libbtrfsutil: don't close fd on error in btrfs_util_subvolume_id_fd()

The caller owns the fd passed to btrfs_util_subvolume_id_fd(), so we
shouldn't close it on error. Fix it, add a regression test, and bump the
library patch version.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

libbtrfsutil/btrfsutil.h

@@ -27,7 +27,7 @@
 
 #define BTRFS_UTIL_VERSION_MAJOR 1
 #define BTRFS_UTIL_VERSION_MINOR 1
-#define BTRFS_UTIL_VERSION_PATCH 0
+#define BTRFS_UTIL_VERSION_PATCH 1
 
 #ifdef __cplusplus
 extern "C" {

libbtrfsutil/python/tests/test_subvolume.py

@@ -64,6 +64,18 @@ class TestSubvolume(BtrfsTestCase):
             with self.subTest(type=type(arg)):
                 self.assertEqual(btrfsutil.subvolume_id(arg), 5)
 
+    def test_subvolume_id_error(self):
+        fd = os.open('/dev/null', os.O_RDONLY)
+        try:
+            btrfsutil.subvolume_id(fd)
+        except Exception:
+            pass
+        finally:
+            # btrfs_util_subvolume_id_fd() had a bug that would erroneously
+            # close the provided file descriptor. In that case, this will fail
+            # with EBADF.
+            os.close(fd)
+
     def test_subvolume_path(self):
         btrfsutil.create_subvolume(os.path.join(self.mountpoint, 'subvol1'))
         os.mkdir(os.path.join(self.mountpoint, 'dir1'))

libbtrfsutil/subvolume.c

@@ -122,10 +122,8 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_id_fd(int fd,
 	int ret;
 
 	ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args);
-	if (ret == -1) {
-		close(fd);
+	if (ret == -1)
 		return BTRFS_UTIL_ERROR_INO_LOOKUP_FAILED;
-	}
 
 	*id_ret = args.treeid;