georep: Fix python3 compatibility (os.pipe)

'os.pipe' returns pair of file descriptors
which are non-inheritable by child processes.
But geo-rep uses te inheritable nature of
pipe fds to communicate between parent and
child processes. Hence wrote a compatiable
pipe routine which works well both with python2
and python3 with inheritable nature.

Updates: #411
Change-Id: I869d7a52eeecdecf3851d44ed400e69b32a612d9
Signed-off-by: Kotresh HR <khiremat@redhat.com>
(cherry picked from commit 173e89a6506bc8c727ce6d8e5ac84b59ad2e21de)

3 files changed, 19 insertions, 7 deletions

diff --git a/geo-replication/syncdaemon/monitor.py b/geo-replication/syncdaemon/monitor.py
index 97274f32422..ca2839059a3 100644
--- a/geo-replication/syncdaemon/monitor.py
+++ b/geo-replication/syncdaemon/monitor.py
@@ -26,7 +26,7 @@ from syncdutils import set_term_handler, GsyncdError
 from syncdutils import Thread, finalize, Volinfo, VolinfoFromGconf
 from syncdutils import gf_event, EVENT_GEOREP_FAULTY, get_up_nodes
 from gsyncdstatus import GeorepStatus, set_monitor_status
-from syncdutils import unshare_propagation_supported
+from syncdutils import unshare_propagation_supported, pipe
 
 ParseError = XET.ParseError if hasattr(XET, 'ParseError') else SyntaxError
 
@@ -158,9 +158,9 @@ class Monitor(object):
             # worker and changelog agent.
 
             # read/write end for agent
-            (ra, ww) = os.pipe()
+            (ra, ww) = pipe()
             # read/write end for worker
-            (rw, wa) = os.pipe()
+            (rw, wa) = pipe()
 
             # spawn the agent process
             apid = os.fork()
@@ -186,7 +186,7 @@ class Monitor(object):
 
                 os.execv(sys.executable, args_to_agent)
 
-            pr, pw = os.pipe()
+            pr, pw = pipe()
             cpid = os.fork()
             if cpid == 0:
                 os.close(pr)
@@ -438,7 +438,7 @@ def startup(go_daemon=True):
     if not go_daemon:
         return
 
-    x, y = os.pipe()
+    x, y = pipe()
     cpid = os.fork()
     if cpid:
         os.close(x)
diff --git a/geo-replication/syncdaemon/resource.py b/geo-replication/syncdaemon/resource.py
index e38027716b7..0c1b9818d2f 100644
--- a/geo-replication/syncdaemon/resource.py
+++ b/geo-replication/syncdaemon/resource.py
@@ -40,7 +40,7 @@ from syncdutils import GX_GFID_CANONICAL_LEN
 from gsyncdstatus import GeorepStatus
 from syncdutils import lf, Popen, sup
 from syncdutils import Xattr, matching_disk_gfid, get_gfid_from_mnt
-from syncdutils import unshare_propagation_supported, get_slv_dir_path
+from syncdutils import unshare_propagation_supported, get_slv_dir_path, pipe
 
 
 ENOTSUP = getattr(errno, 'ENOTSUP', 'EOPNOTSUPP')
@@ -858,7 +858,7 @@ class Mounter(object):
         change into the mount, and lazy unmount the
         filesystem.
         """
-        mpi, mpo = os.pipe()
+        mpi, mpo = pipe()
         mh = Popen.fork()
         if mh:
             # Parent
diff --git a/geo-replication/syncdaemon/syncdutils.py b/geo-replication/syncdaemon/syncdutils.py
index a17789995d8..d13c1c82853 100644
--- a/geo-replication/syncdaemon/syncdutils.py
+++ b/geo-replication/syncdaemon/syncdutils.py
@@ -1018,3 +1018,15 @@ def get_up_nodes(hosts, port):
             up_nodes.append(h)
 
     return up_nodes
+
+
+def pipe():
+    # Pipe routine for python2 and python3 compatiability
+    try:
+        (r, w) = os.pipe()
+        os.set_inheritable(r, True)
+        os.set_inheritable(w, True)
+    except AttributeError:
+        (r, w) = os.pipe()
+
+    return (r, w)