libgfchangelog : use find_library to locate shared library

Issue:

libgfchangelog.so: cannot open shared object file

Due to hardcoded shared library name runtime loader looks for particular version of
a shared library.

Solution:

Using find_library to locate shared library at runtime solves this issue.

Traceback (most recent call last):
  File "/usr/libexec/glusterfs/python/syncdaemon/gsyncd.py", line 323, in main
    func(args)
  File "/usr/libexec/glusterfs/python/syncdaemon/subcmds.py", line 82, in subcmd_worker
    local.service_loop(remote)
  File "/usr/libexec/glusterfs/python/syncdaemon/resource.py", line 1261, in service_loop
    changelog_agent.init()
  File "/usr/libexec/glusterfs/python/syncdaemon/repce.py", line 233, in __call__
    return self.ins(self.meth, *a)
  File "/usr/libexec/glusterfs/python/syncdaemon/repce.py", line 215, in __call__
    raise res
OSError: libgfchangelog.so: cannot open shared object file: No such file or directory

Backport of:
 > Patch: https://review.gluster.org/22557
 > Change-Id: I3dd013d701ed1cd99ba7ef20d1898f343e1db8f5
 > BUG: 1699394
 > Signed-off-by: Sunny Kumar <sunkumar@redhat.com>
(cherry picked from commit f316c8b797283818bd800569771870a4b9bf1310)

Change-Id: I3dd013d701ed1cd99ba7ef20d1898f343e1db8f5
fixes: bz#1770100
Signed-off-by: Sunny Kumar <sunkumar@redhat.com>

3 files changed, 8 insertions, 6 deletions

diff --git a/geo-replication/syncdaemon/libgfchangelog.py b/geo-replication/syncdaemon/libgfchangelog.py
index fff9d24e54f..8d129567075 100644
--- a/geo-replication/syncdaemon/libgfchangelog.py
+++ b/geo-replication/syncdaemon/libgfchangelog.py
@@ -10,13 +10,14 @@
 
 import os
 from ctypes import CDLL, RTLD_GLOBAL, get_errno, byref, c_ulong
+from ctypes.util import find_library
 from syncdutils import ChangelogException, ChangelogHistoryNotAvailable
 from py2py3 import gr_cl_history_changelog, gr_cl_done, gr_create_string_buffer
 from py2py3 import gr_cl_register, gr_cl_history_done, bytearray_to_str
 
 
 class Changes(object):
-    libgfc = CDLL("libgfchangelog.so", mode=RTLD_GLOBAL,
+    libgfc = CDLL(find_library("gfchangelog"), mode=RTLD_GLOBAL,
                   use_errno=True)
 
     @classmethod
diff --git a/tools/glusterfind/src/libgfchangelog.py b/tools/glusterfind/src/libgfchangelog.py
index 1ef177ab2a5..513bb101e93 100644
--- a/tools/glusterfind/src/libgfchangelog.py
+++ b/tools/glusterfind/src/libgfchangelog.py
@@ -9,8 +9,8 @@
 # cases as published by the Free Software Foundation.
 
 import os
-from ctypes import CDLL, get_errno, create_string_buffer, c_ulong, byref
-from ctypes import RTLD_GLOBAL
+from ctypes import CDLL, RTLD_GLOBAL, get_errno, create_string_buffer, c_ulong, byref
+from ctypes.util import find_library
 from gfind_py2py3 import bytearray_to_str, gf_create_string_buffer
 from gfind_py2py3 import gfind_history_changelog, gfind_changelog_register
 from gfind_py2py3 import gfind_history_changelog_done
@@ -19,8 +19,7 @@ from gfind_py2py3 import gfind_history_changelog_done
 class ChangelogException(OSError):
     pass
 
-
-libgfc = CDLL("libgfchangelog.so", use_errno=True, mode=RTLD_GLOBAL)
+libgfc = CDLL(find_library("gfchangelog"), mode=RTLD_GLOBAL, use_errno=True)
 
 
 def raise_oserr(prefix=None):
diff --git a/xlators/features/changelog/lib/examples/python/libgfchangelog.py b/xlators/features/changelog/lib/examples/python/libgfchangelog.py
index 2cdbf1152b9..2da9f2d2a8c 100644
--- a/xlators/features/changelog/lib/examples/python/libgfchangelog.py
+++ b/xlators/features/changelog/lib/examples/python/libgfchangelog.py
@@ -1,8 +1,10 @@
 import os
 from ctypes import *
+from ctypes.util import find_library
 
 class Changes(object):
-    libgfc = CDLL("libgfchangelog.so", mode=RTLD_GLOBAL, use_errno=True)
+    libgfc = CDLL(find_library("gfchangelog"), mode=RTLD_GLOBAL,
+                  use_errno=True)
 
     @classmethod
     def geterrno(cls):