[Libguestfs] [PATCH v2 2/3] api: add mountable_device and mountable_subvolume

[Cédric Bosdonnat]

These two functions allow the user to split the mountable strings
into a device and a subvolume if any. See this thread on the mailing
list for the rationale:

https://www.redhat.com/archives/libguestfs/2016-February/msg00247.html
---
 generator/actions.ml | 26 ++++++++++++++++++++++++++
 po/POTFILES          |  1 +
 src/Makefile.am      |  1 +
 src/mountable.c      | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 79 insertions(+)
 create mode 100644 src/mountable.c

diff --git a/generator/actions.ml b/generator/actions.ml
index 36d08ad..696fd87 100644
--- a/generator/actions.ml
+++ b/generator/actions.ml
@@ -1290,6 +1290,32 @@ Please read L<guestfs(3)/INSPECTION> for more details.
 See also C<guestfs_inspect_get_mountpoints>." };
 
   { defaults with
+    name = "mountable_device"; added = (1, 33, 14);
+    style = RString "device", [Mountable "mountable"], [];
+    shortdesc = "extract the device part of a mountable";
+    longdesc = "\
+Returns the device name of a mountable. In quite a lot of
+cases, the mountable is the device name.
+
+However this doesn't apply for btrfs subvolumes, where the
+mountable is a combination of both the device name and the
+subvolume path (see also C<guestfs_mountable_subvolume> to
+extract the subvolume path of the mountable if any)." };
+
+  { defaults with
+    name = "mountable_subvolume"; added = (1, 33, 14);
+    style = RString "subvolume", [Mountable "mountable"], [];
+    shortdesc = "extract the subvolume part of a mountable";
+    longdesc = "\
+Returns the subvolume path of a mountable. Btrfs subvolumes
+mountables are a combination of both the device name and the
+subvolume path (see also C<guestfs_mountable_device> to extract
+the device of the mountable).
+
+If the mountable does not represent a btrfs subvolume, then
+this function fails and the errno is set to EINVAL." };
+
+  { defaults with
     name = "set_network"; added = (1, 5, 4);
     style = RErr, [Bool "network"], [];
     fish_alias = ["network"]; config_only = true;
diff --git a/po/POTFILES b/po/POTFILES
index 4fbc551..195206f 100644
--- a/po/POTFILES
+++ b/po/POTFILES
@@ -346,6 +346,7 @@ src/libvirt-is-version.c
 src/listfs.c
 src/lpj.c
 src/match.c
+src/mountable.c
 src/osinfo.c
 src/private-data.c
 src/proto.c
diff --git a/src/Makefile.am b/src/Makefile.am
index 60641bf..3b4cd10 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -121,6 +121,7 @@ libguestfs_la_SOURCES = \
 	listfs.c \
 	lpj.c \
 	match.c \
+	mountable.c \
 	osinfo.c \
 	private-data.c \
 	proto.c \
diff --git a/src/mountable.c b/src/mountable.c
new file mode 100644
index 0000000..12ba633
--- /dev/null
+++ b/src/mountable.c
@@ -0,0 +1,51 @@
+/* libguestfs
+ * Copyright (C) 2016 SUSE LLC
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <config.h>
+#include <string.h>
+#include <errno.h>
+
+#include "guestfs.h"
+#include "guestfs-internal.h"
+
+
+char *
+guestfs_impl_mountable_device (guestfs_h *g, const char *mountable)
+{
+    CLEANUP_FREE_INTERNAL_MOUNTABLE struct guestfs_internal_mountable *mnt = NULL;
+
+    mnt = guestfs_internal_parse_mountable (g, mountable);
+    if (mnt == NULL)
+        return NULL;
+
+    return safe_strdup(g, mnt->im_device);
+}
+
+char *
+guestfs_impl_mountable_subvolume (guestfs_h *g, const char *mountable)
+{
+    CLEANUP_FREE_INTERNAL_MOUNTABLE struct guestfs_internal_mountable *mnt = NULL;
+
+    mnt = guestfs_internal_parse_mountable (g, mountable);
+    if (mnt == NULL || STREQ (mnt->im_volume, "")) {
+        guestfs_int_error_errno (g, EINVAL, "not a btrfs subvolume identifier");
+        return NULL;
+    }
+
+    return safe_strdup(g, mnt->im_volume);
+}
-- 
2.6.2