libblkid: fix 'partno' usage

Linux kernel ignores empty partitions, but partition number is always
allocated for the partition. (This rule is used for primary partitions
only.)

For example:

  part 1.  size=12345
  part 2.  size=0
  part 3.  size=24567

the final list of partitions:

  sda1 sda3

'sda2' is not defined and partno=2 is not used for any other
partitions.

The libblkid library has to be compatible with this rule.

Signed-off-by: Karel Zak <kzak@redhat.com>

6 files changed, 26 insertions, 10 deletions

diff --git a/shlibs/blkid/src/partitions/dos.c b/shlibs/blkid/src/partitions/dos.c
index c9865b75d..7c95b8bea 100644
--- a/shlibs/blkid/src/partitions/dos.c
+++ b/shlibs/blkid/src/partitions/dos.c
@@ -203,9 +203,12 @@ static int probe_dos_pt(blkid_probe pr, const struct blkid_idmag *mag)
 		start = dos_partition_start(p) * ssf;
 		size = dos_partition_size(p) * ssf;
 
-		if (!size)
+		if (!size) {
+			/* Linux kernel ignores empty partitions, but partno for
+			 * the empty primary partitions is not reused */
+			blkid_partlist_increment_partno(ls);
 			continue;
-
+		}
 		par = blkid_partlist_add_partition(ls, tab, start, size);
 		if (!par)
 			goto err;
diff --git a/shlibs/blkid/src/partitions/gpt.c b/shlibs/blkid/src/partitions/gpt.c
index 569490131..12100e0f8 100644
--- a/shlibs/blkid/src/partitions/gpt.c
+++ b/shlibs/blkid/src/partitions/gpt.c
@@ -328,14 +328,16 @@ static int probe_gpt_pt(blkid_probe pr, const struct blkid_idmag *mag)
 					le64_to_cpu(e->starting_lba) + 1ULL;
 
 		/* 00000000-0000-0000-0000-000000000000 entry */
-		if (!guidcmp(e->partition_type_guid, GPT_UNUSED_ENTRY_GUID))
+		if (!guidcmp(e->partition_type_guid, GPT_UNUSED_ENTRY_GUID)) {
+			blkid_partlist_increment_partno(ls);
 			continue;
-
+		}
 		/* the partition has to inside usable range */
 		if (start < fu || start + size - 1 > lu) {
 			DBG(DEBUG_LOWPROBE, printf(
 				"GPT entry[%d] overflows usable area - ignore\n",
 				i));
+			blkid_partlist_increment_partno(ls);
 			continue;
 		}
 
diff --git a/shlibs/blkid/src/partitions/partitions.c b/shlibs/blkid/src/partitions/partitions.c
index a5c56c889..219a19732 100644
--- a/shlibs/blkid/src/partitions/partitions.c
+++ b/shlibs/blkid/src/partitions/partitions.c
@@ -27,7 +27,9 @@
  * @short_description: partitions tables detection and parsing
  *
  * This chain supports binary and NAME=value interfaces, but complete PT
- * description is provided by binary interface only.
+ * description is provided by binary interface only. The libblkid prober is
+ * compatible with kernel partition tables parser. The parser does not return
+ * empty (size=0) partitions or special hidden partitions.
  *
  * NAME=value interface, supported tags:
  *
@@ -424,7 +426,7 @@ static blkid_partition new_partition(blkid_partlist ls, blkid_parttable tab)
 
 	ref_parttable(tab);
 	par->tab = tab;
-	par->partno = ls->next_partno++;
+	par->partno = blkid_partlist_increment_partno(ls);
 
 	return par;
 }
@@ -457,6 +459,11 @@ int blkid_partlist_set_partno(blkid_partlist ls, int partno)
 	return 0;
 }
 
+int blkid_partlist_increment_partno(blkid_partlist ls)
+{
+	return ls ? ls->next_partno++ : -1;
+}
+
 /* allows to set "parent" for the next nested partition */
 int blkid_partlist_set_parent(blkid_partlist ls, blkid_partition par)
 {
diff --git a/shlibs/blkid/src/partitions/partitions.h b/shlibs/blkid/src/partitions/partitions.h
index 190918f9e..2a4d20af5 100644
--- a/shlibs/blkid/src/partitions/partitions.h
+++ b/shlibs/blkid/src/partitions/partitions.h
@@ -14,6 +14,8 @@ extern blkid_partition blkid_partlist_add_partition(blkid_partlist ls,
 				blkid_loff_t start, blkid_loff_t size);
 
 extern int blkid_partlist_set_partno(blkid_partlist ls, int partno);
+extern int blkid_partlist_increment_partno(blkid_partlist ls);
+
 extern blkid_partition blkid_partlist_get_parent(blkid_partlist ls);
 
 extern int blkid_partitions_do_subprobe(blkid_probe pr,
diff --git a/shlibs/blkid/src/partitions/sgi.c b/shlibs/blkid/src/partitions/sgi.c
index 3a9cd0a76..945ead542 100644
--- a/shlibs/blkid/src/partitions/sgi.c
+++ b/shlibs/blkid/src/partitions/sgi.c
@@ -126,9 +126,10 @@ static int probe_sgi_pt(blkid_probe pr, const struct blkid_idmag *mag)
 		blkid_partition par;
 
 		if (size == 0 || type == SGI_TYPE_VOLULME ||
-			         type == SGI_TYPE_VOLHDR)
+			         type == SGI_TYPE_VOLHDR) {
+			blkid_partlist_increment_partno(ls);
 			continue;
-
+		}
 		par = blkid_partlist_add_partition(ls, tab, start, size);
 		if (!par)
 			goto err;
diff --git a/shlibs/blkid/src/partitions/sun.c b/shlibs/blkid/src/partitions/sun.c
index d70200c85..dffab24c6 100644
--- a/shlibs/blkid/src/partitions/sun.c
+++ b/shlibs/blkid/src/partitions/sun.c
@@ -148,9 +148,10 @@ static int probe_sun_pt(blkid_probe pr, const struct blkid_idmag *mag)
 			flags = be16_to_cpu(l->vtoc.infos[i].flags);
 		}
 
-		if (type == SUN_TAG_WHOLEDISK || !size)
+		if (type == SUN_TAG_WHOLEDISK || !size) {
+			blkid_partlist_increment_partno(ls);
 			continue;
-
+		}
 		par = blkid_partlist_add_partition(ls, tab, start, size);
 		if (!par)
 			goto err;