add parameter to Command to disable stderr redirection

fixes #2176

Author: Vladimir Kotal

tools/sync/command.py

@@ -49,14 +49,16 @@ class Command:
     TIMEDOUT = "timed out"
 
     def __init__(self, cmd, args_subst=None, args_append=None, logger=None,
-                 excl_subst=False, work_dir=None, env_vars=None, timeout=None):
+                 excl_subst=False, work_dir=None, env_vars=None, timeout=None,
+                 redirect_stderr=True):
         self.cmd = cmd
         self.state = "notrun"
         self.excl_subst = excl_subst
         self.work_dir = work_dir
         self.env_vars = env_vars
         self.timeout = timeout
         self.pid = None
+        self.redirect_stderr = redirect_stderr
 
         self.logger = logger or logging.getLogger(__name__)
         logging.basicConfig()
@@ -167,8 +169,18 @@ def close(self):
                 return
 
         timeout_thread = None
-        event = threading.Event()
-        output_thread = OutputThread(event, self.logger)
+        output_event = threading.Event()
+        output_thread = OutputThread(output_event, self.logger)
+
+        # If stderr redirection is off, setup a thread that will capture
+        # stderr data.
+        if self.redirect_stderr:
+            stderr_dest = subprocess.STDOUT
+        else:
+            stderr_event = threading.Event()
+            stderr_thread = OutputThread(stderr_event, self.logger)
+            stderr_dest = stderr_thread
+
         try:
             start_time = time.time()
             try:
@@ -179,10 +191,10 @@ def close(self):
             if self.env_vars:
                 my_env = os.environ.copy()
                 my_env.update(self.env_vars)
-                p = subprocess.Popen(self.cmd, stderr=subprocess.STDOUT,
+                p = subprocess.Popen(self.cmd, stderr=stderr_dest,
                                      stdout=output_thread, env=my_env)
             else:
-                p = subprocess.Popen(self.cmd, stderr=subprocess.STDOUT,
+                p = subprocess.Popen(self.cmd, stderr=stderr_dest,
                                      stdout=output_thread)
 
             self.pid = p.pid
@@ -226,9 +238,15 @@ def close(self):
             # exit the read loop we have to close it here ourselves.
             output_thread.close()
             self.logger.debug("Waiting on output thread to finish reading")
-            event.wait()
-
+            output_event.wait()
             self.out = output_thread.getoutput()
+
+            if not self.redirect_stderr:
+                stderr_thread.close()
+                self.logger.debug("Waiting on stderr thread to finish reading")
+                stderr_event.wait()
+                self.err = stderr_thread.getoutput()
+
             elapsed_time = time.time() - start_time
             self.logger.debug("Command {} took {} seconds".
                               format(self.cmd, int(elapsed_time)))
@@ -286,6 +304,9 @@ def getoutput(self):
         else:
             return None
 
+    def geterroutput(self):
+        return self.err
+
     def getstate(self):
         return self.state
 

tools/sync/projadm.py

@@ -55,14 +55,15 @@ def exec_command(doit, logger, cmd, msg):
     Execute given command and return its output.
     Exit the program on failure.
     """
-    cmd = Command(cmd, logger=logger)
+    cmd = Command(cmd, logger=logger, redirect_stderr=False)
     if not doit:
         logger.info(cmd)
         return
     cmd.execute()
     if cmd.getstate() is not Command.FINISHED or cmd.getretcode() != 0:
         logger.error(msg)
-        logger.error(cmd.getoutput())
+        logger.error("Standard output: {}".format(cmd.getoutput()))
+        logger.error("Error output: {}".format(cmd.geterroutput()))
         sys.exit(1)
 
     return cmd.getoutput()

tools/sync/test/test_command.py

@@ -121,6 +121,18 @@ def test_notimeout(self):
         self.assertEqual(Command.FINISHED, cmd.getstate())
         self.assertEqual(0, cmd.getretcode())
 
+    @unittest.skipUnless(os.name.startswith("posix"), "requires Unix")
+    def test_stderr(self):
+        cmd = Command(["/bin/cat", "/foo/bar", "/etc/passwd"],
+                      redirect_stderr=False)
+        cmd.execute()
+        self.assertEqual(Command.FINISHED, cmd.getstate())
+        self.assertNotEqual(0, cmd.getretcode())
+        # The error could contain localized output strings so check just
+        # for the path itself.
+        self.assertTrue("/foo/bar" in "\n".join(cmd.geterroutput()))
+        self.assertFalse("/foo/bar" in "\n".join(cmd.getoutput()))
+        self.assertTrue("root" in "\n".join(cmd.getoutput()))
 
 if __name__ == '__main__':
     unittest.main()