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udf: refactor VRS descriptor identification

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Extract code that parses a Volume Recognition Sequence descriptor
(component), in preparation for calling it twice against different
locations in a block.

Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
Link: https://lore.kernel.org/r/20190711133852.16887-1-steve@digidescorp.com
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Steven J. Magnani 2019-07-11 08:38:51 -05:00 committed by Jan Kara
parent 609488bc97
commit ba54aef031
1 changed files with 64 additions and 64 deletions
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128
fs/udf/super.c
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@ -646,16 +646,67 @@ static int udf_remount_fs(struct super_block *sb, int *flags, char *options)
return error;
}
/* Check Volume Structure Descriptors (ECMA 167 2/9.1) */
/* We also check any "CD-ROM Volume Descriptor Set" (ECMA 167 2/8.3.1) */
static loff_t udf_check_vsd(struct super_block *sb)
/*
* Check VSD descriptor. Returns -1 in case we are at the end of volume
* recognition area, 0 if the descriptor is valid but non-interesting, 1 if
* we found one of NSR descriptors we are looking for.
*/
static int identify_vsd(const struct volStructDesc *vsd)
{
int ret = 0;
if (!memcmp(vsd->stdIdent, VSD_STD_ID_CD001, VSD_STD_ID_LEN)) {
switch (vsd->structType) {
case 0:
udf_debug("ISO9660 Boot Record found\n");
break;
case 1:
udf_debug("ISO9660 Primary Volume Descriptor found\n");
break;
case 2:
udf_debug("ISO9660 Supplementary Volume Descriptor found\n");
break;
case 3:
udf_debug("ISO9660 Volume Partition Descriptor found\n");
break;
case 255:
udf_debug("ISO9660 Volume Descriptor Set Terminator found\n");
break;
default:
udf_debug("ISO9660 VRS (%u) found\n", vsd->structType);
break;
}
} else if (!memcmp(vsd->stdIdent, VSD_STD_ID_BEA01, VSD_STD_ID_LEN))
; /* ret = 0 */
else if (!memcmp(vsd->stdIdent, VSD_STD_ID_NSR02, VSD_STD_ID_LEN))
ret = 1;
else if (!memcmp(vsd->stdIdent, VSD_STD_ID_NSR03, VSD_STD_ID_LEN))
ret = 1;
else if (!memcmp(vsd->stdIdent, VSD_STD_ID_BOOT2, VSD_STD_ID_LEN))
; /* ret = 0 */
else if (!memcmp(vsd->stdIdent, VSD_STD_ID_CDW02, VSD_STD_ID_LEN))
; /* ret = 0 */
else {
/* TEA01 or invalid id : end of volume recognition area */
ret = -1;
}
return ret;
}
/*
* Check Volume Structure Descriptors (ECMA 167 2/9.1)
* We also check any "CD-ROM Volume Descriptor Set" (ECMA 167 2/8.3.1)
* @return 1 if NSR02 or NSR03 found,
* -1 if first sector read error, 0 otherwise
*/
static int udf_check_vsd(struct super_block *sb)
{
struct volStructDesc *vsd = NULL;
loff_t sector = VSD_FIRST_SECTOR_OFFSET;
int sectorsize;
struct buffer_head *bh = NULL;
int nsr02 = 0;
int nsr03 = 0;
int nsr = 0;
struct udf_sb_info *sbi;
sbi = UDF_SB(sb);
@ -679,71 +730,20 @@ static loff_t udf_check_vsd(struct super_block *sb)
* activity. This actually happened with uninitialised SSD partitions
* (all 0xFF) before the check for the limit and all valid IDs were
* added */
for (; !nsr02 && !nsr03 && sector < VSD_MAX_SECTOR_OFFSET;
sector += sectorsize) {
for (; !nsr && sector < VSD_MAX_SECTOR_OFFSET; sector += sectorsize) {
/* Read a block */
bh = udf_tread(sb, sector >> sb->s_blocksize_bits);
if (!bh)
break;
/* Look for ISO descriptors */
vsd = (struct volStructDesc *)(bh->b_data +
(sector & (sb->s_blocksize - 1)));
if (!strncmp(vsd->stdIdent, VSD_STD_ID_CD001,
VSD_STD_ID_LEN)) {
switch (vsd->structType) {
case 0:
udf_debug("ISO9660 Boot Record found\n");
break;
case 1:
udf_debug("ISO9660 Primary Volume Descriptor found\n");
break;
case 2:
udf_debug("ISO9660 Supplementary Volume Descriptor found\n");
break;
case 3:
udf_debug("ISO9660 Volume Partition Descriptor found\n");
break;
case 255:
udf_debug("ISO9660 Volume Descriptor Set Terminator found\n");
break;
default:
udf_debug("ISO9660 VRS (%u) found\n",
vsd->structType);
break;
}
} else if (!strncmp(vsd->stdIdent, VSD_STD_ID_BEA01,
VSD_STD_ID_LEN))
; /* nothing */
else if (!strncmp(vsd->stdIdent, VSD_STD_ID_TEA01,
VSD_STD_ID_LEN)) {
brelse(bh);
break;
} else if (!strncmp(vsd->stdIdent, VSD_STD_ID_NSR02,
VSD_STD_ID_LEN))
nsr02 = sector;
else if (!strncmp(vsd->stdIdent, VSD_STD_ID_NSR03,
VSD_STD_ID_LEN))
nsr03 = sector;
else if (!strncmp(vsd->stdIdent, VSD_STD_ID_BOOT2,
VSD_STD_ID_LEN))
; /* nothing */
else if (!strncmp(vsd->stdIdent, VSD_STD_ID_CDW02,
VSD_STD_ID_LEN))
; /* nothing */
else {
/* invalid id : end of volume recognition area */
brelse(bh);
break;
}
nsr = identify_vsd(vsd);
brelse(bh);
}
if (nsr03)
return nsr03;
else if (nsr02)
return nsr02;
if (nsr > 0)
return 1;
else if (!bh && sector - (sbi->s_session << sb->s_blocksize_bits) ==
VSD_FIRST_SECTOR_OFFSET)
return -1;
@ -1915,7 +1915,7 @@ static int udf_load_vrs(struct super_block *sb, struct udf_options *uopt,
int silent, struct kernel_lb_addr *fileset)
{
struct udf_sb_info *sbi = UDF_SB(sb);
loff_t nsr_off;
int nsr = 0;
int ret;
if (!sb_set_blocksize(sb, uopt->blocksize)) {
@ -1926,13 +1926,13 @@ static int udf_load_vrs(struct super_block *sb, struct udf_options *uopt,
sbi->s_last_block = uopt->lastblock;
if (!uopt->novrs) {
/* Check that it is NSR02 compliant */
nsr_off = udf_check_vsd(sb);
if (!nsr_off) {
nsr = udf_check_vsd(sb);
if (!nsr) {
if (!silent)
udf_warn(sb, "No VRS found\n");
return -EINVAL;
}
if (nsr_off == -1)
if (nsr == -1)
udf_debug("Failed to read sector at offset %d. "
"Assuming open disc. Skipping validity "
"check\n", VSD_FIRST_SECTOR_OFFSET);