+/* Windows Registry HKLM\SYSTEM\MountedDevices uses a blob of data
+ * to store partitions. This blob is described here:
+ * http://www.goodells.net/multiboot/partsigs.shtml
+ * The following function maps this blob to a libguestfs partition
+ * name, if possible.
+ */
+static char *
+map_registry_disk_blob (guestfs_h *g, const char *blob)
+{
+ char **devices = NULL;
+ struct guestfs_partition_list *partitions = NULL;
+ char *diskid;
+ size_t i, j, len;
+ char *ret = NULL;
+ uint64_t part_offset;
+
+ /* First 4 bytes are the disk ID. Search all devices to find the
+ * disk with this disk ID.
+ */
+ devices = guestfs_list_devices (g);
+ if (devices == NULL)
+ goto out;
+
+ for (i = 0; devices[i] != NULL; ++i) {
+ /* Read the disk ID. */
+ diskid = guestfs_pread_device (g, devices[i], 4, 0x01b8, &len);
+ if (diskid == NULL)
+ continue;
+ if (len < 4) {
+ free (diskid);
+ continue;
+ }
+ if (memcmp (diskid, blob, 4) == 0) { /* found it */
+ free (diskid);
+ goto found_disk;
+ }
+ free (diskid);
+ }
+ goto out;
+
+ found_disk:
+ /* Next 8 bytes are the offset of the partition in bytes(!) given as
+ * a 64 bit little endian number. Luckily it's easy to get the
+ * partition byte offset from guestfs_part_list.
+ */
+ part_offset = le64toh (* (uint64_t *) &blob[4]);
+
+ partitions = guestfs_part_list (g, devices[i]);
+ if (partitions == NULL)
+ goto out;
+
+ for (j = 0; j < partitions->len; ++j) {
+ if (partitions->val[j].part_start == part_offset) /* found it */
+ goto found_partition;
+ }
+ goto out;
+
+ found_partition:
+ /* Construct the full device name. */
+ ret = safe_asprintf (g, "%s%d", devices[i], partitions->val[j].part_num);
+
+ out:
+ if (devices)
+ guestfs___free_string_list (devices);
+ if (partitions)
+ guestfs_free_partition_list (partitions);
+ return ret;
+}
+