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volume_id: support for long-filename based labels

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This commit is contained in:
Ryan Lortie
2007-05-25 03:36:59 +02:00
committed by Kay Sievers
parent a3b836c6c2
commit 335b8aace3
1 changed files with 127 additions and 15 deletions
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extras/volume_id/lib/fat.c
+127 -15
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@@ -1,7 +1,8 @@
/*
* volume_id - reads filesystem label and uuid
*
* Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
* Copyright (C) 2004-2007 Kay Sievers <kay.sievers@vrfy.org>
* Copyright (C) 2007 Ryan Lortie <desrt@desrt.ca>
*
* 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);