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Diffstat (limited to 'extras/volume_id/lib/fat.c')
-rw-r--r--extras/volume_id/lib/fat.c142
1 files changed, 127 insertions, 15 deletions
diff --git a/extras/volume_id/lib/fat.c b/extras/volume_id/lib/fat.c
index 6ed16ccee0..54e6bab7d2 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 <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);
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-12-26 02:11:53 +0000