diff -r 001788ef4bbb -r 2e9f379de0ac mercurial/commandserver.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/commandserver.py	Fri Jun 03 17:27:41 2011 +0300
@@ -0,0 +1,213 @@
+# commandserver.py - communicate with Mercurial's API over a pipe
+#
+#  Copyright Matt Mackall <mpm@selenic.com>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+from i18n import _
+import struct
+import sys
+import dispatch, encoding, util
+
+logfile = None
+
+def log(*args):
+    if not logfile:
+        return
+
+    for a in args:
+        logfile.write(str(a))
+
+    logfile.flush()
+
+class channeledoutput(object):
+    """
+    Write data from in_ to out in the following format:
+
+    data length (unsigned int),
+    data
+    """
+    def __init__(self, in_, out, channel):
+        self.in_ = in_
+        self.out = out
+        self.channel = channel
+
+    def write(self, data):
+        if not data:
+            return
+        self.out.write(struct.pack('>cI', self.channel, len(data)))
+        self.out.write(data)
+        self.out.flush()
+
+    def __getattr__(self, attr):
+        if attr in ('isatty', 'fileno'):
+            raise AttributeError, attr
+        return getattr(self.in_, attr)
+
+class channeledinput(object):
+    """
+    Read data from in_.
+
+    Requests for input are written to out in the following format:
+    channel identifier - 'I' for plain input, 'L' line based (1 byte)
+    how many bytes to send at most (unsigned int),
+
+    The client replies with:
+    data length (unsigned int), 0 meaning EOF
+    data
+    """
+
+    maxchunksize = 4 * 1024
+
+    def __init__(self, in_, out, channel):
+        self.in_ = in_
+        self.out = out
+        self.channel = channel
+
+    def read(self, size=-1):
+        if size < 0:
+            # if we need to consume all the clients input, ask for 4k chunks
+            # so the pipe doesn't fill up risking a deadlock
+            size = self.maxchunksize
+            s = self._read(size, self.channel)
+            buf = s
+            while s:
+                buf += s
+                s = self._read(size, self.channel)
+
+            return buf
+        else:
+            return self._read(size, self.channel)
+
+    def _read(self, size, channel):
+        if not size:
+            return ''
+        assert size > 0
+
+        # tell the client we need at most size bytes
+        self.out.write(struct.pack('>cI', channel, size))
+        self.out.flush()
+
+        length = self.in_.read(4)
+        length = struct.unpack('>I', length)[0]
+        if not length:
+            return ''
+        else:
+            return self.in_.read(length)
+
+    def readline(self, size=-1):
+        if size < 0:
+            size = self.maxchunksize
+            s = self._read(size, 'L')
+            buf = s
+            # keep asking for more until there's either no more or
+            # we got a full line
+            while s and s[-1] != '\n':
+                buf += s
+                s = self._read(size, 'L')
+
+            return buf
+        else:
+            return self._read(size, 'L')
+
+    def __iter__(self):
+        return self
+
+    def next(self):
+        l = self.readline()
+        if not l:
+            raise StopIteration
+        return l
+
+    def __getattr__(self, attr):
+        if attr in ('isatty', 'fileno'):
+            raise AttributeError, attr
+        return getattr(self.in_, attr)
+
+class server(object):
+    """
+    Listens for commands on stdin, runs them and writes the output on a channel
+    based stream to stdout.
+    """
+    def __init__(self, ui, repo, mode):
+        self.ui = ui
+
+        logpath = ui.config("cmdserver", "log", None)
+        if logpath:
+            global logfile
+            if logpath == '-':
+                # write log on a special 'd'ebug channel
+                logfile = channeledoutput(sys.stdout, sys.stdout, 'd')
+            else:
+                logfile = open(logpath, 'a')
+
+        self.repo = repo
+
+        if mode == 'pipe':
+            self.cerr = channeledoutput(sys.stderr, sys.stdout, 'e')
+            self.cout = channeledoutput(sys.stdout, sys.stdout, 'o')
+            self.cin = channeledinput(sys.stdin, sys.stdout, 'I')
+            self.cresult = channeledoutput(sys.stdout, sys.stdout, 'r')
+
+            self.client = sys.stdin
+        else:
+            raise util.Abort(_('unknown mode %s') % mode)
+
+    def _read(self, size):
+        data = self.client.read(size)
+
+        # is the other end closed?
+        if not data:
+            raise EOFError()
+
+        return data
+
+    def runcommand(self):
+        """ reads a list of \0 terminated arguments, executes
+        and writes the return code to the result channel """
+
+        length = struct.unpack('>I', self._read(4))[0]
+        args = self._read(length).split('\0')
+
+        # copy the ui so changes to it don't persist between requests
+        req = dispatch.request(args, self.ui.copy(), self.repo, self.cin,
+                               self.cout, self.cerr)
+
+        ret = dispatch.dispatch(req) or 0 # might return None
+
+        self.cresult.write(struct.pack('>i', int(ret)))
+
+    def getencoding(self):
+        """ writes the current encoding to the result channel """
+        self.cresult.write(encoding.encoding)
+
+    def serveone(self):
+        cmd = self.client.readline()[:-1]
+        if cmd:
+            handler = self.capabilities.get(cmd)
+            if handler:
+                handler(self)
+            else:
+                # clients are expected to check what commands are supported by
+                # looking at the servers capabilities
+                raise util.Abort(_('unknown command %s') % cmd)
+
+        return cmd != ''
+
+    capabilities = {'runcommand'  : runcommand,
+                    'getencoding' : getencoding}
+
+    def serve(self):
+        self.cout.write('capabilities: %s' % ' '.join(self.capabilities.keys()))
+        self.cout.write('encoding: %s' % encoding.encoding)
+
+        try:
+            while self.serveone():
+                pass
+        except EOFError:
+            # we'll get here if the client disconnected while we were reading
+            # its request
+            return 1
+
+        return 0