Merge pull request #1745 from Bastian-Krause/bst/rawnetworkinterface-fixes

RawNetworkInterfaceDriver/labgrid-raw-interface Fixes

Author: Bastian-Krause

helpers/labgrid-raw-interface

@@ -73,12 +73,7 @@ def main(program, options):
             args.append(str(options.count))
 
         if options.timeout:
-            # The timeout is implemented by specifying the number of seconds before rotating the
-            # dump file, but limiting the number of files to 1
-            args.append("-G")
-            args.append(str(options.timeout))
-            args.append("-W")
-            args.append("1")
+            args = ["timeout", "--signal=INT", "--preserve-status", str(options.timeout)] + args
 
     elif program == "ip":
         args.append("link")
@@ -131,7 +126,7 @@ if __name__ == "__main__":
     # tcpdump
     tcpdump_parser = subparsers.add_parser("tcpdump")
     tcpdump_parser.add_argument("ifname", type=str, help="interface name")
-    tcpdump_parser.add_argument("count", type=int, default=None, help="amount of frames to capture while recording")
+    tcpdump_parser.add_argument("count", type=int, nargs="?", default=None, help="amount of frames to capture while recording")
     tcpdump_parser.add_argument(
         "--timeout", type=int, default=None, help="Amount of time to capture while recording. 0 means capture forever"
     )

labgrid/driver/rawnetworkinterfacedriver.py

@@ -216,10 +216,30 @@ def start_record(self, filename, *, count=None, timeout=None):
             cmd.append(str(timeout))
         cmd = self._wrap_command(cmd)
         if filename is None:
-            self._record_handle = subprocess.Popen(cmd, stdout=subprocess.PIPE)
+            self._record_handle = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
         else:
             with open(filename, "wb") as outdata:
                 self._record_handle = subprocess.Popen(cmd, stdout=outdata, stderr=subprocess.PIPE)
+
+        # wait for capture start
+        stderr = b""
+        while True:
+            line = self._record_handle.stderr.readline()
+            if not line:  # process ended prematurely
+                try:
+                    self._stop(self._record_handle)
+                except subprocess.CalledProcessError as e:
+                    # readd consumed stderr to exception
+                    e.stderr = stderr
+                    raise
+
+            if line.startswith(b"tcpdump: listening on"):
+                break
+
+            # collect and log other lines in stderr before capturing has started
+            stderr += line
+            self.logger.warning(line.decode().rstrip())
+
         return self._record_handle
 
     @Driver.check_active