geo-rep: Fix traceback with symlink metadata sync

While syncing metadata, 'os.chmod', 'os.chown',
'os.utime' should be used without de-reference.
But python supports only 'os.chown' without
de-reference. That's mostly because Linux
doesn't support 'chmod' on symlink file itself
but it does support 'chown'.

So while syncing metadata ops, if it's symlink
we should only sync 'chown' and not do 'chmod'
and 'utime'. It will lead to tracebacks with
errors like EROFS, EPERM, ACCESS, ENOENT.
All the three errors (EPERM, ACCESS, ENOENT)
were handled except EROFS. But the way it was
handled was not fool proof. The operation is
tried and failure was handled based on the errors.
All the errors with symlink file for 'chown',
'utime' had to be passed to safe errors list of
'errno_wrap'. This patch handles it better by
avoiding 'chmod' and 'utime' if it's symlink
file.

fixes: bz#1646104
Change-Id: Ic354206455cdc7ab2a87d741d81f4efe1f19d77d
Signed-off-by: Kotresh HR <khiremat@redhat.com>

1 files changed, 11 insertions, 15 deletions

diff --git a/geo-replication/syncdaemon/resource.py b/geo-replication/syncdaemon/resource.py
index 80e1fbcb133..c8575f00e70 100644
--- a/geo-replication/syncdaemon/resource.py
+++ b/geo-replication/syncdaemon/resource.py
@@ -750,10 +750,8 @@ class Server(object):
             # 'lchown' 'lchmod' 'utime with no-deference' blindly.
             # But since 'lchmod' and 'utime with no de-reference' is
             # not supported in python3, we have to rely on 'chmod'
-            # and 'utime with de-reference'. But 'chmod'
-            # de-reference the symlink and gets ENOENT, EACCES,
-            # EPERM errors, hence ignoring those errors if it's on
-            # symlink file.
+            # and 'utime with de-reference'. Hence avoiding 'chmod'
+            # and 'utime' if it's symlink file.
 
             is_symlink = False
             cmd_ret = errno_wrap(os.lchown, [go, uid, gid], [ENOENT],
@@ -761,19 +759,17 @@ class Server(object):
             if isinstance(cmd_ret, int):
                 continue
 
-            cmd_ret = errno_wrap(os.chmod, [go, mode],
-                                 [ENOENT, EACCES, EPERM], [ESTALE, EINVAL])
-            if isinstance(cmd_ret, int):
-                is_symlink = os.path.islink(go)
-                if not is_symlink:
+            is_symlink = os.path.islink(go)
+
+            if not is_symlink:
+                cmd_ret = errno_wrap(os.chmod, [go, mode],
+                                     [ENOENT, EACCES, EPERM], [ESTALE, EINVAL])
+                if isinstance(cmd_ret, int):
                     failures.append((e, cmd_ret, "chmod"))
 
-            cmd_ret = errno_wrap(os.utime, [go, (atime, mtime)],
-                                 [ENOENT, EACCES, EPERM], [ESTALE, EINVAL])
-            if isinstance(cmd_ret, int):
-                if not is_symlink:
-                    is_symlink = os.path.islink(go)
-                if not is_symlink:
+                cmd_ret = errno_wrap(os.utime, [go, (atime, mtime)],
+                                     [ENOENT, EACCES, EPERM], [ESTALE, EINVAL])
+                if isinstance(cmd_ret, int):
                     failures.append((e, cmd_ret, "utime"))
         return failures