inotify: raise QueryFailed when the server crash

When the server crashes, it does not write back on the socket. The message
which is then read from the socket is '', which raises a TypeError.
Catching TypeError to raise QueryFailed instead.

hgext/inotify/client.py

@@ -1,153 +1,159 b''
 # client.py - inotify status client
 #
 # Copyright 2006, 2007, 2008 Bryan O'Sullivan <[e-mail]>
 # Copyright 2007, 2008 Brendan Cully <[e-mail]>
 # Copyright 2009 Nicolas Dumazet <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2, incorporated herein by reference.
 
 from mercurial.i18n import _
 import common, server
 import errno, os, socket, struct
 
 class QueryFailed(Exception): pass
 
 def start_server(function):
     """
     Decorator.
     Tries to call function, if it fails, try to (re)start inotify server.
     Raise QueryFailed if something went wrong
     """
     def decorated_function(self, *args):
         result = None
         try:
             return function(self, *args)
         except (OSError, socket.error), err:
             autostart = self.ui.configbool('inotify', 'autostart', True)
 
             if err[0] == errno.ECONNREFUSED:
                 self.ui.warn(_('(found dead inotify server socket; '
                                'removing it)\n'))
                 os.unlink(self.repo.join('inotify.sock'))
             if err[0] in (errno.ECONNREFUSED, errno.ENOENT) and autostart:
                 self.ui.debug(_('(starting inotify server)\n'))
                 try:
                     try:
                         server.start(self.ui, self.repo)
                     except server.AlreadyStartedException, inst:
                         # another process may have started its own
                         # inotify server while this one was starting.
                         self.ui.debug(str(inst))
                 except Exception, inst:
                     self.ui.warn(_('could not start inotify server: '
                                    '%s\n') % inst)
                 else:
                     try:
                         return function(self, *args)
                     except socket.error, err:
                         self.ui.warn(_('could not talk to new inotify '
                                        'server: %s\n') % err[-1])
             elif err[0] in (errno.ECONNREFUSED, errno.ENOENT):
                 # silently ignore normal errors if autostart is False
                 self.ui.debug(_('(inotify server not running)\n'))
             else:
                 self.ui.warn(_('failed to contact inotify server: %s\n')
                          % err[-1])
 
         self.ui.traceback()
         raise QueryFailed('inotify query failed')
 
     return decorated_function
 
 
 class client(object):
     def __init__(self, ui, repo):
         self.ui = ui
         self.repo = repo
         self.sock = socket.socket(socket.AF_UNIX)
 
     def _connect(self):
         sockpath = self.repo.join('inotify.sock')
         try:
             self.sock.connect(sockpath)
         except socket.error, err:
             if err[0] == "AF_UNIX path too long":
                 sockpath = os.readlink(sockpath)
                 self.sock.connect(sockpath)
             else:
                 raise
 
     def _send(self, type, data):
         """Sends protocol version number, and the data"""
         self.sock.sendall(chr(common.version) + type + data)
 
         self.sock.shutdown(socket.SHUT_WR)
 
     def _receive(self, type):
         """
         Read data, check version number, extract headers,
         and returns a tuple (data descriptor, header)
         Raises QueryFailed on error
         """
         cs = common.recvcs(self.sock)
-        version = ord(cs.read(1))
+        try:
+            version = ord(cs.read(1))
+        except TypeError:
+            # empty answer, assume the server crashed
+            self.ui.warn(_('received empty answer from inotify server'))
+            raise QueryFailed('server crashed')
+
         if version != common.version:
             self.ui.warn(_('(inotify: received response from incompatible '
                       'server version %d)\n') % version)
             raise QueryFailed('incompatible server version')
 
         readtype = cs.read(4)
         if readtype != type:
             self.ui.warn(_('(inotify: received \'%s\' response when expecting'
                        ' \'%s\')\n') % (readtype, type))
             raise QueryFailed('wrong response type')
 
         hdrfmt = common.resphdrfmts[type]
         hdrsize = common.resphdrsizes[type]
         try:
             resphdr = struct.unpack(hdrfmt, cs.read(hdrsize))
         except struct.error:
             raise QueryFailed('unable to retrieve query response headers')
 
         return cs, resphdr
 
     def query(self, type, req):
         self._connect()
 
         self._send(type, req)
 
         return self._receive(type)
 
     @start_server
     def statusquery(self, names, match, ignored, clean, unknown=True):
 
         def genquery():
             for n in names:
                 yield n
             states = 'almrx!'
             if ignored:
                 raise ValueError('this is insanity')
             if clean: states += 'c'
             if unknown: states += '?'
             yield states
 
         req = '\0'.join(genquery())
 
         cs, resphdr = self.query('STAT', req)
 
         def readnames(nbytes):
             if nbytes:
                 names = cs.read(nbytes)
                 if names:
                     return filter(match, names.split('\0'))
             return []
         return map(readnames, resphdr)
 
     @start_server
     def debugquery(self):
         cs, resphdr = self.query('DBUG', '')
 
         nbytes = resphdr[0]
         names = cs.read(nbytes)
         return names.split('\0')