hgext/pager.py

mq: fix the deprecation comment for qsave & qrestore.

Changeset bcf90e712dc3 deprecated qsave and qrestore. In the
deprecating comment, users were referred to 'rebase --mq' which -- at
the time the message was written -- didn't exist. Currently, on the
default branch, rebase *does* take a '--mq' option, but it probably
doesn't do what Dirkjan expected it to do when he wrote the message.

In the original, deprecating commit, little context was provided as to
why this change was made. Based on my recollection, concensus at the
Paris Sprint in February 2010 was that one of the problems with MQ was
that it exposed far too many commands. Notable among these were qsave
& qrestore: very few core developers understood what they did and even
fewer (none, IIRC) actually used them. However, they couldn't be
removed; not only do the usual backwards compatibility reasons apply,
but the hg book refers to them.

# pager.py - display output using a pager
#
# Copyright 2008 David Soria Parra <[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.
#
# To load the extension, add it to your configuration file:
#
#   [extension]
#   pager =
#
# Run "hg help pager" to get info on configuration.

'''browse command output with an external pager

To set the pager that should be used, set the application variable::

  [pager]
  pager = LESS='FSRX' less

If no pager is set, the pager extensions uses the environment variable
$PAGER. If neither pager.pager, nor $PAGER is set, no pager is used.

If you notice "BROKEN PIPE" error messages, you can disable them by
setting::

  [pager]
  quiet = True

You can disable the pager for certain commands by adding them to the
pager.ignore list::

  [pager]
  ignore = version, help, update

You can also enable the pager only for certain commands using
pager.attend. Below is the default list of commands to be paged::

  [pager]
  attend = annotate, cat, diff, export, glog, log, qdiff

Setting pager.attend to an empty value will cause all commands to be
paged.

If pager.attend is present, pager.ignore will be ignored.

To ignore global commands like :hg:`version` or :hg:`help`, you have
to specify them in your user configuration file.
'''

import sys, os, signal, shlex, errno
from mercurial import dispatch, util, extensions

def _runpager(p):
    if not hasattr(os, 'fork'):
        sys.stderr = sys.stdout = util.popen(p, 'wb')
        return
    fdin, fdout = os.pipe()
    pid = os.fork()
    if pid == 0:
        os.close(fdin)
        os.dup2(fdout, sys.stdout.fileno())
        os.dup2(fdout, sys.stderr.fileno())
        os.close(fdout)
        return
    os.dup2(fdin, sys.stdin.fileno())
    os.close(fdin)
    os.close(fdout)
    try:
        os.execvp('/bin/sh', ['/bin/sh', '-c', p])
    except OSError, e:
        if e.errno == errno.ENOENT:
            # no /bin/sh, try executing the pager directly
            args = shlex.split(p)
            os.execvp(args[0], args)
        else:
            raise

def uisetup(ui):
    if ui.plain():
        return

    def pagecmd(orig, ui, options, cmd, cmdfunc):
        p = ui.config("pager", "pager", os.environ.get("PAGER"))
        if p and sys.stdout.isatty() and '--debugger' not in sys.argv:
            attend = ui.configlist('pager', 'attend', attended)
            if (cmd in attend or
                (cmd not in ui.configlist('pager', 'ignore') and not attend)):
                ui.setconfig('ui', 'formatted', ui.formatted())
                ui.setconfig('ui', 'interactive', False)
                _runpager(p)
                if ui.configbool('pager', 'quiet'):
                    signal.signal(signal.SIGPIPE, signal.SIG_DFL)
        return orig(ui, options, cmd, cmdfunc)

    extensions.wrapfunction(dispatch, '_runcommand', pagecmd)

attended = ['annotate', 'cat', 'diff', 'export', 'glog', 'log', 'qdiff']