Made testserver communicate to parent process with JSON

This is so that if the testserver needs to communicate anything more than
the port in the future (e.g., xmpp port for the test sync server), it
can do so in a flexible manner.

BUG=53934
TEST=manually

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=66879

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=67018

Review URL: http://codereview.chromium.org/5196001

git-svn-id: http://src.chromium.org/svn/trunk/src/net/tools/testserver@67386 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
diff --git a/testserver.py b/testserver.py
index 2551139..b69eb2f 100755
--- a/testserver.py
+++ b/testserver.py
@@ -27,6 +27,13 @@
 import urlparse
 import warnings
 
+# If we use simplejson always, we get some warnings when we run under
+# 2.6.
+if sys.version_info < (2, 6):
+  import simplejson as json
+else:
+  import json
+
 # Ignore deprecation warnings, they make our output more cluttered.
 warnings.filterwarnings("ignore", category=DeprecationWarning)
 
@@ -1321,15 +1328,22 @@
   # Notify the parent that we've started. (BaseServer subclasses
   # bind their sockets on construction.)
   if options.startup_pipe is not None:
+    server_data = {
+      'port': listen_port
+    }
+    server_data_json = json.dumps(server_data)
+    debug('sending server_data: %s' % server_data_json)
+    server_data_len = len(server_data_json)
     if sys.platform == 'win32':
       fd = msvcrt.open_osfhandle(options.startup_pipe, 0)
     else:
       fd = options.startup_pipe
     startup_pipe = os.fdopen(fd, "w")
-    # Write the listening port as a 2 byte value. This is _not_ using
-    # network byte ordering since the other end of the pipe is on the same
-    # machine.
-    startup_pipe.write(struct.pack('@H', listen_port))
+    # First write the data length as an unsigned 4-byte value.  This
+    # is _not_ using network byte ordering since the other end of the
+    # pipe is on the same machine.
+    startup_pipe.write(struct.pack('=L', server_data_len))
+    startup_pipe.write(server_data_json)
     startup_pipe.close()
 
   try: