From d16202fa66f981949fc49573030721cda35705dc Mon Sep 17 00:00:00 2001
From: Pino Toscano <ptoscano@redhat.com>
Date: Wed, 14 Jan 2015 18:55:13 +0100
Subject: [PATCH] daemon: use btrfs(1) to get btrfs labels

blkid(1) (or actually, libblkid) seems to handle filesystem labels up
to 127 characters. Considering that btrfs labels can be up to 255
characters, this means long labels are not read correctly (i.e. get
truncated) by blkid.

Get the filesystem type, and if btrfs is available invoke
`btrfs filesystem` to get the label of btrfs filesystems.

Related to RHBZ#1164708.

(cherry picked from commit 6db3c100e7c18820ff9ecc22415940eb5fedc64e)
---
 daemon/blkid.c  |  8 ++++++++
 daemon/btrfs.c  | 24 ++++++++++++++++++++++++
 daemon/daemon.h |  3 +++
 3 files changed, 35 insertions(+)

diff --git a/daemon/blkid.c b/daemon/blkid.c
index b98c155..e8e7b58 100644
--- a/daemon/blkid.c
+++ b/daemon/blkid.c
@@ -26,6 +26,7 @@
 
 #include "daemon.h"
 #include "actions.h"
+#include "optgroups.h"
 
 GUESTFSD_EXT_CMD(str_blkid, blkid);
 
@@ -76,6 +77,13 @@ do_vfs_type (const mountable_t *mountable)
 char *
 do_vfs_label (const mountable_t *mountable)
 {
+  CLEANUP_FREE char *type = do_vfs_type (mountable);
+
+  if (type) {
+    if (STREQ (type, "btrfs") && optgroup_btrfs_available ())
+      return btrfs_get_label (mountable->device);
+  }
+
   return get_blkid_tag (mountable->device, "LABEL");
 }
 
diff --git a/daemon/btrfs.c b/daemon/btrfs.c
index 7a4d43d..86bad36 100644
--- a/daemon/btrfs.c
+++ b/daemon/btrfs.c
@@ -42,6 +42,30 @@ optgroup_btrfs_available (void)
   return prog_exists (str_btrfs) && filesystem_available ("btrfs") > 0;
 }
 
+char *
+btrfs_get_label (const char *device)
+{
+  int r;
+  CLEANUP_FREE char *err = NULL;
+  char *out = NULL;
+  size_t len;
+
+  r = command (&out, &err, str_btrfs, "filesystem", "label",
+               device, NULL);
+  if (r == -1) {
+    reply_with_error ("%s", err);
+    free (out);
+    return NULL;
+  }
+
+  /* Trim trailing \n if present. */
+  len = strlen (out);
+  if (len > 0 && out[len-1] == '\n')
+    out[len-1] = '\0';
+
+  return out;
+}
+
 /* Takes optional arguments, consult optargs_bitmask. */
 int
 do_btrfs_filesystem_resize (const char *filesystem, int64_t size)
diff --git a/daemon/daemon.h b/daemon/daemon.h
index f442efd..24ee46a 100644
--- a/daemon/daemon.h
+++ b/daemon/daemon.h
@@ -257,6 +257,9 @@ extern int copy_xattrs (const char *src, const char *dest);
 /* Documented in xfs_admin(8). */
 #define XFS_LABEL_MAX 12
 
+/*-- in btrfs.c --*/
+extern char *btrfs_get_label (const char *device);
+
 /* ordinary daemon functions use these to indicate errors
  * NB: you don't need to prefix the string with the current command,
  * it is added automatically by the client-side RPC stubs.
-- 
1.8.3.1