api: add glfs_get_volfile

From the API-header description:

> Sometimes it's useful e.g. for scripts to see the volfile, so that
> they can parse it and find subvolumes to do things like split-brain
> resolution or custom layouts.  The API here was specifically intended
> to make access e.g. from Python as simple as possible.
>
> Note that the volume must be started (not necessarily mounted) for
> this to work.

Change-Id: If3f55ee9611cdf4b77aa53659f0af0d21957817d
Signed-off-by: Jeff Darcy <jdarcy@redhat.com>
Reviewed-on: http://review.gluster.org/7183
Reviewed-by: Anand Avati <avati@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/api/src/glfs.c b/api/src/glfs.c
index ea10fb55c65..9e9a55ccb65 100644
--- a/api/src/glfs.c
+++ b/api/src/glfs.c
@@ -680,3 +680,23 @@ glfs_fini (struct glfs *fs)
 
         return ret;
 }
+
+ssize_t
+glfs_get_volfile (struct glfs *fs, void *buf, size_t len)
+{
+        ssize_t         res;
+
+        glfs_lock(fs);
+        if (len >= fs->oldvollen) {
+                gf_log ("glfs", GF_LOG_TRACE, "copying %lu to %p", len, buf);
+                memcpy(buf,fs->oldvolfile,len);
+                res = len;
+        }
+        else {
+                res = len - fs->oldvollen;
+                gf_log ("glfs", GF_LOG_TRACE, "buffer is %ld too short", -res);
+        }
+        glfs_unlock(fs);
+
+        return res;
+}