contrib: add a script to help diagnose raw output of the cmdserver

contrib/debugcmdserver.py

@@ -0,0 +1,47 b''
+#!/usr/bin/env python
+#
+# Dumps output generated by Mercurial's command server in a formatted style to a
+# given file or stderr if '-' is specified. Output is also written in its raw
+# format to stdout.
+#
+# $ ./hg serve --cmds pipe | ./contrib/debugcmdserver.py -
+# o, 52   -> 'capabilities: getencoding runcommand\nencoding: UTF-8'
+
+import sys, struct
+
+if len(sys.argv) != 2:
+    print 'usage: debugcmdserver.py FILE'
+    sys.exit(1)
+
+outputfmt = '>cI'
+outputfmtsize = struct.calcsize(outputfmt)
+
+if sys.argv[1] == '-':
+    log = sys.stderr
+else:
+    log = open(sys.argv[1], 'a')
+
+def read(size):
+    data = sys.stdin.read(size)
+    if not data:
+        raise EOFError()
+    sys.stdout.write(data)
+    sys.stdout.flush()
+    return data
+
+try:
+    while True:
+        header = read(outputfmtsize)
+        channel, length = struct.unpack(outputfmt, header)
+        log.write('%s, %-4d' % (channel, length))
+        if channel in 'IL':
+            log.write(' -> waiting for input\n')
+        else:
+            data = read(length)
+            log.write(' -> %r\n' % data)
+        log.flush()
+except EOFError:
+    pass
+finally:
+    if log != sys.stderr:
+        log.close()