dispatch: force \n for newlines on sys.std* streams (BC)

The sys.std* streams behave differently on Python 3. On Python 3,
these streams are an io.TextIOWrapper that wraps a binary buffer
stored on a .buffer attribute. These TextIOWrapper instances
normalize \n to os.linesep by default. On Windows, this means
that \n is normalized to \r\n. So functions like print() which
have an implicit end='\n' will actually emit \r\n for line endings.

While most parts of Mercurial go through the ui.write() layer to
print output, some code - notably in extensions and hooks - can use
print(). If this code was using print() or otherwise writing to
sys.std* on Windows, Mercurial would emit \r\n.

In reality, pretty much everything on Windows reacts to \n just fine.
Mercurial itself doesn't emit \r\n when going through the ui layer.
Changing the sys.std* streams to not normalize line endings sounds
like a scary change. But I think it is safe. It also makes Mercurial
on Python 3 behave similarly to Python 2, which did not perform \r\n
normalization in print() by default.

.. bc:: sys.{stdout, stderr, stdin} now use \n line endings on Python 3

Differential Revision: https://phab.mercurial-scm.org/D8339

mercurial/dispatch.py

@@ -1,1286 +1,1330 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 difflib
 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,
     profiling,
     pycompat,
     rcutil,
     registrar,
     scmutil,
     ui as uimod,
     util,
 )
 
 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 run():
     """run the command in sys.argv"""
     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
 
     _silencestdio()
     sys.exit(status & 255)
 
 
 if pycompat.ispy3:
 
     def initstdio():
-        pass
+        # 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
+        )
+
+        # 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 _getsimilar(symbols, value):
     sim = lambda x: difflib.SequenceMatcher(None, value, x).ratio()
     # The cutoff for similarity here is pretty arbitrary. It should
     # probably be investigated and tweaked.
     return [s for s in symbols if sim(s) > 0.6]
 
 
 def _reportsimilar(write, similar):
     if len(similar) == 1:
         write(_(b"(did you mean %s?)\n") % similar[0])
     elif similar:
         ss = b", ".join(sorted(similar))
         write(_(b"(did you mean one of %s?)\n") % ss)
 
 
 def _formatparse(write, inst):
     similar = []
     if isinstance(inst, error.UnknownIdentifier):
         # make sure to check fileset first, as revset can invoke fileset
         similar = _getsimilar(inst.symbols, inst.function)
     if len(inst.args) > 1:
         write(
             _(b"hg: parse error at %s: %s\n")
             % (pycompat.bytestr(inst.args[1]), inst.args[0])
         )
         if inst.args[0].startswith(b' '):
             write(_(b"unexpected leading whitespace\n"))
     else:
         write(_(b"hg: parse error: %s\n") % inst.args[0])
         _reportsimilar(write, similar)
     if inst.hint:
         write(_(b"(%s)\n") % inst.hint)
 
 
 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(_(b"abort: %s\n") % inst)
             if inst.hint:
                 ferr.write(_(b"(%s)\n") % inst.hint)
             return -1
         except error.ParseError as inst:
             _formatparse(ferr.write, inst)
             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()
             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
         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.args[0], b" ".join(inst.args[1]))
         )
     except error.CommandError as inst:
         if inst.args[0]:
             ui.pager(b'help')
             msgbytes = pycompat.bytestr(inst.args[1])
             ui.warn(_(b"hg %s: %s\n") % (inst.args[0], msgbytes))
             commands.help_(ui, inst.args[0], full=False, command=True)
         else:
             ui.warn(_(b"hg: %s\n") % inst.args[1])
             ui.warn(_(b"(use 'hg help -v' for a list of global options)\n"))
     except error.ParseError as inst:
         _formatparse(ui.warn, inst)
         return -1
     except error.UnknownCommand as inst:
         nocmdmsg = _(b"hg: unknown command '%s'\n") % inst.args[0]
         try:
             # check if the command is in a disabled extension
             # (but don't check for extensions themselves)
             formatted = help.formattedhelp(
                 ui, commands, inst.args[0], unknowncmd=True
             )
             ui.warn(nocmdmsg)
             ui.write(formatted)
         except (error.UnknownCommand, error.Abort):
             suggested = False
             if len(inst.args) == 2:
                 sim = _getsimilar(inst.args[1], inst.args[0])
                 if sim:
                     ui.warn(nocmdmsg)
                     _reportsimilar(ui.warn, 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.Abort(_(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.Abort(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 _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():
             lui.readconfig(os.path.join(path, b".hg", b"hgrc"), path)
 
     if rpath:
         path = lui.expandpath(rpath)
         lui = ui.copy()
         if rcutil.use_repo_hgrc():
             lui.readconfig(os.path.join(path, b".hg", b"hgrc"), 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.Abort(_(b"option --config may not be abbreviated!"))
         if options[b"cwd"] != req.earlyoptions[b"cwd"]:
             raise error.Abort(_(b"option --cwd may not be abbreviated!"))
         if options[b"repository"] != req.earlyoptions[b"repository"]:
             raise error.Abort(
                 _(
                     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.Abort(_(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.Abort(
                             _(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.RepoError(
                                 _(
                                     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''
     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'')
             )
             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
                 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
     if worst[0] is not None:
         name, testedwith, report = worst
         if not isinstance(testedwith, (bytes, str)):
             testedwith = b'.'.join(
                 [stringutil.forcebytestr(c) for c in testedwith]
             )
         warning = _(
             b'** Unknown exception encountered with '
             b'possibly-broken third-party extension %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, 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'')
     warning += (
         (_(b"** Python %s\n") % sysversion)
         + (_(b"** Mercurial Distributed SCM (version %s)\n") % util.version())
         + (
             _(b"** Extensions loaded: %s\n")
             % b", ".join([x[0] for x in 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