/* lfn.c - Functions for handling VFAT long filenames
Copyright (C) 1998 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>
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 Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
On Debian systems, the complete text of the GNU General Public License
can be found in /usr/share/common-licenses/GPL-3 file.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <time.h>
#include "common.h"
#include "io.h"
#include "dosfsck.h"
#include "lfn.h"
#include "file.h"
typedef struct {
__u8 id; /* sequence number for slot */
__u8 name0_4[10]; /* first 5 characters in name */
__u8 attr; /* attribute byte */
__u8 reserved; /* always 0 */
__u8 alias_checksum; /* checksum for 8.3 alias */
__u8 name5_10[12]; /* 6 more characters in name */
__u16 start; /* starting cluster number, 0 in long slots */
__u8 name11_12[4]; /* last 2 characters in name */
} LFN_ENT;
#define LFN_ID_START 0x40
#define LFN_ID_SLOTMASK 0x1f
#define CHARS_PER_LFN 13
/* These modul-global vars represent the state of the LFN parser */
unsigned char *lfn_unicode = NULL;
unsigned char lfn_checksum;
int lfn_slot = -1;
loff_t *lfn_offsets = NULL;
int lfn_parts = 0;
static unsigned char fat_uni2esc[64] = {
'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F',
'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V',
'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
'u', 'v', 'w', 'x', 'y', 'z', '+', '-'
};
/* This defines which unicode chars are directly convertable to ISO-8859-1 */
#define UNICODE_CONVERTABLE(cl,ch) (ch == 0 && (cl < 0x80 || cl >= 0xa0))
/* for maxlen param */
#define UNTIL_0 INT_MAX
/* Convert name part in 'lfn' from unicode to ASCII */
#define CNV_THIS_PART(lfn) \
({ \
unsigned char __part_uni[CHARS_PER_LFN*2]; \
copy_lfn_part( __part_uni, lfn ); \
cnv_unicode( __part_uni, CHARS_PER_LFN, 0 ); \
})
/* Convert name parts collected so far (from previous slots) from unicode to
* ASCII */
#define CNV_PARTS_SO_FAR() \
(cnv_unicode( lfn_unicode+(lfn_slot*CHARS_PER_LFN*2), \
lfn_parts*CHARS_PER_LFN, 0 ))
/* This function converts an unicode string to a normal ASCII string, assuming
* ISO-8859-1 charset. Characters not in 8859-1 are converted to the same
* escape notation as used by the kernel, i.e. the uuencode-like ":xxx" */
static char *cnv_unicode(const unsigned char *uni, int maxlen, int use_q)
{
const unsigned char *up;
unsigned char *out, *cp;
int len, val;
for (len = 0, up = uni; (up - uni) / 2 < maxlen && (up[0] || up[1]);
up += 2) {
if (UNICODE_CONVERTABLE(up[0], up[1]))
++len;
else
len += 4;
}
cp = out = use_q ? qalloc(&mem_queue, len + 1) : alloc(len + 1);
for (up = uni; (up - uni) / 2 < maxlen && (up[0] || up[1]); up += 2) {
if (UNICODE_CONVERTABLE(up[0], up[1]))
*cp++ = up[0];
else {
/* here the same escape notation is used as in the Linux kernel */
*cp++ = ':';
val = (up[1] << 8) + up[0];
cp[2] = fat_uni2esc[val & 0x3f];
val >>= 6;
cp[1] = fat_uni2esc[val & 0x3f];
val >>= 6;
cp[0] = fat_uni2esc[val & 0x3f];
cp += 3;
}
}
*cp = 0;
return (char *)out;
}
static void copy_lfn_part(unsigned char *dst, LFN_ENT * lfn)
{
memcpy(dst, lfn->name0_4, 10);
memcpy(dst + 10, lfn->name5_10, 12);
memcpy(dst + 22, lfn->name11_12, 4);
}
static void clear_lfn_slots(int start, int end)
{
int i;
LFN_ENT empty;
/* New dir entry is zeroed except first byte, which is set to 0xe5.
* This is to avoid that some FAT-reading OSes (not Linux! ;) stop reading
* a directory at the first zero entry...
*/
memset(&empty, 0, sizeof(empty));
empty.id = DELETED_FLAG;
for (i = start; i <= end; ++i) {
fs_write(lfn_offsets[i], sizeof(LFN_ENT), &empty);
}
}
void lfn_fix_checksum(loff_t from, loff_t to, const char *short_name)
{
int i;
__u8 sum;
for (sum = 0, i = 0; i < 11; i++)
sum = (((sum & 1) << 7) | ((sum & 0xfe) >> 1)) + short_name[i];
for (; from < to; from += sizeof(LFN_ENT)) {
fs_write(from + offsetof(LFN_ENT, alias_checksum), sizeof(sum), &sum);
}
}
void lfn_reset(void)
{
if (lfn_unicode)
free(lfn_unicode);
lfn_unicode = NULL;
if (lfn_offsets)
free(lfn_offsets);
lfn_offsets = NULL;
lfn_slot = -1;
}
/* This function is only called with de->attr == VFAT_LN_ATTR. It stores part
* of the long name. */
void lfn_add_slot(DIR_ENT * de, loff_t dir_offset)
{
LFN_ENT *lfn = (LFN_ENT *) de;
int slot = lfn->id & LFN_ID_SLOTMASK;
unsigned offset;
if (lfn_slot == 0)
lfn_check_orphaned();
if (de->attr != VFAT_LN_ATTR)
die("lfn_add_slot called with non-LFN directory entry");
if (lfn->id & LFN_ID_START && slot != 0) {
if (lfn_slot != -1) {
int can_clear = 0;
/* There is already a LFN "in progess", so it is an error that a
* new start entry is here. */
/* Causes: 1) if slot# == expected: start bit set mysteriously, 2)
* old LFN overwritten by new one */
/* Fixes: 1) delete previous LFN 2) if slot# == expected and
* checksum ok: clear start bit */
/* XXX: Should delay that until next LFN known (then can better
* display the name) */
printf("A new long file name starts within an old one.\n");
if (slot == lfn_slot && lfn->alias_checksum == lfn_checksum) {
char *part1 = CNV_THIS_PART(lfn);
char *part2 = CNV_PARTS_SO_FAR();
printf(" It could be that the LFN start bit is wrong here\n"
" if \"%s\" seems to match \"%s\".\n", part1, part2);
free(part1);
free(part2);
can_clear = 1;
}
if (interactive) {
printf("1: Delete previous LFN\n2: Leave it as it is.\n");
if (can_clear)
printf("3: Clear start bit and concatenate LFNs\n");
} else
printf(" Not auto-correcting this.\n");
if (interactive) {
switch (get_key(can_clear ? "123" : "12", "?")) {
case '1':
clear_lfn_slots(0, lfn_parts - 1);
lfn_reset();
break;
case '2':
break;
case '3':
lfn->id &= ~LFN_ID_START;
fs_write(dir_offset + offsetof(LFN_ENT, id),
sizeof(lfn->id), &lfn->id);
break;
}
}
}
lfn_slot = slot;
lfn_checksum = lfn->alias_checksum;
lfn_unicode = alloc((lfn_slot * CHARS_PER_LFN + 1) * 2);
lfn_offsets = alloc(lfn_slot * sizeof(loff_t));
lfn_parts = 0;
} else if (lfn_slot == -1 && slot != 0) {
/* No LFN in progress, but slot found; start bit missing */
/* Causes: 1) start bit got lost, 2) Previous slot with start bit got
* lost */
/* Fixes: 1) delete LFN, 2) set start bit */
char *part = CNV_THIS_PART(lfn);
printf("Long filename fragment \"%s\" found outside a LFN "
"sequence.\n (Maybe the start bit is missing on the "
"last fragment)\n", part);
if (interactive) {
printf("1: Delete fragment\n2: Leave it as it is.\n"
"3: Set start bit\n");
} else
printf(" Not auto-correcting this.\n");
switch (interactive ? get_key("123", "?") : '2') {
case '1':
if (!lfn_offsets)
lfn_offsets = alloc(sizeof(loff_t));
lfn_offsets[0] = dir_offset;
clear_lfn_slots(0, 0);
lfn_reset();
return;
case '2':
lfn_reset();
return;
case '3':
lfn->id |= LFN_ID_START;
fs_write(dir_offset + offsetof(LFN_ENT, id),
sizeof(lfn->id), &lfn->id);
lfn_slot = slot;
lfn_checksum = lfn->alias_checksum;
lfn_unicode = alloc((lfn_slot * CHARS_PER_LFN + 1) * 2);
lfn_offsets = alloc(lfn_slot * sizeof(loff_t));
lfn_parts = 0;
break;
}
} else if (slot != lfn_slot) {
/* wrong sequence number */
/* Causes: 1) seq-no destroyed */
/* Fixes: 1) delete LFN, 2) fix number (maybe only if following parts
* are ok?, maybe only if checksum is ok?) (Attention: space
* for name was allocated before!) */
int can_fix = 0;
printf("Unexpected long filename sequence number "
"(%d vs. expected %d).\n", slot, lfn_slot);
if (lfn->alias_checksum == lfn_checksum && lfn_slot > 0) {
char *part1 = CNV_THIS_PART(lfn);
char *part2 = CNV_PARTS_SO_FAR();
printf(" It could be that just the number is wrong\n"
" if \"%s\" seems to match \"%s\".\n", part1, part2);
free(part1);
free(part2);
can_fix = 1;
}
if (interactive) {
printf
("1: Delete LFN\n2: Leave it as it is (and ignore LFN so far)\n");
if (can_fix)
printf("3: Correct sequence number\n");
} else
printf(" Not auto-correcting this.\n");
switch (interactive ? get_key(can_fix ? "123" : "12", "?") : '2') {
case '1':
if (!lfn_offsets) {
lfn_offsets = alloc(sizeof(loff_t));
lfn_parts = 0;
}
lfn_offsets[lfn_parts++] = dir_offset;
clear_lfn_slots(0, lfn_parts - 1);
lfn_reset();
return;
case '2':
lfn_reset();
return;
case '3':
lfn->id = (lfn->id & ~LFN_ID_SLOTMASK) | lfn_slot;
fs_write(dir_offset + offsetof(LFN_ENT, id),
sizeof(lfn->id), &lfn->id);
break;
}
}
if (lfn->alias_checksum != lfn_checksum) {
/* checksum mismatch */
/* Causes: 1) checksum field here destroyed */
/* Fixes: 1) delete LFN, 2) fix checksum */
printf("Checksum in long filename part wrong "
"(%02x vs. expected %02x).\n",
lfn->alias_checksum, lfn_checksum);
if (interactive) {
printf("1: Delete LFN\n2: Leave it as it is.\n"
"3: Correct checksum\n");
} else
printf(" Not auto-correcting this.\n");
if (interactive) {
switch (get_key("123", "?")) {
case '1':
lfn_offsets[lfn_parts++] = dir_offset;
clear_lfn_slots(0, lfn_parts - 1);
lfn_reset();
return;
case '2':
break;
case '3':
lfn->alias_checksum = lfn_checksum;
fs_write(dir_offset + offsetof(LFN_ENT, alias_checksum),
sizeof(lfn->alias_checksum), &lfn->alias_checksum);
break;
}
}
}
if (lfn_slot != -1) {
lfn_slot--;
offset = lfn_slot * CHARS_PER_LFN * 2;
copy_lfn_part(lfn_unicode + offset, lfn);
if (lfn->id & LFN_ID_START)
lfn_unicode[offset + 26] = lfn_unicode[offset + 27] = 0;
lfn_offsets[lfn_parts++] = dir_offset;
}
if (lfn->reserved != 0) {
printf("Reserved field in VFAT long filename slot is not 0 "
"(but 0x%02x).\n", lfn->reserved);
if (interactive)
printf("1: Fix.\n2: Leave it.\n");
else
printf("Auto-setting to 0.\n");
if (!interactive || get_key("12", "?") == '1') {
lfn->reserved = 0;
fs_write(dir_offset + offsetof(LFN_ENT, reserved),
sizeof(lfn->reserved), &lfn->reserved);
}
}
if (lfn->start != CT_LE_W(0)) {
printf("Start cluster field in VFAT long filename slot is not 0 "
"(but 0x%04x).\n", lfn->start);
if (interactive)
printf("1: Fix.\n2: Leave it.\n");
else
printf("Auto-setting to 0.\n");
if (!interactive || get_key("12", "?") == '1') {
lfn->start = CT_LE_W(0);
fs_write(dir_offset + offsetof(LFN_ENT, start),
sizeof(lfn->start), &lfn->start);
}
}
}
/* This function is always called when de->attr != VFAT_LN_ATTR is found, to
* retrieve the previously constructed LFN. */
char *lfn_get(DIR_ENT * de, loff_t * lfn_offset)
{
char *lfn;
__u8 sum;
int i;
*lfn_offset = 0;
if (de->attr == VFAT_LN_ATTR)
die("lfn_get called with LFN directory entry");
#if 0
if (de->lcase)
printf("lcase=%02x\n", de->lcase);
#endif
if (lfn_slot == -1)
/* no long name for this file */
return NULL;
if (lfn_slot != 0) {
/* The long name isn't finished yet. */
/* Causes: 1) LFN slot overwritten by non-VFAT aware tool */
/* Fixes: 1) delete LFN 2) move overwriting entry to somewhere else
* and let user enter missing part of LFN (hard to do :-()
* 3) renumber entries and truncate name */
char *long_name = CNV_PARTS_SO_FAR();
char *short_name = file_name(de->name);
printf("Unfinished long file name \"%s\".\n"
" (Start may have been overwritten by %s)\n",
long_name, short_name);
free(long_name);
if (interactive) {
printf("1: Delete LFN\n2: Leave it as it is.\n"
"3: Fix numbering (truncates long name and attaches "
"it to short name %s)\n", short_name);
} else
printf(" Not auto-correcting this.\n");
switch (interactive ? get_key("123", "?") : '2') {
case '1':
clear_lfn_slots(0, lfn_parts - 1);
lfn_reset();
return NULL;
case '2':
lfn_reset();
return NULL;
case '3':
for (i = 0; i < lfn_parts; ++i) {
__u8 id = (lfn_parts - i) | (i == 0 ? LFN_ID_START : 0);
fs_write(lfn_offsets[i] + offsetof(LFN_ENT, id),
sizeof(id), &id);
}
memmove(lfn_unicode, lfn_unicode + lfn_slot * CHARS_PER_LFN * 2,
lfn_parts * CHARS_PER_LFN * 2);
break;
}
}
for (sum = 0, i = 0; i < 11; i++)
sum = (((sum & 1) << 7) | ((sum & 0xfe) >> 1)) + de->name[i];
if (sum != lfn_checksum) {
/* checksum doesn't match, long name doesn't apply to this alias */
/* Causes: 1) alias renamed */
/* Fixes: 1) Fix checksum in LFN entries */
char *long_name = CNV_PARTS_SO_FAR();
char *short_name = file_name(de->name);
printf("Wrong checksum for long file name \"%s\".\n"
" (Short name %s may have changed without updating the long name)\n",
long_name, short_name);
free(long_name);
if (interactive) {
printf("1: Delete LFN\n2: Leave it as it is.\n"
"3: Fix checksum (attaches to short name %s)\n", short_name);
} else
printf(" Not auto-correcting this.\n");
if (interactive) {
switch (get_key("123", "?")) {
case '1':
clear_lfn_slots(0, lfn_parts - 1);
lfn_reset();
return NULL;
case '2':
lfn_reset();
return NULL;
case '3':
for (i = 0; i < lfn_parts; ++i) {
fs_write(lfn_offsets[i] + offsetof(LFN_ENT, alias_checksum),
sizeof(sum), &sum);
}
break;
}
}
}
*lfn_offset = lfn_offsets[0];
lfn = cnv_unicode(lfn_unicode, UNTIL_0, 1);
lfn_reset();
return (lfn);
}
void lfn_check_orphaned(void)
{
char *long_name;
if (lfn_slot == -1)
return;
long_name = CNV_PARTS_SO_FAR();
printf("Orphaned long file name part \"%s\"\n", long_name);
if (interactive)
printf("1: Delete.\n2: Leave it.\n");
else
printf(" Auto-deleting.\n");
if (!interactive || get_key("12", "?") == '1') {
clear_lfn_slots(0, lfn_parts - 1);
}
lfn_reset();
}
