cmdserver: don't raise EOFError when trying to read 0 bytes from the client

mercurial/commandserver.py

@@ -1,213 +1,216 b''
 # commandserver.py - communicate with Mercurial's API over a pipe
 #
 #  Copyright Matt Mackall <[e-mail]>
 #
 # 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):
+        if not size:
+            return ''
+
         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