From: Ryan Lortie Date: Fri, 25 May 2007 01:36:59 +0000 (+0200) Subject: volume_id: support for long-filename based labels X-Git-Tag: 174~1931 X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=335b8aace33a2018c947381d32c33bcebe6cbe37 volume_id: support for long-filename based labels --- diff --git a/extras/volume_id/lib/fat.c b/extras/volume_id/lib/fat.c index 6ed16ccee..54e6bab7d 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]; @@ -88,9 +96,10 @@ struct fat32_fsinfo { 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; @@ -99,7 +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; @@ -124,17 +235,18 @@ 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, uint64_t size) { + uint8_t filename[255 * 3]; struct vfat_super_block *vs; struct vfat_dir_entry *dir; struct fat32_fsinfo *fsinfo; @@ -154,9 +266,9 @@ int volume_id_probe_vfat(struct volume_id *id, uint64_t off, uint64_t size) 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); @@ -275,15 +387,15 @@ 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); @@ -337,8 +449,8 @@ 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 */ @@ -359,9 +471,9 @@ 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);