# dispatch.py - command dispatching for mercurial
#
# Copyright 2005-2007 Matt Mackall <mpm@selenic.com>
#
# 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 atexit
import difflib
import errno
import os
import pdb
import re
import shlex
import signal
import socket
import sys
import time
import traceback


from .i18n import _

from . import (
    cmdutil,
    commands,
    demandimport,
    encoding,
    error,
    extensions,
    fancyopts,
    fileset,
    hg,
    hook,
    profiling,
    revset,
    templatefilters,
    templatekw,
    templater,
    ui as uimod,
    util,
)

class request(object):
    def __init__(self, args, ui=None, repo=None, fin=None, fout=None,
                 ferr=None):
        self.args = args
        self.ui = ui
        self.repo = repo

        # input/output/error streams
        self.fin = fin
        self.fout = fout
        self.ferr = ferr

def run():
    "run the command in sys.argv"
    sys.exit((dispatch(request(sys.argv[1:])) or 0) & 255)

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(_("(did you mean %s?)\n") % similar[0])
    elif similar:
        ss = ", ".join(sorted(similar))
        write(_("(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(_("hg: parse error at %s: %s\n") %
                         (inst.args[1], inst.args[0]))
        if (inst.args[0][0] == ' '):
            write(_("unexpected leading whitespace\n"))
    else:
        write(_("hg: parse error: %s\n") % inst.args[0])
        _reportsimilar(write, similar)
    if inst.hint:
        write(_("(%s)\n") % inst.hint)

def dispatch(req):
    "run the command specified in req.args"
    if req.ferr:
        ferr = req.ferr
    elif req.ui:
        ferr = req.ui.ferr
    else:
        ferr = sys.stderr

    try:
        if not req.ui:
            req.ui = uimod.ui()
        if '--traceback' in req.args:
            req.ui.setconfig('ui', 'traceback', 'on', '--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
    except error.Abort as inst:
        ferr.write(_("abort: %s\n") % inst)
        if inst.hint:
            ferr.write(_("(%s)\n") % inst.hint)
        return -1
    except error.ParseError as inst:
        _formatparse(ferr.write, inst)
        return -1

    msg = ' '.join(' ' in a and repr(a) or a for a in req.args)
    starttime = time.time()
    ret = None
    try:
        ret = _runcatch(req)
    except KeyboardInterrupt:
        try:
            req.ui.warn(_("interrupted!\n"))
        except IOError as inst:
            if inst.errno != errno.EPIPE:
                raise
        ret = -1
    finally:
        duration = time.time() - starttime
        req.ui.flush()
        req.ui.log("commandfinish", "%s exited %s after %0.2f seconds\n",
                   msg, ret or 0, duration)
    return ret

def _runcatch(req):
    def catchterm(*args):
        raise error.SignalInterrupt

    ui = req.ui
    try:
        for name in 'SIGBREAK', 'SIGHUP', 'SIGTERM':
            num = getattr(signal, name, None)
            if num:
                signal.signal(num, catchterm)
    except ValueError:
        pass # happens if called in a thread

    def _runcatchfunc():
        try:
            debugger = 'pdb'
            debugtrace = {
                'pdb' : pdb.set_trace
            }
            debugmortem = {
                'pdb' : pdb.post_mortem
            }

            # read --config before doing anything else
            # (e.g. to change trust settings for reading .hg/hgrc)
            cfgs = _parseconfig(req.ui, _earlygetopt(['--config'], req.args))

            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='--config')

            # developer config: ui.debugger
            debugger = ui.config("ui", "debugger")
            debugmod = pdb
            if not debugger or ui.plain():
                # if we are in HGPLAIN mode, then disable custom debugging
                debugger = 'pdb'
            elif '--debugger' in req.args:
                # 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 '--debugger' in req.args:
                ui.warn(_("entering debugger - "
                        "type c to continue starting hg or h for help\n"))

                if (debugger != 'pdb' and
                    debugtrace[debugger] == debugtrace['pdb']):
                    ui.warn(_("%s debugger specified "
                              "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 '--debugger' in req.args:
                traceback.print_exc()
                debugmortem[debugger](sys.exc_info()[2])
            ui.traceback()
            raise

    return callcatch(ui, _runcatchfunc)

def callcatch(ui, func):
    """call func() with global exception handling

    return func() if no exception happens. otherwise do some error handling
    and return an exit code accordingly.
    """
    try:
        return func()
    # Global exception handling, alphabetically
    # Mercurial-specific first, followed by built-in and library exceptions
    except error.AmbiguousCommand as inst:
        ui.warn(_("hg: command '%s' is ambiguous:\n    %s\n") %
                (inst.args[0], " ".join(inst.args[1])))
    except error.ParseError as inst:
        _formatparse(ui.warn, inst)
        return -1
    except error.LockHeld as inst:
        if inst.errno == errno.ETIMEDOUT:
            reason = _('timed out waiting for lock held by %s') % inst.locker
        else:
            reason = _('lock held by %s') % inst.locker
        ui.warn(_("abort: %s: %s\n") % (inst.desc or inst.filename, reason))
    except error.LockUnavailable as inst:
        ui.warn(_("abort: could not lock %s: %s\n") %
               (inst.desc or inst.filename, inst.strerror))
    except error.CommandError as inst:
        if inst.args[0]:
            ui.warn(_("hg %s: %s\n") % (inst.args[0], inst.args[1]))
            commands.help_(ui, inst.args[0], full=False, command=True)
        else:
            ui.warn(_("hg: %s\n") % inst.args[1])
            commands.help_(ui, 'shortlist')
    except error.OutOfBandError as inst:
        if inst.args:
            msg = _("abort: remote error:\n")
        else:
            msg = _("abort: remote error\n")
        ui.warn(msg)
        if inst.args:
            ui.warn(''.join(inst.args))
        if inst.hint:
            ui.warn('(%s)\n' % inst.hint)
    except error.RepoError as inst:
        ui.warn(_("abort: %s!\n") % inst)
        if inst.hint:
            ui.warn(_("(%s)\n") % inst.hint)
    except error.ResponseError as inst:
        ui.warn(_("abort: %s") % inst.args[0])
        if not isinstance(inst.args[1], basestring):
            ui.warn(" %r\n" % (inst.args[1],))
        elif not inst.args[1]:
            ui.warn(_(" empty string\n"))
        else:
            ui.warn("\n%r\n" % util.ellipsis(inst.args[1]))
    except error.CensoredNodeError as inst:
        ui.warn(_("abort: file censored %s!\n") % inst)
    except error.RevlogError as inst:
        ui.warn(_("abort: %s!\n") % inst)
    except error.SignalInterrupt:
        ui.warn(_("killed!\n"))
    except error.UnknownCommand as inst:
        ui.warn(_("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)
            commands.help_(ui, inst.args[0], unknowncmd=True)
        except (error.UnknownCommand, error.Abort):
            suggested = False
            if len(inst.args) == 2:
                sim = _getsimilar(inst.args[1], inst.args[0])
                if sim:
                    _reportsimilar(ui.warn, sim)
                    suggested = True
            if not suggested:
                commands.help_(ui, 'shortlist')
    except error.InterventionRequired as inst:
        ui.warn("%s\n" % inst)
        if inst.hint:
            ui.warn(_("(%s)\n") % inst.hint)
        return 1
    except error.Abort as inst:
        ui.warn(_("abort: %s\n") % inst)
        if inst.hint:
            ui.warn(_("(%s)\n") % inst.hint)
    except ImportError as inst:
        ui.warn(_("abort: %s!\n") % inst)
        m = str(inst).split()[-1]
        if m in "mpatch bdiff".split():
            ui.warn(_("(did you forget to compile extensions?)\n"))
        elif m in "zlib".split():
            ui.warn(_("(is your Python install correct?)\n"))
    except IOError as inst:
        if util.safehasattr(inst, "code"):
            ui.warn(_("abort: %s\n") % inst)
        elif util.safehasattr(inst, "reason"):
            try: # usually it is in the form (errno, strerror)
                reason = inst.reason.args[1]
            except (AttributeError, IndexError):
                # it might be anything, for example a string
                reason = inst.reason
            if isinstance(reason, unicode):
                # SSLError of Python 2.7.9 contains a unicode
                reason = reason.encode(encoding.encoding, 'replace')
            ui.warn(_("abort: error: %s\n") % reason)
        elif (util.safehasattr(inst, "args")
              and inst.args and inst.args[0] == errno.EPIPE):
            pass
        elif getattr(inst, "strerror", None):
            if getattr(inst, "filename", None):
                ui.warn(_("abort: %s: %s\n") % (inst.strerror, inst.filename))
            else:
                ui.warn(_("abort: %s\n") % inst.strerror)
        else:
            raise
    except OSError as inst:
        if getattr(inst, "filename", None) is not None:
            ui.warn(_("abort: %s: '%s'\n") % (inst.strerror, inst.filename))
        else:
            ui.warn(_("abort: %s\n") % inst.strerror)
    except KeyboardInterrupt:
        raise
    except MemoryError:
        ui.warn(_("abort: out of memory\n"))
    except SystemExit as inst:
        # Commands shouldn't sys.exit directly, but give a return code.
        # Just in case catch this and and pass exit code to caller.
        return inst.code
    except socket.error as inst:
        ui.warn(_("abort: %s\n") % inst.args[-1])
    except:  # perhaps re-raises
        if not handlecommandexception(ui):
            raise

    return -1

def aliasargs(fn, givenargs):
    args = getattr(fn, 'args', [])
    if args:
        cmd = ' '.join(map(util.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(_('too few arguments for command alias'))
        cmd = re.sub(r'\$(\d+|\$)', replacer, cmd)
        givenargs = [x for i, x in enumerate(givenargs)
                     if i not in nums]
        args = shlex.split(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 "$@" (with quotes) because it's only
    # built to match prefix + patterns.
    replacemap = dict(('$%d' % (i + 1), arg) for i, arg in enumerate(args))
    replacemap['$0'] = name
    replacemap['$$'] = '$'
    replacemap['$@'] = ' '.join(args)
    # Typical Unix shells interpolate "$@" (with quotes) as all the positional
    # parameters, separated out into words. Emulate the same behavior here by
    # quoting the arguments individually. POSIX shells will then typically
    # tokenize each argument into exactly one word.
    replacemap['"$@"'] = ' '.join(util.shellquote(arg) for arg in args)
    # escape '\$' for regex
    regex = '|'.join(replacemap.keys()).replace('$', r'\$')
    r = re.compile(regex)
    return r.sub(lambda x: replacemap[x.group()], cmd)

class cmdalias(object):
    def __init__(self, name, definition, cmdtable, source):
        self.name = self.cmd = name
        self.cmdname = ''
        self.definition = definition
        self.fn = None
        self.givenargs = []
        self.opts = []
        self.help = ''
        self.badalias = None
        self.unknowncmd = False
        self.source = source

        try:
            aliases, entry = cmdutil.findcmd(self.name, cmdtable)
            for alias, e in cmdtable.iteritems():
                if e is entry:
                    self.cmd = alias
                    break
            self.shadows = True
        except error.UnknownCommand:
            self.shadows = False

        if not self.definition:
            self.badalias = _("no definition for alias '%s'") % self.name
            return

        if self.definition.startswith('!'):
            self.shell = True
            def fn(ui, *args):
                env = {'HG_ARGS': ' '.join((self.name,) + args)}
                def _checkvar(m):
                    if m.groups()[0] == '$':
                        return m.group()
                    elif int(m.groups()[0]) <= len(args):
                        return m.group()
                    else:
                        ui.debug("No argument found for substitution "
                                 "of %i variable in alias '%s' definition."
                                 % (int(m.groups()[0]), self.name))
                        return ''
                cmd = re.sub(r'\$(\d+|\$)', _checkvar, self.definition[1:])
                cmd = aliasinterpolate(self.name, args, cmd)
                return ui.system(cmd, environ=env)
            self.fn = fn
            return

        try:
            args = shlex.split(self.definition)
        except ValueError as inst:
            self.badalias = (_("error in definition for alias '%s': %s")
                             % (self.name, inst))
            return
        self.cmdname = cmd = args.pop(0)
        self.givenargs = args

        for invalidarg in ("--cwd", "-R", "--repository", "--repo", "--config"):
            if _earlygetopt([invalidarg], args):
                self.badalias = (_("error in definition for alias '%s': %s may "
                                   "only be given on the command line")
                                 % (self.name, invalidarg))
                return

        try:
            tableentry = cmdutil.findcmd(cmd, cmdtable, False)[1]
            if len(tableentry) > 2:
                self.fn, self.opts, self.help = tableentry
            else:
                self.fn, self.opts = tableentry

            if self.help.startswith("hg " + cmd):
                # drop prefix in old-style help lines so hg shows the alias
                self.help = self.help[4 + len(cmd):]
            self.__doc__ = self.fn.__doc__

        except error.UnknownCommand:
            self.badalias = (_("alias '%s' resolves to unknown command '%s'")
                             % (self.name, cmd))
            self.unknowncmd = True
        except error.AmbiguousCommand:
            self.badalias = (_("alias '%s' resolves to ambiguous command '%s'")
                             % (self.name, cmd))

    @property
    def args(self):
        args = map(util.expandpath, self.givenargs)
        return aliasargs(self.fn, args)

    def __getattr__(self, name):
        adefaults = {'norepo': True, 'optionalrepo': False, 'inferrepo': False}
        if name not in adefaults:
            raise AttributeError(name)
        if self.badalias or util.safehasattr(self, '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 = _("'%s' is provided by '%s' extension") % (cmd, ext)
                except error.UnknownCommand:
                    pass
            raise error.Abort(self.badalias, hint=hint)
        if self.shadows:
            ui.debug("alias '%s' shadows command '%s'\n" %
                     (self.name, self.cmdname))

        if util.safehasattr(self, 'shell'):
            return self.fn(ui, *args, **opts)
        else:
            try:
                return util.checksignature(self.fn)(ui, *args, **opts)
            except error.SignatureError:
                args = ' '.join([self.cmdname] + self.args)
                ui.debug("alias '%s' expands to '%s'\n" % (self.name, args))
                raise

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('alias'):
        source = ui.configsource('alias', alias)
        aliasdef = cmdalias(alias, definition, cmdtable, source)

        try:
            olddef = cmdtable[aliasdef.cmd][0]
            if olddef.definition == aliasdef.definition:
                continue
        except (KeyError, AttributeError):
            # definition might not exist or it might not be a cmdalias
            pass

        cmdtable[aliasdef.name] = (aliasdef, aliasdef.opts, aliasdef.help)

def _parse(ui, args):
    options = {}
    cmdoptions = {}

    try:
        args = fancyopts.fancyopts(args, commands.globalopts, options)
    except fancyopts.getopt.GetoptError as inst:
        raise error.CommandError(None, inst)

    if args:
        cmd, args = args[0], args[1:]
        aliases, entry = cmdutil.findcmd(cmd, commands.table,
                                         ui.configbool("ui", "strict"))
        cmd = aliases[0]
        args = aliasargs(entry[0], args)
        defaults = ui.config("defaults", cmd)
        if defaults:
            args = map(util.expandpath, shlex.split(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 fancyopts.getopt.GetoptError as inst:
        raise error.CommandError(cmd, 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('=', 1)]
            section, name = name.split('.', 1)
            if not section or not name:
                raise IndexError
            ui.setconfig(section, name, value, '--config')
            configs.append((section, name, value))
        except (IndexError, ValueError):
            raise error.Abort(_('malformed --config option: %r '
                               '(use --config section.name=value)') % cfg)

    return configs

def _earlygetopt(aliases, args):
    """Return list of values for an option (or aliases).

    The values are listed in the order they appear in args.
    The options and values are removed from args.

    >>> args = ['x', '--cwd', 'foo', 'y']
    >>> _earlygetopt(['--cwd'], args), args
    (['foo'], ['x', 'y'])

    >>> args = ['x', '--cwd=bar', 'y']
    >>> _earlygetopt(['--cwd'], args), args
    (['bar'], ['x', 'y'])

    >>> args = ['x', '-R', 'foo', 'y']
    >>> _earlygetopt(['-R'], args), args
    (['foo'], ['x', 'y'])

    >>> args = ['x', '-Rbar', 'y']
    >>> _earlygetopt(['-R'], args), args
    (['bar'], ['x', 'y'])
    """
    try:
        argcount = args.index("--")
    except ValueError:
        argcount = len(args)
    shortopts = [opt for opt in aliases if len(opt) == 2]
    values = []
    pos = 0
    while pos < argcount:
        fullarg = arg = args[pos]
        equals = arg.find('=')
        if equals > -1:
            arg = arg[:equals]
        if arg in aliases:
            del args[pos]
            if equals > -1:
                values.append(fullarg[equals + 1:])
                argcount -= 1
            else:
                if pos + 1 >= argcount:
                    # ignore and let getopt report an error if there is no value
                    break
                values.append(args.pop(pos))
                argcount -= 2
        elif arg[:2] in shortopts:
            # short option can have no following space, e.g. hg log -Rfoo
            values.append(args.pop(pos)[2:])
            argcount -= 1
        else:
            pos += 1
    return values

def runcommand(lui, repo, cmd, fullargs, ui, options, d, cmdpats, cmdoptions):
    # run pre-hook, and abort if it fails
    hook.hook(lui, repo, "pre-%s" % cmd, True, args=" ".join(fullargs),
              pats=cmdpats, opts=cmdoptions)
    try:
        ret = _runcommand(ui, options, cmd, d)
        # run post-hook, passing command result
        hook.hook(lui, repo, "post-%s" % cmd, False, args=" ".join(fullargs),
                  result=ret, pats=cmdpats, opts=cmdoptions)
    except Exception:
        # run failure hook and re-raise
        hook.hook(lui, repo, "fail-%s" % cmd, False, args=" ".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 = os.getcwd()
        except OSError as e:
            raise error.Abort(_("error getting current working directory: %s") %
                              e.strerror)
    path = cmdutil.findrepo(wd) or ""
    if not path:
        lui = ui
    else:
        lui = ui.copy()
        lui.readconfig(os.path.join(path, ".hg", "hgrc"), path)

    if rpath and rpath[-1]:
        path = lui.expandpath(rpath[-1])
        lui = ui.copy()
        lui.readconfig(os.path.join(path, ".hg", "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 fancyopts.getopt.GetoptError:
        return

    if not args:
        return

    cmdtable = commands.table

    cmd = args[0]
    try:
        strict = ui.configbool("ui", "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, 'shell'):
        d = lambda: fn(ui, *args[1:])
        return lambda: runcommand(lui, None, cmd, args[:1], ui, options, d,
                                  [], {})

def _cmdattr(ui, cmd, func, attr):
    try:
        return getattr(func, attr)
    except AttributeError:
        ui.deprecwarn("missing attribute '%s', use @command decorator "
                      "to register '%s'" % (attr, cmd), '3.8')
        return False

_loaded = set()

# list of (objname, loadermod, loadername) tuple:
# - objname is the name of an object in extension module, from which
#   extra information is loaded
# - loadermod is the module where loader is placed
# - loadername is the name of the function, which takes (ui, extensionname,
#   extraobj) arguments
extraloaders = [
    ('cmdtable', commands, 'loadcmdtable'),
    ('filesetpredicate', fileset, 'loadpredicate'),
    ('revsetpredicate', revset, 'loadpredicate'),
    ('templatefilter', templatefilters, 'loadfilter'),
    ('templatefunc', templater, 'loadfunction'),
    ('templatekeyword', templatekw, 'loadkeyword'),
]

def _dispatch(req):
    args = req.args
    ui = req.ui

    # check for cwd
    cwd = _earlygetopt(['--cwd'], args)
    if cwd:
        os.chdir(cwd[-1])

    rpath = _earlygetopt(["-R", "--repository", "--repo"], args)
    path, lui = _getlocal(ui, rpath)

    # Configure extensions in phases: uisetup, extsetup, cmdtable, and
    # reposetup. Programs like TortoiseHg will call _dispatch several
    # times so we keep track of configured extensions in _loaded.
    extensions.loadall(lui)
    exts = [ext for ext in extensions.extensions() if ext[0] not in _loaded]
    # Propagate any changes to lui.__class__ by extensions
    ui.__class__ = lui.__class__

    # (uisetup and extsetup are handled in extensions.loadall)

    for name, module in exts:
        for objname, loadermod, loadername in extraloaders:
            extraobj = getattr(module, objname, None)
            if extraobj is not None:
                getattr(loadermod, loadername)(ui, name, extraobj)
        _loaded.add(name)

    # (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:
        return shellaliasfn()

    # check for fallback encoding
    fallback = lui.config('ui', 'fallbackencoding')
    if fallback:
        encoding.fallbackencoding = fallback

    fullargs = args
    cmd, func, args, options, cmdoptions = _parse(lui, args)

    if options["config"]:
        raise error.Abort(_("option --config may not be abbreviated!"))
    if options["cwd"]:
        raise error.Abort(_("option --cwd may not be abbreviated!"))
    if options["repository"]:
        raise error.Abort(_(
            "option -R has to be separated from other options (e.g. not -qR) "
            "and --repository may only be abbreviated as --repo!"))

    if options["encoding"]:
        encoding.encoding = options["encoding"]
    if options["encodingmode"]:
        encoding.encodingmode = options["encodingmode"]
    if options["time"]:
        def get_times():
            t = os.times()
            if t[4] == 0.0: # Windows leaves this as zero, so use time.clock()
                t = (t[0], t[1], t[2], t[3], time.clock())
            return t
        s = get_times()
        def print_time():
            t = get_times()
            ui.warn(_("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]))
        atexit.register(print_time)

    uis = set([ui, lui])

    if req.repo:
        uis.add(req.repo.ui)

    if options['verbose'] or options['debug'] or options['quiet']:
        for opt in ('verbose', 'debug', 'quiet'):
            val = str(bool(options[opt]))
            for ui_ in uis:
                ui_.setconfig('ui', opt, val, '--' + opt)

    if options['profile']:
        for ui_ in uis:
            ui_.setconfig('profiling', 'enabled', 'true', '--profile')

    if options['traceback']:
        for ui_ in uis:
            ui_.setconfig('ui', 'traceback', 'on', '--traceback')

    if options['noninteractive']:
        for ui_ in uis:
            ui_.setconfig('ui', 'interactive', 'off', '-y')

    if cmdoptions.get('insecure', False):
        for ui_ in uis:
            ui_.insecureconnections = True

    if options['version']:
        return commands.version_(ui)
    if options['help']:
        return commands.help_(ui, cmd, command=cmd is not None)
    elif not cmd:
        return commands.help_(ui, 'shortlist')

    repo = None
    cmdpats = args[:]
    if not _cmdattr(ui, cmd, 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
        else:
            try:
                repo = hg.repository(ui, path=path)
                if not repo.local():
                    raise error.Abort(_("repository '%s' is not local") % path)
                repo.ui.setconfig("bundle", "mainreporoot", repo.root, 'repo')
            except error.RequirementError:
                raise
            except error.RepoError:
                if rpath and rpath[-1]: # invalid -R path
                    raise
                if not _cmdattr(ui, cmd, func, 'optionalrepo'):
                    if (_cmdattr(ui, cmd, func, 'inferrepo') and
                        args and not path):
                        # try to infer -R from command args
                        repos = map(cmdutil.findrepo, args)
                        guess = repos[0]
                        if guess and repos.count(guess) == len(repos):
                            req.args = ['--repository', guess] + fullargs
                            return _dispatch(req)
                    if not path:
                        raise error.RepoError(_("no repository found in '%s'"
                                                " (.hg not found)")
                                              % os.getcwd())
                    raise
        if repo:
            ui = repo.ui
            if options['hidden']:
                repo = repo.unfiltered()
        args.insert(0, repo)
    elif rpath:
        ui.warn(_("warning: --repository ignored\n"))

    msg = ' '.join(' ' in a and repr(a) or a for a in fullargs)
    ui.log("command", '%s\n', msg)
    d = lambda: util.checksignature(func)(ui, *args, **cmdoptions)
    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."""
    with profiling.maybeprofile(ui):
        try:
            return cmdfunc()
        except error.SignatureError:
            raise error.CommandError(cmd, _('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, ''
    if ui.config('ui', 'supportcontact', None) is None:
        for name, mod in extensions.extensions():
            testedwith = getattr(mod, 'testedwith', '')
            report = getattr(mod, 'buglink', _('the extension author.'))
            if not testedwith.strip():
                # We found an untested extension. It's likely the culprit.
                worst = name, 'unknown', report
                break

            # Never blame on extensions bundled with Mercurial.
            if testedwith == 'ships-with-hg-core':
                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, str):
            testedwith = '.'.join([str(c) for c in testedwith])
        warning = (_('** Unknown exception encountered with '
                     'possibly-broken third-party extension %s\n'
                     '** which supports versions %s of Mercurial.\n'
                     '** Please disable %s and try your action again.\n'
                     '** If that fixes the bug please report it to %s\n')
                   % (name, testedwith, name, report))
    else:
        bugtracker = ui.config('ui', 'supportcontact', None)
        if bugtracker is None:
            bugtracker = _("https://mercurial-scm.org/wiki/BugTracker")
        warning = (_("** unknown exception encountered, "
                     "please report by visiting\n** ") + bugtracker + '\n')
    warning += ((_("** Python %s\n") % sys.version.replace('\n', '')) +
                (_("** Mercurial Distributed SCM (version %s)\n") %
                 util.version()) +
                (_("** Extensions loaded: %s\n") %
                 ", ".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("commandexception", "%s\n%s\n", warning, traceback.format_exc())
    ui.warn(warning)
    return False  # re-raise the exception