cmdserver: protect pipe server streams against corruption caused by direct io

Because pipe-mode server uses stdio as IPC channel, other modules should not
touch stdio directly and use ui instead.  However, this strategy is brittle
because several Python functions read and write stdio implicitly.

    print 'hello'  # should use ui.write()
    # => ch = 'h', size = 1701604463 'ello', data = '\n'

This patch adds protection for such mistakes.  Both stdio files and low-level
file descriptors are redirected to /dev/null while command server uses them.

mercurial/commandserver.py

@@ -1,324 +1,353 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 os, errno, traceback, SocketServer
+import sys, os, errno, traceback, SocketServer
 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 to out in the following format:
 
     data length (unsigned int),
     data
     """
     def __init__(self, out, channel):
         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.out, 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:
                 s = self._read(size, self.channel)
                 buf += s
 
             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':
                 s = self._read(size, 'L')
                 buf += s
 
             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 fin, runs them and writes the output on a channel
     based stream to fout.
     """
     def __init__(self, ui, repo, fin, fout):
         self.cwd = os.getcwd()
 
         logpath = ui.config("cmdserver", "log", None)
         if logpath:
             global logfile
             if logpath == '-':
                 # write log on a special 'd' (debug) channel
                 logfile = channeledoutput(fout, 'd')
             else:
                 logfile = open(logpath, 'a')
 
         if repo:
             # the ui here is really the repo ui so take its baseui so we don't
             # end up with its local configuration
             self.ui = repo.baseui
             self.repo = repo
             self.repoui = repo.ui
         else:
             self.ui = ui
             self.repo = self.repoui = None
 
         self.cerr = channeledoutput(fout, 'e')
         self.cout = channeledoutput(fout, 'o')
         self.cin = channeledinput(fin, fout, 'I')
         self.cresult = channeledoutput(fout, 'r')
 
         self.client = fin
 
     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]
         if not length:
             args = []
         else:
             args = self._read(length).split('\0')
 
         # copy the uis so changes (e.g. --config or --verbose) don't
         # persist between requests
         copiedui = self.ui.copy()
         uis = [copiedui]
         if self.repo:
             self.repo.baseui = copiedui
             # clone ui without using ui.copy because this is protected
             repoui = self.repoui.__class__(self.repoui)
             repoui.copy = copiedui.copy # redo copy protection
             uis.append(repoui)
             self.repo.ui = self.repo.dirstate._ui = repoui
             self.repo.invalidateall()
 
         for ui in uis:
             # any kind of interaction must use server channels
             ui.setconfig('ui', 'nontty', 'true', 'commandserver')
 
         req = dispatch.request(args[:], copiedui, self.repo, self.cin,
                                self.cout, self.cerr)
 
         ret = (dispatch.dispatch(req) or 0) & 255 # might return None
 
         # restore old cwd
         if '--cwd' in args:
             os.chdir(self.cwd)
 
         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):
         hellomsg = 'capabilities: ' + ' '.join(sorted(self.capabilities))
         hellomsg += '\n'
         hellomsg += 'encoding: ' + encoding.encoding
         hellomsg += '\n'
         hellomsg += 'pid: %d' % os.getpid()
 
         # write the hello msg in -one- chunk
         self.cout.write(hellomsg)
 
         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
 
+def _protectio(ui):
+    """ duplicates streams and redirect original to null if ui uses stdio """
+    ui.flush()
+    newfiles = []
+    nullfd = os.open(os.devnull, os.O_RDWR)
+    for f, sysf, mode in [(ui.fin, sys.stdin, 'rb'),
+                          (ui.fout, sys.stdout, 'wb')]:
+        if f is sysf:
+            newfd = os.dup(f.fileno())
+            os.dup2(nullfd, f.fileno())
+            f = os.fdopen(newfd, mode)
+        newfiles.append(f)
+    os.close(nullfd)
+    return tuple(newfiles)
+
+def _restoreio(ui, fin, fout):
+    """ restores streams from duplicated ones """
+    ui.flush()
+    for f, uif in [(fin, ui.fin), (fout, ui.fout)]:
+        if f is not uif:
+            os.dup2(f.fileno(), uif.fileno())
+            f.close()
+
 class pipeservice(object):
     def __init__(self, ui, repo, opts):
         self.ui = ui
         self.repo = repo
 
     def init(self):
         pass
 
     def run(self):
         ui = self.ui
-        sv = server(ui, self.repo, ui.fin, ui.fout)
-        return sv.serve()
+        # redirect stdio to null device so that broken extensions or in-process
+        # hooks will never cause corruption of channel protocol.
+        fin, fout = _protectio(ui)
+        try:
+            sv = server(ui, self.repo, fin, fout)
+            return sv.serve()
+        finally:
+            _restoreio(ui, fin, fout)
 
 class _requesthandler(SocketServer.StreamRequestHandler):
     def handle(self):
         ui = self.server.ui
         repo = self.server.repo
         sv = server(ui, repo, self.rfile, self.wfile)
         try:
             try:
                 sv.serve()
             # handle exceptions that may be raised by command server. most of
             # known exceptions are caught by dispatch.
             except util.Abort, inst:
                 ui.warn(_('abort: %s\n') % inst)
             except IOError, inst:
                 if inst.errno != errno.EPIPE:
                     raise
             except KeyboardInterrupt:
                 pass
         except: # re-raises
             # also write traceback to error channel. otherwise client cannot
             # see it because it is written to server's stderr by default.
             traceback.print_exc(file=sv.cerr)
             raise
 
 class unixservice(object):
     """
     Listens on unix domain socket and forks server per connection
     """
     def __init__(self, ui, repo, opts):
         self.ui = ui
         self.repo = repo
         self.address = opts['address']
         if not util.safehasattr(SocketServer, 'UnixStreamServer'):
             raise util.Abort(_('unsupported platform'))
         if not self.address:
             raise util.Abort(_('no socket path specified with --address'))
 
     def init(self):
         class cls(SocketServer.ForkingMixIn, SocketServer.UnixStreamServer):
             ui = self.ui
             repo = self.repo
         self.server = cls(self.address, _requesthandler)
         self.ui.status(_('listening at %s\n') % self.address)
         self.ui.flush()  # avoid buffering of status message
 
     def run(self):
         try:
             self.server.serve_forever()
         finally:
             os.unlink(self.address)
 
 _servicemap = {
     'pipe': pipeservice,
     'unix': unixservice,
     }
 
 def createservice(ui, repo, opts):
     mode = opts['cmdserver']
     try:
         return _servicemap[mode](ui, repo, opts)
     except KeyError:
         raise util.Abort(_('unknown mode %s') % mode)

tests/test-commandserver.t

@@ -1,633 +1,647 b''
 #if windows
   $ PYTHONPATH="$TESTDIR/../contrib;$PYTHONPATH"
 #else
   $ PYTHONPATH="$TESTDIR/../contrib:$PYTHONPATH"
 #endif
   $ export PYTHONPATH
 
 typical client does not want echo-back messages, so test without it:
 
   $ grep -v '^promptecho ' < $HGRCPATH >> $HGRCPATH.new
   $ mv $HGRCPATH.new $HGRCPATH
 
   $ hg init repo
   $ cd repo
 
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def hellomessage(server):
   ...     ch, data = readchannel(server)
   ...     print '%c, %r' % (ch, data)
   ...     # run an arbitrary command to make sure the next thing the server
   ...     # sends isn't part of the hello message
   ...     runcommand(server, ['id'])
   o, 'capabilities: getencoding runcommand\nencoding: *\npid: *' (glob)
   *** runcommand id
   000000000000 tip
 
   >>> from hgclient import check
   >>> @check
   ... def unknowncommand(server):
   ...     server.stdin.write('unknowncommand\n')
   abort: unknown command unknowncommand
 
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def checkruncommand(server):
   ...     # hello block
   ...     readchannel(server)
   ... 
   ...     # no args
   ...     runcommand(server, [])
   ... 
   ...     # global options
   ...     runcommand(server, ['id', '--quiet'])
   ... 
   ...     # make sure global options don't stick through requests
   ...     runcommand(server, ['id'])
   ... 
   ...     # --config
   ...     runcommand(server, ['id', '--config', 'ui.quiet=True'])
   ... 
   ...     # make sure --config doesn't stick
   ...     runcommand(server, ['id'])
   ... 
   ...     # negative return code should be masked
   ...     runcommand(server, ['id', '-runknown'])
   *** runcommand 
   Mercurial Distributed SCM
   
   basic commands:
   
    add           add the specified files on the next commit
    annotate      show changeset information by line for each file
    clone         make a copy of an existing repository
    commit        commit the specified files or all outstanding changes
    diff          diff repository (or selected files)
    export        dump the header and diffs for one or more changesets
    forget        forget the specified files on the next commit
    init          create a new repository in the given directory
    log           show revision history of entire repository or files
    merge         merge working directory with another revision
    pull          pull changes from the specified source
    push          push changes to the specified destination
    remove        remove the specified files on the next commit
    serve         start stand-alone webserver
    status        show changed files in the working directory
    summary       summarize working directory state
    update        update working directory (or switch revisions)
   
   (use "hg help" for the full list of commands or "hg -v" for details)
   *** runcommand id --quiet
   000000000000
   *** runcommand id
   000000000000 tip
   *** runcommand id --config ui.quiet=True
   000000000000
   *** runcommand id
   000000000000 tip
   *** runcommand id -runknown
   abort: unknown revision 'unknown'!
    [255]
 
   >>> from hgclient import readchannel, check
   >>> @check
   ... def inputeof(server):
   ...     readchannel(server)
   ...     server.stdin.write('runcommand\n')
   ...     # close stdin while server is waiting for input
   ...     server.stdin.close()
   ... 
   ...     # server exits with 1 if the pipe closed while reading the command
   ...     print 'server exit code =', server.wait()
   server exit code = 1
 
   >>> import cStringIO
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def serverinput(server):
   ...     readchannel(server)
   ... 
   ...     patch = """
   ... # HG changeset patch
   ... # User test
   ... # Date 0 0
   ... # Node ID c103a3dec114d882c98382d684d8af798d09d857
   ... # Parent  0000000000000000000000000000000000000000
   ... 1
   ... 
   ... diff -r 000000000000 -r c103a3dec114 a
   ... --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
   ... +++ b/a	Thu Jan 01 00:00:00 1970 +0000
   ... @@ -0,0 +1,1 @@
   ... +1
   ... """
   ... 
   ...     runcommand(server, ['import', '-'], input=cStringIO.StringIO(patch))
   ...     runcommand(server, ['log'])
   *** runcommand import -
   applying patch from stdin
   *** runcommand log
   changeset:   0:eff892de26ec
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     1
   
 
 check that --cwd doesn't persist between requests:
 
   $ mkdir foo
   $ touch foo/bar
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def cwd(server):
   ...     readchannel(server)
   ...     runcommand(server, ['--cwd', 'foo', 'st', 'bar'])
   ...     runcommand(server, ['st', 'foo/bar'])
   *** runcommand --cwd foo st bar
   ? bar
   *** runcommand st foo/bar
   ? foo/bar
 
   $ rm foo/bar
 
 
 check that local configs for the cached repo aren't inherited when -R is used:
 
   $ cat <<EOF >> .hg/hgrc
   > [ui]
   > foo = bar
   > EOF
 
   >>> from hgclient import readchannel, sep, runcommand, check
   >>> @check
   ... def localhgrc(server):
   ...     readchannel(server)
   ... 
   ...     # the cached repo local hgrc contains ui.foo=bar, so showconfig should
   ...     # show it
   ...     runcommand(server, ['showconfig'], outfilter=sep)
   ... 
   ...     # but not for this repo
   ...     runcommand(server, ['init', 'foo'])
   ...     runcommand(server, ['-R', 'foo', 'showconfig', 'ui', 'defaults'])
   *** runcommand showconfig
   bundle.mainreporoot=$TESTTMP/repo
   defaults.backout=-d "0 0"
   defaults.commit=-d "0 0"
   defaults.shelve=--date "0 0"
   defaults.tag=-d "0 0"
   ui.slash=True
   ui.interactive=False
   ui.mergemarkers=detailed
   ui.foo=bar
   ui.nontty=true
   *** runcommand init foo
   *** runcommand -R foo showconfig ui defaults
   defaults.backout=-d "0 0"
   defaults.commit=-d "0 0"
   defaults.shelve=--date "0 0"
   defaults.tag=-d "0 0"
   ui.slash=True
   ui.interactive=False
   ui.mergemarkers=detailed
   ui.nontty=true
 
   $ rm -R foo
 
 #if windows
   $ PYTHONPATH="$TESTTMP/repo;$PYTHONPATH"
 #else
   $ PYTHONPATH="$TESTTMP/repo:$PYTHONPATH"
 #endif
 
   $ cat <<EOF > hook.py
   > import sys
   > def hook(**args):
   >     print 'hook talking'
   >     print 'now try to read something: %r' % sys.stdin.read()
   > EOF
 
   >>> import cStringIO
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def hookoutput(server):
   ...     readchannel(server)
   ...     runcommand(server, ['--config',
   ...                         'hooks.pre-identify=python:hook.hook',
   ...                         'id'],
   ...                input=cStringIO.StringIO('some input'))
   *** runcommand --config hooks.pre-identify=python:hook.hook id
   hook talking
   now try to read something: 'some input'
   eff892de26ec tip
 
   $ rm hook.py*
 
   $ echo a >> a
   >>> import os
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def outsidechanges(server):
   ...     readchannel(server)
   ...     runcommand(server, ['status'])
   ...     os.system('hg ci -Am2')
   ...     runcommand(server, ['tip'])
   ...     runcommand(server, ['status'])
   *** runcommand status
   M a
   *** runcommand tip
   changeset:   1:d3a0a68be6de
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     2
   
   *** runcommand status
 
   >>> import os
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def bookmarks(server):
   ...     readchannel(server)
   ...     runcommand(server, ['bookmarks'])
   ... 
   ...     # changes .hg/bookmarks
   ...     os.system('hg bookmark -i bm1')
   ...     os.system('hg bookmark -i bm2')
   ...     runcommand(server, ['bookmarks'])
   ... 
   ...     # changes .hg/bookmarks.current
   ...     os.system('hg upd bm1 -q')
   ...     runcommand(server, ['bookmarks'])
   ... 
   ...     runcommand(server, ['bookmarks', 'bm3'])
   ...     f = open('a', 'ab')
   ...     f.write('a\n')
   ...     f.close()
   ...     runcommand(server, ['commit', '-Amm'])
   ...     runcommand(server, ['bookmarks'])
   *** runcommand bookmarks
   no bookmarks set
   *** runcommand bookmarks
      bm1                       1:d3a0a68be6de
      bm2                       1:d3a0a68be6de
   *** runcommand bookmarks
    * bm1                       1:d3a0a68be6de
      bm2                       1:d3a0a68be6de
   *** runcommand bookmarks bm3
   *** runcommand commit -Amm
   *** runcommand bookmarks
      bm1                       1:d3a0a68be6de
      bm2                       1:d3a0a68be6de
    * bm3                       2:aef17e88f5f0
 
   >>> import os
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def tagscache(server):
   ...     readchannel(server)
   ...     runcommand(server, ['id', '-t', '-r', '0'])
   ...     os.system('hg tag -r 0 foo')
   ...     runcommand(server, ['id', '-t', '-r', '0'])
   *** runcommand id -t -r 0
   
   *** runcommand id -t -r 0
   foo
 
   >>> import os
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def setphase(server):
   ...     readchannel(server)
   ...     runcommand(server, ['phase', '-r', '.'])
   ...     os.system('hg phase -r . -p')
   ...     runcommand(server, ['phase', '-r', '.'])
   *** runcommand phase -r .
   3: draft
   *** runcommand phase -r .
   3: public
 
   $ echo a >> a
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def rollback(server):
   ...     readchannel(server)
   ...     runcommand(server, ['phase', '-r', '.', '-p'])
   ...     runcommand(server, ['commit', '-Am.'])
   ...     runcommand(server, ['rollback'])
   ...     runcommand(server, ['phase', '-r', '.'])
   *** runcommand phase -r . -p
   no phases changed
    [1]
   *** runcommand commit -Am.
   *** runcommand rollback
   repository tip rolled back to revision 3 (undo commit)
   working directory now based on revision 3
   *** runcommand phase -r .
   3: public
 
   >>> import os
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def branch(server):
   ...     readchannel(server)
   ...     runcommand(server, ['branch'])
   ...     os.system('hg branch foo')
   ...     runcommand(server, ['branch'])
   ...     os.system('hg branch default')
   *** runcommand branch
   default
   marked working directory as branch foo
   (branches are permanent and global, did you want a bookmark?)
   *** runcommand branch
   foo
   marked working directory as branch default
   (branches are permanent and global, did you want a bookmark?)
 
   $ touch .hgignore
   >>> import os
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def hgignore(server):
   ...     readchannel(server)
   ...     runcommand(server, ['commit', '-Am.'])
   ...     f = open('ignored-file', 'ab')
   ...     f.write('')
   ...     f.close()
   ...     f = open('.hgignore', 'ab')
   ...     f.write('ignored-file')
   ...     f.close()
   ...     runcommand(server, ['status', '-i', '-u'])
   *** runcommand commit -Am.
   adding .hgignore
   *** runcommand status -i -u
   I ignored-file
 
   >>> import os
   >>> from hgclient import readchannel, sep, runcommand, check
   >>> @check
   ... def phasecacheafterstrip(server):
   ...     readchannel(server)
   ... 
   ...     # create new head, 5:731265503d86
   ...     runcommand(server, ['update', '-C', '0'])
   ...     f = open('a', 'ab')
   ...     f.write('a\n')
   ...     f.close()
   ...     runcommand(server, ['commit', '-Am.', 'a'])
   ...     runcommand(server, ['log', '-Gq'])
   ... 
   ...     # make it public; draft marker moves to 4:7966c8e3734d
   ...     runcommand(server, ['phase', '-p', '.'])
   ...     # load _phasecache.phaseroots
   ...     runcommand(server, ['phase', '.'], outfilter=sep)
   ... 
   ...     # strip 1::4 outside server
   ...     os.system('hg -q --config extensions.mq= strip 1')
   ... 
   ...     # shouldn't raise "7966c8e3734d: no node!"
   ...     runcommand(server, ['branches'])
   *** runcommand update -C 0
   1 files updated, 0 files merged, 2 files removed, 0 files unresolved
   (leaving bookmark bm3)
   *** runcommand commit -Am. a
   created new head
   *** runcommand log -Gq
   @  5:731265503d86
   |
   | o  4:7966c8e3734d
   | |
   | o  3:b9b85890c400
   | |
   | o  2:aef17e88f5f0
   | |
   | o  1:d3a0a68be6de
   |/
   o  0:eff892de26ec
   
   *** runcommand phase -p .
   *** runcommand phase .
   5: public
   *** runcommand branches
   default                        1:731265503d86
 
   $ cat >> .hg/hgrc << EOF
   > [experimental]
   > evolution=createmarkers
   > EOF
 
   >>> import os
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def obsolete(server):
   ...     readchannel(server)
   ... 
   ...     runcommand(server, ['up', 'null'])
   ...     runcommand(server, ['phase', '-df', 'tip'])
   ...     cmd = 'hg debugobsolete `hg log -r tip --template {node}`'
   ...     if os.name == 'nt':
   ...         cmd = 'sh -c "%s"' % cmd # run in sh, not cmd.exe
   ...     os.system(cmd)
   ...     runcommand(server, ['log', '--hidden'])
   ...     runcommand(server, ['log'])
   *** runcommand up null
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   *** runcommand phase -df tip
   *** runcommand log --hidden
   changeset:   1:731265503d86
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     .
   
   changeset:   0:eff892de26ec
   bookmark:    bm1
   bookmark:    bm2
   bookmark:    bm3
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     1
   
   *** runcommand log
   changeset:   0:eff892de26ec
   bookmark:    bm1
   bookmark:    bm2
   bookmark:    bm3
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     1
   
 
   $ cat <<EOF >> .hg/hgrc
   > [extensions]
   > mq =
   > EOF
 
   >>> import os
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def mqoutsidechanges(server):
   ...     readchannel(server)
   ... 
   ...     # load repo.mq
   ...     runcommand(server, ['qapplied'])
   ...     os.system('hg qnew 0.diff')
   ...     # repo.mq should be invalidated
   ...     runcommand(server, ['qapplied'])
   ... 
   ...     runcommand(server, ['qpop', '--all'])
   ...     os.system('hg qqueue --create foo')
   ...     # repo.mq should be recreated to point to new queue
   ...     runcommand(server, ['qqueue', '--active'])
   *** runcommand qapplied
   *** runcommand qapplied
   0.diff
   *** runcommand qpop --all
   popping 0.diff
   patch queue now empty
   *** runcommand qqueue --active
   foo
 
   $ cat <<EOF > dbgui.py
+  > import os, sys
   > from mercurial import cmdutil, commands
   > cmdtable = {}
   > command = cmdutil.command(cmdtable)
   > @command("debuggetpass", norepo=True)
   > def debuggetpass(ui):
   >     ui.write("%s\\n" % ui.getpass())
   > @command("debugprompt", norepo=True)
   > def debugprompt(ui):
   >     ui.write("%s\\n" % ui.prompt("prompt:"))
+  > @command("debugreadstdin", norepo=True)
+  > def debugreadstdin(ui):
+  >     ui.write("read: %r\n" % sys.stdin.read(1))
+  > @command("debugwritestdout", norepo=True)
+  > def debugwritestdout(ui):
+  >     os.write(1, "low-level stdout fd and\n")
+  >     sys.stdout.write("stdout should be redirected to /dev/null\n")
+  >     sys.stdout.flush()
   > EOF
   $ cat <<EOF >> .hg/hgrc
   > [extensions]
   > dbgui = dbgui.py
   > EOF
 
   >>> import cStringIO
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def getpass(server):
   ...     readchannel(server)
   ...     runcommand(server, ['debuggetpass', '--config',
   ...                         'ui.interactive=True'],
   ...                input=cStringIO.StringIO('1234\n'))
   ...     runcommand(server, ['debugprompt', '--config',
   ...                         'ui.interactive=True'],
   ...                input=cStringIO.StringIO('5678\n'))
+  ...     runcommand(server, ['debugreadstdin'])
+  ...     runcommand(server, ['debugwritestdout'])
   *** runcommand debuggetpass --config ui.interactive=True
   password: 1234
   *** runcommand debugprompt --config ui.interactive=True
   prompt: 5678
+  *** runcommand debugreadstdin
+  read: ''
+  *** runcommand debugwritestdout
 
 
 run commandserver in commandserver, which is silly but should work:
 
   >>> import cStringIO
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def nested(server):
   ...     print '%c, %r' % readchannel(server)
   ...     class nestedserver(object):
   ...         stdin = cStringIO.StringIO('getencoding\n')
   ...         stdout = cStringIO.StringIO()
   ...     runcommand(server, ['serve', '--cmdserver', 'pipe'],
   ...                output=nestedserver.stdout, input=nestedserver.stdin)
   ...     nestedserver.stdout.seek(0)
   ...     print '%c, %r' % readchannel(nestedserver)  # hello
   ...     print '%c, %r' % readchannel(nestedserver)  # getencoding
   o, 'capabilities: getencoding runcommand\nencoding: *\npid: *' (glob)
   *** runcommand serve --cmdserver pipe
   o, 'capabilities: getencoding runcommand\nencoding: *\npid: *' (glob)
   r, '*' (glob)
 
 
 start without repository:
 
   $ cd ..
 
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def hellomessage(server):
   ...     ch, data = readchannel(server)
   ...     print '%c, %r' % (ch, data)
   ...     # run an arbitrary command to make sure the next thing the server
   ...     # sends isn't part of the hello message
   ...     runcommand(server, ['id'])
   o, 'capabilities: getencoding runcommand\nencoding: *\npid: *' (glob)
   *** runcommand id
   abort: there is no Mercurial repository here (.hg not found)
    [255]
 
   >>> from hgclient import readchannel, runcommand, check
   >>> @check
   ... def startwithoutrepo(server):
   ...     readchannel(server)
   ...     runcommand(server, ['init', 'repo2'])
   ...     runcommand(server, ['id', '-R', 'repo2'])
   *** runcommand init repo2
   *** runcommand id -R repo2
   000000000000 tip
 
 
 unix domain socket:
 
   $ cd repo
   $ hg update -q
 
 #if unix-socket unix-permissions
 
   >>> import cStringIO
   >>> from hgclient import unixserver, readchannel, runcommand, check
   >>> server = unixserver('.hg/server.sock', '.hg/server.log')
   >>> def hellomessage(conn):
   ...     ch, data = readchannel(conn)
   ...     print '%c, %r' % (ch, data)
   ...     runcommand(conn, ['id'])
   >>> check(hellomessage, server.connect)
   o, 'capabilities: getencoding runcommand\nencoding: *\npid: *' (glob)
   *** runcommand id
   eff892de26ec tip bm1/bm2/bm3
   >>> def unknowncommand(conn):
   ...     readchannel(conn)
   ...     conn.stdin.write('unknowncommand\n')
   >>> check(unknowncommand, server.connect)  # error sent to server.log
   >>> def serverinput(conn):
   ...     readchannel(conn)
   ...     patch = """
   ... # HG changeset patch
   ... # User test
   ... # Date 0 0
   ... 2
   ... 
   ... diff -r eff892de26ec -r 1ed24be7e7a0 a
   ... --- a/a
   ... +++ b/a
   ... @@ -1,1 +1,2 @@
   ...  1
   ... +2
   ... """
   ...     runcommand(conn, ['import', '-'], input=cStringIO.StringIO(patch))
   ...     runcommand(conn, ['log', '-rtip', '-q'])
   >>> check(serverinput, server.connect)
   *** runcommand import -
   applying patch from stdin
   *** runcommand log -rtip -q
   2:1ed24be7e7a0
   >>> server.shutdown()
 
   $ cat .hg/server.log
   listening at .hg/server.sock
   abort: unknown command unknowncommand
   killed!
 #endif
 #if no-unix-socket
 
   $ hg serve --cmdserver unix -a .hg/server.sock
   abort: unsupported platform
   [255]
 
 #endif