[PATCH] wic/engine: improve error reporting when using rm with wic

[Anuj Mittal <anuj.mittal@intel.com>]

When trying to delete something from an ext partition using debugfs, we
don't show any error to the user when that operation fails.

Change this behavior to show the error generated by debugfs. Also,
fallback to use rmdir in case we are trying to delete a directory. However,
unlike mdeltree that is used for a FAT partition, there's no easy way to
delete a non empty directory. Show an error instead when that happens so
user can take appropriate action.

Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
---
 scripts/lib/wic/engine.py | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/scripts/lib/wic/engine.py b/scripts/lib/wic/engine.py
index f0c5ff0aaf..3f2eaa4ff8 100644
--- a/scripts/lib/wic/engine.py
+++ b/scripts/lib/wic/engine.py
@@ -340,9 +340,21 @@ class Disk:
         """Remove files/dirs from the partition."""
         partimg = self._get_part_image(pnum)
         if self.partitions[pnum].fstype.startswith('ext'):
-            exec_cmd("{} {} -wR 'rm {}'".format(self.debugfs,
+            cmd = "{} {} -wR 'rm {}'".format(self.debugfs,
                                                 self._get_part_image(pnum),
-                                                path), as_shell=True)
+                                                path)
+            out = exec_cmd(cmd , as_shell=True)
+            for line in out.splitlines():
+                if line.startswith("rm:"):
+                    if "file is a directory" in line:
+                        # Try rmdir to see if this is an empty directory. This won't delete
+                        # any non empty directory so let user know about any error that this might
+                        # generate.
+                        print(exec_cmd("{} {} -wR 'rmdir {}'".format(self.debugfs,
+                                                    self._get_part_image(pnum),
+                                                    path), as_shell=True))
+                    else:
+                        raise WicError("Could not complete operation: wic %s" % str(line))
         else: # fat
             cmd = "{} -i {} ::{}".format(self.mdel, partimg, path)
             try:
-- 
2.17.1