] << 8); + if (sect_count == 0) + sect_count = le32_to_cpu(ms->ms_total_sect); + + fat_length = le16_to_cpu(ms->ms_fat_length); + if (fat_length == 0) + fat_length = le32_to_cpu(vs->vs_fat32_length); + + fat_size = fat_length * ms->ms_fats; + dir_size = ((dir_entries * sizeof(struct vfat_dir_entry)) + + (sector_size-1)) / sector_size; + + cluster_count = sect_count - (reserved + fat_size + dir_size); + if (ms->ms_cluster_size == 0) + return 1; + cluster_count /= ms->ms_cluster_size; + + if (cluster_count > FAT32_MAX) + return 1; + + if (ms->ms_fat_length) { + /* the label may be an attribute in the root directory */ + root_start = (reserved + fat_size) * sector_size; + root_dir_entries = vs->vs_dir_entries[0] + + (vs->vs_dir_entries[1] << 8); + + buf_size = root_dir_entries * sizeof(struct vfat_dir_entry); + dir = (struct vfat_dir_entry *) + blkid_probe_get_buffer(pr, root_start, buf_size); + if (dir) + vol_label = search_fat_label(dir, root_dir_entries); + + if (!vol_label || !memcmp(vol_label, no_name, 11)) + vol_label = ms->ms_label; + vol_serno = ms->ms_serno; + + blkid_probe_set_value(pr, "SEC_TYPE", (unsigned char *) "msdos", + sizeof("msdos")); + + if (cluster_count < FAT12_MAX) + version = "FAT12"; + else if (cluster_count < FAT16_MAX) + version = "FAT16"; + } else { + unsigned char *buf; + uint16_t fsinfo_sect; + + /* Search the FAT32 root dir for the label attribute */ + buf_size = vs->vs_cluster_size * sector_size; + start_data_sect = reserved + fat_size; + + version = "FAT32"; + + next = le32_to_cpu(vs->vs_root_cluster); + while (next && --maxloop) { + uint32_t next_sect_off; + uint64_t next_off, fat_entry_off; + int count; + + next_sect_off = (next - 2) * vs->vs_cluster_size; + next_off = (start_data_sect + next_sect_off) * + sector_size; + + dir = (struct vfat_dir_entry *) + blkid_probe_get_buffer(pr, next_off, buf_size); + if (dir == NULL) + break; + + count = buf_size / sizeof(struct vfat_dir_entry); + + vol_label = search_fat_label(dir, count); + if (vol_label) + break; + + /* get FAT entry */ + fat_entry_off = (reserved * sector_size) + + (next * sizeof(uint32_t)); + buf = blkid_probe_get_buffer(pr, fat_entry_off, buf_size); + if (buf == NULL) + break; + + /* set next cluster */ + next = le32_to_cpu(*((uint32_t *) buf) & 0x0fffffff); + } + + if (!vol_label || !memcmp(vol_label, no_name, 11)) + vol_label = vs->vs_label; + vol_serno = vs->vs_serno; + + /* + * FAT32 should have a valid signature in the fsinfo block, + * but also allow all bytes set to '\0', because some volumes + * do not set the signature at all. + */ + fsinfo_sect = le16_to_cpu(vs->vs_fsinfo_sector); + if (fsinfo_sect) { + struct fat32_fsinfo *fsinfo; + + buf = blkid_probe_get_buffer(pr, + fsinfo_sect * sector_size, + sizeof(struct fat32_fsinfo)); + if (buf == NULL) + return -1; + + fsinfo = (struct fat32_fsinfo *) buf; + if (memcmp(fsinfo->signature1, "\x52\x52\x61\x41", 4) != 0 && + memcmp(fsinfo->signature1, "\x00\x00\x00\x00", 4) != 0) + return -1; + if (memcmp(fsinfo->signature2, "\x72\x72\x41\x61", 4) != 0 && + memcmp(fsinfo->signature2, "\x00\x00\x00\x00", 4) != 0) + return -1; + } + } + + if (vol_label && memcmp(vol_label, no_name, 11)) + blkid_probe_set_label(pr, (unsigned char *) vol_label, 11); + + /* We can't just print them as %04X, because they are unaligned */ + blkid_probe_sprintf_uuid(pr, vol_serno, 4, "%02X%02X-%02X%02X", + vol_serno[3], vol_serno[2], vol_serno[1], vol_serno[0]); + + if (version) + blkid_probe_set_version(pr, version); + + return 0; +} + + +const struct blkid_idinfo vfat_idinfo = +{ + .name = "vfat", + .usage = BLKID_USAGE_FILESYSTEM, + .probefunc = probe_vfat, + .magics = + { + { .magic = "MSWIN", .len = 5, .sboff = 0x52 }, + { .magic = "FAT32 ", .len = 8, .sboff = 0x52 }, + { .magic = "MSDOS", .len = 5, .sboff = 0x36 }, + { .magic = "FAT16 ", .len = 8, .sboff = 0x36 }, + { .magic = "FAT12 ", .len = 8, .sboff = 0x36 }, + { .magic = "\353", .len = 1, }, + { .magic = "\351", .len = 1, }, + { .magic = "\125\252", .len = 2, .sboff = 0x1fe }, + { NULL } + } +}; + |