pager: set some environment variables if they're not set

Git did this already [1] [2]. We want this behavior too [3].

This provides a better default user experience (like, supporting colors) if
users have things like "PAGER=less" set, which is not uncommon.

The environment variables are provided by a method so extensions can
override them on demand.

[1]: https://github.com/git/git/blob/6a5ff7acb5965718cc7016c0ab6c601454fd7cde/pager.c#L87
[2]: https://github.com/git/git/blob/6a5ff7acb5965718cc7016c0ab6c601454fd7cde/Makefile#L1545
[3]: https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-March/094780.html

mercurial/chgserver.py

@@ -1,578 +1,578
 # chgserver.py - command server extension for cHg
 #
 # Copyright 2011 Yuya Nishihara <[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.
 
 """command server extension for cHg
 
 'S' channel (read/write)
     propagate ui.system() request to client
 
 'attachio' command
     attach client's stdio passed by sendmsg()
 
 'chdir' command
     change current directory
 
 'setenv' command
     replace os.environ completely
 
 'setumask' command
     set umask
 
 'validate' command
     reload the config and check if the server is up to date
 
 Config
 ------
 
 ::
 
   [chgserver]
   # how long (in seconds) should an idle chg server exit
   idletimeout = 3600
 
   # whether to skip config or env change checks
   skiphash = False
 """
 
 from __future__ import absolute_import
 
 import hashlib
 import inspect
 import os
 import re
 import struct
 import time
 
 from .i18n import _
 
 from . import (
     commandserver,
     encoding,
     error,
     extensions,
     osutil,
     pycompat,
     util,
 )
 
 _log = commandserver.log
 
 def _hashlist(items):
     """return sha1 hexdigest for a list"""
     return hashlib.sha1(str(items)).hexdigest()
 
 # sensitive config sections affecting confighash
 _configsections = [
     'alias',  # affects global state commands.table
     'extdiff',  # uisetup will register new commands
     'extensions',
 ]
 
 # sensitive environment variables affecting confighash
 _envre = re.compile(r'''\A(?:
                     CHGHG
                     |HG(?:[A-Z].*)?
                     |LANG(?:UAGE)?
                     |LC_.*
                     |LD_.*
                     |PATH
                     |PYTHON.*
                     |TERM(?:INFO)?
                     |TZ
                     )\Z''', re.X)
 
 def _confighash(ui):
     """return a quick hash for detecting config/env changes
 
     confighash is the hash of sensitive config items and environment variables.
 
     for chgserver, it is designed that once confighash changes, the server is
     not qualified to serve its client and should redirect the client to a new
     server. different from mtimehash, confighash change will not mark the
     server outdated and exit since the user can have different configs at the
     same time.
     """
     sectionitems = []
     for section in _configsections:
         sectionitems.append(ui.configitems(section))
     sectionhash = _hashlist(sectionitems)
     envitems = [(k, v) for k, v in encoding.environ.iteritems()
                 if _envre.match(k)]
     envhash = _hashlist(sorted(envitems))
     return sectionhash[:6] + envhash[:6]
 
 def _getmtimepaths(ui):
     """get a list of paths that should be checked to detect change
 
     The list will include:
     - extensions (will not cover all files for complex extensions)
     - mercurial/__version__.py
     - python binary
     """
     modules = [m for n, m in extensions.extensions(ui)]
     try:
         from . import __version__
         modules.append(__version__)
     except ImportError:
         pass
     files = [pycompat.sysexecutable]
     for m in modules:
         try:
             files.append(inspect.getabsfile(m))
         except TypeError:
             pass
     return sorted(set(files))
 
 def _mtimehash(paths):
     """return a quick hash for detecting file changes
 
     mtimehash calls stat on given paths and calculate a hash based on size and
     mtime of each file. mtimehash does not read file content because reading is
     expensive. therefore it's not 100% reliable for detecting content changes.
     it's possible to return different hashes for same file contents.
     it's also possible to return a same hash for different file contents for
     some carefully crafted situation.
 
     for chgserver, it is designed that once mtimehash changes, the server is
     considered outdated immediately and should no longer provide service.
 
     mtimehash is not included in confighash because we only know the paths of
     extensions after importing them (there is imp.find_module but that faces
     race conditions). We need to calculate confighash without importing.
     """
     def trystat(path):
         try:
             st = os.stat(path)
             return (st.st_mtime, st.st_size)
         except OSError:
             # could be ENOENT, EPERM etc. not fatal in any case
             pass
     return _hashlist(map(trystat, paths))[:12]
 
 class hashstate(object):
     """a structure storing confighash, mtimehash, paths used for mtimehash"""
     def __init__(self, confighash, mtimehash, mtimepaths):
         self.confighash = confighash
         self.mtimehash = mtimehash
         self.mtimepaths = mtimepaths
 
     @staticmethod
     def fromui(ui, mtimepaths=None):
         if mtimepaths is None:
             mtimepaths = _getmtimepaths(ui)
         confighash = _confighash(ui)
         mtimehash = _mtimehash(mtimepaths)
         _log('confighash = %s mtimehash = %s\n' % (confighash, mtimehash))
         return hashstate(confighash, mtimehash, mtimepaths)
 
 def _newchgui(srcui, csystem, attachio):
     class chgui(srcui.__class__):
         def __init__(self, src=None):
             super(chgui, self).__init__(src)
             if src:
                 self._csystem = getattr(src, '_csystem', csystem)
             else:
                 self._csystem = csystem
 
         def _runsystem(self, cmd, environ, cwd, out):
             # fallback to the original system method if the output needs to be
             # captured (to self._buffers), or the output stream is not stdout
             # (e.g. stderr, cStringIO), because the chg client is not aware of
             # these situations and will behave differently (write to stdout).
             if (out is not self.fout
                 or not util.safehasattr(self.fout, 'fileno')
                 or self.fout.fileno() != util.stdout.fileno()):
                 return util.system(cmd, environ=environ, cwd=cwd, out=out)
             self.flush()
             return self._csystem(cmd, util.shellenviron(environ), cwd)
 
-        def _runpager(self, cmd):
-            self._csystem(cmd, util.shellenviron(), type='pager',
+        def _runpager(self, cmd, env=None):
+            self._csystem(cmd, util.shellenviron(env), type='pager',
                           cmdtable={'attachio': attachio})
             return True
 
     return chgui(srcui)
 
 def _loadnewui(srcui, args):
     from . import dispatch  # avoid cycle
 
     newui = srcui.__class__.load()
     for a in ['fin', 'fout', 'ferr', 'environ']:
         setattr(newui, a, getattr(srcui, a))
     if util.safehasattr(srcui, '_csystem'):
         newui._csystem = srcui._csystem
 
     # command line args
     args = args[:]
     dispatch._parseconfig(newui, dispatch._earlygetopt(['--config'], args))
 
     # stolen from tortoisehg.util.copydynamicconfig()
     for section, name, value in srcui.walkconfig():
         source = srcui.configsource(section, name)
         if ':' in source or source == '--config' or source.startswith('$'):
             # path:line or command line, or environ
             continue
         newui.setconfig(section, name, value, source)
 
     # load wd and repo config, copied from dispatch.py
     cwds = dispatch._earlygetopt(['--cwd'], args)
     cwd = cwds and os.path.realpath(cwds[-1]) or None
     rpath = dispatch._earlygetopt(["-R", "--repository", "--repo"], args)
     path, newlui = dispatch._getlocal(newui, rpath, wd=cwd)
 
     return (newui, newlui)
 
 class channeledsystem(object):
     """Propagate ui.system() request in the following format:
 
     payload length (unsigned int),
     type, '\0',
     cmd, '\0',
     cwd, '\0',
     envkey, '=', val, '\0',
     ...
     envkey, '=', val
 
     if type == 'system', waits for:
 
     exitcode length (unsigned int),
     exitcode (int)
 
     if type == 'pager', repetitively waits for a command name ending with '\n'
     and executes it defined by cmdtable, or exits the loop if the command name
     is empty.
     """
     def __init__(self, in_, out, channel):
         self.in_ = in_
         self.out = out
         self.channel = channel
 
     def __call__(self, cmd, environ, cwd=None, type='system', cmdtable=None):
         args = [type, util.quotecommand(cmd), os.path.abspath(cwd or '.')]
         args.extend('%s=%s' % (k, v) for k, v in environ.iteritems())
         data = '\0'.join(args)
         self.out.write(struct.pack('>cI', self.channel, len(data)))
         self.out.write(data)
         self.out.flush()
 
         if type == 'system':
             length = self.in_.read(4)
             length, = struct.unpack('>I', length)
             if length != 4:
                 raise error.Abort(_('invalid response'))
             rc, = struct.unpack('>i', self.in_.read(4))
             return rc
         elif type == 'pager':
             while True:
                 cmd = self.in_.readline()[:-1]
                 if not cmd:
                     break
                 if cmdtable and cmd in cmdtable:
                     _log('pager subcommand: %s' % cmd)
                     cmdtable[cmd]()
                 else:
                     raise error.Abort(_('unexpected command: %s') % cmd)
         else:
             raise error.ProgrammingError('invalid S channel type: %s' % type)
 
 _iochannels = [
     # server.ch, ui.fp, mode
     ('cin', 'fin', pycompat.sysstr('rb')),
     ('cout', 'fout', pycompat.sysstr('wb')),
     ('cerr', 'ferr', pycompat.sysstr('wb')),
 ]
 
 class chgcmdserver(commandserver.server):
     def __init__(self, ui, repo, fin, fout, sock, hashstate, baseaddress):
         super(chgcmdserver, self).__init__(
             _newchgui(ui, channeledsystem(fin, fout, 'S'), self.attachio),
             repo, fin, fout)
         self.clientsock = sock
         self._oldios = []  # original (self.ch, ui.fp, fd) before "attachio"
         self.hashstate = hashstate
         self.baseaddress = baseaddress
         if hashstate is not None:
             self.capabilities = self.capabilities.copy()
             self.capabilities['validate'] = chgcmdserver.validate
 
     def cleanup(self):
         super(chgcmdserver, self).cleanup()
         # dispatch._runcatch() does not flush outputs if exception is not
         # handled by dispatch._dispatch()
         self.ui.flush()
         self._restoreio()
 
     def attachio(self):
         """Attach to client's stdio passed via unix domain socket; all
         channels except cresult will no longer be used
         """
         # tell client to sendmsg() with 1-byte payload, which makes it
         # distinctive from "attachio\n" command consumed by client.read()
         self.clientsock.sendall(struct.pack('>cI', 'I', 1))
         clientfds = osutil.recvfds(self.clientsock.fileno())
         _log('received fds: %r\n' % clientfds)
 
         ui = self.ui
         ui.flush()
         first = self._saveio()
         for fd, (cn, fn, mode) in zip(clientfds, _iochannels):
             assert fd > 0
             fp = getattr(ui, fn)
             os.dup2(fd, fp.fileno())
             os.close(fd)
             if not first:
                 continue
             # reset buffering mode when client is first attached. as we want
             # to see output immediately on pager, the mode stays unchanged
             # when client re-attached. ferr is unchanged because it should
             # be unbuffered no matter if it is a tty or not.
             if fn == 'ferr':
                 newfp = fp
             else:
                 # make it line buffered explicitly because the default is
                 # decided on first write(), where fout could be a pager.
                 if fp.isatty():
                     bufsize = 1  # line buffered
                 else:
                     bufsize = -1  # system default
                 newfp = os.fdopen(fp.fileno(), mode, bufsize)
                 setattr(ui, fn, newfp)
             setattr(self, cn, newfp)
 
         self.cresult.write(struct.pack('>i', len(clientfds)))
 
     def _saveio(self):
         if self._oldios:
             return False
         ui = self.ui
         for cn, fn, _mode in _iochannels:
             ch = getattr(self, cn)
             fp = getattr(ui, fn)
             fd = os.dup(fp.fileno())
             self._oldios.append((ch, fp, fd))
         return True
 
     def _restoreio(self):
         ui = self.ui
         for (ch, fp, fd), (cn, fn, _mode) in zip(self._oldios, _iochannels):
             newfp = getattr(ui, fn)
             # close newfp while it's associated with client; otherwise it
             # would be closed when newfp is deleted
             if newfp is not fp:
                 newfp.close()
             # restore original fd: fp is open again
             os.dup2(fd, fp.fileno())
             os.close(fd)
             setattr(self, cn, ch)
             setattr(ui, fn, fp)
         del self._oldios[:]
 
     def validate(self):
         """Reload the config and check if the server is up to date
 
         Read a list of '\0' separated arguments.
         Write a non-empty list of '\0' separated instruction strings or '\0'
         if the list is empty.
         An instruction string could be either:
             - "unlink $path", the client should unlink the path to stop the
               outdated server.
             - "redirect $path", the client should attempt to connect to $path
               first. If it does not work, start a new server. It implies
               "reconnect".
             - "exit $n", the client should exit directly with code n.
               This may happen if we cannot parse the config.
             - "reconnect", the client should close the connection and
               reconnect.
         If neither "reconnect" nor "redirect" is included in the instruction
         list, the client can continue with this server after completing all
         the instructions.
         """
         from . import dispatch  # avoid cycle
 
         args = self._readlist()
         try:
             self.ui, lui = _loadnewui(self.ui, args)
         except error.ParseError as inst:
             dispatch._formatparse(self.ui.warn, inst)
             self.ui.flush()
             self.cresult.write('exit 255')
             return
         newhash = hashstate.fromui(lui, self.hashstate.mtimepaths)
         insts = []
         if newhash.mtimehash != self.hashstate.mtimehash:
             addr = _hashaddress(self.baseaddress, self.hashstate.confighash)
             insts.append('unlink %s' % addr)
             # mtimehash is empty if one or more extensions fail to load.
             # to be compatible with hg, still serve the client this time.
             if self.hashstate.mtimehash:
                 insts.append('reconnect')
         if newhash.confighash != self.hashstate.confighash:
             addr = _hashaddress(self.baseaddress, newhash.confighash)
             insts.append('redirect %s' % addr)
         _log('validate: %s\n' % insts)
         self.cresult.write('\0'.join(insts) or '\0')
 
     def chdir(self):
         """Change current directory
 
         Note that the behavior of --cwd option is bit different from this.
         It does not affect --config parameter.
         """
         path = self._readstr()
         if not path:
             return
         _log('chdir to %r\n' % path)
         os.chdir(path)
 
     def setumask(self):
         """Change umask"""
         mask = struct.unpack('>I', self._read(4))[0]
         _log('setumask %r\n' % mask)
         os.umask(mask)
 
     def runcommand(self):
         return super(chgcmdserver, self).runcommand()
 
     def setenv(self):
         """Clear and update os.environ
 
         Note that not all variables can make an effect on the running process.
         """
         l = self._readlist()
         try:
             newenv = dict(s.split('=', 1) for s in l)
         except ValueError:
             raise ValueError('unexpected value in setenv request')
         _log('setenv: %r\n' % sorted(newenv.keys()))
         encoding.environ.clear()
         encoding.environ.update(newenv)
 
     capabilities = commandserver.server.capabilities.copy()
     capabilities.update({'attachio': attachio,
                          'chdir': chdir,
                          'runcommand': runcommand,
                          'setenv': setenv,
                          'setumask': setumask})
 
     if util.safehasattr(osutil, 'setprocname'):
         def setprocname(self):
             """Change process title"""
             name = self._readstr()
             _log('setprocname: %r\n' % name)
             osutil.setprocname(name)
         capabilities['setprocname'] = setprocname
 
 def _tempaddress(address):
     return '%s.%d.tmp' % (address, os.getpid())
 
 def _hashaddress(address, hashstr):
     # if the basename of address contains '.', use only the left part. this
     # makes it possible for the client to pass 'server.tmp$PID' and follow by
     # an atomic rename to avoid locking when spawning new servers.
     dirname, basename = os.path.split(address)
     basename = basename.split('.', 1)[0]
     return '%s-%s' % (os.path.join(dirname, basename), hashstr)
 
 class chgunixservicehandler(object):
     """Set of operations for chg services"""
 
     pollinterval = 1  # [sec]
 
     def __init__(self, ui):
         self.ui = ui
         self._idletimeout = ui.configint('chgserver', 'idletimeout', 3600)
         self._lastactive = time.time()
 
     def bindsocket(self, sock, address):
         self._inithashstate(address)
         self._checkextensions()
         self._bind(sock)
         self._createsymlink()
 
     def _inithashstate(self, address):
         self._baseaddress = address
         if self.ui.configbool('chgserver', 'skiphash', False):
             self._hashstate = None
             self._realaddress = address
             return
         self._hashstate = hashstate.fromui(self.ui)
         self._realaddress = _hashaddress(address, self._hashstate.confighash)
 
     def _checkextensions(self):
         if not self._hashstate:
             return
         if extensions.notloaded():
             # one or more extensions failed to load. mtimehash becomes
             # meaningless because we do not know the paths of those extensions.
             # set mtimehash to an illegal hash value to invalidate the server.
             self._hashstate.mtimehash = ''
 
     def _bind(self, sock):
         # use a unique temp address so we can stat the file and do ownership
         # check later
         tempaddress = _tempaddress(self._realaddress)
         util.bindunixsocket(sock, tempaddress)
         self._socketstat = os.stat(tempaddress)
         # rename will replace the old socket file if exists atomically. the
         # old server will detect ownership change and exit.
         util.rename(tempaddress, self._realaddress)
 
     def _createsymlink(self):
         if self._baseaddress == self._realaddress:
             return
         tempaddress = _tempaddress(self._baseaddress)
         os.symlink(os.path.basename(self._realaddress), tempaddress)
         util.rename(tempaddress, self._baseaddress)
 
     def _issocketowner(self):
         try:
             stat = os.stat(self._realaddress)
             return (stat.st_ino == self._socketstat.st_ino and
                     stat.st_mtime == self._socketstat.st_mtime)
         except OSError:
             return False
 
     def unlinksocket(self, address):
         if not self._issocketowner():
             return
         # it is possible to have a race condition here that we may
         # remove another server's socket file. but that's okay
         # since that server will detect and exit automatically and
         # the client will start a new server on demand.
         util.tryunlink(self._realaddress)
 
     def printbanner(self, address):
         # no "listening at" message should be printed to simulate hg behavior
         pass
 
     def shouldexit(self):
         if not self._issocketowner():
             self.ui.debug('%s is not owned, exiting.\n' % self._realaddress)
             return True
         if time.time() - self._lastactive > self._idletimeout:
             self.ui.debug('being idle too long. exiting.\n')
             return True
         return False
 
     def newconnection(self):
         self._lastactive = time.time()
 
     def createcmdserver(self, repo, conn, fin, fout):
         return chgcmdserver(self.ui, repo, fin, fout, conn,
                             self._hashstate, self._baseaddress)
 
 def chgunixservice(ui, repo, opts):
     # CHGINTERNALMARK is temporarily set by chg client to detect if chg will
     # start another chg. drop it to avoid possible side effects.
     if 'CHGINTERNALMARK' in encoding.environ:
         del encoding.environ['CHGINTERNALMARK']
 
     if repo:
         # one chgserver can serve multiple repos. drop repo information
         ui.setconfig('bundle', 'mainreporoot', '', 'repo')
     h = chgunixservicehandler(ui)
     return commandserver.unixforkingservice(ui, repo=None, opts=opts, handler=h)

mercurial/rcutil.py

@@ -1,92 +1,98
 # rcutil.py - utilities about config paths, special config sections etc.
 #
 #  Copyright Mercurial Contributors
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 import os
 
 from . import (
     encoding,
     osutil,
     pycompat,
     util,
 )
 
 if pycompat.osname == 'nt':
     from . import scmwindows as scmplatform
 else:
     from . import scmposix as scmplatform
 
 systemrcpath = scmplatform.systemrcpath
 userrcpath = scmplatform.userrcpath
 
 def _expandrcpath(path):
     '''path could be a file or a directory. return a list of file paths'''
     p = util.expandpath(path)
     if os.path.isdir(p):
         join = os.path.join
         return [join(p, f) for f, k in osutil.listdir(p) if f.endswith('.rc')]
     return [p]
 
 def envrcitems(env=None):
     '''Return [(section, name, value, source)] config items.
 
     The config items are extracted from environment variables specified by env,
     used to override systemrc, but not userrc.
 
     If env is not provided, encoding.environ will be used.
     '''
     if env is None:
         env = encoding.environ
     checklist = [
         ('EDITOR', 'ui', 'editor'),
         ('VISUAL', 'ui', 'editor'),
         ('PAGER', 'pager', 'pager'),
     ]
     result = []
     for envname, section, configname in checklist:
         if envname not in env:
             continue
         result.append((section, configname, env[envname], '$%s' % envname))
     return result
 
 def defaultrcpath():
     '''return rc paths in default.d'''
     path = []
     defaultpath = os.path.join(util.datapath, 'default.d')
     if os.path.isdir(defaultpath):
         path = _expandrcpath(defaultpath)
     return path
 
 def rccomponents():
     '''return an ordered [(type, obj)] about where to load configs.
 
     respect $HGRCPATH. if $HGRCPATH is empty, only .hg/hgrc of current repo is
     used. if $HGRCPATH is not set, the platform default will be used.
 
     if a directory is provided, *.rc files under it will be used.
 
     type could be either 'path' or 'items', if type is 'path', obj is a string,
     and is the config file path. if type is 'items', obj is a list of (section,
     name, value, source) that should fill the config directly.
     '''
     envrc = ('items', envrcitems())
 
     if 'HGRCPATH' in encoding.environ:
         # assume HGRCPATH is all about user configs so environments can be
         # overridden.
         _rccomponents = [envrc]
         for p in encoding.environ['HGRCPATH'].split(pycompat.ospathsep):
             if not p:
                 continue
             _rccomponents.extend(('path', p) for p in _expandrcpath(p))
     else:
         normpaths = lambda paths: [('path', os.path.normpath(p)) for p in paths]
         _rccomponents = normpaths(defaultrcpath() + systemrcpath())
         _rccomponents.append(envrc)
         _rccomponents.extend(normpaths(userrcpath()))
     return _rccomponents
+
+def defaultpagerenv():
+    '''return a dict of default environment variables and their values,
+    intended to be set before starting a pager.
+    '''
+    return {'LESS': 'FRX', 'LV': '-c'}

mercurial/ui.py

@@ -1,1654 +1,1660
 # ui.py - user interface bits 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
 
 import atexit
 import collections
 import contextlib
 import errno
 import getpass
 import inspect
 import os
 import re
 import signal
 import socket
 import subprocess
 import sys
 import tempfile
 import traceback
 
 from .i18n import _
 from .node import hex
 
 from . import (
     color,
     config,
     encoding,
     error,
     formatter,
     progress,
     pycompat,
     rcutil,
     scmutil,
     util,
 )
 
 urlreq = util.urlreq
 
 # for use with str.translate(None, _keepalnum), to keep just alphanumerics
 _keepalnum = ''.join(c for c in map(pycompat.bytechr, range(256))
                      if not c.isalnum())
 
 samplehgrcs = {
     'user':
 """# example user config (see 'hg help config' for more info)
 [ui]
 # name and email, e.g.
 # username = Jane Doe <[e-mail]>
 username =
 
 # uncomment to colorize command output
 # color = auto
 
 [extensions]
 # uncomment these lines to enable some popular extensions
 # (see 'hg help extensions' for more info)
 #
 # pager =""",
 
     'cloned':
 """# example repository config (see 'hg help config' for more info)
 [paths]
 default = %s
 
 # path aliases to other clones of this repo in URLs or filesystem paths
 # (see 'hg help config.paths' for more info)
 #
 # default:pushurl = ssh://[e-mail]/hg/jdoes-fork
 # my-fork         = ssh://[e-mail]/hg/jdoes-fork
 # my-clone        = /home/jdoe/jdoes-clone
 
 [ui]
 # name and email (local to this repository, optional), e.g.
 # username = Jane Doe <[e-mail]>
 """,
 
     'local':
 """# example repository config (see 'hg help config' for more info)
 [paths]
 # path aliases to other clones of this repo in URLs or filesystem paths
 # (see 'hg help config.paths' for more info)
 #
 # default         = http://example.com/hg/example-repo
 # default:pushurl = ssh://[e-mail]/hg/jdoes-fork
 # my-fork         = ssh://[e-mail]/hg/jdoes-fork
 # my-clone        = /home/jdoe/jdoes-clone
 
 [ui]
 # name and email (local to this repository, optional), e.g.
 # username = Jane Doe <[e-mail]>
 """,
 
     'global':
 """# example system-wide hg config (see 'hg help config' for more info)
 
 [ui]
 # uncomment to colorize command output
 # color = auto
 
 [extensions]
 # uncomment these lines to enable some popular extensions
 # (see 'hg help extensions' for more info)
 #
 # blackbox =
 # pager =""",
 }
 
 
 class httppasswordmgrdbproxy(object):
     """Delays loading urllib2 until it's needed."""
     def __init__(self):
         self._mgr = None
 
     def _get_mgr(self):
         if self._mgr is None:
             self._mgr = urlreq.httppasswordmgrwithdefaultrealm()
         return self._mgr
 
     def add_password(self, *args, **kwargs):
         return self._get_mgr().add_password(*args, **kwargs)
 
     def find_user_password(self, *args, **kwargs):
         return self._get_mgr().find_user_password(*args, **kwargs)
 
 def _catchterm(*args):
     raise error.SignalInterrupt
 
 class ui(object):
     def __init__(self, src=None):
         """Create a fresh new ui object if no src given
 
         Use uimod.ui.load() to create a ui which knows global and user configs.
         In most cases, you should use ui.copy() to create a copy of an existing
         ui object.
         """
         # _buffers: used for temporary capture of output
         self._buffers = []
         # 3-tuple describing how each buffer in the stack behaves.
         # Values are (capture stderr, capture subprocesses, apply labels).
         self._bufferstates = []
         # When a buffer is active, defines whether we are expanding labels.
         # This exists to prevent an extra list lookup.
         self._bufferapplylabels = None
         self.quiet = self.verbose = self.debugflag = self.tracebackflag = False
         self._reportuntrusted = True
         self._ocfg = config.config() # overlay
         self._tcfg = config.config() # trusted
         self._ucfg = config.config() # untrusted
         self._trustusers = set()
         self._trustgroups = set()
         self.callhooks = True
         # Insecure server connections requested.
         self.insecureconnections = False
         # Blocked time
         self.logblockedtimes = False
         # color mode: see mercurial/color.py for possible value
         self._colormode = None
         self._terminfoparams = {}
         self._styles = {}
 
         if src:
             self.fout = src.fout
             self.ferr = src.ferr
             self.fin = src.fin
             self.pageractive = src.pageractive
             self._disablepager = src._disablepager
 
             self._tcfg = src._tcfg.copy()
             self._ucfg = src._ucfg.copy()
             self._ocfg = src._ocfg.copy()
             self._trustusers = src._trustusers.copy()
             self._trustgroups = src._trustgroups.copy()
             self.environ = src.environ
             self.callhooks = src.callhooks
             self.insecureconnections = src.insecureconnections
             self._colormode = src._colormode
             self._terminfoparams = src._terminfoparams.copy()
             self._styles = src._styles.copy()
 
             self.fixconfig()
 
             self.httppasswordmgrdb = src.httppasswordmgrdb
             self._blockedtimes = src._blockedtimes
         else:
             self.fout = util.stdout
             self.ferr = util.stderr
             self.fin = util.stdin
             self.pageractive = False
             self._disablepager = False
 
             # shared read-only environment
             self.environ = encoding.environ
 
             self.httppasswordmgrdb = httppasswordmgrdbproxy()
             self._blockedtimes = collections.defaultdict(int)
 
         allowed = self.configlist('experimental', 'exportableenviron')
         if '*' in allowed:
             self._exportableenviron = self.environ
         else:
             self._exportableenviron = {}
             for k in allowed:
                 if k in self.environ:
                     self._exportableenviron[k] = self.environ[k]
 
     @classmethod
     def load(cls):
         """Create a ui and load global and user configs"""
         u = cls()
         # we always trust global config files and environment variables
         for t, f in rcutil.rccomponents():
             if t == 'path':
                 u.readconfig(f, trust=True)
             elif t == 'items':
                 sections = set()
                 for section, name, value, source in f:
                     # do not set u._ocfg
                     # XXX clean this up once immutable config object is a thing
                     u._tcfg.set(section, name, value, source)
                     u._ucfg.set(section, name, value, source)
                     sections.add(section)
                 for section in sections:
                     u.fixconfig(section=section)
             else:
                 raise error.ProgrammingError('unknown rctype: %s' % t)
         return u
 
     def copy(self):
         return self.__class__(self)
 
     def resetstate(self):
         """Clear internal state that shouldn't persist across commands"""
         if self._progbar:
             self._progbar.resetstate()  # reset last-print time of progress bar
         self.httppasswordmgrdb = httppasswordmgrdbproxy()
 
     @contextlib.contextmanager
     def timeblockedsection(self, key):
         # this is open-coded below - search for timeblockedsection to find them
         starttime = util.timer()
         try:
             yield
         finally:
             self._blockedtimes[key + '_blocked'] += \
                 (util.timer() - starttime) * 1000
 
     def formatter(self, topic, opts):
         return formatter.formatter(self, topic, opts)
 
     def _trusted(self, fp, f):
         st = util.fstat(fp)
         if util.isowner(st):
             return True
 
         tusers, tgroups = self._trustusers, self._trustgroups
         if '*' in tusers or '*' in tgroups:
             return True
 
         user = util.username(st.st_uid)
         group = util.groupname(st.st_gid)
         if user in tusers or group in tgroups or user == util.username():
             return True
 
         if self._reportuntrusted:
             self.warn(_('not trusting file %s from untrusted '
                         'user %s, group %s\n') % (f, user, group))
         return False
 
     def readconfig(self, filename, root=None, trust=False,
                    sections=None, remap=None):
         try:
             fp = open(filename, u'rb')
         except IOError:
             if not sections: # ignore unless we were looking for something
                 return
             raise
 
         cfg = config.config()
         trusted = sections or trust or self._trusted(fp, filename)
 
         try:
             cfg.read(filename, fp, sections=sections, remap=remap)
             fp.close()
         except error.ConfigError as inst:
             if trusted:
                 raise
             self.warn(_("ignored: %s\n") % str(inst))
 
         if self.plain():
             for k in ('debug', 'fallbackencoding', 'quiet', 'slash',
                       'logtemplate', 'statuscopies', 'style',
                       'traceback', 'verbose'):
                 if k in cfg['ui']:
                     del cfg['ui'][k]
             for k, v in cfg.items('defaults'):
                 del cfg['defaults'][k]
             for k, v in cfg.items('commands'):
                 del cfg['commands'][k]
         # Don't remove aliases from the configuration if in the exceptionlist
         if self.plain('alias'):
             for k, v in cfg.items('alias'):
                 del cfg['alias'][k]
         if self.plain('revsetalias'):
             for k, v in cfg.items('revsetalias'):
                 del cfg['revsetalias'][k]
         if self.plain('templatealias'):
             for k, v in cfg.items('templatealias'):
                 del cfg['templatealias'][k]
 
         if trusted:
             self._tcfg.update(cfg)
             self._tcfg.update(self._ocfg)
         self._ucfg.update(cfg)
         self._ucfg.update(self._ocfg)
 
         if root is None:
             root = os.path.expanduser('~')
         self.fixconfig(root=root)
 
     def fixconfig(self, root=None, section=None):
         if section in (None, 'paths'):
             # expand vars and ~
             # translate paths relative to root (or home) into absolute paths
             root = root or pycompat.getcwd()
             for c in self._tcfg, self._ucfg, self._ocfg:
                 for n, p in c.items('paths'):
                     # Ignore sub-options.
                     if ':' in n:
                         continue
                     if not p:
                         continue
                     if '%%' in p:
                         s = self.configsource('paths', n) or 'none'
                         self.warn(_("(deprecated '%%' in path %s=%s from %s)\n")
                                   % (n, p, s))
                         p = p.replace('%%', '%')
                     p = util.expandpath(p)
                     if not util.hasscheme(p) and not os.path.isabs(p):
                         p = os.path.normpath(os.path.join(root, p))
                     c.set("paths", n, p)
 
         if section in (None, 'ui'):
             # update ui options
             self.debugflag = self.configbool('ui', 'debug')
             self.verbose = self.debugflag or self.configbool('ui', 'verbose')
             self.quiet = not self.debugflag and self.configbool('ui', 'quiet')
             if self.verbose and self.quiet:
                 self.quiet = self.verbose = False
             self._reportuntrusted = self.debugflag or self.configbool("ui",
                 "report_untrusted", True)
             self.tracebackflag = self.configbool('ui', 'traceback', False)
             self.logblockedtimes = self.configbool('ui', 'logblockedtimes')
 
         if section in (None, 'trusted'):
             # update trust information
             self._trustusers.update(self.configlist('trusted', 'users'))
             self._trustgroups.update(self.configlist('trusted', 'groups'))
 
     def backupconfig(self, section, item):
         return (self._ocfg.backup(section, item),
                 self._tcfg.backup(section, item),
                 self._ucfg.backup(section, item),)
     def restoreconfig(self, data):
         self._ocfg.restore(data[0])
         self._tcfg.restore(data[1])
         self._ucfg.restore(data[2])
 
     def setconfig(self, section, name, value, source=''):
         for cfg in (self._ocfg, self._tcfg, self._ucfg):
             cfg.set(section, name, value, source)
         self.fixconfig(section=section)
 
     def _data(self, untrusted):
         return untrusted and self._ucfg or self._tcfg
 
     def configsource(self, section, name, untrusted=False):
         return self._data(untrusted).source(section, name)
 
     def config(self, section, name, default=None, untrusted=False):
         if isinstance(name, list):
             alternates = name
         else:
             alternates = [name]
 
         for n in alternates:
             value = self._data(untrusted).get(section, n, None)
             if value is not None:
                 name = n
                 break
         else:
             value = default
 
         if self.debugflag and not untrusted and self._reportuntrusted:
             for n in alternates:
                 uvalue = self._ucfg.get(section, n)
                 if uvalue is not None and uvalue != value:
                     self.debug("ignoring untrusted configuration option "
                                "%s.%s = %s\n" % (section, n, uvalue))
         return value
 
     def configsuboptions(self, section, name, default=None, untrusted=False):
         """Get a config option and all sub-options.
 
         Some config options have sub-options that are declared with the
         format "key:opt = value". This method is used to return the main
         option and all its declared sub-options.
 
         Returns a 2-tuple of ``(option, sub-options)``, where `sub-options``
         is a dict of defined sub-options where keys and values are strings.
         """
         data = self._data(untrusted)
         main = data.get(section, name, default)
         if self.debugflag and not untrusted and self._reportuntrusted:
             uvalue = self._ucfg.get(section, name)
             if uvalue is not None and uvalue != main:
                 self.debug('ignoring untrusted configuration option '
                            '%s.%s = %s\n' % (section, name, uvalue))
 
         sub = {}
         prefix = '%s:' % name
         for k, v in data.items(section):
             if k.startswith(prefix):
                 sub[k[len(prefix):]] = v
 
         if self.debugflag and not untrusted and self._reportuntrusted:
             for k, v in sub.items():
                 uvalue = self._ucfg.get(section, '%s:%s' % (name, k))
                 if uvalue is not None and uvalue != v:
                     self.debug('ignoring untrusted configuration option '
                                '%s:%s.%s = %s\n' % (section, name, k, uvalue))
 
         return main, sub
 
     def configpath(self, section, name, default=None, untrusted=False):
         'get a path config item, expanded relative to repo root or config file'
         v = self.config(section, name, default, untrusted)
         if v is None:
             return None
         if not os.path.isabs(v) or "://" not in v:
             src = self.configsource(section, name, untrusted)
             if ':' in src:
                 base = os.path.dirname(src.rsplit(':')[0])
                 v = os.path.join(base, os.path.expanduser(v))
         return v
 
     def configbool(self, section, name, default=False, untrusted=False):
         """parse a configuration element as a boolean
 
         >>> u = ui(); s = 'foo'
         >>> u.setconfig(s, 'true', 'yes')
         >>> u.configbool(s, 'true')
         True
         >>> u.setconfig(s, 'false', 'no')
         >>> u.configbool(s, 'false')
         False
         >>> u.configbool(s, 'unknown')
         False
         >>> u.configbool(s, 'unknown', True)
         True
         >>> u.setconfig(s, 'invalid', 'somevalue')
         >>> u.configbool(s, 'invalid')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not a boolean ('somevalue')
         """
 
         v = self.config(section, name, None, untrusted)
         if v is None:
             return default
         if isinstance(v, bool):
             return v
         b = util.parsebool(v)
         if b is None:
             raise error.ConfigError(_("%s.%s is not a boolean ('%s')")
                                     % (section, name, v))
         return b
 
     def configwith(self, convert, section, name, default=None,
                    desc=None, untrusted=False):
         """parse a configuration element with a conversion function
 
         >>> u = ui(); s = 'foo'
         >>> u.setconfig(s, 'float1', '42')
         >>> u.configwith(float, s, 'float1')
         42.0
         >>> u.setconfig(s, 'float2', '-4.25')
         >>> u.configwith(float, s, 'float2')
         -4.25
         >>> u.configwith(float, s, 'unknown', 7)
         7
         >>> u.setconfig(s, 'invalid', 'somevalue')
         >>> u.configwith(float, s, 'invalid')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not a valid float ('somevalue')
         >>> u.configwith(float, s, 'invalid', desc='womble')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not a valid womble ('somevalue')
         """
 
         v = self.config(section, name, None, untrusted)
         if v is None:
             return default
         try:
             return convert(v)
         except ValueError:
             if desc is None:
                 desc = convert.__name__
             raise error.ConfigError(_("%s.%s is not a valid %s ('%s')")
                                     % (section, name, desc, v))
 
     def configint(self, section, name, default=None, untrusted=False):
         """parse a configuration element as an integer
 
         >>> u = ui(); s = 'foo'
         >>> u.setconfig(s, 'int1', '42')
         >>> u.configint(s, 'int1')
         42
         >>> u.setconfig(s, 'int2', '-42')
         >>> u.configint(s, 'int2')
         -42
         >>> u.configint(s, 'unknown', 7)
         7
         >>> u.setconfig(s, 'invalid', 'somevalue')
         >>> u.configint(s, 'invalid')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not a valid integer ('somevalue')
         """
 
         return self.configwith(int, section, name, default, 'integer',
                                untrusted)
 
     def configbytes(self, section, name, default=0, untrusted=False):
         """parse a configuration element as a quantity in bytes
 
         Units can be specified as b (bytes), k or kb (kilobytes), m or
         mb (megabytes), g or gb (gigabytes).
 
         >>> u = ui(); s = 'foo'
         >>> u.setconfig(s, 'val1', '42')
         >>> u.configbytes(s, 'val1')
         42
         >>> u.setconfig(s, 'val2', '42.5 kb')
         >>> u.configbytes(s, 'val2')
         43520
         >>> u.configbytes(s, 'unknown', '7 MB')
         7340032
         >>> u.setconfig(s, 'invalid', 'somevalue')
         >>> u.configbytes(s, 'invalid')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not a byte quantity ('somevalue')
         """
 
         value = self.config(section, name, None, untrusted)
         if value is None:
             if not isinstance(default, str):
                 return default
             value = default
         try:
             return util.sizetoint(value)
         except error.ParseError:
             raise error.ConfigError(_("%s.%s is not a byte quantity ('%s')")
                                     % (section, name, value))
 
     def configlist(self, section, name, default=None, untrusted=False):
         """parse a configuration element as a list of comma/space separated
         strings
 
         >>> u = ui(); s = 'foo'
         >>> u.setconfig(s, 'list1', 'this,is "a small" ,test')
         >>> u.configlist(s, 'list1')
         ['this', 'is', 'a small', 'test']
         """
         # default is not always a list
         if isinstance(default, bytes):
             default = config.parselist(default)
         return self.configwith(config.parselist, section, name, default or [],
                                'list', untrusted)
 
     def hasconfig(self, section, name, untrusted=False):
         return self._data(untrusted).hasitem(section, name)
 
     def has_section(self, section, untrusted=False):
         '''tell whether section exists in config.'''
         return section in self._data(untrusted)
 
     def configitems(self, section, untrusted=False, ignoresub=False):
         items = self._data(untrusted).items(section)
         if ignoresub:
             newitems = {}
             for k, v in items:
                 if ':' not in k:
                     newitems[k] = v
             items = newitems.items()
         if self.debugflag and not untrusted and self._reportuntrusted:
             for k, v in self._ucfg.items(section):
                 if self._tcfg.get(section, k) != v:
                     self.debug("ignoring untrusted configuration option "
                                "%s.%s = %s\n" % (section, k, v))
         return items
 
     def walkconfig(self, untrusted=False):
         cfg = self._data(untrusted)
         for section in cfg.sections():
             for name, value in self.configitems(section, untrusted):
                 yield section, name, value
 
     def plain(self, feature=None):
         '''is plain mode active?
 
         Plain mode means that all configuration variables which affect
         the behavior and output of Mercurial should be
         ignored. Additionally, the output should be stable,
         reproducible and suitable for use in scripts or applications.
 
         The only way to trigger plain mode is by setting either the
         `HGPLAIN' or `HGPLAINEXCEPT' environment variables.
 
         The return value can either be
         - False if HGPLAIN is not set, or feature is in HGPLAINEXCEPT
         - True otherwise
         '''
         if ('HGPLAIN' not in encoding.environ and
                 'HGPLAINEXCEPT' not in encoding.environ):
             return False
         exceptions = encoding.environ.get('HGPLAINEXCEPT',
                 '').strip().split(',')
         if feature and exceptions:
             return feature not in exceptions
         return True
 
     def username(self):
         """Return default username to be used in commits.
 
         Searched in this order: $HGUSER, [ui] section of hgrcs, $EMAIL
         and stop searching if one of these is set.
         If not found and ui.askusername is True, ask the user, else use
         ($LOGNAME or $USER or $LNAME or $USERNAME) + "@full.hostname".
         """
         user = encoding.environ.get("HGUSER")
         if user is None:
             user = self.config("ui", ["username", "user"])
             if user is not None:
                 user = os.path.expandvars(user)
         if user is None:
             user = encoding.environ.get("EMAIL")
         if user is None and self.configbool("ui", "askusername"):
             user = self.prompt(_("enter a commit username:"), default=None)
         if user is None and not self.interactive():
             try:
                 user = '%s@%s' % (util.getuser(), socket.getfqdn())
                 self.warn(_("no username found, using '%s' instead\n") % user)
             except KeyError:
                 pass
         if not user:
             raise error.Abort(_('no username supplied'),
                              hint=_("use 'hg config --edit' "
                                     'to set your username'))
         if "\n" in user:
             raise error.Abort(_("username %s contains a newline\n")
                               % repr(user))
         return user
 
     def shortuser(self, user):
         """Return a short representation of a user name or email address."""
         if not self.verbose:
             user = util.shortuser(user)
         return user
 
     def expandpath(self, loc, default=None):
         """Return repository location relative to cwd or from [paths]"""
         try:
             p = self.paths.getpath(loc)
             if p:
                 return p.rawloc
         except error.RepoError:
             pass
 
         if default:
             try:
                 p = self.paths.getpath(default)
                 if p:
                     return p.rawloc
             except error.RepoError:
                 pass
 
         return loc
 
     @util.propertycache
     def paths(self):
         return paths(self)
 
     def pushbuffer(self, error=False, subproc=False, labeled=False):
         """install a buffer to capture standard output of the ui object
 
         If error is True, the error output will be captured too.
 
         If subproc is True, output from subprocesses (typically hooks) will be
         captured too.
 
         If labeled is True, any labels associated with buffered
         output will be handled. By default, this has no effect
         on the output returned, but extensions and GUI tools may
         handle this argument and returned styled output. If output
         is being buffered so it can be captured and parsed or
         processed, labeled should not be set to True.
         """
         self._buffers.append([])
         self._bufferstates.append((error, subproc, labeled))
         self._bufferapplylabels = labeled
 
     def popbuffer(self):
         '''pop the last buffer and return the buffered output'''
         self._bufferstates.pop()
         if self._bufferstates:
             self._bufferapplylabels = self._bufferstates[-1][2]
         else:
             self._bufferapplylabels = None
 
         return "".join(self._buffers.pop())
 
     def write(self, *args, **opts):
         '''write args to output
 
         By default, this method simply writes to the buffer or stdout.
         Color mode can be set on the UI class to have the output decorated
         with color modifier before being written to stdout.
 
         The color used is controlled by an optional keyword argument, "label".
         This should be a string containing label names separated by space.
         Label names take the form of "topic.type". For example, ui.debug()
         issues a label of "ui.debug".
 
         When labeling output for a specific command, a label of
         "cmdname.type" is recommended. For example, status issues
         a label of "status.modified" for modified files.
         '''
         if self._buffers and not opts.get('prompt', False):
             if self._bufferapplylabels:
                 label = opts.get('label', '')
                 self._buffers[-1].extend(self.label(a, label) for a in args)
             else:
                 self._buffers[-1].extend(args)
         elif self._colormode == 'win32':
             # windows color printing is its own can of crab, defer to
             # the color module and that is it.
             color.win32print(self, self._write, *args, **opts)
         else:
             msgs = args
             if self._colormode is not None:
                 label = opts.get('label', '')
                 msgs = [self.label(a, label) for a in args]
             self._write(*msgs, **opts)
 
     def _write(self, *msgs, **opts):
         self._progclear()
         # opencode timeblockedsection because this is a critical path
         starttime = util.timer()
         try:
             for a in msgs:
                 self.fout.write(a)
         finally:
             self._blockedtimes['stdio_blocked'] += \
                 (util.timer() - starttime) * 1000
 
     def write_err(self, *args, **opts):
         self._progclear()
         if self._bufferstates and self._bufferstates[-1][0]:
             self.write(*args, **opts)
         elif self._colormode == 'win32':
             # windows color printing is its own can of crab, defer to
             # the color module and that is it.
             color.win32print(self, self._write_err, *args, **opts)
         else:
             msgs = args
             if self._colormode is not None:
                 label = opts.get('label', '')
                 msgs = [self.label(a, label) for a in args]
             self._write_err(*msgs, **opts)
 
     def _write_err(self, *msgs, **opts):
         try:
             with self.timeblockedsection('stdio'):
                 if not getattr(self.fout, 'closed', False):
                     self.fout.flush()
                 for a in msgs:
                     self.ferr.write(a)
                 # stderr may be buffered under win32 when redirected to files,
                 # including stdout.
                 if not getattr(self.ferr, 'closed', False):
                     self.ferr.flush()
         except IOError as inst:
             if inst.errno not in (errno.EPIPE, errno.EIO, errno.EBADF):
                 raise
 
     def flush(self):
         # opencode timeblockedsection because this is a critical path
         starttime = util.timer()
         try:
             try: self.fout.flush()
             except (IOError, ValueError): pass
             try: self.ferr.flush()
             except (IOError, ValueError): pass
         finally:
             self._blockedtimes['stdio_blocked'] += \
                 (util.timer() - starttime) * 1000
 
     def _isatty(self, fh):
         if self.configbool('ui', 'nontty', False):
             return False
         return util.isatty(fh)
 
     def disablepager(self):
         self._disablepager = True
 
     def pager(self, command):
         """Start a pager for subsequent command output.
 
         Commands which produce a long stream of output should call
         this function to activate the user's preferred pagination
         mechanism (which may be no pager). Calling this function
         precludes any future use of interactive functionality, such as
         prompting the user or activating curses.
 
         Args:
           command: The full, non-aliased name of the command. That is, "log"
                    not "history, "summary" not "summ", etc.
         """
         if (self._disablepager
             or self.pageractive
             or command in self.configlist('pager', 'ignore')
             or not self.configbool('pager', 'enable', True)
             or not self.configbool('pager', 'attend-' + command, True)
             # TODO: if we want to allow HGPLAINEXCEPT=pager,
             # formatted() will need some adjustment.
             or not self.formatted()
             or self.plain()
             # TODO: expose debugger-enabled on the UI object
             or '--debugger' in pycompat.sysargv):
             # We only want to paginate if the ui appears to be
             # interactive, the user didn't say HGPLAIN or
             # HGPLAINEXCEPT=pager, and the user didn't specify --debug.
             return
 
         fallbackpager = 'more'
         pagercmd = self.config('pager', 'pager', fallbackpager)
         if not pagercmd:
             return
 
+        pagerenv = {}
+        for name, value in rcutil.defaultpagerenv().items():
+            if name not in encoding.environ:
+                pagerenv[name] = value
+
         self.debug('starting pager for command %r\n' % command)
         self.flush()
 
         wasformatted = self.formatted()
         if util.safehasattr(signal, "SIGPIPE"):
             signal.signal(signal.SIGPIPE, _catchterm)
-        if self._runpager(pagercmd):
+        if self._runpager(pagercmd, pagerenv):
             self.pageractive = True
             # Preserve the formatted-ness of the UI. This is important
             # because we mess with stdout, which might confuse
             # auto-detection of things being formatted.
             self.setconfig('ui', 'formatted', wasformatted, 'pager')
             self.setconfig('ui', 'interactive', False, 'pager')
 
             # If pagermode differs from color.mode, reconfigure color now that
             # pageractive is set.
             cm = self._colormode
             if cm != self.config('color', 'pagermode', cm):
                 color.setup(self)
         else:
             # If the pager can't be spawned in dispatch when --pager=on is
             # given, don't try again when the command runs, to avoid a duplicate
             # warning about a missing pager command.
             self.disablepager()
 
-    def _runpager(self, command):
+    def _runpager(self, command, env=None):
         """Actually start the pager and set up file descriptors.
 
         This is separate in part so that extensions (like chg) can
         override how a pager is invoked.
         """
         if command == 'cat':
             # Save ourselves some work.
             return False
         # If the command doesn't contain any of these characters, we
         # assume it's a binary and exec it directly. This means for
         # simple pager command configurations, we can degrade
         # gracefully and tell the user about their broken pager.
         shell = any(c in command for c in "|&;<>()$`\\\"' \t\n*?[#~=%")
 
         if pycompat.osname == 'nt' and not shell:
             # Window's built-in `more` cannot be invoked with shell=False, but
             # its `more.com` can.  Hide this implementation detail from the
             # user so we can also get sane bad PAGER behavior.  MSYS has
             # `more.exe`, so do a cmd.exe style resolution of the executable to
             # determine which one to use.
             fullcmd = util.findexe(command)
             if not fullcmd:
                 self.warn(_("missing pager command '%s', skipping pager\n")
                           % command)
                 return False
 
             command = fullcmd
 
         try:
             pager = subprocess.Popen(
                 command, shell=shell, bufsize=-1,
                 close_fds=util.closefds, stdin=subprocess.PIPE,
-                stdout=util.stdout, stderr=util.stderr)
+                stdout=util.stdout, stderr=util.stderr,
+                env=util.shellenviron(env))
         except OSError as e:
             if e.errno == errno.ENOENT and not shell:
                 self.warn(_("missing pager command '%s', skipping pager\n")
                           % command)
                 return False
             raise
 
         # back up original file descriptors
         stdoutfd = os.dup(util.stdout.fileno())
         stderrfd = os.dup(util.stderr.fileno())
 
         os.dup2(pager.stdin.fileno(), util.stdout.fileno())
         if self._isatty(util.stderr):
             os.dup2(pager.stdin.fileno(), util.stderr.fileno())
 
         @atexit.register
         def killpager():
             if util.safehasattr(signal, "SIGINT"):
                 signal.signal(signal.SIGINT, signal.SIG_IGN)
             # restore original fds, closing pager.stdin copies in the process
             os.dup2(stdoutfd, util.stdout.fileno())
             os.dup2(stderrfd, util.stderr.fileno())
             pager.stdin.close()
             pager.wait()
 
         return True
 
     def interface(self, feature):
         """what interface to use for interactive console features?
 
         The interface is controlled by the value of `ui.interface` but also by
         the value of feature-specific configuration. For example:
 
         ui.interface.histedit = text
         ui.interface.chunkselector = curses
 
         Here the features are "histedit" and "chunkselector".
 
         The configuration above means that the default interfaces for commands
         is curses, the interface for histedit is text and the interface for
         selecting chunk is crecord (the best curses interface available).
 
         Consider the following example:
         ui.interface = curses
         ui.interface.histedit = text
 
         Then histedit will use the text interface and chunkselector will use
         the default curses interface (crecord at the moment).
         """
         alldefaults = frozenset(["text", "curses"])
 
         featureinterfaces = {
             "chunkselector": [
                 "text",
                 "curses",
             ]
         }
 
         # Feature-specific interface
         if feature not in featureinterfaces.keys():
             # Programming error, not user error
             raise ValueError("Unknown feature requested %s" % feature)
 
         availableinterfaces = frozenset(featureinterfaces[feature])
         if alldefaults > availableinterfaces:
             # Programming error, not user error. We need a use case to
             # define the right thing to do here.
             raise ValueError(
                 "Feature %s does not handle all default interfaces" %
                 feature)
 
         if self.plain():
             return "text"
 
         # Default interface for all the features
         defaultinterface = "text"
         i = self.config("ui", "interface", None)
         if i in alldefaults:
             defaultinterface = i
 
         choseninterface = defaultinterface
         f = self.config("ui", "interface.%s" % feature, None)
         if f in availableinterfaces:
             choseninterface = f
 
         if i is not None and defaultinterface != i:
             if f is not None:
                 self.warn(_("invalid value for ui.interface: %s\n") %
                           (i,))
             else:
                 self.warn(_("invalid value for ui.interface: %s (using %s)\n") %
                          (i, choseninterface))
         if f is not None and choseninterface != f:
             self.warn(_("invalid value for ui.interface.%s: %s (using %s)\n") %
                       (feature, f, choseninterface))
 
         return choseninterface
 
     def interactive(self):
         '''is interactive input allowed?
 
         An interactive session is a session where input can be reasonably read
         from `sys.stdin'. If this function returns false, any attempt to read
         from stdin should fail with an error, unless a sensible default has been
         specified.
 
         Interactiveness is triggered by the value of the `ui.interactive'
         configuration variable or - if it is unset - when `sys.stdin' points
         to a terminal device.
 
         This function refers to input only; for output, see `ui.formatted()'.
         '''
         i = self.configbool("ui", "interactive", None)
         if i is None:
             # some environments replace stdin without implementing isatty
             # usually those are non-interactive
             return self._isatty(self.fin)
 
         return i
 
     def termwidth(self):
         '''how wide is the terminal in columns?
         '''
         if 'COLUMNS' in encoding.environ:
             try:
                 return int(encoding.environ['COLUMNS'])
             except ValueError:
                 pass
         return scmutil.termsize(self)[0]
 
     def formatted(self):
         '''should formatted output be used?
 
         It is often desirable to format the output to suite the output medium.
         Examples of this are truncating long lines or colorizing messages.
         However, this is not often not desirable when piping output into other
         utilities, e.g. `grep'.
 
         Formatted output is triggered by the value of the `ui.formatted'
         configuration variable or - if it is unset - when `sys.stdout' points
         to a terminal device. Please note that `ui.formatted' should be
         considered an implementation detail; it is not intended for use outside
         Mercurial or its extensions.
 
         This function refers to output only; for input, see `ui.interactive()'.
         This function always returns false when in plain mode, see `ui.plain()'.
         '''
         if self.plain():
             return False
 
         i = self.configbool("ui", "formatted", None)
         if i is None:
             # some environments replace stdout without implementing isatty
             # usually those are non-interactive
             return self._isatty(self.fout)
 
         return i
 
     def _readline(self, prompt=''):
         if self._isatty(self.fin):
             try:
                 # magically add command line editing support, where
                 # available
                 import readline
                 # force demandimport to really load the module
                 readline.read_history_file
                 # windows sometimes raises something other than ImportError
             except Exception:
                 pass
 
         # call write() so output goes through subclassed implementation
         # e.g. color extension on Windows
         self.write(prompt, prompt=True)
 
         # instead of trying to emulate raw_input, swap (self.fin,
         # self.fout) with (sys.stdin, sys.stdout)
         oldin = sys.stdin
         oldout = sys.stdout
         sys.stdin = self.fin
         sys.stdout = self.fout
         # prompt ' ' must exist; otherwise readline may delete entire line
         # - http://bugs.python.org/issue12833
         with self.timeblockedsection('stdio'):
             line = raw_input(' ')
         sys.stdin = oldin
         sys.stdout = oldout
 
         # When stdin is in binary mode on Windows, it can cause
         # raw_input() to emit an extra trailing carriage return
         if pycompat.oslinesep == '\r\n' and line and line[-1] == '\r':
             line = line[:-1]
         return line
 
     def prompt(self, msg, default="y"):
         """Prompt user with msg, read response.
         If ui is not interactive, the default is returned.
         """
         if not self.interactive():
             self.write(msg, ' ', default or '', "\n")
             return default
         try:
             r = self._readline(self.label(msg, 'ui.prompt'))
             if not r:
                 r = default
             if self.configbool('ui', 'promptecho'):
                 self.write(r, "\n")
             return r
         except EOFError:
             raise error.ResponseExpected()
 
     @staticmethod
     def extractchoices(prompt):
         """Extract prompt message and list of choices from specified prompt.
 
         This returns tuple "(message, choices)", and "choices" is the
         list of tuple "(response character, text without &)".
 
         >>> ui.extractchoices("awake? $$ &Yes $$ &No")
         ('awake? ', [('y', 'Yes'), ('n', 'No')])
         >>> ui.extractchoices("line\\nbreak? $$ &Yes $$ &No")
         ('line\\nbreak? ', [('y', 'Yes'), ('n', 'No')])
         >>> ui.extractchoices("want lots of $$money$$?$$Ye&s$$N&o")
         ('want lots of $$money$$?', [('s', 'Yes'), ('o', 'No')])
         """
 
         # Sadly, the prompt string may have been built with a filename
         # containing "$$" so let's try to find the first valid-looking
         # prompt to start parsing. Sadly, we also can't rely on
         # choices containing spaces, ASCII, or basically anything
         # except an ampersand followed by a character.
         m = re.match(r'(?s)(.+?)\$\$([^\$]*&[^ \$].*)', prompt)
         msg = m.group(1)
         choices = [p.strip(' ') for p in m.group(2).split('$$')]
         return (msg,
                 [(s[s.index('&') + 1].lower(), s.replace('&', '', 1))
                  for s in choices])
 
     def promptchoice(self, prompt, default=0):
         """Prompt user with a message, read response, and ensure it matches
         one of the provided choices. The prompt is formatted as follows:
 
            "would you like fries with that (Yn)? $$ &Yes $$ &No"
 
         The index of the choice is returned. Responses are case
         insensitive. If ui is not interactive, the default is
         returned.
         """
 
         msg, choices = self.extractchoices(prompt)
         resps = [r for r, t in choices]
         while True:
             r = self.prompt(msg, resps[default])
             if r.lower() in resps:
                 return resps.index(r.lower())
             self.write(_("unrecognized response\n"))
 
     def getpass(self, prompt=None, default=None):
         if not self.interactive():
             return default
         try:
             self.write_err(self.label(prompt or _('password: '), 'ui.prompt'))
             # disable getpass() only if explicitly specified. it's still valid
             # to interact with tty even if fin is not a tty.
             with self.timeblockedsection('stdio'):
                 if self.configbool('ui', 'nontty'):
                     l = self.fin.readline()
                     if not l:
                         raise EOFError
                     return l.rstrip('\n')
                 else:
                     return getpass.getpass('')
         except EOFError:
             raise error.ResponseExpected()
     def status(self, *msg, **opts):
         '''write status message to output (if ui.quiet is False)
 
         This adds an output label of "ui.status".
         '''
         if not self.quiet:
             opts[r'label'] = opts.get(r'label', '') + ' ui.status'
             self.write(*msg, **opts)
     def warn(self, *msg, **opts):
         '''write warning message to output (stderr)
 
         This adds an output label of "ui.warning".
         '''
         opts[r'label'] = opts.get(r'label', '') + ' ui.warning'
         self.write_err(*msg, **opts)
     def note(self, *msg, **opts):
         '''write note to output (if ui.verbose is True)
 
         This adds an output label of "ui.note".
         '''
         if self.verbose:
             opts[r'label'] = opts.get(r'label', '') + ' ui.note'
             self.write(*msg, **opts)
     def debug(self, *msg, **opts):
         '''write debug message to output (if ui.debugflag is True)
 
         This adds an output label of "ui.debug".
         '''
         if self.debugflag:
             opts[r'label'] = opts.get(r'label', '') + ' ui.debug'
             self.write(*msg, **opts)
 
     def edit(self, text, user, extra=None, editform=None, pending=None,
              repopath=None):
         extra_defaults = {
             'prefix': 'editor',
             'suffix': '.txt',
         }
         if extra is not None:
             extra_defaults.update(extra)
         extra = extra_defaults
 
         rdir = None
         if self.configbool('experimental', 'editortmpinhg'):
             rdir = repopath
         (fd, name) = tempfile.mkstemp(prefix='hg-' + extra['prefix'] + '-',
                                       suffix=extra['suffix'],
                                       dir=rdir)
         try:
             f = os.fdopen(fd, r'wb')
             f.write(util.tonativeeol(text))
             f.close()
 
             environ = {'HGUSER': user}
             if 'transplant_source' in extra:
                 environ.update({'HGREVISION': hex(extra['transplant_source'])})
             for label in ('intermediate-source', 'source', 'rebase_source'):
                 if label in extra:
                     environ.update({'HGREVISION': extra[label]})
                     break
             if editform:
                 environ.update({'HGEDITFORM': editform})
             if pending:
                 environ.update({'HG_PENDING': pending})
 
             editor = self.geteditor()
 
             self.system("%s \"%s\"" % (editor, name),
                         environ=environ,
                         onerr=error.Abort, errprefix=_("edit failed"),
                         blockedtag='editor')
 
             f = open(name, r'rb')
             t = util.fromnativeeol(f.read())
             f.close()
         finally:
             os.unlink(name)
 
         return t
 
     def system(self, cmd, environ=None, cwd=None, onerr=None, errprefix=None,
                blockedtag=None):
         '''execute shell command with appropriate output stream. command
         output will be redirected if fout is not stdout.
 
         if command fails and onerr is None, return status, else raise onerr
         object as exception.
         '''
         if blockedtag is None:
             # Long cmds tend to be because of an absolute path on cmd. Keep
             # the tail end instead
             cmdsuffix = cmd.translate(None, _keepalnum)[-85:]
             blockedtag = 'unknown_system_' + cmdsuffix
         out = self.fout
         if any(s[1] for s in self._bufferstates):
             out = self
         with self.timeblockedsection(blockedtag):
             rc = self._runsystem(cmd, environ=environ, cwd=cwd, out=out)
         if rc and onerr:
             errmsg = '%s %s' % (os.path.basename(cmd.split(None, 1)[0]),
                                 util.explainexit(rc)[0])
             if errprefix:
                 errmsg = '%s: %s' % (errprefix, errmsg)
             raise onerr(errmsg)
         return rc
 
     def _runsystem(self, cmd, environ, cwd, out):
         """actually execute the given shell command (can be overridden by
         extensions like chg)"""
         return util.system(cmd, environ=environ, cwd=cwd, out=out)
 
     def traceback(self, exc=None, force=False):
         '''print exception traceback if traceback printing enabled or forced.
         only to call in exception handler. returns true if traceback
         printed.'''
         if self.tracebackflag or force:
             if exc is None:
                 exc = sys.exc_info()
             cause = getattr(exc[1], 'cause', None)
 
             if cause is not None:
                 causetb = traceback.format_tb(cause[2])
                 exctb = traceback.format_tb(exc[2])
                 exconly = traceback.format_exception_only(cause[0], cause[1])
 
                 # exclude frame where 'exc' was chained and rethrown from exctb
                 self.write_err('Traceback (most recent call last):\n',
                                ''.join(exctb[:-1]),
                                ''.join(causetb),
                                ''.join(exconly))
             else:
                 output = traceback.format_exception(exc[0], exc[1], exc[2])
                 data = r''.join(output)
                 if pycompat.ispy3:
                     enc = pycompat.sysstr(encoding.encoding)
                     data = data.encode(enc, errors=r'replace')
                 self.write_err(data)
         return self.tracebackflag or force
 
     def geteditor(self):
         '''return editor to use'''
         if pycompat.sysplatform == 'plan9':
             # vi is the MIPS instruction simulator on Plan 9. We
             # instead default to E to plumb commit messages to
             # avoid confusion.
             editor = 'E'
         else:
             editor = 'vi'
         return (encoding.environ.get("HGEDITOR") or
                 self.config("ui", "editor", editor))
 
     @util.propertycache
     def _progbar(self):
         """setup the progbar singleton to the ui object"""
         if (self.quiet or self.debugflag
                 or self.configbool('progress', 'disable', False)
                 or not progress.shouldprint(self)):
             return None
         return getprogbar(self)
 
     def _progclear(self):
         """clear progress bar output if any. use it before any output"""
         if '_progbar' not in vars(self): # nothing loaded yet
             return
         if self._progbar is not None and self._progbar.printed:
             self._progbar.clear()
 
     def progress(self, topic, pos, item="", unit="", total=None):
         '''show a progress message
 
         By default a textual progress bar will be displayed if an operation
         takes too long. 'topic' is the current operation, 'item' is a
         non-numeric marker of the current position (i.e. the currently
         in-process file), 'pos' is the current numeric position (i.e.
         revision, bytes, etc.), unit is a corresponding unit label,
         and total is the highest expected pos.
 
         Multiple nested topics may be active at a time.
 
         All topics should be marked closed by setting pos to None at
         termination.
         '''
         if self._progbar is not None:
             self._progbar.progress(topic, pos, item=item, unit=unit,
                                    total=total)
         if pos is None or not self.configbool('progress', 'debug'):
             return
 
         if unit:
             unit = ' ' + unit
         if item:
             item = ' ' + item
 
         if total:
             pct = 100.0 * pos / total
             self.debug('%s:%s %s/%s%s (%4.2f%%)\n'
                      % (topic, item, pos, total, unit, pct))
         else:
             self.debug('%s:%s %s%s\n' % (topic, item, pos, unit))
 
     def log(self, service, *msg, **opts):
         '''hook for logging facility extensions
 
         service should be a readily-identifiable subsystem, which will
         allow filtering.
 
         *msg should be a newline-terminated format string to log, and
         then any values to %-format into that format string.
 
         **opts currently has no defined meanings.
         '''
 
     def label(self, msg, label):
         '''style msg based on supplied label
 
         If some color mode is enabled, this will add the necessary control
         characters to apply such color. In addition, 'debug' color mode adds
         markup showing which label affects a piece of text.
 
         ui.write(s, 'label') is equivalent to
         ui.write(ui.label(s, 'label')).
         '''
         if self._colormode is not None:
             return color.colorlabel(self, msg, label)
         return msg
 
     def develwarn(self, msg, stacklevel=1, config=None):
         """issue a developer warning message
 
         Use 'stacklevel' to report the offender some layers further up in the
         stack.
         """
         if not self.configbool('devel', 'all-warnings'):
             if config is not None and not self.configbool('devel', config):
                 return
         msg = 'devel-warn: ' + msg
         stacklevel += 1 # get in develwarn
         if self.tracebackflag:
             util.debugstacktrace(msg, stacklevel, self.ferr, self.fout)
             self.log('develwarn', '%s at:\n%s' %
                      (msg, ''.join(util.getstackframes(stacklevel))))
         else:
             curframe = inspect.currentframe()
             calframe = inspect.getouterframes(curframe, 2)
             self.write_err('%s at: %s:%s (%s)\n'
                            % ((msg,) + calframe[stacklevel][1:4]))
             self.log('develwarn', '%s at: %s:%s (%s)\n',
                      msg, *calframe[stacklevel][1:4])
             curframe = calframe = None  # avoid cycles
 
     def deprecwarn(self, msg, version):
         """issue a deprecation warning
 
         - msg: message explaining what is deprecated and how to upgrade,
         - version: last version where the API will be supported,
         """
         if not (self.configbool('devel', 'all-warnings')
                 or self.configbool('devel', 'deprec-warn')):
             return
         msg += ("\n(compatibility will be dropped after Mercurial-%s,"
                 " update your code.)") % version
         self.develwarn(msg, stacklevel=2, config='deprec-warn')
 
     def exportableenviron(self):
         """The environment variables that are safe to export, e.g. through
         hgweb.
         """
         return self._exportableenviron
 
     @contextlib.contextmanager
     def configoverride(self, overrides, source=""):
         """Context manager for temporary config overrides
         `overrides` must be a dict of the following structure:
         {(section, name) : value}"""
         backups = {}
         try:
             for (section, name), value in overrides.items():
                 backups[(section, name)] = self.backupconfig(section, name)
                 self.setconfig(section, name, value, source)
             yield
         finally:
             for __, backup in backups.items():
                 self.restoreconfig(backup)
             # just restoring ui.quiet config to the previous value is not enough
             # as it does not update ui.quiet class member
             if ('ui', 'quiet') in overrides:
                 self.fixconfig(section='ui')
 
 class paths(dict):
     """Represents a collection of paths and their configs.
 
     Data is initially derived from ui instances and the config files they have
     loaded.
     """
     def __init__(self, ui):
         dict.__init__(self)
 
         for name, loc in ui.configitems('paths', ignoresub=True):
             # No location is the same as not existing.
             if not loc:
                 continue
             loc, sub = ui.configsuboptions('paths', name)
             self[name] = path(ui, name, rawloc=loc, suboptions=sub)
 
     def getpath(self, name, default=None):
         """Return a ``path`` from a string, falling back to default.
 
         ``name`` can be a named path or locations. Locations are filesystem
         paths or URIs.
 
         Returns None if ``name`` is not a registered path, a URI, or a local
         path to a repo.
         """
         # Only fall back to default if no path was requested.
         if name is None:
             if not default:
                 default = ()
             elif not isinstance(default, (tuple, list)):
                 default = (default,)
             for k in default:
                 try:
                     return self[k]
                 except KeyError:
                     continue
             return None
 
         # Most likely empty string.
         # This may need to raise in the future.
         if not name:
             return None
 
         try:
             return self[name]
         except KeyError:
             # Try to resolve as a local path or URI.
             try:
                 # We don't pass sub-options in, so no need to pass ui instance.
                 return path(None, None, rawloc=name)
             except ValueError:
                 raise error.RepoError(_('repository %s does not exist') %
                                         name)
 
 _pathsuboptions = {}
 
 def pathsuboption(option, attr):
     """Decorator used to declare a path sub-option.
 
     Arguments are the sub-option name and the attribute it should set on
     ``path`` instances.
 
     The decorated function will receive as arguments a ``ui`` instance,
     ``path`` instance, and the string value of this option from the config.
     The function should return the value that will be set on the ``path``
     instance.
 
     This decorator can be used to perform additional verification of
     sub-options and to change the type of sub-options.
     """
     def register(func):
         _pathsuboptions[option] = (attr, func)
         return func
     return register
 
 @pathsuboption('pushurl', 'pushloc')
 def pushurlpathoption(ui, path, value):
     u = util.url(value)
     # Actually require a URL.
     if not u.scheme:
         ui.warn(_('(paths.%s:pushurl not a URL; ignoring)\n') % path.name)
         return None
 
     # Don't support the #foo syntax in the push URL to declare branch to
     # push.
     if u.fragment:
         ui.warn(_('("#fragment" in paths.%s:pushurl not supported; '
                   'ignoring)\n') % path.name)
         u.fragment = None
 
     return str(u)
 
 @pathsuboption('pushrev', 'pushrev')
 def pushrevpathoption(ui, path, value):
     return value
 
 class path(object):
     """Represents an individual path and its configuration."""
 
     def __init__(self, ui, name, rawloc=None, suboptions=None):
         """Construct a path from its config options.
 
         ``ui`` is the ``ui`` instance the path is coming from.
         ``name`` is the symbolic name of the path.
         ``rawloc`` is the raw location, as defined in the config.
         ``pushloc`` is the raw locations pushes should be made to.
 
         If ``name`` is not defined, we require that the location be a) a local
         filesystem path with a .hg directory or b) a URL. If not,
         ``ValueError`` is raised.
         """
         if not rawloc:
             raise ValueError('rawloc must be defined')
 
         # Locations may define branches via syntax <base>#<branch>.
         u = util.url(rawloc)
         branch = None
         if u.fragment:
             branch = u.fragment
             u.fragment = None
 
         self.url = u
         self.branch = branch
 
         self.name = name
         self.rawloc = rawloc
         self.loc = '%s' % u
 
         # When given a raw location but not a symbolic name, validate the
         # location is valid.
         if not name and not u.scheme and not self._isvalidlocalpath(self.loc):
             raise ValueError('location is not a URL or path to a local '
                              'repo: %s' % rawloc)
 
         suboptions = suboptions or {}
 
         # Now process the sub-options. If a sub-option is registered, its
         # attribute will always be present. The value will be None if there
         # was no valid sub-option.
         for suboption, (attr, func) in _pathsuboptions.iteritems():
             if suboption not in suboptions:
                 setattr(self, attr, None)
                 continue
 
             value = func(ui, self, suboptions[suboption])
             setattr(self, attr, value)
 
     def _isvalidlocalpath(self, path):
         """Returns True if the given path is a potentially valid repository.
         This is its own function so that extensions can change the definition of
         'valid' in this case (like when pulling from a git repo into a hg
         one)."""
         return os.path.isdir(os.path.join(path, '.hg'))
 
     @property
     def suboptions(self):
         """Return sub-options and their values for this path.
 
         This is intended to be used for presentation purposes.
         """
         d = {}
         for subopt, (attr, _func) in _pathsuboptions.iteritems():
             value = getattr(self, attr)
             if value is not None:
                 d[subopt] = value
         return d
 
 # we instantiate one globally shared progress bar to avoid
 # competing progress bars when multiple UI objects get created
 _progresssingleton = None
 
 def getprogbar(ui):
     global _progresssingleton
     if _progresssingleton is None:
         # passing 'ui' object to the singleton is fishy,
         # this is how the extension used to work but feel free to rework it.
         _progresssingleton = progress.progbar(ui)
     return _progresssingleton

tests/test-pager.t

@@ -1,256 +1,282
   $ cat >> fakepager.py <<EOF
   > import sys
   > for line in sys.stdin:
   >     sys.stdout.write('paged! %r\n' % line)
   > EOF
 
 Enable ui.formatted because pager won't fire without it, and set up
 pager and tell it to use our fake pager that lets us see when the
 pager was running.
   $ cat >> $HGRCPATH <<EOF
   > [ui]
   > formatted = yes
   > [pager]
   > pager = python $TESTTMP/fakepager.py
   > EOF
 
   $ hg init repo
   $ cd repo
   $ echo a >> a
   $ hg add a
   $ hg ci -m 'add a'
   $ for x in `python $TESTDIR/seq.py 1 10`; do
   >   echo a $x >> a
   >   hg ci -m "modify a $x"
   > done
 
 By default diff and log are paged, but id is not:
 
   $ hg diff -c 2 --pager=yes
   paged! 'diff -r f4be7687d414 -r bce265549556 a\n'
   paged! '--- a/a\tThu Jan 01 00:00:00 1970 +0000\n'
   paged! '+++ b/a\tThu Jan 01 00:00:00 1970 +0000\n'
   paged! '@@ -1,2 +1,3 @@\n'
   paged! ' a\n'
   paged! ' a 1\n'
   paged! '+a 2\n'
 
   $ hg log --limit 2
   paged! 'changeset:   10:46106edeeb38\n'
   paged! 'tag:         tip\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 10\n'
   paged! '\n'
   paged! 'changeset:   9:6dd8ea7dd621\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 9\n'
   paged! '\n'
 
   $ hg id
   46106edeeb38 tip
 
 We can enable the pager on id:
 
 BROKEN: should be paged
   $ hg --config pager.attend-id=yes id
   46106edeeb38 tip
 
 Setting attend-$COMMAND to a false value works, even with pager in
 core:
   $ hg --config pager.attend-diff=no diff -c 2
   diff -r f4be7687d414 -r bce265549556 a
   --- a/a	Thu Jan 01 00:00:00 1970 +0000
   +++ b/a	Thu Jan 01 00:00:00 1970 +0000
   @@ -1,2 +1,3 @@
    a
    a 1
   +a 2
 
 If 'log' is in attend, then 'history' should also be paged:
   $ hg history --limit 2 --config pager.attend=log
   paged! 'changeset:   10:46106edeeb38\n'
   paged! 'tag:         tip\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 10\n'
   paged! '\n'
   paged! 'changeset:   9:6dd8ea7dd621\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 9\n'
   paged! '\n'
 
 Pager should not start if stdout is not a tty.
 
   $ hg log -l1 -q --config ui.formatted=False
   10:46106edeeb38
 
 Pager should be disabled if pager.pager is empty (otherwise the output would
 be silently lost.)
 
   $ hg log -l1 -q --config pager.pager=
   10:46106edeeb38
 
 Pager with color enabled allows colors to come through by default,
 even though stdout is no longer a tty.
   $ cat >> $HGRCPATH <<EOF
   > [extensions]
   > color=
   > [color]
   > mode = ansi
   > EOF
   $ hg log --limit 3
   paged! '\x1b[0;33mchangeset:   10:46106edeeb38\x1b[0m\n'
   paged! 'tag:         tip\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 10\n'
   paged! '\n'
   paged! '\x1b[0;33mchangeset:   9:6dd8ea7dd621\x1b[0m\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 9\n'
   paged! '\n'
   paged! '\x1b[0;33mchangeset:   8:cff05a6312fe\x1b[0m\n'
   paged! 'user:        test\n'
   paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
   paged! 'summary:     modify a 8\n'
   paged! '\n'
 
 An invalid pager command name is reported sensibly if we don't have to
 use shell=True in the subprocess call:
   $ hg log --limit 3 --config pager.pager=this-command-better-never-exist
   missing pager command 'this-command-better-never-exist', skipping pager
   \x1b[0;33mchangeset:   10:46106edeeb38\x1b[0m (esc)
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a 10
   
   \x1b[0;33mchangeset:   9:6dd8ea7dd621\x1b[0m (esc)
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a 9
   
   \x1b[0;33mchangeset:   8:cff05a6312fe\x1b[0m (esc)
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a 8
   
 
 A complicated pager command gets worse behavior. Bonus points if you can
 improve this.
   $ hg log --limit 3 \
   >   --config pager.pager='this-command-better-never-exist --seriously' \
   >  2>/dev/null || true
 
 Pager works with shell aliases.
 
   $ cat >> $HGRCPATH <<EOF
   > [alias]
   > echoa = !echo a
   > EOF
 
   $ hg echoa
   a
 BROKEN: should be paged
   $ hg --config pager.attend-echoa=yes echoa
   a
 
 Pager works with hg aliases including environment variables.
 
   $ cat >> $HGRCPATH <<'EOF'
   > [alias]
   > printa = log -T "$A\n" -r 0
   > EOF
 
   $ A=1 hg --config pager.attend-printa=yes printa
   paged! '1\n'
   $ A=2 hg --config pager.attend-printa=yes printa
   paged! '2\n'
 
 Something that's explicitly attended is still not paginated if the
 pager is globally set to off using a flag:
   $ A=2 hg --config pager.attend-printa=yes printa --pager=no
   2
 
 Pager should not override the exit code of other commands
 
   $ cat >> $TESTTMP/fortytwo.py <<'EOF'
   > from mercurial import cmdutil, commands
   > cmdtable = {}
   > command = cmdutil.command(cmdtable)
   > @command('fortytwo', [], 'fortytwo', norepo=True)
   > def fortytwo(ui, *opts):
   >     ui.write('42\n')
   >     return 42
   > EOF
 
   $ cat >> $HGRCPATH <<'EOF'
   > [extensions]
   > fortytwo = $TESTTMP/fortytwo.py
   > EOF
 
   $ hg fortytwo --pager=on
   paged! '42\n'
   [42]
 
 A command that asks for paging using ui.pager() directly works:
   $ hg blame a
   paged! ' 0: a\n'
   paged! ' 1: a 1\n'
   paged! ' 2: a 2\n'
   paged! ' 3: a 3\n'
   paged! ' 4: a 4\n'
   paged! ' 5: a 5\n'
   paged! ' 6: a 6\n'
   paged! ' 7: a 7\n'
   paged! ' 8: a 8\n'
   paged! ' 9: a 9\n'
   paged! '10: a 10\n'
 but not with HGPLAIN
   $ HGPLAIN=1 hg blame a
    0: a
    1: a 1
    2: a 2
    3: a 3
    4: a 4
    5: a 5
    6: a 6
    7: a 7
    8: a 8
    9: a 9
   10: a 10
 explicit flags work too:
   $ hg blame --pager=no a
    0: a
    1: a 1
    2: a 2
    3: a 3
    4: a 4
    5: a 5
    6: a 6
    7: a 7
    8: a 8
    9: a 9
   10: a 10
 
 Put annotate in the ignore list for pager:
   $ cat >> $HGRCPATH <<EOF
   > [pager]
   > ignore = annotate
   > EOF
   $ hg blame a
    0: a
    1: a 1
    2: a 2
    3: a 3
    4: a 4
    5: a 5
    6: a 6
    7: a 7
    8: a 8
    9: a 9
   10: a 10
+
+Environment variables like LESS and LV are set automatically:
+  $ cat > $TESTTMP/printlesslv.py <<EOF
+  > import os, sys
+  > sys.stdin.read()
+  > for name in ['LESS', 'LV']:
+  >     sys.stdout.write(('%s=%s\n') % (name, os.environ.get(name, '-')))
+  > sys.stdout.flush()
+  > EOF
+
+  $ cat >> $HGRCPATH <<EOF
+  > [alias]
+  > noop = log -r 0 -T ''
+  > [ui]
+  > formatted=1
+  > [pager]
+  > pager = $PYTHON $TESTTMP/printlesslv.py
+  > EOF
+  $ unset LESS
+  $ unset LV
+  $ hg noop --pager=on
+  LESS=FRX
+  LV=-c
+  $ LESS=EFGH hg noop --pager=on
+  LESS=EFGH
+  LV=-c