mercurial/dispatch.py

registrar: replace "cmdtype" with an intent-based mechanism (API)

Commands perform varied actions and repositories vary in their
capabilities.

Historically, the .hg/requires file has been used to lock out clients
lacking a requirement. But this is a very heavy-handed approach and
is typically reserved for cases where the on-disk storage format
changes and we want to prevent incompatible clients from operating on
a repo.

Outside of the .hg/requires file, we tend to deal with things like
optional, extension-provided features via checking at call sites.
We'll either have checks in core or extensions will monkeypatch
functions in core disabling incompatible features, enabling new
features, etc.

Things are somewhat tolerable today. But once we introduce alternate
storage backends with varying support for repository features and
vastly different modes of behavior, the current model will quickly
grow unwieldy. For example, the implementation of the "simple store"
required a lot of hacks to deal with stripping and verify because
various parts of core assume things are implemented a certain way.
Partial clone will require new ways of modeling file data retrieval,
because we can no longer assume that all file data is already local.
In this new world, some commands might not make any sense for certain
types of repositories.

What we need is a mechanism to affect the construction of repository
(and eventually peer) instances so the requirements/capabilities
needed for the current operation can be taken into account. "Current
operation" can almost certainly be defined by a command. So it makes
sense for commands to declare their intended actions.

This commit introduces the "intents" concept on the command registrar.
"intents" captures a set of strings that declare actions that are
anticipated to be taken, requirements the repository must possess, etc.
These intents will be passed into hg.repo(), which will pass them into
localrepository, where they can be used to influence the object being
created. Some use cases for this include:

* For read-only intents, constructing a repository object that doesn't
  expose methods that can mutate the repository. Its VFS instances
  don't even allow opening a file with write access.
* For read-only intents, constructing a repository object without
  cache invalidation logic. If the repo never changes during its lifetime,
  nothing ever needs to be invalidated and we don't need to do expensive
  things like verify the changelog's hidden revisions state is accurate
  every time we access repo.changelog.
* We can automatically hide commands from `hg help` when the current
  repository doesn't provide that command. For example, an alternate
  storage backend may not support `hg commit`, so we can hide that
  command or anything else that would perform local commits.

We already kind of had an "intents" mechanism on the registrar in the
form of "cmdtype." However, it was never used. And it was limited to
a single value. We really need something that supports multiple
intents. And because intents may be defined by extensions and at this
point are advisory, I think it is best to define them in a set rather
than as separate arguments/attributes on the command.

Differential Revision: https://phab.mercurial-scm.org/D3376

# 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 os
import pdb
import re
import signal
import sys
import time
import traceback


from .i18n import _

from . import (
    cmdutil,
    color,
    commands,
    demandimport,
    encoding,
    error,
    extensions,
    fancyopts,
    help,
    hg,
    hook,
    profiling,
    pycompat,
    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, prereposetups=None):
        self.args = args
        self.ui = ui
        self.repo = repo

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

        # 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 []

    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.warn(('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()
    req = request(pycompat.sysargv[1:])
    err = None
    try:
        status = (dispatch(req) or 0)
    except error.StdioError as e:
        err = e
        status = -1
    if util.safehasattr(req.ui, 'fout'):
        try:
            req.ui.fout.flush()
        except IOError as e:
            err = e
            status = -1
    if util.safehasattr(req.ui, 'ferr'):
        try:
            if err is not None and err.errno != errno.EPIPE:
                req.ui.ferr.write('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

    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(_("(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") %
              (pycompat.bytestr(inst.args[1]), inst.args[0]))
        if inst.args[0].startswith(' '):
            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 _formatargs(args):
    return ' '.join(procutil.shellquote(a) for a in args)

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 = procutil.stderr

    try:
        if not req.ui:
            req.ui = uimod.ui.load()
        req.earlyoptions.update(_earlyparseopts(req.ui, req.args))
        if req.earlyoptions['traceback']:
            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 = _formatargs(req.args)
    starttime = util.timer()
    ret = None
    try:
        ret = _runcatch(req)
    except error.ProgrammingError as inst:
        req.ui.warn(_('** ProgrammingError: %s\n') % inst)
        if inst.hint:
            req.ui.warn(_('** (%s)\n') % inst.hint)
        raise
    except KeyboardInterrupt as inst:
        try:
            if isinstance(inst, error.SignalInterrupt):
                msg = _("killed!\n")
            else:
                msg = _("interrupted!\n")
            req.ui.warn(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['command_duration'] = duration * 1000
            req.ui.log('uiblocked', 'ui blocked ms',
                       **pycompat.strkwargs(req.ui._blockedtimes))
        req.ui.log("commandfinish", "%s exited %d after %0.2f seconds\n",
                   msg, ret or 0, duration)
        try:
            req._runexithandlers()
        except: # exiting, so no re-raises
            ret = ret or -1
    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():
        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 == 'serve' and '--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] != '-R' or
                req.args[1].startswith('--') or
                req.args[2] != 'serve' or
                req.args[3] != '--stdio'):
                raise error.Abort(
                    _('potentially unsafe serve --stdio invocation: %r') %
                    (req.args,))

        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, req.earlyoptions['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='--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 req.earlyoptions['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['debugger']:
                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 req.earlyoptions['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(_("hg: command '%s' is ambiguous:\n    %s\n") %
                (inst.args[0], " ".join(inst.args[1])))
    except error.CommandError as inst:
        if inst.args[0]:
            ui.pager('help')
            msgbytes = pycompat.bytestr(inst.args[1])
            ui.warn(_("hg %s: %s\n") % (inst.args[0], msgbytes))
            commands.help_(ui, inst.args[0], full=False, command=True)
        else:
            ui.pager('help')
            ui.warn(_("hg: %s\n") % inst.args[1])
            commands.help_(ui, 'shortlist')
    except error.ParseError as inst:
        _formatparse(ui.warn, inst)
        return -1
    except error.UnknownCommand as inst:
        nocmdmsg = _("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.pager('help')
                ui.warn(nocmdmsg)
                commands.help_(ui, 'shortlist')
    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, '_origfunc'):
        args = getattr(fn, 'args', args)
    if args:
        cmd = ' '.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(_('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 "$@" (with quotes) because it's only
    # built to match prefix + patterns.
    replacemap = dict(('$%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(procutil.shellquote(arg) for arg in args)
    # escape '\$' for regex
    regex = '|'.join(replacemap.keys()).replace('$', 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 = ''
        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('!'):
            shdef = self.definition[1:]
            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.\n"
                                 % (int(m.groups()[0]), self.name))
                        return ''
                cmd = re.sub(br'\$(\d+|\$)', _checkvar, shdef)
                cmd = aliasinterpolate(self.name, args, cmd)
                return ui.system(cmd, environ=env,
                                 blockedtag='alias_%s' % self.name)
            self.fn = fn
            self._populatehelp(ui, name, shdef, self.fn)
            return

        try:
            args = pycompat.shlexsplit(self.definition)
        except ValueError as inst:
            self.badalias = (_("error in definition for alias '%s': %s")
                             % (self.name, stringutil.forcebytestr(inst)))
            return
        earlyopts, args = _earlysplitopts(args)
        if earlyopts:
            self.badalias = (_("error in definition for alias '%s': %s may "
                               "only be given on the command line")
                             % (self.name, '/'.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._populatehelp(ui, name, cmd, self.fn, cmdhelp)

        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))

    def _populatehelp(self, ui, name, cmd, fn, defaulthelp=None):
        # confine strings to be passed to i18n.gettext()
        cfg = {}
        for k in ('doc', 'help'):
            v = ui.config('alias', '%s:%s' % (name, k), None)
            if v is None:
                continue
            if not encoding.isasciistr(v):
                self.badalias = (_("non-ASCII character in alias definition "
                                   "'%s:%s'") % (name, k))
                return
            cfg[k] = v

        self.help = cfg.get('help', defaulthelp or '')
        if self.help and self.help.startswith("hg " + cmd):
            # drop prefix in old-style help lines so hg shows the alias
            self.help = self.help[4 + len(cmd):]

        doc = cfg.get('doc', pycompat.getdoc(fn))
        if doc is not None:
            doc = pycompat.sysstr(doc)
        self.__doc__ = doc

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

    def __getattr__(self, name):
        adefaults = {r'norepo': True, r'intents': set(),
                     r'optionalrepo': False, r'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))

        ui.log('commandalias', "alias '%s' expands to '%s'\n",
               self.name, self.definition)
        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

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

    @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('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('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("ui", "strict"))
        cmd = aliases[0]
        args = aliasargs(entry[0], args)
        defaults = ui.config("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('=', 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)')
                              % pycompat.bytestr(cfg))

    return configs

def _earlyparseopts(ui, args):
    options = {}
    fancyopts.fancyopts(args, commands.globalopts, options,
                        gnu=not ui.plain('strictflags'), early=True,
                        optaliases={'repository': ['repo']})
    return options

def _earlysplitopts(args):
    """Split args into a list of possible early options and remainder args"""
    shortoptions = 'R:'
    # TODO: perhaps 'debugger' should be included
    longoptions = ['cwd=', 'repository=', 'repo=', '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, "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 = pycompat.getcwd()
        except OSError as e:
            raise error.Abort(_("error getting current working directory: %s") %
                              encoding.strtolocal(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:
        path = lui.expandpath(rpath)
        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 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'):
        # 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['cwd']
    if cwd:
        os.chdir(cwd)

    rpath = req.earlyoptions['repository']
    path, lui = _getlocal(ui, rpath)

    uis = {ui, lui}

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

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

    profile = lui.configbool('profiling', '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:
            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"] != req.earlyoptions["config"]:
            raise error.Abort(_("option --config may not be abbreviated!"))
        if options["cwd"] != req.earlyoptions["cwd"]:
            raise error.Abort(_("option --cwd may not be abbreviated!"))
        if options["repository"] != req.earlyoptions["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["debugger"] != req.earlyoptions["debugger"]:
            raise error.Abort(_("option --debugger may not be abbreviated!"))
        # don't validate --profile/--traceback, which can be enabled from now

        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]))
            ui.atexit(print_time)
        if options["profile"]:
            profiler.start()

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

        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

        # setup color handling before pager, because setting up pager
        # might cause incorrect console information
        coloropt = options['color']
        for ui_ in uis:
            if coloropt:
                ui_.setconfig('ui', 'color', coloropt, '--color')
            color.setup(ui_)

        if stringutil.parsebool(options['pager']):
            # ui.pager() expects 'internal-always-' prefix in this case
            ui.pager('internal-always-' + cmd)
        elif options['pager'] != 'auto':
            for ui_ in uis:
                ui_.disablepager()

        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 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,
                                         presetupfuncs=req.prereposetups)
                    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: # 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 = ['--repository', guess] + fullargs
                                req.earlyoptions['repository'] = guess
                                return _dispatch(req)
                        if not path:
                            raise error.RepoError(_("no repository found in"
                                                    " '%s' (.hg not found)")
                                                  % pycompat.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 = _formatargs(fullargs)
        ui.log("command", '%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:
        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') 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', ''))
            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 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 = '.'.join([stringutil.forcebytestr(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')
        if bugtracker is None:
            bugtracker = _("https://mercurial-scm.org/wiki/BugTracker")
        warning = (_("** unknown exception encountered, "
                     "please report by visiting\n** ") + bugtracker + '\n')
    sysversion = pycompat.sysbytes(sys.version).replace('\n', '')
    warning += ((_("** Python %s\n") % sysversion) +
                (_("** 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,
           pycompat.sysbytes(traceback.format_exc()))
    ui.warn(warning)
    return False  # re-raise the exception