commandserver: handle IOError related to flushing of streams

After dispatch, without chg we have handling of flushing of streams and
exception handling related to it. The exception handling part is important
because there can be exceptions when flushing fout or ferr.

One such case is in `test-basic.t` which was failing on python3+chg without this
patch as this handling was missing from chg.

Failure can be seen at
https://foss.heptapod.net/octobus/mercurial-devel/-/jobs/128399

Honestly I am not sure which one of `chgserver.py` or `commandserver.py` the
change should go in.

Differential Revision: https://phab.mercurial-scm.org/D9517

mercurial/commandserver.py

@@ -1,771 +1,782 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 __future__ import absolute_import
 
 import errno
 import gc
 import os
 import random
 import signal
 import socket
 import struct
 import traceback
 
 try:
     import selectors
 
     selectors.BaseSelector
 except ImportError:
     from .thirdparty import selectors2 as selectors
 
 from .i18n import _
 from .pycompat import getattr
 from . import (
     encoding,
     error,
     loggingutil,
     pycompat,
     repocache,
     util,
     vfs as vfsmod,
 )
 from .utils import (
     cborutil,
     procutil,
 )
 
 
 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
 
     @property
     def name(self):
         return b'<%c-channel>' % self.channel
 
     def write(self, data):
         if not data:
             return
         # single write() to guarantee the same atomicity as the underlying file
         self.out.write(struct.pack(b'>cI', self.channel, len(data)) + data)
         self.out.flush()
 
     def __getattr__(self, attr):
         if attr in ('isatty', 'fileno', 'tell', 'seek'):
             raise AttributeError(attr)
         return getattr(self.out, attr)
 
 
 class channeledmessage(object):
     """
     Write encoded message and metadata to out in the following format:
 
     data length (unsigned int),
     encoded message and metadata, as a flat key-value dict.
 
     Each message should have 'type' attribute. Messages of unknown type
     should be ignored.
     """
 
     # teach ui that write() can take **opts
     structured = True
 
     def __init__(self, out, channel, encodename, encodefn):
         self._cout = channeledoutput(out, channel)
         self.encoding = encodename
         self._encodefn = encodefn
 
     def write(self, data, **opts):
         opts = pycompat.byteskwargs(opts)
         if data is not None:
             opts[b'data'] = data
         self._cout.write(self._encodefn(opts))
 
     def __getattr__(self, attr):
         return getattr(self._cout, 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
 
     @property
     def name(self):
         return b'<%c-channel>' % self.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 b''
         assert size > 0
 
         # tell the client we need at most size bytes
         self.out.write(struct.pack(b'>cI', channel, size))
         self.out.flush()
 
         length = self.in_.read(4)
         length = struct.unpack(b'>I', length)[0]
         if not length:
             return b''
         else:
             return self.in_.read(length)
 
     def readline(self, size=-1):
         if size < 0:
             size = self.maxchunksize
             s = self._read(size, b'L')
             buf = s
             # keep asking for more until there's either no more or
             # we got a full line
             while s and not s.endswith(b'\n'):
                 s = self._read(size, b'L')
                 buf += s
 
             return buf
         else:
             return self._read(size, b'L')
 
     def __iter__(self):
         return self
 
     def next(self):
         l = self.readline()
         if not l:
             raise StopIteration
         return l
 
     __next__ = next
 
     def __getattr__(self, attr):
         if attr in ('isatty', 'fileno', 'tell', 'seek'):
             raise AttributeError(attr)
         return getattr(self.in_, attr)
 
 
 _messageencoders = {
     b'cbor': lambda v: b''.join(cborutil.streamencode(v)),
 }
 
 
 def _selectmessageencoder(ui):
     encnames = ui.configlist(b'cmdserver', b'message-encodings')
     for n in encnames:
         f = _messageencoders.get(n)
         if f:
             return n, f
     raise error.Abort(
         b'no supported message encodings: %s' % b' '.join(encnames)
     )
 
 
 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, prereposetups=None):
         self.cwd = encoding.getcwd()
 
         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._prereposetups = prereposetups
 
         self.cdebug = channeledoutput(fout, b'd')
         self.cerr = channeledoutput(fout, b'e')
         self.cout = channeledoutput(fout, b'o')
         self.cin = channeledinput(fin, fout, b'I')
         self.cresult = channeledoutput(fout, b'r')
 
         if self.ui.config(b'cmdserver', b'log') == b'-':
             # switch log stream of server's ui to the 'd' (debug) channel
             # (don't touch repo.ui as its lifetime is longer than the server)
             self.ui = self.ui.copy()
             setuplogging(self.ui, repo=None, fp=self.cdebug)
 
         self.cmsg = None
         if ui.config(b'ui', b'message-output') == b'channel':
             encname, encfn = _selectmessageencoder(ui)
             self.cmsg = channeledmessage(fout, b'm', encname, encfn)
 
         self.client = fin
 
         # If shutdown-on-interrupt is off, the default SIGINT handler is
         # removed so that client-server communication wouldn't be interrupted.
         # For example, 'runcommand' handler will issue three short read()s.
         # If one of the first two read()s were interrupted, the communication
         # channel would be left at dirty state and the subsequent request
         # wouldn't be parsed. So catching KeyboardInterrupt isn't enough.
         self._shutdown_on_interrupt = ui.configbool(
             b'cmdserver', b'shutdown-on-interrupt'
         )
         self._old_inthandler = None
         if not self._shutdown_on_interrupt:
             self._old_inthandler = signal.signal(signal.SIGINT, signal.SIG_IGN)
 
     def cleanup(self):
         """release and restore resources taken during server session"""
         if not self._shutdown_on_interrupt:
             signal.signal(signal.SIGINT, self._old_inthandler)
 
     def _read(self, size):
         if not size:
             return b''
 
         data = self.client.read(size)
 
         # is the other end closed?
         if not data:
             raise EOFError
 
         return data
 
     def _readstr(self):
         """read a string from the channel
 
         format:
         data length (uint32), data
         """
         length = struct.unpack(b'>I', self._read(4))[0]
         if not length:
             return b''
         return self._read(length)
 
     def _readlist(self):
         """read a list of NULL separated strings from the channel"""
         s = self._readstr()
         if s:
             return s.split(b'\0')
         else:
             return []
 
     def _dispatchcommand(self, req):
         from . import dispatch  # avoid cycle
 
         if self._shutdown_on_interrupt:
             # no need to restore SIGINT handler as it is unmodified.
             return dispatch.dispatch(req)
 
         try:
             signal.signal(signal.SIGINT, self._old_inthandler)
             return dispatch.dispatch(req)
         except error.SignalInterrupt:
             # propagate SIGBREAK, SIGHUP, or SIGTERM.
             raise
         except KeyboardInterrupt:
             # SIGINT may be received out of the try-except block of dispatch(),
             # so catch it as last ditch. Another KeyboardInterrupt may be
             # raised while handling exceptions here, but there's no way to
             # avoid that except for doing everything in C.
             pass
         finally:
             signal.signal(signal.SIGINT, signal.SIG_IGN)
         # On KeyboardInterrupt, print error message and exit *after* SIGINT
         # handler removed.
         req.ui.error(_(b'interrupted!\n'))
         return -1
 
     def runcommand(self):
         """reads a list of \0 terminated arguments, executes
         and writes the return code to the result channel"""
         from . import dispatch  # avoid cycle
 
         args = self._readlist()
 
         # 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:
             ui.resetstate()
             # any kind of interaction must use server channels, but chg may
             # replace channels by fully functional tty files. so nontty is
             # enforced only if cin is a channel.
             if not util.safehasattr(self.cin, b'fileno'):
                 ui.setconfig(b'ui', b'nontty', b'true', b'commandserver')
 
         req = dispatch.request(
             args[:],
             copiedui,
             self.repo,
             self.cin,
             self.cout,
             self.cerr,
             self.cmsg,
             prereposetups=self._prereposetups,
         )
 
         try:
-            ret = self._dispatchcommand(req) & 255
+            err = None
+            try:
+                status = self._dispatchcommand(req)
+            except error.StdioError as e:
+                status = -1
+                err = e
+
+            retval = dispatch.closestdio(req.ui, err)
+            if retval:
+                status = retval
+
+            ret = status & 255
             # If shutdown-on-interrupt is off, it's important to write the
             # result code *after* SIGINT handler removed. If the result code
             # were lost, the client wouldn't be able to continue processing.
             self.cresult.write(struct.pack(b'>i', int(ret)))
         finally:
             # restore old cwd
             if b'--cwd' in args:
                 os.chdir(self.cwd)
 
     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 error.Abort(_(b'unknown command %s') % cmd)
 
         return cmd != b''
 
     capabilities = {b'runcommand': runcommand, b'getencoding': getencoding}
 
     def serve(self):
         hellomsg = b'capabilities: ' + b' '.join(sorted(self.capabilities))
         hellomsg += b'\n'
         hellomsg += b'encoding: ' + encoding.encoding
         hellomsg += b'\n'
         if self.cmsg:
             hellomsg += b'message-encoding: %s\n' % self.cmsg.encoding
         hellomsg += b'pid: %d' % procutil.getpid()
         if util.safehasattr(os, b'getpgid'):
             hellomsg += b'\n'
             hellomsg += b'pgid: %d' % os.getpgid(0)
 
         # 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 setuplogging(ui, repo=None, fp=None):
     """Set up server logging facility
 
     If cmdserver.log is '-', log messages will be sent to the given fp.
     It should be the 'd' channel while a client is connected, and otherwise
     is the stderr of the server process.
     """
     # developer config: cmdserver.log
     logpath = ui.config(b'cmdserver', b'log')
     if not logpath:
         return
     # developer config: cmdserver.track-log
     tracked = set(ui.configlist(b'cmdserver', b'track-log'))
 
     if logpath == b'-' and fp:
         logger = loggingutil.fileobjectlogger(fp, tracked)
     elif logpath == b'-':
         logger = loggingutil.fileobjectlogger(ui.ferr, tracked)
     else:
         logpath = os.path.abspath(util.expandpath(logpath))
         # developer config: cmdserver.max-log-files
         maxfiles = ui.configint(b'cmdserver', b'max-log-files')
         # developer config: cmdserver.max-log-size
         maxsize = ui.configbytes(b'cmdserver', b'max-log-size')
         vfs = vfsmod.vfs(os.path.dirname(logpath))
         logger = loggingutil.filelogger(
             vfs,
             os.path.basename(logpath),
             tracked,
             maxfiles=maxfiles,
             maxsize=maxsize,
         )
 
     targetuis = {ui}
     if repo:
         targetuis.add(repo.baseui)
         targetuis.add(repo.ui)
     for u in targetuis:
         u.setlogger(b'cmdserver', logger)
 
 
 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
         # redirect stdio to null device so that broken extensions or in-process
         # hooks will never cause corruption of channel protocol.
         with ui.protectedfinout() as (fin, fout):
             sv = server(ui, self.repo, fin, fout)
             try:
                 return sv.serve()
             finally:
                 sv.cleanup()
 
 
 def _initworkerprocess():
     # use a different process group from the master process, in order to:
     # 1. make the current process group no longer "orphaned" (because the
     #    parent of this process is in a different process group while
     #    remains in a same session)
     #    according to POSIX 2.2.2.52, orphaned process group will ignore
     #    terminal-generated stop signals like SIGTSTP (Ctrl+Z), which will
     #    cause trouble for things like ncurses.
     # 2. the client can use kill(-pgid, sig) to simulate terminal-generated
     #    SIGINT (Ctrl+C) and process-exit-generated SIGHUP. our child
     #    processes like ssh will be killed properly, without affecting
     #    unrelated processes.
     os.setpgid(0, 0)
     # change random state otherwise forked request handlers would have a
     # same state inherited from parent.
     random.seed()
 
 
 def _serverequest(ui, repo, conn, createcmdserver, prereposetups):
     fin = conn.makefile('rb')
     fout = conn.makefile('wb')
     sv = None
     try:
         sv = createcmdserver(repo, conn, fin, fout, prereposetups)
         try:
             sv.serve()
         # handle exceptions that may be raised by command server. most of
         # known exceptions are caught by dispatch.
         except error.Abort as inst:
             ui.error(_(b'abort: %s\n') % inst.message)
         except IOError as inst:
             if inst.errno != errno.EPIPE:
                 raise
         except KeyboardInterrupt:
             pass
         finally:
             sv.cleanup()
     except:  # re-raises
         # also write traceback to error channel. otherwise client cannot
         # see it because it is written to server's stderr by default.
         if sv:
             cerr = sv.cerr
         else:
             cerr = channeledoutput(fout, b'e')
         cerr.write(encoding.strtolocal(traceback.format_exc()))
         raise
     finally:
         fin.close()
         try:
             fout.close()  # implicit flush() may cause another EPIPE
         except IOError as inst:
             if inst.errno != errno.EPIPE:
                 raise
 
 
 class unixservicehandler(object):
     """Set of pluggable operations for unix-mode services
 
     Almost all methods except for createcmdserver() are called in the main
     process. You can't pass mutable resource back from createcmdserver().
     """
 
     pollinterval = None
 
     def __init__(self, ui):
         self.ui = ui
 
     def bindsocket(self, sock, address):
         util.bindunixsocket(sock, address)
         sock.listen(socket.SOMAXCONN)
         self.ui.status(_(b'listening at %s\n') % address)
         self.ui.flush()  # avoid buffering of status message
 
     def unlinksocket(self, address):
         os.unlink(address)
 
     def shouldexit(self):
         """True if server should shut down; checked per pollinterval"""
         return False
 
     def newconnection(self):
         """Called when main process notices new connection"""
 
     def createcmdserver(self, repo, conn, fin, fout, prereposetups):
         """Create new command server instance; called in the process that
         serves for the current connection"""
         return server(self.ui, repo, fin, fout, prereposetups)
 
 
 class unixforkingservice(object):
     """
     Listens on unix domain socket and forks server per connection
     """
 
     def __init__(self, ui, repo, opts, handler=None):
         self.ui = ui
         self.repo = repo
         self.address = opts[b'address']
         if not util.safehasattr(socket, b'AF_UNIX'):
             raise error.Abort(_(b'unsupported platform'))
         if not self.address:
             raise error.Abort(_(b'no socket path specified with --address'))
         self._servicehandler = handler or unixservicehandler(ui)
         self._sock = None
         self._mainipc = None
         self._workeripc = None
         self._oldsigchldhandler = None
         self._workerpids = set()  # updated by signal handler; do not iterate
         self._socketunlinked = None
         # experimental config: cmdserver.max-repo-cache
         maxlen = ui.configint(b'cmdserver', b'max-repo-cache')
         if maxlen < 0:
             raise error.Abort(_(b'negative max-repo-cache size not allowed'))
         self._repoloader = repocache.repoloader(ui, maxlen)
         # attempt to avoid crash in CoreFoundation when using chg after fix in
         # a89381e04c58
         if pycompat.isdarwin:
             procutil.gui()
 
     def init(self):
         self._sock = socket.socket(socket.AF_UNIX)
         # IPC channel from many workers to one main process; this is actually
         # a uni-directional pipe, but is backed by a DGRAM socket so each
         # message can be easily separated.
         o = socket.socketpair(socket.AF_UNIX, socket.SOCK_DGRAM)
         self._mainipc, self._workeripc = o
         self._servicehandler.bindsocket(self._sock, self.address)
         if util.safehasattr(procutil, b'unblocksignal'):
             procutil.unblocksignal(signal.SIGCHLD)
         o = signal.signal(signal.SIGCHLD, self._sigchldhandler)
         self._oldsigchldhandler = o
         self._socketunlinked = False
         self._repoloader.start()
 
     def _unlinksocket(self):
         if not self._socketunlinked:
             self._servicehandler.unlinksocket(self.address)
             self._socketunlinked = True
 
     def _cleanup(self):
         signal.signal(signal.SIGCHLD, self._oldsigchldhandler)
         self._sock.close()
         self._mainipc.close()
         self._workeripc.close()
         self._unlinksocket()
         self._repoloader.stop()
         # don't kill child processes as they have active clients, just wait
         self._reapworkers(0)
 
     def run(self):
         try:
             self._mainloop()
         finally:
             self._cleanup()
 
     def _mainloop(self):
         exiting = False
         h = self._servicehandler
         selector = selectors.DefaultSelector()
         selector.register(
             self._sock, selectors.EVENT_READ, self._acceptnewconnection
         )
         selector.register(
             self._mainipc, selectors.EVENT_READ, self._handlemainipc
         )
         while True:
             if not exiting and h.shouldexit():
                 # clients can no longer connect() to the domain socket, so
                 # we stop queuing new requests.
                 # for requests that are queued (connect()-ed, but haven't been
                 # accept()-ed), handle them before exit. otherwise, clients
                 # waiting for recv() will receive ECONNRESET.
                 self._unlinksocket()
                 exiting = True
             try:
                 events = selector.select(timeout=h.pollinterval)
             except OSError as inst:
                 # selectors2 raises ETIMEDOUT if timeout exceeded while
                 # handling signal interrupt. That's probably wrong, but
                 # we can easily get around it.
                 if inst.errno != errno.ETIMEDOUT:
                     raise
                 events = []
             if not events:
                 # only exit if we completed all queued requests
                 if exiting:
                     break
                 continue
             for key, _mask in events:
                 key.data(key.fileobj, selector)
         selector.close()
 
     def _acceptnewconnection(self, sock, selector):
         h = self._servicehandler
         try:
             conn, _addr = sock.accept()
         except socket.error as inst:
             if inst.args[0] == errno.EINTR:
                 return
             raise
 
         # Future improvement: On Python 3.7, maybe gc.freeze() can be used
         # to prevent COW memory from being touched by GC.
         # https://instagram-engineering.com/
         #   copy-on-write-friendly-python-garbage-collection-ad6ed5233ddf
         pid = os.fork()
         if pid:
             try:
                 self.ui.log(
                     b'cmdserver', b'forked worker process (pid=%d)\n', pid
                 )
                 self._workerpids.add(pid)
                 h.newconnection()
             finally:
                 conn.close()  # release handle in parent process
         else:
             try:
                 selector.close()
                 sock.close()
                 self._mainipc.close()
                 self._runworker(conn)
                 conn.close()
                 self._workeripc.close()
                 os._exit(0)
             except:  # never return, hence no re-raises
                 try:
                     self.ui.traceback(force=True)
                 finally:
                     os._exit(255)
 
     def _handlemainipc(self, sock, selector):
         """Process messages sent from a worker"""
         try:
             path = sock.recv(32768)  # large enough to receive path
         except socket.error as inst:
             if inst.args[0] == errno.EINTR:
                 return
             raise
         self._repoloader.load(path)
 
     def _sigchldhandler(self, signal, frame):
         self._reapworkers(os.WNOHANG)
 
     def _reapworkers(self, options):
         while self._workerpids:
             try:
                 pid, _status = os.waitpid(-1, options)
             except OSError as inst:
                 if inst.errno == errno.EINTR:
                     continue
                 if inst.errno != errno.ECHILD:
                     raise
                 # no child processes at all (reaped by other waitpid()?)
                 self._workerpids.clear()
                 return
             if pid == 0:
                 # no waitable child processes
                 return
             self.ui.log(b'cmdserver', b'worker process exited (pid=%d)\n', pid)
             self._workerpids.discard(pid)
 
     def _runworker(self, conn):
         signal.signal(signal.SIGCHLD, self._oldsigchldhandler)
         _initworkerprocess()
         h = self._servicehandler
         try:
             _serverequest(
                 self.ui,
                 self.repo,
                 conn,
                 h.createcmdserver,
                 prereposetups=[self._reposetup],
             )
         finally:
             gc.collect()  # trigger __del__ since worker process uses os._exit
 
     def _reposetup(self, ui, repo):
         if not repo.local():
             return
 
         class unixcmdserverrepo(repo.__class__):
             def close(self):
                 super(unixcmdserverrepo, self).close()
                 try:
                     self._cmdserveripc.send(self.root)
                 except socket.error:
                     self.ui.log(
                         b'cmdserver', b'failed to send repo root to master\n'
                     )
 
         repo.__class__ = unixcmdserverrepo
         repo._cmdserveripc = self._workeripc
 
         cachedrepo = self._repoloader.get(repo.root)
         if cachedrepo is None:
             return
         repo.ui.log(b'repocache', b'repo from cache: %s\n', repo.root)
         repocache.copycache(cachedrepo, repo)

mercurial/dispatch.py

@@ -1,1346 +1,1354 b''
 # dispatch.py - command dispatching for mercurial
 #
 # Copyright 2005-2007 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 __future__ import absolute_import, print_function
 
 import errno
 import getopt
 import io
 import os
 import pdb
 import re
 import signal
 import sys
 import traceback
 
 
 from .i18n import _
 from .pycompat import getattr
 
 from hgdemandimport import tracing
 
 from . import (
     cmdutil,
     color,
     commands,
     demandimport,
     encoding,
     error,
     extensions,
     fancyopts,
     help,
     hg,
     hook,
     localrepo,
     profiling,
     pycompat,
     rcutil,
     registrar,
     requirements as requirementsmod,
     scmutil,
     ui as uimod,
     util,
     vfs,
 )
 
 from .utils import (
     procutil,
     stringutil,
 )
 
 
 class request(object):
     def __init__(
         self,
         args,
         ui=None,
         repo=None,
         fin=None,
         fout=None,
         ferr=None,
         fmsg=None,
         prereposetups=None,
     ):
         self.args = args
         self.ui = ui
         self.repo = repo
 
         # input/output/error streams
         self.fin = fin
         self.fout = fout
         self.ferr = ferr
         # separate stream for status/error messages
         self.fmsg = fmsg
 
         # remember options pre-parsed by _earlyparseopts()
         self.earlyoptions = {}
 
         # reposetups which run before extensions, useful for chg to pre-fill
         # low-level repo state (for example, changelog) before extensions.
         self.prereposetups = prereposetups or []
 
         # store the parsed and canonical command
         self.canonical_command = None
 
     def _runexithandlers(self):
         exc = None
         handlers = self.ui._exithandlers
         try:
             while handlers:
                 func, args, kwargs = handlers.pop()
                 try:
                     func(*args, **kwargs)
                 except:  # re-raises below
                     if exc is None:
                         exc = sys.exc_info()[1]
                     self.ui.warnnoi18n(b'error in exit handlers:\n')
                     self.ui.traceback(force=True)
         finally:
             if exc is not None:
                 raise exc
 
 
+def closestdio(ui, err):
+    status = None
+    # In all cases we try to flush stdio streams.
+    if util.safehasattr(ui, b'fout'):
+        assert ui is not None  # help pytype
+        assert ui.fout is not None  # help pytype
+        try:
+            ui.fout.flush()
+        except IOError as e:
+            err = e
+            status = -1
+
+    if util.safehasattr(ui, b'ferr'):
+        assert ui is not None  # help pytype
+        assert ui.ferr is not None  # help pytype
+        try:
+            if err is not None and err.errno != errno.EPIPE:
+                ui.ferr.write(
+                    b'abort: %s\n' % encoding.strtolocal(err.strerror)
+                )
+            ui.ferr.flush()
+        # There's not much we can do about an I/O error here. So (possibly)
+        # change the status code and move on.
+        except IOError:
+            status = -1
+
+    return status
+
+
 def run():
     """run the command in sys.argv"""
     try:
         initstdio()
         with tracing.log('parse args into request'):
             req = request(pycompat.sysargv[1:])
         err = None
         try:
             status = dispatch(req)
         except error.StdioError as e:
             err = e
             status = -1
 
-        # In all cases we try to flush stdio streams.
-        if util.safehasattr(req.ui, b'fout'):
-            assert req.ui is not None  # help pytype
-            assert req.ui.fout is not None  # help pytype
-            try:
-                req.ui.fout.flush()
-            except IOError as e:
-                err = e
-                status = -1
-
-        if util.safehasattr(req.ui, b'ferr'):
-            assert req.ui is not None  # help pytype
-            assert req.ui.ferr is not None  # help pytype
-            try:
-                if err is not None and err.errno != errno.EPIPE:
-                    req.ui.ferr.write(
-                        b'abort: %s\n' % encoding.strtolocal(err.strerror)
-                    )
-                req.ui.ferr.flush()
-            # There's not much we can do about an I/O error here. So (possibly)
-            # change the status code and move on.
-            except IOError:
-                status = -1
-
+        ret = closestdio(req.ui, err)
+        if ret:
+            status = ret
         _silencestdio()
     except KeyboardInterrupt:
         # Catch early/late KeyboardInterrupt as last ditch. Here nothing will
         # be printed to console to avoid another IOError/KeyboardInterrupt.
         status = -1
     sys.exit(status & 255)
 
 
 if pycompat.ispy3:
 
     def initstdio():
         # stdio streams on Python 3 are io.TextIOWrapper instances proxying another
         # buffer. These streams will normalize \n to \r\n by default. Mercurial's
         # preferred mechanism for writing output (ui.write()) uses io.BufferedWriter
         # instances, which write to the underlying stdio file descriptor in binary
         # mode. ui.write() uses \n for line endings and no line ending normalization
         # is attempted through this interface. This "just works," even if the system
         # preferred line ending is not \n.
         #
         # But some parts of Mercurial (e.g. hooks) can still send data to sys.stdout
         # and sys.stderr. They will inherit the line ending normalization settings,
         # potentially causing e.g. \r\n to be emitted. Since emitting \n should
         # "just work," here we change the sys.* streams to disable line ending
         # normalization, ensuring compatibility with our ui type.
 
         # write_through is new in Python 3.7.
         kwargs = {
             "newline": "\n",
             "line_buffering": sys.stdout.line_buffering,
         }
         if util.safehasattr(sys.stdout, "write_through"):
             kwargs["write_through"] = sys.stdout.write_through
         sys.stdout = io.TextIOWrapper(
             sys.stdout.buffer, sys.stdout.encoding, sys.stdout.errors, **kwargs
         )
 
         kwargs = {
             "newline": "\n",
             "line_buffering": sys.stderr.line_buffering,
         }
         if util.safehasattr(sys.stderr, "write_through"):
             kwargs["write_through"] = sys.stderr.write_through
         sys.stderr = io.TextIOWrapper(
             sys.stderr.buffer, sys.stderr.encoding, sys.stderr.errors, **kwargs
         )
 
         if sys.stdin is not None:
             # No write_through on read-only stream.
             sys.stdin = io.TextIOWrapper(
                 sys.stdin.buffer,
                 sys.stdin.encoding,
                 sys.stdin.errors,
                 # None is universal newlines mode.
                 newline=None,
                 line_buffering=sys.stdin.line_buffering,
             )
 
     def _silencestdio():
         for fp in (sys.stdout, sys.stderr):
             # Check if the file is okay
             try:
                 fp.flush()
                 continue
             except IOError:
                 pass
             # Otherwise mark it as closed to silence "Exception ignored in"
             # message emitted by the interpreter finalizer. Be careful to
             # not close procutil.stdout, which may be a fdopen-ed file object
             # and its close() actually closes the underlying file descriptor.
             try:
                 fp.close()
             except IOError:
                 pass
 
 
 else:
 
     def initstdio():
         for fp in (sys.stdin, sys.stdout, sys.stderr):
             procutil.setbinary(fp)
 
     def _silencestdio():
         pass
 
 
 def _formatargs(args):
     return b' '.join(procutil.shellquote(a) for a in args)
 
 
 def dispatch(req):
     """run the command specified in req.args; returns an integer status code"""
     with tracing.log('dispatch.dispatch'):
         if req.ferr:
             ferr = req.ferr
         elif req.ui:
             ferr = req.ui.ferr
         else:
             ferr = procutil.stderr
 
         try:
             if not req.ui:
                 req.ui = uimod.ui.load()
             req.earlyoptions.update(_earlyparseopts(req.ui, req.args))
             if req.earlyoptions[b'traceback']:
                 req.ui.setconfig(b'ui', b'traceback', b'on', b'--traceback')
 
             # set ui streams from the request
             if req.fin:
                 req.ui.fin = req.fin
             if req.fout:
                 req.ui.fout = req.fout
             if req.ferr:
                 req.ui.ferr = req.ferr
             if req.fmsg:
                 req.ui.fmsg = req.fmsg
         except error.Abort as inst:
             ferr.write(inst.format())
             return -1
 
         msg = _formatargs(req.args)
         starttime = util.timer()
         ret = 1  # default of Python exit code on unhandled exception
         try:
             ret = _runcatch(req) or 0
         except error.ProgrammingError as inst:
             req.ui.error(_(b'** ProgrammingError: %s\n') % inst)
             if inst.hint:
                 req.ui.error(_(b'** (%s)\n') % inst.hint)
             raise
         except KeyboardInterrupt as inst:
             try:
                 if isinstance(inst, error.SignalInterrupt):
                     msg = _(b"killed!\n")
                 else:
                     msg = _(b"interrupted!\n")
                 req.ui.error(msg)
             except error.SignalInterrupt:
                 # maybe pager would quit without consuming all the output, and
                 # SIGPIPE was raised. we cannot print anything in this case.
                 pass
             except IOError as inst:
                 if inst.errno != errno.EPIPE:
                     raise
             ret = -1
         finally:
             duration = util.timer() - starttime
             req.ui.flush()  # record blocked times
             if req.ui.logblockedtimes:
                 req.ui._blockedtimes[b'command_duration'] = duration * 1000
                 req.ui.log(
                     b'uiblocked',
                     b'ui blocked ms\n',
                     **pycompat.strkwargs(req.ui._blockedtimes)
                 )
             return_code = ret & 255
             req.ui.log(
                 b"commandfinish",
                 b"%s exited %d after %0.2f seconds\n",
                 msg,
                 return_code,
                 duration,
                 return_code=return_code,
                 duration=duration,
                 canonical_command=req.canonical_command,
             )
             try:
                 req._runexithandlers()
             except:  # exiting, so no re-raises
                 ret = ret or -1
             # do flush again since ui.log() and exit handlers may write to ui
             req.ui.flush()
         return ret
 
 
 def _runcatch(req):
     with tracing.log('dispatch._runcatch'):
 
         def catchterm(*args):
             raise error.SignalInterrupt
 
         ui = req.ui
         try:
             for name in b'SIGBREAK', b'SIGHUP', b'SIGTERM':
                 num = getattr(signal, name, None)
                 if num:
                     signal.signal(num, catchterm)
         except ValueError:
             pass  # happens if called in a thread
 
         def _runcatchfunc():
             realcmd = None
             try:
                 cmdargs = fancyopts.fancyopts(
                     req.args[:], commands.globalopts, {}
                 )
                 cmd = cmdargs[0]
                 aliases, entry = cmdutil.findcmd(cmd, commands.table, False)
                 realcmd = aliases[0]
             except (
                 error.UnknownCommand,
                 error.AmbiguousCommand,
                 IndexError,
                 getopt.GetoptError,
             ):
                 # Don't handle this here. We know the command is
                 # invalid, but all we're worried about for now is that
                 # it's not a command that server operators expect to
                 # be safe to offer to users in a sandbox.
                 pass
             if realcmd == b'serve' and b'--stdio' in cmdargs:
                 # We want to constrain 'hg serve --stdio' instances pretty
                 # closely, as many shared-ssh access tools want to grant
                 # access to run *only* 'hg -R $repo serve --stdio'. We
                 # restrict to exactly that set of arguments, and prohibit
                 # any repo name that starts with '--' to prevent
                 # shenanigans wherein a user does something like pass
                 # --debugger or --config=ui.debugger=1 as a repo
                 # name. This used to actually run the debugger.
                 if (
                     len(req.args) != 4
                     or req.args[0] != b'-R'
                     or req.args[1].startswith(b'--')
                     or req.args[2] != b'serve'
                     or req.args[3] != b'--stdio'
                 ):
                     raise error.Abort(
                         _(b'potentially unsafe serve --stdio invocation: %s')
                         % (stringutil.pprint(req.args),)
                     )
 
             try:
                 debugger = b'pdb'
                 debugtrace = {b'pdb': pdb.set_trace}
                 debugmortem = {b'pdb': pdb.post_mortem}
 
                 # read --config before doing anything else
                 # (e.g. to change trust settings for reading .hg/hgrc)
                 cfgs = _parseconfig(req.ui, req.earlyoptions[b'config'])
 
                 if req.repo:
                     # copy configs that were passed on the cmdline (--config) to
                     # the repo ui
                     for sec, name, val in cfgs:
                         req.repo.ui.setconfig(
                             sec, name, val, source=b'--config'
                         )
 
                 # developer config: ui.debugger
                 debugger = ui.config(b"ui", b"debugger")
                 debugmod = pdb
                 if not debugger or ui.plain():
                     # if we are in HGPLAIN mode, then disable custom debugging
                     debugger = b'pdb'
                 elif req.earlyoptions[b'debugger']:
                     # This import can be slow for fancy debuggers, so only
                     # do it when absolutely necessary, i.e. when actual
                     # debugging has been requested
                     with demandimport.deactivated():
                         try:
                             debugmod = __import__(debugger)
                         except ImportError:
                             pass  # Leave debugmod = pdb
 
                 debugtrace[debugger] = debugmod.set_trace
                 debugmortem[debugger] = debugmod.post_mortem
 
                 # enter the debugger before command execution
                 if req.earlyoptions[b'debugger']:
                     ui.warn(
                         _(
                             b"entering debugger - "
                             b"type c to continue starting hg or h for help\n"
                         )
                     )
 
                     if (
                         debugger != b'pdb'
                         and debugtrace[debugger] == debugtrace[b'pdb']
                     ):
                         ui.warn(
                             _(
                                 b"%s debugger specified "
                                 b"but its module was not found\n"
                             )
                             % debugger
                         )
                     with demandimport.deactivated():
                         debugtrace[debugger]()
                 try:
                     return _dispatch(req)
                 finally:
                     ui.flush()
             except:  # re-raises
                 # enter the debugger when we hit an exception
                 if req.earlyoptions[b'debugger']:
                     traceback.print_exc()
                     debugmortem[debugger](sys.exc_info()[2])
                 raise
 
         return _callcatch(ui, _runcatchfunc)
 
 
 def _callcatch(ui, func):
     """like scmutil.callcatch but handles more high-level exceptions about
     config parsing and commands. besides, use handlecommandexception to handle
     uncaught exceptions.
     """
     try:
         return scmutil.callcatch(ui, func)
     except error.AmbiguousCommand as inst:
         ui.warn(
             _(b"hg: command '%s' is ambiguous:\n    %s\n")
             % (inst.prefix, b" ".join(inst.matches))
         )
     except error.CommandError as inst:
         if inst.command:
             ui.pager(b'help')
             msgbytes = pycompat.bytestr(inst.message)
             ui.warn(_(b"hg %s: %s\n") % (inst.command, msgbytes))
             commands.help_(ui, inst.command, full=False, command=True)
         else:
             ui.warn(_(b"hg: %s\n") % inst.message)
             ui.warn(_(b"(use 'hg help -v' for a list of global options)\n"))
     except error.UnknownCommand as inst:
         nocmdmsg = _(b"hg: unknown command '%s'\n") % inst.command
         try:
             # check if the command is in a disabled extension
             # (but don't check for extensions themselves)
             formatted = help.formattedhelp(
                 ui, commands, inst.command, unknowncmd=True
             )
             ui.warn(nocmdmsg)
             ui.write(formatted)
         except (error.UnknownCommand, error.Abort):
             suggested = False
             if inst.all_commands:
                 sim = error.getsimilar(inst.all_commands, inst.command)
                 if sim:
                     ui.warn(nocmdmsg)
                     ui.warn(b"(%s)\n" % error.similarity_hint(sim))
                     suggested = True
             if not suggested:
                 ui.warn(nocmdmsg)
                 ui.warn(_(b"(use 'hg help' for a list of commands)\n"))
     except IOError:
         raise
     except KeyboardInterrupt:
         raise
     except:  # probably re-raises
         if not handlecommandexception(ui):
             raise
 
     return -1
 
 
 def aliasargs(fn, givenargs):
     args = []
     # only care about alias 'args', ignore 'args' set by extensions.wrapfunction
     if not util.safehasattr(fn, b'_origfunc'):
         args = getattr(fn, 'args', args)
     if args:
         cmd = b' '.join(map(procutil.shellquote, args))
 
         nums = []
 
         def replacer(m):
             num = int(m.group(1)) - 1
             nums.append(num)
             if num < len(givenargs):
                 return givenargs[num]
             raise error.InputError(_(b'too few arguments for command alias'))
 
         cmd = re.sub(br'\$(\d+|\$)', replacer, cmd)
         givenargs = [x for i, x in enumerate(givenargs) if i not in nums]
         args = pycompat.shlexsplit(cmd)
     return args + givenargs
 
 
 def aliasinterpolate(name, args, cmd):
     """interpolate args into cmd for shell aliases
 
     This also handles $0, $@ and "$@".
     """
     # util.interpolate can't deal with "$@" (with quotes) because it's only
     # built to match prefix + patterns.
     replacemap = {b'$%d' % (i + 1): arg for i, arg in enumerate(args)}
     replacemap[b'$0'] = name
     replacemap[b'$$'] = b'$'
     replacemap[b'$@'] = b' '.join(args)
     # Typical Unix shells interpolate "$@" (with quotes) as all the positional
     # parameters, separated out into words. Emulate the same behavior here by
     # quoting the arguments individually. POSIX shells will then typically
     # tokenize each argument into exactly one word.
     replacemap[b'"$@"'] = b' '.join(procutil.shellquote(arg) for arg in args)
     # escape '\$' for regex
     regex = b'|'.join(replacemap.keys()).replace(b'$', br'\$')
     r = re.compile(regex)
     return r.sub(lambda x: replacemap[x.group()], cmd)
 
 
 class cmdalias(object):
     def __init__(self, ui, name, definition, cmdtable, source):
         self.name = self.cmd = name
         self.cmdname = b''
         self.definition = definition
         self.fn = None
         self.givenargs = []
         self.opts = []
         self.help = b''
         self.badalias = None
         self.unknowncmd = False
         self.source = source
 
         try:
             aliases, entry = cmdutil.findcmd(self.name, cmdtable)
             for alias, e in pycompat.iteritems(cmdtable):
                 if e is entry:
                     self.cmd = alias
                     break
             self.shadows = True
         except error.UnknownCommand:
             self.shadows = False
 
         if not self.definition:
             self.badalias = _(b"no definition for alias '%s'") % self.name
             return
 
         if self.definition.startswith(b'!'):
             shdef = self.definition[1:]
             self.shell = True
 
             def fn(ui, *args):
                 env = {b'HG_ARGS': b' '.join((self.name,) + args)}
 
                 def _checkvar(m):
                     if m.groups()[0] == b'$':
                         return m.group()
                     elif int(m.groups()[0]) <= len(args):
                         return m.group()
                     else:
                         ui.debug(
                             b"No argument found for substitution "
                             b"of %i variable in alias '%s' definition.\n"
                             % (int(m.groups()[0]), self.name)
                         )
                         return b''
 
                 cmd = re.sub(br'\$(\d+|\$)', _checkvar, shdef)
                 cmd = aliasinterpolate(self.name, args, cmd)
                 return ui.system(
                     cmd, environ=env, blockedtag=b'alias_%s' % self.name
                 )
 
             self.fn = fn
             self.alias = True
             self._populatehelp(ui, name, shdef, self.fn)
             return
 
         try:
             args = pycompat.shlexsplit(self.definition)
         except ValueError as inst:
             self.badalias = _(b"error in definition for alias '%s': %s") % (
                 self.name,
                 stringutil.forcebytestr(inst),
             )
             return
         earlyopts, args = _earlysplitopts(args)
         if earlyopts:
             self.badalias = _(
                 b"error in definition for alias '%s': %s may "
                 b"only be given on the command line"
             ) % (self.name, b'/'.join(pycompat.ziplist(*earlyopts)[0]))
             return
         self.cmdname = cmd = args.pop(0)
         self.givenargs = args
 
         try:
             tableentry = cmdutil.findcmd(cmd, cmdtable, False)[1]
             if len(tableentry) > 2:
                 self.fn, self.opts, cmdhelp = tableentry
             else:
                 self.fn, self.opts = tableentry
                 cmdhelp = None
 
             self.alias = True
             self._populatehelp(ui, name, cmd, self.fn, cmdhelp)
 
         except error.UnknownCommand:
             self.badalias = _(
                 b"alias '%s' resolves to unknown command '%s'"
             ) % (
                 self.name,
                 cmd,
             )
             self.unknowncmd = True
         except error.AmbiguousCommand:
             self.badalias = _(
                 b"alias '%s' resolves to ambiguous command '%s'"
             ) % (
                 self.name,
                 cmd,
             )
 
     def _populatehelp(self, ui, name, cmd, fn, defaulthelp=None):
         # confine strings to be passed to i18n.gettext()
         cfg = {}
         for k in (b'doc', b'help', b'category'):
             v = ui.config(b'alias', b'%s:%s' % (name, k), None)
             if v is None:
                 continue
             if not encoding.isasciistr(v):
                 self.badalias = _(
                     b"non-ASCII character in alias definition '%s:%s'"
                 ) % (name, k)
                 return
             cfg[k] = v
 
         self.help = cfg.get(b'help', defaulthelp or b'')
         if self.help and self.help.startswith(b"hg " + cmd):
             # drop prefix in old-style help lines so hg shows the alias
             self.help = self.help[4 + len(cmd) :]
 
         self.owndoc = b'doc' in cfg
         doc = cfg.get(b'doc', pycompat.getdoc(fn))
         if doc is not None:
             doc = pycompat.sysstr(doc)
         self.__doc__ = doc
 
         self.helpcategory = cfg.get(
             b'category', registrar.command.CATEGORY_NONE
         )
 
     @property
     def args(self):
         args = pycompat.maplist(util.expandpath, self.givenargs)
         return aliasargs(self.fn, args)
 
     def __getattr__(self, name):
         adefaults = {
             'norepo': True,
             'intents': set(),
             'optionalrepo': False,
             'inferrepo': False,
         }
         if name not in adefaults:
             raise AttributeError(name)
         if self.badalias or util.safehasattr(self, b'shell'):
             return adefaults[name]
         return getattr(self.fn, name)
 
     def __call__(self, ui, *args, **opts):
         if self.badalias:
             hint = None
             if self.unknowncmd:
                 try:
                     # check if the command is in a disabled extension
                     cmd, ext = extensions.disabledcmd(ui, self.cmdname)[:2]
                     hint = _(b"'%s' is provided by '%s' extension") % (cmd, ext)
                 except error.UnknownCommand:
                     pass
             raise error.ConfigError(self.badalias, hint=hint)
         if self.shadows:
             ui.debug(
                 b"alias '%s' shadows command '%s'\n" % (self.name, self.cmdname)
             )
 
         ui.log(
             b'commandalias',
             b"alias '%s' expands to '%s'\n",
             self.name,
             self.definition,
         )
         if util.safehasattr(self, b'shell'):
             return self.fn(ui, *args, **opts)
         else:
             try:
                 return util.checksignature(self.fn)(ui, *args, **opts)
             except error.SignatureError:
                 args = b' '.join([self.cmdname] + self.args)
                 ui.debug(b"alias '%s' expands to '%s'\n" % (self.name, args))
                 raise
 
 
 class lazyaliasentry(object):
     """like a typical command entry (func, opts, help), but is lazy"""
 
     def __init__(self, ui, name, definition, cmdtable, source):
         self.ui = ui
         self.name = name
         self.definition = definition
         self.cmdtable = cmdtable.copy()
         self.source = source
         self.alias = True
 
     @util.propertycache
     def _aliasdef(self):
         return cmdalias(
             self.ui, self.name, self.definition, self.cmdtable, self.source
         )
 
     def __getitem__(self, n):
         aliasdef = self._aliasdef
         if n == 0:
             return aliasdef
         elif n == 1:
             return aliasdef.opts
         elif n == 2:
             return aliasdef.help
         else:
             raise IndexError
 
     def __iter__(self):
         for i in range(3):
             yield self[i]
 
     def __len__(self):
         return 3
 
 
 def addaliases(ui, cmdtable):
     # aliases are processed after extensions have been loaded, so they
     # may use extension commands. Aliases can also use other alias definitions,
     # but only if they have been defined prior to the current definition.
     for alias, definition in ui.configitems(b'alias', ignoresub=True):
         try:
             if cmdtable[alias].definition == definition:
                 continue
         except (KeyError, AttributeError):
             # definition might not exist or it might not be a cmdalias
             pass
 
         source = ui.configsource(b'alias', alias)
         entry = lazyaliasentry(ui, alias, definition, cmdtable, source)
         cmdtable[alias] = entry
 
 
 def _parse(ui, args):
     options = {}
     cmdoptions = {}
 
     try:
         args = fancyopts.fancyopts(args, commands.globalopts, options)
     except getopt.GetoptError as inst:
         raise error.CommandError(None, stringutil.forcebytestr(inst))
 
     if args:
         cmd, args = args[0], args[1:]
         aliases, entry = cmdutil.findcmd(
             cmd, commands.table, ui.configbool(b"ui", b"strict")
         )
         cmd = aliases[0]
         args = aliasargs(entry[0], args)
         defaults = ui.config(b"defaults", cmd)
         if defaults:
             args = (
                 pycompat.maplist(util.expandpath, pycompat.shlexsplit(defaults))
                 + args
             )
         c = list(entry[1])
     else:
         cmd = None
         c = []
 
     # combine global options into local
     for o in commands.globalopts:
         c.append((o[0], o[1], options[o[1]], o[3]))
 
     try:
         args = fancyopts.fancyopts(args, c, cmdoptions, gnu=True)
     except getopt.GetoptError as inst:
         raise error.CommandError(cmd, stringutil.forcebytestr(inst))
 
     # separate global options back out
     for o in commands.globalopts:
         n = o[1]
         options[n] = cmdoptions[n]
         del cmdoptions[n]
 
     return (cmd, cmd and entry[0] or None, args, options, cmdoptions)
 
 
 def _parseconfig(ui, config):
     """parse the --config options from the command line"""
     configs = []
 
     for cfg in config:
         try:
             name, value = [cfgelem.strip() for cfgelem in cfg.split(b'=', 1)]
             section, name = name.split(b'.', 1)
             if not section or not name:
                 raise IndexError
             ui.setconfig(section, name, value, b'--config')
             configs.append((section, name, value))
         except (IndexError, ValueError):
             raise error.Abort(
                 _(
                     b'malformed --config option: %r '
                     b'(use --config section.name=value)'
                 )
                 % pycompat.bytestr(cfg)
             )
 
     return configs
 
 
 def _earlyparseopts(ui, args):
     options = {}
     fancyopts.fancyopts(
         args,
         commands.globalopts,
         options,
         gnu=not ui.plain(b'strictflags'),
         early=True,
         optaliases={b'repository': [b'repo']},
     )
     return options
 
 
 def _earlysplitopts(args):
     """Split args into a list of possible early options and remainder args"""
     shortoptions = b'R:'
     # TODO: perhaps 'debugger' should be included
     longoptions = [b'cwd=', b'repository=', b'repo=', b'config=']
     return fancyopts.earlygetopt(
         args, shortoptions, longoptions, gnu=True, keepsep=True
     )
 
 
 def runcommand(lui, repo, cmd, fullargs, ui, options, d, cmdpats, cmdoptions):
     # run pre-hook, and abort if it fails
     hook.hook(
         lui,
         repo,
         b"pre-%s" % cmd,
         True,
         args=b" ".join(fullargs),
         pats=cmdpats,
         opts=cmdoptions,
     )
     try:
         ret = _runcommand(ui, options, cmd, d)
         # run post-hook, passing command result
         hook.hook(
             lui,
             repo,
             b"post-%s" % cmd,
             False,
             args=b" ".join(fullargs),
             result=ret,
             pats=cmdpats,
             opts=cmdoptions,
         )
     except Exception:
         # run failure hook and re-raise
         hook.hook(
             lui,
             repo,
             b"fail-%s" % cmd,
             False,
             args=b" ".join(fullargs),
             pats=cmdpats,
             opts=cmdoptions,
         )
         raise
     return ret
 
 
 def _readsharedsourceconfig(ui, path):
     """if the current repository is shared one, this tries to read
     .hg/hgrc of shared source if we are in share-safe mode
 
     Config read is loaded into the ui object passed
 
     This should be called before reading .hg/hgrc or the main repo
     as that overrides config set in shared source"""
     try:
         with open(os.path.join(path, b".hg", b"requires"), "rb") as fp:
             requirements = set(fp.read().splitlines())
             if not (
                 requirementsmod.SHARESAFE_REQUIREMENT in requirements
                 and requirementsmod.SHARED_REQUIREMENT in requirements
             ):
                 return
             hgvfs = vfs.vfs(os.path.join(path, b".hg"))
             sharedvfs = localrepo._getsharedvfs(hgvfs, requirements)
             root = sharedvfs.base
             ui.readconfig(sharedvfs.join(b"hgrc"), root)
     except IOError:
         pass
 
 
 def _getlocal(ui, rpath, wd=None):
     """Return (path, local ui object) for the given target path.
 
     Takes paths in [cwd]/.hg/hgrc into account."
     """
     if wd is None:
         try:
             wd = encoding.getcwd()
         except OSError as e:
             raise error.Abort(
                 _(b"error getting current working directory: %s")
                 % encoding.strtolocal(e.strerror)
             )
 
     path = cmdutil.findrepo(wd) or b""
     if not path:
         lui = ui
     else:
         lui = ui.copy()
         if rcutil.use_repo_hgrc():
             _readsharedsourceconfig(lui, path)
             lui.readconfig(os.path.join(path, b".hg", b"hgrc"), path)
             lui.readconfig(os.path.join(path, b".hg", b"hgrc-not-shared"), path)
 
     if rpath:
         path = lui.expandpath(rpath)
         lui = ui.copy()
         if rcutil.use_repo_hgrc():
             _readsharedsourceconfig(lui, path)
             lui.readconfig(os.path.join(path, b".hg", b"hgrc"), path)
             lui.readconfig(os.path.join(path, b".hg", b"hgrc-not-shared"), path)
 
     return path, lui
 
 
 def _checkshellalias(lui, ui, args):
     """Return the function to run the shell alias, if it is required"""
     options = {}
 
     try:
         args = fancyopts.fancyopts(args, commands.globalopts, options)
     except getopt.GetoptError:
         return
 
     if not args:
         return
 
     cmdtable = commands.table
 
     cmd = args[0]
     try:
         strict = ui.configbool(b"ui", b"strict")
         aliases, entry = cmdutil.findcmd(cmd, cmdtable, strict)
     except (error.AmbiguousCommand, error.UnknownCommand):
         return
 
     cmd = aliases[0]
     fn = entry[0]
 
     if cmd and util.safehasattr(fn, b'shell'):
         # shell alias shouldn't receive early options which are consumed by hg
         _earlyopts, args = _earlysplitopts(args)
         d = lambda: fn(ui, *args[1:])
         return lambda: runcommand(
             lui, None, cmd, args[:1], ui, options, d, [], {}
         )
 
 
 def _dispatch(req):
     args = req.args
     ui = req.ui
 
     # check for cwd
     cwd = req.earlyoptions[b'cwd']
     if cwd:
         os.chdir(cwd)
 
     rpath = req.earlyoptions[b'repository']
     path, lui = _getlocal(ui, rpath)
 
     uis = {ui, lui}
 
     if req.repo:
         uis.add(req.repo.ui)
 
     if (
         req.earlyoptions[b'verbose']
         or req.earlyoptions[b'debug']
         or req.earlyoptions[b'quiet']
     ):
         for opt in (b'verbose', b'debug', b'quiet'):
             val = pycompat.bytestr(bool(req.earlyoptions[opt]))
             for ui_ in uis:
                 ui_.setconfig(b'ui', opt, val, b'--' + opt)
 
     if req.earlyoptions[b'profile']:
         for ui_ in uis:
             ui_.setconfig(b'profiling', b'enabled', b'true', b'--profile')
 
     profile = lui.configbool(b'profiling', b'enabled')
     with profiling.profile(lui, enabled=profile) as profiler:
         # Configure extensions in phases: uisetup, extsetup, cmdtable, and
         # reposetup
         extensions.loadall(lui)
         # Propagate any changes to lui.__class__ by extensions
         ui.__class__ = lui.__class__
 
         # (uisetup and extsetup are handled in extensions.loadall)
 
         # (reposetup is handled in hg.repository)
 
         addaliases(lui, commands.table)
 
         # All aliases and commands are completely defined, now.
         # Check abbreviation/ambiguity of shell alias.
         shellaliasfn = _checkshellalias(lui, ui, args)
         if shellaliasfn:
             # no additional configs will be set, set up the ui instances
             for ui_ in uis:
                 extensions.populateui(ui_)
             return shellaliasfn()
 
         # check for fallback encoding
         fallback = lui.config(b'ui', b'fallbackencoding')
         if fallback:
             encoding.fallbackencoding = fallback
 
         fullargs = args
         cmd, func, args, options, cmdoptions = _parse(lui, args)
 
         # store the canonical command name in request object for later access
         req.canonical_command = cmd
 
         if options[b"config"] != req.earlyoptions[b"config"]:
             raise error.InputError(_(b"option --config may not be abbreviated"))
         if options[b"cwd"] != req.earlyoptions[b"cwd"]:
             raise error.InputError(_(b"option --cwd may not be abbreviated"))
         if options[b"repository"] != req.earlyoptions[b"repository"]:
             raise error.InputError(
                 _(
                     b"option -R has to be separated from other options (e.g. not "
                     b"-qR) and --repository may only be abbreviated as --repo"
                 )
             )
         if options[b"debugger"] != req.earlyoptions[b"debugger"]:
             raise error.InputError(
                 _(b"option --debugger may not be abbreviated")
             )
         # don't validate --profile/--traceback, which can be enabled from now
 
         if options[b"encoding"]:
             encoding.encoding = options[b"encoding"]
         if options[b"encodingmode"]:
             encoding.encodingmode = options[b"encodingmode"]
         if options[b"time"]:
 
             def get_times():
                 t = os.times()
                 if t[4] == 0.0:
                     # Windows leaves this as zero, so use time.perf_counter()
                     t = (t[0], t[1], t[2], t[3], util.timer())
                 return t
 
             s = get_times()
 
             def print_time():
                 t = get_times()
                 ui.warn(
                     _(b"time: real %.3f secs (user %.3f+%.3f sys %.3f+%.3f)\n")
                     % (
                         t[4] - s[4],
                         t[0] - s[0],
                         t[2] - s[2],
                         t[1] - s[1],
                         t[3] - s[3],
                     )
                 )
 
             ui.atexit(print_time)
         if options[b"profile"]:
             profiler.start()
 
         # if abbreviated version of this were used, take them in account, now
         if options[b'verbose'] or options[b'debug'] or options[b'quiet']:
             for opt in (b'verbose', b'debug', b'quiet'):
                 if options[opt] == req.earlyoptions[opt]:
                     continue
                 val = pycompat.bytestr(bool(options[opt]))
                 for ui_ in uis:
                     ui_.setconfig(b'ui', opt, val, b'--' + opt)
 
         if options[b'traceback']:
             for ui_ in uis:
                 ui_.setconfig(b'ui', b'traceback', b'on', b'--traceback')
 
         if options[b'noninteractive']:
             for ui_ in uis:
                 ui_.setconfig(b'ui', b'interactive', b'off', b'-y')
 
         if cmdoptions.get(b'insecure', False):
             for ui_ in uis:
                 ui_.insecureconnections = True
 
         # setup color handling before pager, because setting up pager
         # might cause incorrect console information
         coloropt = options[b'color']
         for ui_ in uis:
             if coloropt:
                 ui_.setconfig(b'ui', b'color', coloropt, b'--color')
             color.setup(ui_)
 
         if stringutil.parsebool(options[b'pager']):
             # ui.pager() expects 'internal-always-' prefix in this case
             ui.pager(b'internal-always-' + cmd)
         elif options[b'pager'] != b'auto':
             for ui_ in uis:
                 ui_.disablepager()
 
         # configs are fully loaded, set up the ui instances
         for ui_ in uis:
             extensions.populateui(ui_)
 
         if options[b'version']:
             return commands.version_(ui)
         if options[b'help']:
             return commands.help_(ui, cmd, command=cmd is not None)
         elif not cmd:
             return commands.help_(ui, b'shortlist')
 
         repo = None
         cmdpats = args[:]
         assert func is not None  # help out pytype
         if not func.norepo:
             # use the repo from the request only if we don't have -R
             if not rpath and not cwd:
                 repo = req.repo
 
             if repo:
                 # set the descriptors of the repo ui to those of ui
                 repo.ui.fin = ui.fin
                 repo.ui.fout = ui.fout
                 repo.ui.ferr = ui.ferr
                 repo.ui.fmsg = ui.fmsg
             else:
                 try:
                     repo = hg.repository(
                         ui,
                         path=path,
                         presetupfuncs=req.prereposetups,
                         intents=func.intents,
                     )
                     if not repo.local():
                         raise error.InputError(
                             _(b"repository '%s' is not local") % path
                         )
                     repo.ui.setconfig(
                         b"bundle", b"mainreporoot", repo.root, b'repo'
                     )
                 except error.RequirementError:
                     raise
                 except error.RepoError:
                     if rpath:  # invalid -R path
                         raise
                     if not func.optionalrepo:
                         if func.inferrepo and args and not path:
                             # try to infer -R from command args
                             repos = pycompat.maplist(cmdutil.findrepo, args)
                             guess = repos[0]
                             if guess and repos.count(guess) == len(repos):
                                 req.args = [b'--repository', guess] + fullargs
                                 req.earlyoptions[b'repository'] = guess
                                 return _dispatch(req)
                         if not path:
                             raise error.InputError(
                                 _(
                                     b"no repository found in"
                                     b" '%s' (.hg not found)"
                                 )
                                 % encoding.getcwd()
                             )
                         raise
             if repo:
                 ui = repo.ui
                 if options[b'hidden']:
                     repo = repo.unfiltered()
             args.insert(0, repo)
         elif rpath:
             ui.warn(_(b"warning: --repository ignored\n"))
 
         msg = _formatargs(fullargs)
         ui.log(b"command", b'%s\n', msg)
         strcmdopt = pycompat.strkwargs(cmdoptions)
         d = lambda: util.checksignature(func)(ui, *args, **strcmdopt)
         try:
             return runcommand(
                 lui, repo, cmd, fullargs, ui, options, d, cmdpats, cmdoptions
             )
         finally:
             if repo and repo != req.repo:
                 repo.close()
 
 
 def _runcommand(ui, options, cmd, cmdfunc):
     """Run a command function, possibly with profiling enabled."""
     try:
         with tracing.log("Running %s command" % cmd):
             return cmdfunc()
     except error.SignatureError:
         raise error.CommandError(cmd, _(b'invalid arguments'))
 
 
 def _exceptionwarning(ui):
     """Produce a warning message for the current active exception"""
 
     # For compatibility checking, we discard the portion of the hg
     # version after the + on the assumption that if a "normal
     # user" is running a build with a + in it the packager
     # probably built from fairly close to a tag and anyone with a
     # 'make local' copy of hg (where the version number can be out
     # of date) will be clueful enough to notice the implausible
     # version number and try updating.
     ct = util.versiontuple(n=2)
     worst = None, ct, b'', b''
     if ui.config(b'ui', b'supportcontact') is None:
         for name, mod in extensions.extensions():
             # 'testedwith' should be bytes, but not all extensions are ported
             # to py3 and we don't want UnicodeException because of that.
             testedwith = stringutil.forcebytestr(
                 getattr(mod, 'testedwith', b'')
             )
             version = extensions.moduleversion(mod)
             report = getattr(mod, 'buglink', _(b'the extension author.'))
             if not testedwith.strip():
                 # We found an untested extension. It's likely the culprit.
                 worst = name, b'unknown', report, version
                 break
 
             # Never blame on extensions bundled with Mercurial.
             if extensions.ismoduleinternal(mod):
                 continue
 
             tested = [util.versiontuple(t, 2) for t in testedwith.split()]
             if ct in tested:
                 continue
 
             lower = [t for t in tested if t < ct]
             nearest = max(lower or tested)
             if worst[0] is None or nearest < worst[1]:
                 worst = name, nearest, report, version
     if worst[0] is not None:
         name, testedwith, report, version = worst
         if not isinstance(testedwith, (bytes, str)):
             testedwith = b'.'.join(
                 [stringutil.forcebytestr(c) for c in testedwith]
             )
         extver = version or _(b"(version N/A)")
         warning = _(
             b'** Unknown exception encountered with '
             b'possibly-broken third-party extension "%s" %s\n'
             b'** which supports versions %s of Mercurial.\n'
             b'** Please disable "%s" and try your action again.\n'
             b'** If that fixes the bug please report it to %s\n'
         ) % (name, extver, testedwith, name, stringutil.forcebytestr(report))
     else:
         bugtracker = ui.config(b'ui', b'supportcontact')
         if bugtracker is None:
             bugtracker = _(b"https://mercurial-scm.org/wiki/BugTracker")
         warning = (
             _(
                 b"** unknown exception encountered, "
                 b"please report by visiting\n** "
             )
             + bugtracker
             + b'\n'
         )
     sysversion = pycompat.sysbytes(sys.version).replace(b'\n', b'')
 
     def ext_with_ver(x):
         ext = x[0]
         ver = extensions.moduleversion(x[1])
         if ver:
             ext += b' ' + ver
         return ext
 
     warning += (
         (_(b"** Python %s\n") % sysversion)
         + (_(b"** Mercurial Distributed SCM (version %s)\n") % util.version())
         + (
             _(b"** Extensions loaded: %s\n")
             % b", ".join(
                 [ext_with_ver(x) for x in sorted(extensions.extensions())]
             )
         )
     )
     return warning
 
 
 def handlecommandexception(ui):
     """Produce a warning message for broken commands
 
     Called when handling an exception; the exception is reraised if
     this function returns False, ignored otherwise.
     """
     warning = _exceptionwarning(ui)
     ui.log(
         b"commandexception",
         b"%s\n%s\n",
         warning,
         pycompat.sysbytes(traceback.format_exc()),
     )
     ui.warn(warning)
     return False  # re-raise the exception