dispatch: handle IOError when writing to stderr

Previously, attempts to write to stderr in dispatch.run() may lead to
an exception being thrown. This would likely be handled by Python's
default exception handler, which would print the exception and exit
1.

Code in this function is already catching IOError for stdout failures
and converting to exit code 255 (-1 & 255 == 255). Why we weren't
doing the same for stderr for the sake of consistency, I don't know.
I do know that chg and hg diverged in behavior here (as the changed
test-basic.t shows).

After this commit, we catch I/O failure on stderr and change the
exit code to 255. chg and hg now behave consistently. As a bonus,
Rust hg also now passes this test.

I'm skeptical at changing the exit code due to failures this late
in the process. I think we should consider preserving the current
exit code - assuming it is non-0. And, we may want to preserve the
exit code completely if the I/O error is EPIPE (and potentially
other special error classes). There's definitely room to tweak
behavior. But for now, let's at least prevent the uncaught exception.

Differential Revision: https://phab.mercurial-scm.org/D1860

mercurial/dispatch.py

@@ -1,996 +1,1002 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 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,
     registrar,
     scmutil,
     ui as uimod,
     util,
 )
 
 unrecoverablewrite = registrar.command.unrecoverablewrite
 
 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) & 255
     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'):
-        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()
+        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
+
     sys.exit(status & 255)
 
 def _initstdio():
     for fp in (sys.stdin, sys.stdout, sys.stderr):
         util.setbinary(fp)
 
 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 _formatargs(args):
     return ' '.join(util.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 = util.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(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(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(util.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, 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.\n"
                                  % (int(m.groups()[0]), self.name))
                         return ''
                 cmd = re.sub(br'\$(\d+|\$)', _checkvar, self.definition[1:])
                 cmd = aliasinterpolate(self.name, args, cmd)
                 return ui.system(cmd, environ=env,
                                  blockedtag='alias_%s' % self.name)
             self.fn = fn
             return
 
         try:
             args = pycompat.shlexsplit(self.definition)
         except ValueError as inst:
             self.badalias = (_("error in definition for alias '%s': %s")
                              % (self.name, 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(zip(*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, 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 = pycompat.maplist(util.expandpath, self.givenargs)
         return aliasargs(self.fn, args)
 
     def __getattr__(self, name):
         adefaults = {r'norepo': True, r'cmdtype': unrecoverablewrite,
                      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, name, definition, cmdtable, source):
         self.name = name
         self.definition = definition
         self.cmdtable = cmdtable.copy()
         self.source = source
 
     @util.propertycache
     def _aliasdef(self):
         return cmdalias(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'):
         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(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, 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, 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 _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 = str(bool(options[opt]))
                 if pycompat.ispy3:
                     val = val.encode('ascii')
                 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 util.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 = getattr(mod, 'testedwith', '')
             if pycompat.ispy3 and isinstance(testedwith, str):
                 testedwith = testedwith.encode(u'utf-8')
             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([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')
         if bugtracker is None:
             bugtracker = _("https://mercurial-scm.org/wiki/BugTracker")
         warning = (_("** unknown exception encountered, "
                      "please report by visiting\n** ") + bugtracker + '\n')
     if pycompat.ispy3:
         sysversion = sys.version.encode(u'utf-8')
     else:
         sysversion = sys.version
     sysversion = sysversion.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, traceback.format_exc())
     ui.warn(warning)
     return False  # re-raise the exception

tests/test-basic.t

@@ -1,100 +1,92 b''
 Create a repository:
 
   $ hg config
   devel.all-warnings=true
   devel.default-date=0 0
   extensions.fsmonitor= (fsmonitor !)
   largefiles.usercache=$TESTTMP/.cache/largefiles
   lfs.usercache=$TESTTMP/.cache/lfs
   ui.slash=True
   ui.interactive=False
   ui.mergemarkers=detailed
   ui.promptecho=True
   web.address=localhost
   web\.ipv6=(?:True|False) (re)
   $ hg init t
   $ cd t
 
 Prepare a changeset:
 
   $ echo a > a
   $ hg add a
 
   $ hg status
   A a
 
 Writes to stdio succeed and fail appropriately
 
 #if devfull
   $ hg status 2>/dev/full
   A a
 
   $ hg status >/dev/full
   abort: No space left on device
   [255]
 #endif
 
-#if devfull no-chg
-  $ hg status >/dev/full 2>&1
-  [1]
-
-  $ hg status ENOENT 2>/dev/full
-  [1]
-#endif
-
-#if devfull chg
+#if devfull
   $ hg status >/dev/full 2>&1
   [255]
 
   $ hg status ENOENT 2>/dev/full
   [255]
 #endif
 
   $ hg commit -m test
 
 This command is ancient:
 
   $ hg history
   changeset:   0:acb14030fe0a
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     test
   
 
 Verify that updating to revision 0 via commands.update() works properly
 
   $ cat <<EOF > update_to_rev0.py
   > from mercurial import ui, hg, commands
   > myui = ui.ui.load()
   > repo = hg.repository(myui, path='.')
   > commands.update(myui, repo, rev=0)
   > EOF
   $ hg up null
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ $PYTHON ./update_to_rev0.py
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg identify -n
   0
 
 
 Poke around at hashes:
 
   $ hg manifest --debug
   b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   a
 
   $ hg cat a
   a
 
 Verify should succeed:
 
   $ hg verify
   checking changesets
   checking manifests
   crosschecking files in changesets and manifests
   checking files
   1 files, 1 changesets, 1 total revisions
 
 At the end...
 
   $ cd ..