libblkid: generate pseudo-UUID for ISO9660 image file

The UUID is generated from the modification date in the ISO volume
descriptor. As GRUB 2 is using this definition for the pseudo UUID for
ISO9660 files libblkid would be perfectly compatible with GRUB 2.

Signed-off-by: Andreas Vogel <Andreas.Vogel@anvo-it.de>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libblkid/src/superblocks/iso9660.c b/libblkid/src/superblocks/iso9660.c
index 36bf07713400f13435836f80074bc760e102f628..f7d2b760ab6952d3cb1ae60b1dca8f27665f81d4 100644 (file)
--- a/libblkid/src/superblocks/iso9660.c
+++ b/libblkid/src/superblocks/iso9660.c
@@ -19,6 +19,17 @@
 
 #include "superblocks.h"
 
+struct iso9660_date {
+       unsigned char year[4];
+       unsigned char month[2];
+       unsigned char day[2];
+       unsigned char hour[2];
+       unsigned char minute[2];
+       unsigned char second[2];
+       unsigned char hundredth[2];
+       unsigned char offset;
+} __attribute__ ((packed));
+
 /* PVD - Primary volume descriptor */
 struct iso_volume_descriptor {
        unsigned char   vd_type;
@@ -30,6 +41,9 @@ struct iso_volume_descriptor {
        unsigned char   unused[8];
        unsigned char   space_size[8];
        unsigned char   escape_sequences[8];
+       unsigned char   unused1[717];
+       struct iso9660_date created;
+       struct iso9660_date modified;
 } __attribute__((packed));
 
 #define ISO_SUPERBLOCK_OFFSET          0x8000
@@ -77,6 +91,51 @@ static int probe_iso9660_hsfs(blkid_probe pr, const struct blkid_idmag *mag)
        return 0;
 }
 
+static int probe_iso9660_set_uuid (blkid_probe pr, const struct iso9660_date *date)
+{
+       unsigned char buffer[16];
+       unsigned int i, zeros = 0;
+
+       buffer[0] = date->year[0];
+       buffer[1] = date->year[1];
+       buffer[2] = date->year[2];
+       buffer[3] = date->year[3];
+       buffer[4] = date->month[0];
+       buffer[5] = date->month[1];
+       buffer[6] = date->day[0];
+       buffer[7] = date->day[1];
+       buffer[8] = date->hour[0];
+       buffer[9] = date->hour[1];
+       buffer[10] = date->minute[0];
+       buffer[11] = date->minute[1];
+       buffer[12] = date->second[0];
+       buffer[13] = date->second[1];
+       buffer[14] = date->hundredth[0];
+       buffer[15] = date->hundredth[1];
+
+       /* count the number of zeros ('0') in the date buffer */
+       for (i = 0, zeros = 0; i < sizeof(buffer); i++)
+               if (buffer[i] == '0')
+                       zeros++;
+
+       /* due to the iso9660 standard if all date fields are '0' and offset is 0, the date is unset */
+       if (zeros == sizeof(buffer) && date->offset == 0)
+               return 0;
+
+       /* generate an UUID using this date and return success */
+       blkid_probe_sprintf_uuid (pr, buffer, sizeof(buffer),
+               "%c%c%c%c-%c%c-%c%c-%c%c-%c%c-%c%c-%c%c",
+               buffer[0], buffer[1], buffer[2], buffer[3],
+               buffer[4], buffer[5],
+               buffer[6], buffer[7],
+               buffer[8], buffer[9],
+               buffer[10], buffer[11],
+               buffer[12], buffer[13],
+               buffer[14], buffer[15]);
+
+       return 1;
+}
+
 /* iso9660 [+ Microsoft Joliet Extension] */
 static int probe_iso9660(blkid_probe pr, const struct blkid_idmag *mag)
 {
@@ -94,6 +153,10 @@ static int probe_iso9660(blkid_probe pr, const struct blkid_idmag *mag)
 
        memcpy(label, iso->volume_id, sizeof(label));
 
+       /* create an UUID using the modified/created date */
+       if (! probe_iso9660_set_uuid(pr, &iso->modified))
+               probe_iso9660_set_uuid(pr, &iso->created);
+
        /* Joliet Extension */
        off = ISO_VD_OFFSET;
        for (i = 0; i < ISO_VD_MAX; i++) {
@@ -136,7 +199,6 @@ has_label:
        return 0;
 }
 
-
 const struct blkid_idinfo iso9660_idinfo =
 {
        .name           = "iso9660",