udf: refactor VRS descriptor identification
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>
diff --git a/fs/udf/super.c b/fs/udf/super.c
index a143461..14a9195 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -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);