diff options
Diffstat (limited to 'libblkid/src/superblocks/exfat.c')
| -rw-r--r-- | libblkid/src/superblocks/exfat.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/libblkid/src/superblocks/exfat.c b/libblkid/src/superblocks/exfat.c new file mode 100644 index 0000000..f586ec7 --- /dev/null +++ b/libblkid/src/superblocks/exfat.c @@ -0,0 +1,157 @@ +/* + * Copyright (C) 2010 Andrew Nayenko <resver@gmail.com> + * + * This file may be redistributed under the terms of the + * GNU Lesser General Public License. + */ +#include "superblocks.h" + +struct exfat_super_block { + uint8_t jump[3]; + uint8_t oem_name[8]; + uint8_t __unused1[53]; + uint64_t block_start; + uint64_t block_count; + uint32_t fat_block_start; + uint32_t fat_block_count; + uint32_t cluster_block_start; + uint32_t cluster_count; + uint32_t rootdir_cluster; + uint8_t volume_serial[4]; + struct { + uint8_t vermin; + uint8_t vermaj; + } version; + uint16_t volume_state; + uint8_t block_bits; + uint8_t bpc_bits; + uint8_t fat_count; + uint8_t drive_no; + uint8_t allocated_percent; +} __attribute__((__packed__)); + +struct exfat_entry_label { + uint8_t type; + uint8_t length; + uint8_t name[22]; + uint8_t reserved[8]; +} __attribute__((__packed__)); + +#define BLOCK_SIZE(sb) (1u << (sb)->block_bits) +#define CLUSTER_SIZE(sb) (BLOCK_SIZE(sb) << (sb)->bpc_bits) +#define EXFAT_FIRST_DATA_CLUSTER 2 +#define EXFAT_LAST_DATA_CLUSTER 0xffffff6 +#define EXFAT_ENTRY_SIZE 32 + +#define EXFAT_ENTRY_EOD 0x00 +#define EXFAT_ENTRY_LABEL 0x83 + +static uint64_t block_to_offset(const struct exfat_super_block *sb, + uint64_t block) +{ + return block << sb->block_bits; +} + +static uint64_t cluster_to_block(const struct exfat_super_block *sb, + uint32_t cluster) +{ + return le32_to_cpu(sb->cluster_block_start) + + ((uint64_t) (cluster - EXFAT_FIRST_DATA_CLUSTER) + << sb->bpc_bits); +} + +static uint64_t cluster_to_offset(const struct exfat_super_block *sb, + uint32_t cluster) +{ + return block_to_offset(sb, cluster_to_block(sb, cluster)); +} + +static uint32_t next_cluster(blkid_probe pr, + const struct exfat_super_block *sb, uint32_t cluster) +{ + uint32_t *next; + uint64_t fat_offset; + + fat_offset = block_to_offset(sb, le32_to_cpu(sb->fat_block_start)) + + (uint64_t) cluster * sizeof(cluster); + next = (uint32_t *) blkid_probe_get_buffer(pr, fat_offset, + sizeof(uint32_t)); + if (!next) + return 0; + return le32_to_cpu(*next); +} + +static struct exfat_entry_label *find_label(blkid_probe pr, + const struct exfat_super_block *sb) +{ + uint32_t cluster = le32_to_cpu(sb->rootdir_cluster); + uint64_t offset = cluster_to_offset(sb, cluster); + uint8_t *entry; + const size_t max_iter = 10000; + size_t i = 0; + + for (; i < max_iter; i++) { + entry = (uint8_t *) blkid_probe_get_buffer(pr, offset, + EXFAT_ENTRY_SIZE); + if (!entry) + return NULL; + if (entry[0] == EXFAT_ENTRY_EOD) + return NULL; + if (entry[0] == EXFAT_ENTRY_LABEL) + return (struct exfat_entry_label *) entry; + + offset += EXFAT_ENTRY_SIZE; + if (offset % CLUSTER_SIZE(sb) == 0) { + cluster = next_cluster(pr, sb, cluster); + if (cluster < EXFAT_FIRST_DATA_CLUSTER) + return NULL; + if (cluster > EXFAT_LAST_DATA_CLUSTER) + return NULL; + offset = cluster_to_offset(sb, cluster); + } + } + + return NULL; +} + +static int probe_exfat(blkid_probe pr, const struct blkid_idmag *mag) +{ + struct exfat_super_block *sb; + struct exfat_entry_label *label; + + sb = blkid_probe_get_sb(pr, mag, struct exfat_super_block); + if (!sb || !CLUSTER_SIZE(sb)) + return errno ? -errno : BLKID_PROBE_NONE; + + label = find_label(pr, sb); + if (label) + blkid_probe_set_utf8label(pr, label->name, + min((size_t) label->length * 2, sizeof(label->name)), + UL_ENCODE_UTF16LE); + else if (errno) + return -errno; + + blkid_probe_sprintf_uuid(pr, sb->volume_serial, 4, + "%02hhX%02hhX-%02hhX%02hhX", + sb->volume_serial[3], sb->volume_serial[2], + sb->volume_serial[1], sb->volume_serial[0]); + + blkid_probe_sprintf_version(pr, "%u.%u", + sb->version.vermaj, sb->version.vermin); + + blkid_probe_set_block_size(pr, BLOCK_SIZE(sb)); + + return BLKID_PROBE_OK; +} + +const struct blkid_idinfo exfat_idinfo = +{ + .name = "exfat", + .usage = BLKID_USAGE_FILESYSTEM, + .probefunc = probe_exfat, + .magics = + { + { .magic = "EXFAT ", .len = 8, .sboff = 3 }, + { NULL } + } +}; |