New API: part-to-partnum

This converts a partition device name (eg. /dev/sda1) to a partition
number (eg. 1).  This is useful in conjunction with the parted APIs
that mostly take a disk device + partnum.

3 files changed, 43 insertions, 2 deletions

diff --git a/daemon/devsparts.c b/daemon/devsparts.c
index 52a6d304..79da41b0 100644
--- a/daemon/devsparts.c
+++ b/daemon/devsparts.c
@@ -220,3 +220,28 @@ do_part_to_dev (const char *part)
 
   return r;
 }
+
+int
+do_part_to_partnum (const char *part)
+{
+  int err = 1;
+  size_t n = strlen (part);
+
+  while (n >= 1 && c_isdigit (part[n-1])) {
+    err = 0;
+    n--;
+  }
+
+  if (err) {
+    reply_with_error ("device name is not a partition");
+    return -1;
+  }
+
+  int r;
+  if (sscanf (&part[n], "%d", &r) != 1) {
+    reply_with_error ("could not parse number");
+    return -1;
+  }
+
+  return r;
+}
diff --git a/generator/generator_actions.ml b/generator/generator_actions.ml
index e8a32ac0..ce3382fa 100644
--- a/generator/generator_actions.ml
+++ b/generator/generator_actions.ml
@@ -5850,7 +5850,9 @@ removes the partition number, returning the device name
 (eg. \"/dev/sdb\").
 
 The named partition must exist, for example as a string returned
-from C<guestfs_list_partitions>.");
+from C<guestfs_list_partitions>.
+
+See also C<guestfs_part_to_partnum>.");
 
   ("upload_offset", (RErr, [FileIn "filename"; Dev_or_Path "remotefilename"; Int64 "offset"], []), 273, [Progress],
    (let md5 = Digest.to_hex (Digest.file "COPYING.LIB") in
@@ -6211,6 +6213,20 @@ file C<zdevice>.
 The C<ctype> and optional C<level> parameters have the same meaning
 as in C<guestfs_compress_out>.");
 
+  ("part_to_partnum", (RInt "partnum", [Device "partition"], []), 293, [],
+   [InitPartition, Always, TestOutputInt (
+      [["part_to_partnum"; "/dev/sda1"]], 1);
+    InitEmpty, Always, TestLastFail (
+      [["part_to_partnum"; "/dev/sda"]])],
+   "convert partition name to partition number",
+   "\
+This function takes a partition name (eg. \"/dev/sdb1\") and
+returns the partition number (eg. C<1>).
+
+The named partition must exist, for example as a string returned
+from C<guestfs_list_partitions>.
+
+See also C<guestfs_part_to_dev>.");
 ]
 
 let all_functions = non_daemon_functions @ daemon_functions
diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
index f20bd4ef..4438e305 100644
--- a/src/MAX_PROC_NR
+++ b/src/MAX_PROC_NR
@@ -1 +1 @@
-292
+293