X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=extras%2Fvolume_id%2Flib%2Ffat.c;h=3ddf0258eb631fafd051efc4e443d441d778cddb;hb=8b5238670d2e741bc71ae3e79b499682965dc2fd;hp=74336b4e6d0df79ca773e382d04d4f4ba5d6e7d3;hpb=f7dd3a57a40282f1c3fb9ad90a30d58b31b64ff8;p=elogind.git diff --git a/extras/volume_id/lib/fat.c b/extras/volume_id/lib/fat.c index 74336b4e6..3ddf0258e 100644 --- a/extras/volume_id/lib/fat.c +++ b/extras/volume_id/lib/fat.c @@ -1,7 +1,8 @@ /* * volume_id - reads filesystem label and uuid * - * Copyright (C) 2004 Kay Sievers + * Copyright (C) 2004-2007 Kay Sievers + * Copyright (C) 2007 Ryan Lortie * * 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 @@ -34,6 +35,13 @@ #define FAT_ATTR_MASK 0x3f #define FAT_ENTRY_FREE 0xe5 +#define VFAT_LFN_SEQ_MASK 0x3f +#define VFAT_LFN_SEQ_LAST 0x40 +#define VFAT_LFN_SEQ_MAX 20 +#define VFAT_LFN_CHARS_PER_ENTRY (5 + 6 + 2) +#define VFAT_LOWERCASE_NAME 0x10 +#define VFAT_LOWERCASE_EXT 0x08 + struct vfat_super_block { uint8_t boot_jump[3]; uint8_t sysid[8]; @@ -63,7 +71,7 @@ struct vfat_super_block { uint16_t flags; uint8_t version[2]; uint32_t root_cluster; - uint16_t insfo_sector; + uint16_t fsinfo_sector; uint16_t backup_boot; uint16_t reserved2[6]; uint8_t unknown[3]; @@ -76,12 +84,22 @@ struct vfat_super_block { } PACKED type; } PACKED; +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]; +} PACKED; + struct vfat_dir_entry { uint8_t name[11]; uint8_t attr; + uint8_t lowercase; + uint8_t fine_time_creat; uint16_t time_creat; uint16_t date_creat; - uint16_t time_acc; uint16_t date_acc; uint16_t cluster_high; uint16_t time_write; @@ -90,7 +108,109 @@ struct vfat_dir_entry { uint32_t size; } PACKED; -static uint8_t *get_attr_volume_id(struct vfat_dir_entry *dir, unsigned int count) + +struct vfat_lfn_entry { + uint8_t seq; + uint16_t name0[5]; + uint8_t attr; + uint8_t reserved; + uint8_t cksum; + uint16_t name1[6]; + uint16_t cluster; + uint16_t name2[2]; +} PACKED; + +static uint8_t fat_lfn_checksum(const uint8_t name[11]) +{ + uint8_t cksum = 0; + int i; + + /* http://en.wikipedia.org/wiki/File_Allocation_Table */ + for (i = 0; i < 11; i++) + cksum = ((cksum & 1) ? 0x80 : 0) + (cksum >> 1) + name[i]; + + return cksum; +} + +static size_t fat_read_lfn(uint8_t *filename, size_t fnsize, + struct vfat_dir_entry *dir, + struct vfat_dir_entry *entry) +{ + uint8_t buffer[VFAT_LFN_SEQ_MAX * VFAT_LFN_CHARS_PER_ENTRY * 2]; + uint8_t expected_seq = 1; + uint8_t cksum; + size_t len = 0; + size_t fnlen = 0; + + cksum = fat_lfn_checksum(entry->name); + + while (--entry >= dir) { + struct vfat_lfn_entry *lfn = (struct vfat_lfn_entry *) entry; + + if (expected_seq > VFAT_LFN_SEQ_MAX) + break; + + if ((lfn->attr & FAT_ATTR_MASK) != FAT_ATTR_LONG_NAME) + break; + + if (lfn->cksum != cksum) + break; + + if ((lfn->seq & VFAT_LFN_SEQ_MASK) != expected_seq++) + break; + + if (lfn->cluster != 0) + break; + + /* extra paranoia -- should never happen */ + if (len + sizeof(lfn->name0) + sizeof(lfn->name1) + + sizeof(lfn->name2) > sizeof(buffer)) + break; + + memcpy (&buffer[len], lfn->name0, sizeof(lfn->name0)); + len += sizeof(lfn->name0); + memcpy (&buffer[len], lfn->name1, sizeof(lfn->name1)); + len += sizeof(lfn->name1); + memcpy (&buffer[len], lfn->name2, sizeof(lfn->name2)); + len += sizeof(lfn->name2); + + if (lfn->seq & VFAT_LFN_SEQ_LAST) { + fnlen = volume_id_set_unicode16(filename, fnsize, buffer, LE, len); + break; + } + } + + return fnlen; +} + +static size_t fat_read_filename(uint8_t *filename, size_t fnsize, + struct vfat_dir_entry *dir, struct vfat_dir_entry *entry) +{ + size_t len; + int i; + + /* check if maybe we have LFN entries */ + len = fat_read_lfn(filename, fnsize, dir, entry); + if (len > 0) + goto out; + + /* else, read the normal 8.3 name */ + for (i = 0; i < 11; i++) { + if (entry->lowercase & ((i < 8) ? VFAT_LOWERCASE_NAME : VFAT_LOWERCASE_EXT)) + filename[i] = tolower(entry->name[i]); + else + filename[i] = entry->name[i]; + } + len = 11; + +out: + filename[len] = '\0'; + return len; +} + +/* fills filename, returns string length */ +static size_t get_fat_attr_volume_id(uint8_t *filename, size_t fnsize, + struct vfat_dir_entry *dir, unsigned int count) { unsigned int i; @@ -115,19 +235,21 @@ static uint8_t *get_attr_volume_id(struct vfat_dir_entry *dir, unsigned int coun continue; dbg("found ATTR_VOLUME_ID id in root dir"); - return dir[i].name; + return fat_read_filename(filename, fnsize, dir, &dir[i]); } dbg("skip dir entry"); } - return NULL; + return 0; } -int volume_id_probe_vfat(struct volume_id *id, uint64_t off) +int volume_id_probe_vfat(struct volume_id *id, uint64_t off, uint64_t size) { + uint8_t filename[255 * 3]; struct vfat_super_block *vs; struct vfat_dir_entry *dir; + struct fat32_fsinfo *fsinfo; uint16_t sector_size; uint16_t dir_entries; uint32_t sect_count; @@ -141,24 +263,28 @@ int volume_id_probe_vfat(struct volume_id *id, uint64_t off) uint64_t root_start; uint32_t start_data_sect; uint16_t root_dir_entries; + uint16_t fsinfo_sect; uint8_t *buf; uint32_t buf_size; - uint8_t *label = NULL; uint32_t next; int maxloop; + size_t fnlen; info("probing at offset 0x%llx", (unsigned long long) off); - vs = (struct vfat_super_block *) volume_id_get_buffer(id, off, 0x200); - if (vs == NULL) + buf = volume_id_get_buffer(id, off, 0x400); + if (buf == NULL) + return -1; + + /* check signature */ + if (buf[510] != 0x55 || buf[511] != 0xaa) return -1; - /* believe only that's fat, don't trust the version - * the cluster_count will tell us - */ + vs = (struct vfat_super_block *) buf; if (memcmp(vs->sysid, "NTFS", 4) == 0) return -1; + /* believe only that's fat, don't trust the version */ if (memcmp(vs->type.fat32.magic, "MSWIN", 5) == 0) goto magic; @@ -174,9 +300,7 @@ int volume_id_probe_vfat(struct volume_id *id, uint64_t off) if (memcmp(vs->type.fat.magic, "FAT12 ", 8) == 0) goto magic; - /* some old floppies don't have a magic, so we expect the boot code to match */ - - /* boot jump address check */ + /* some old floppies don't have a magic, expect the boot jump address to match */ if ((vs->boot_jump[0] != 0xeb || vs->boot_jump[2] != 0x90) && vs->boot_jump[0] != 0xe9) return -1; @@ -186,7 +310,7 @@ magic: if (!vs->reserved) return -1; - /* fat count*/ + /* fat count */ if (!vs->fats) return -1; @@ -194,15 +318,14 @@ magic: if (vs->media < 0xf8 && vs->media != 0xf0) return -1; - /* cluster size check*/ + /* cluster size check */ if (vs->sectors_per_cluster == 0 || (vs->sectors_per_cluster & (vs->sectors_per_cluster-1))) return -1; /* sector size check */ sector_size = le16_to_cpu(vs->sector_size); - if (sector_size != 0x200 && sector_size != 0x400 && - sector_size != 0x800 && sector_size != 0x1000) + if (sector_size == 0 || ((sector_size & (sector_size-1)) != 0)) return -1; dbg("sector_size 0x%x", sector_size); @@ -263,23 +386,38 @@ magic: dir = (struct vfat_dir_entry*) buf; - label = get_attr_volume_id(dir, root_dir_entries); + fnlen = get_fat_attr_volume_id(filename, sizeof(filename), dir, root_dir_entries); vs = (struct vfat_super_block *) volume_id_get_buffer(id, off, 0x200); if (vs == NULL) return -1; - if (label != NULL && memcmp(label, "NO NAME ", 11) != 0) { - volume_id_set_label_raw(id, label, 11); - volume_id_set_label_string(id, label, 11); + if (fnlen > 0 && memcmp(filename, "NO NAME ", 11) != 0) { + volume_id_set_label_raw(id, filename, fnlen); + volume_id_set_label_string(id, filename, fnlen); } else if (memcmp(vs->type.fat.label, "NO NAME ", 11) != 0) { volume_id_set_label_raw(id, vs->type.fat.label, 11); volume_id_set_label_string(id, vs->type.fat.label, 11); } - volume_id_set_uuid(id, vs->type.fat.serno, UUID_DOS); + volume_id_set_uuid(id, vs->type.fat.serno, 0, UUID_DOS); goto found; fat32: + /* FAT32 should have a valid signature in the fsinfo block */ + fsinfo_sect = le16_to_cpu(vs->type.fat32.fsinfo_sector); + buf = volume_id_get_buffer(id, off + (fsinfo_sect * sector_size), 0x200); + if (buf == NULL) + return -1; + fsinfo = (struct fat32_fsinfo *) buf; + if (memcmp(fsinfo->signature1, "\x52\x52\x61\x41", 4) != 0) + return -1; + if (memcmp(fsinfo->signature2, "\x72\x72\x41\x61", 4) != 0) + return -1 ; + + vs = (struct vfat_super_block *) volume_id_get_buffer(id, off, 0x200); + if (vs == NULL) + return -1; + strcpy(id->type_version, "FAT32"); /* FAT32 root dir is a cluster chain like any other directory */ @@ -310,8 +448,8 @@ fat32: count = buf_size / sizeof(struct vfat_dir_entry); dbg("expected entries 0x%x", count); - label = get_attr_volume_id(dir, count); - if (label) + fnlen = get_fat_attr_volume_id(filename, sizeof(filename), dir, count); + if (fnlen > 0) break; /* get FAT entry */ @@ -322,7 +460,7 @@ fat32: /* set next cluster */ next = le32_to_cpu(*((uint32_t *) buf)) & 0x0fffffff; - if (next == 0) + if (next < 2 || next >= 0x0ffffff0) break; } if (maxloop == 0) @@ -332,14 +470,14 @@ fat32: if (vs == NULL) return -1; - if (label != NULL && memcmp(label, "NO NAME ", 11) != 0) { - volume_id_set_label_raw(id, label, 11); - volume_id_set_label_string(id, label, 11); + if (fnlen > 0 && memcmp(filename, "NO NAME ", 11) != 0) { + volume_id_set_label_raw(id, filename, fnlen); + volume_id_set_label_string(id, filename, fnlen); } else if (memcmp(vs->type.fat32.label, "NO NAME ", 11) != 0) { volume_id_set_label_raw(id, vs->type.fat32.label, 11); volume_id_set_label_string(id, vs->type.fat32.label, 11); } - volume_id_set_uuid(id, vs->type.fat32.serno, UUID_DOS); + volume_id_set_uuid(id, vs->type.fat32.serno, 0, UUID_DOS); found: volume_id_set_usage(id, VOLUME_ID_FILESYSTEM);