util/ssh: explicitly pass /dev/null for stdin

This avoids a problem where SSH tries to interact with the terminal,
which shouldn't happen here.

Signed-off-by: Jan Luebbe <jlu@pengutronix.de>

labgrid/util/ssh.py

@@ -168,7 +168,8 @@ def _run_socket_command(self, command, forward=None):
         complete_cmd.append(self.host)
         res = subprocess.check_call(
             complete_cmd,
-            timeout=2
+            stdin=subprocess.DEVNULL,
+            timeout=2,
         )
 
         return res
@@ -201,7 +202,8 @@ def run_command(self, command):
         complete_cmd = ["ssh"] + self._get_ssh_args()
         complete_cmd += [self.host, command]
         res = subprocess.check_call(
-            complete_cmd
+            complete_cmd,
+            stdin=subprocess.DEVNULL,
         )
 
         return res
@@ -214,7 +216,10 @@ def get_file(self, remote_file, local_file):
                 "{}:{}".format(self.host, remote_file),
                 "{}".format(local_file)
         ]
-        subprocess.check_call(complete_cmd)
+        subprocess.check_call(
+            complete_cmd,
+            stdin=subprocess.DEVNULL,
+        )
 
     @_check_connected
     def put_file(self, local_file, remote_path):
@@ -224,7 +229,10 @@ def put_file(self, local_file, remote_path):
                 "{}".format(local_file),
                 "{}:{}".format(self.host, remote_path)
         ]
-        subprocess.check_call(complete_cmd)
+        subprocess.check_call(
+            complete_cmd,
+            stdin=subprocess.DEVNULL,
+        )
 
     @_check_connected
     def add_port_forward(self, remote_host, remote_port):
@@ -280,9 +288,9 @@ def _check_external_master(self):
         # capture and parse it.
         proc = subprocess.Popen(
             args,
+            stdin=subprocess.DEVNULL,
+            stdout=subprocess.PIPE,
             stderr=subprocess.STDOUT,
-            stdin=subprocess.PIPE,
-            stdout=subprocess.PIPE
         )
         stdout, _ = proc.communicate(timeout=60)
         check = proc.wait(args)
@@ -314,9 +322,9 @@ def _start_own_master(self):
         assert self._master is None
         self._master = subprocess.Popen(
             args,
+            stdin=subprocess.DEVNULL,
+            stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
-            stdin=subprocess.PIPE,
-            stdout=subprocess.PIPE
         )
 
         try:
@@ -361,9 +369,9 @@ def _start_keepalive(self):
         assert self._keepalive is None
         self._keepalive = subprocess.Popen(
             args,
-            stderr=subprocess.PIPE,
             stdin=subprocess.PIPE,
-            stdout=subprocess.PIPE
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
         )
 
         self._logger.debug('Started keepalive for %s', self.host)