[Libguestfs] [PATCH 4/5] New API: btrfs_subvolume_get_default

[Hu Tao]

btrfs_subvolume_get_default is for getting the default subvolume of
a btrfs filesystem.

Signed-off-by: Hu Tao <hutao at cn.fujitsu.com>
---
 daemon/btrfs.c       | 38 ++++++++++++++++++++++++++++++++++++++
 generator/actions.ml |  9 +++++++++
 src/MAX_PROC_NR      |  2 +-
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/daemon/btrfs.c b/daemon/btrfs.c
index 754fdcd..471cfbd 100644
--- a/daemon/btrfs.c
+++ b/daemon/btrfs.c
@@ -545,6 +545,44 @@ do_btrfs_subvolume_set_default (int64_t id, const char *fs)
   return 0;
 }
 
+int64_t
+do_btrfs_subvolume_get_default (const char *mountpoint)
+{
+  const size_t MAX_ARGS = 64;
+  const char *argv[MAX_ARGS];
+  size_t i = 0;
+  CLEANUP_FREE char *fs_buf = NULL;
+  CLEANUP_FREE char *err = NULL;
+  CLEANUP_FREE char *out = NULL;
+  int r;
+  int64_t ret;
+
+  fs_buf = sysroot_path (mountpoint);
+  if (fs_buf == NULL) {
+    reply_with_perror ("malloc");
+    return -1;
+  }
+
+  ADD_ARG (argv, i, str_btrfs);
+  ADD_ARG (argv, i, "subvolume");
+  ADD_ARG (argv, i, "get-default");
+  ADD_ARG (argv, i, fs_buf);
+  ADD_ARG (argv, i, NULL);
+
+  r = commandv (&out, &err, argv);
+  if (r == -1) {
+    reply_with_error ("%s: %s", mountpoint, err);
+    return -1;
+  }
+  r = xstrtol (out + 2, NULL, 10, &ret, NULL);
+  if (r != LONGINT_OK) {
+    reply_with_error ("%s: could not parse subvolume id: %s.", argv[0], out);
+    return -1;
+  }
+
+  return ret;
+}
+
 int
 do_btrfs_filesystem_sync (const char *fs)
 {
diff --git a/generator/actions.ml b/generator/actions.ml
index a35fe50..2dcf938 100644
--- a/generator/actions.ml
+++ b/generator/actions.ml
@@ -12026,6 +12026,15 @@ Set readahead (in 512-byte sectors) for the device.
 
 This uses the L<blockdev(8)> command." };
 
+  { defaults with
+    name = "btrfs_subvolume_get_default";
+    style = RInt64 "id", [Pathname "mountpoint"], [];
+    proc_nr = Some 425;
+    optional = Some "btrfs"; camel_name = "BTRFSSubvolumeGetDefault";
+    shortdesc = "get the default subvolume or snapshot of a filesystem";
+    longdesc = "\
+Get the default subvolume or snapshot of a filesystem mounted at C<mountpoint>." };
+
 ]
 
 (* Non-API meta-commands available only in guestfish.
diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
index 9524ef4..5e4a522 100644
--- a/src/MAX_PROC_NR
+++ b/src/MAX_PROC_NR
@@ -1 +1 @@
-424
+425
-- 
1.9.3