libblkid: add blkid_partlist_get_partition_by_partno()

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

4 files changed, 40 insertions, 0 deletions

diff --git a/libblkid/docs/libblkid-sections.txt b/libblkid/docs/libblkid-sections.txt
index 69723459e..53cf84b78 100644
--- a/libblkid/docs/libblkid-sections.txt
+++ b/libblkid/docs/libblkid-sections.txt
@@ -100,6 +100,7 @@ blkid_partition_is_logical
 blkid_partition_is_primary
 <SUBSECTION>
 blkid_partlist_get_partition
+blkid_partlist_get_partition_by_partno
 blkid_partlist_numof_partitions
 blkid_partlist_devno_to_partition
 blkid_partlist_get_table
diff --git a/libblkid/src/blkid.h.in b/libblkid/src/blkid.h.in
index c140fc6b2..b10c28630 100644
--- a/libblkid/src/blkid.h.in
+++ b/libblkid/src/blkid.h.in
@@ -327,7 +327,9 @@ extern blkid_partlist blkid_probe_get_partitions(blkid_probe pr);
 extern int blkid_partlist_numof_partitions(blkid_partlist ls);
 extern blkid_parttable blkid_partlist_get_table(blkid_partlist ls);
 extern blkid_partition blkid_partlist_get_partition(blkid_partlist ls, int n);
+extern blkid_partition blkid_partlist_get_partition_by_partno(blkid_partlist ls, int n);
 extern blkid_partition blkid_partlist_devno_to_partition(blkid_partlist ls, dev_t devno);
+extern blkid_partition blkid_partlist_get_partition_by_partno(blkid_partlist ls, int n);
 extern blkid_parttable blkid_partition_get_table(blkid_partition par);
 
 extern const char *blkid_partition_get_name(blkid_partition par);
diff --git a/libblkid/src/blkid.sym b/libblkid/src/blkid.sym
index 7d3b71d2e..80cb4d487 100644
--- a/libblkid/src/blkid.sym
+++ b/libblkid/src/blkid.sym
@@ -155,3 +155,10 @@ global:
 	blkid_parttable_get_id;
 	blkid_init_debug;
 } BLKID_2.21;
+
+/*
+ * symbols since util-linux 2.25
+ */
+BLKID_2.25 {
+	blkid_partlist_get_partition_by_partno;
+} BLKID_2.23;
diff --git a/libblkid/src/partitions/partitions.c b/libblkid/src/partitions/partitions.c
index f7d6c4533..f83b868cc 100644
--- a/libblkid/src/partitions/partitions.c
+++ b/libblkid/src/partitions/partitions.c
@@ -902,6 +902,35 @@ blkid_partition blkid_partlist_get_partition(blkid_partlist ls, int n)
 }
 
 /**
+ * blkid_partlist_get_partition_by_partno
+ * @ls: partitions list
+ * @n: the partition number (e.g. 'N' from sda'N')
+ *
+ * This does not assume any order of the input blkid_partlist.  And correctly
+ * handles "out of order" partition tables.  partition N is located after
+ * partition N+1 on the disk.
+ *
+ * Returns: partition object or NULL in case or error.
+ */
+blkid_partition blkid_partlist_get_partition_by_partno(blkid_partlist ls, int n)
+{
+	int i, nparts;
+	blkid_partition par;
+
+	if (!ls)
+		return NULL;
+
+	nparts = blkid_partlist_numof_partitions(ls);
+	for (i = 0; i < nparts; i++) {
+		par = blkid_partlist_get_partition(ls, i);
+		if (n == blkid_partition_get_partno(par))
+			return par;
+	}
+	return NULL;
+}
+
+
+/**
  * blkid_partlist_devno_to_partition:
  * @ls: partitions list
  * @devno: requested partition
@@ -1001,6 +1030,7 @@ blkid_partition blkid_partlist_devno_to_partition(blkid_partlist ls, dev_t devno
 	return NULL;
 }
 
+
 int blkid_parttable_set_uuid(blkid_parttable tab, const unsigned char *id)
 {
 	if (!tab)