pager: recreate stdout to make it line-buffered
We want to see partial command results as soon as possible. But the buffering
mode of stdout (= pager's stdin) was set to fully-buffered because it isn't
associated with a tty. So, this patch recreates new stdout object to force its
buffering mode.
Because two file objects are associated with the same stdout fd and their
destructors will call close(), one of them must be closed carefully. Python
expects that the stdout fd never be closed even after sys.stdout.close() [1],
but newstdout has no such hack. So this patch calls newstdout.close()
immediately before duplicating the original stdout fd to sys.stdout.
operation sys.stdout newstdout fd
--------------------- ---------- --------- --------
newstdout.close() open closed closed
os.dup2(stdoutfd, ..) open closed open
del sys.stdout closed closed open [1]
[1]: https://hg.python.org/cpython/file/v2.7.10/Python/sysmodule.c#l1391
# pager.py - display output using a pager
#
# Copyright 2008 David Soria Parra <dsp@php.net>
#
# 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 -FRX
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.
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.
Lastly, you can enable and disable paging for individual commands with
the attend-<command> option. This setting takes precedence over
existing attend and ignore options and defaults::
[pager]
attend-cat = false
To ignore global commands like :hg:`version` or :hg:`help`, you have
to specify them in your user configuration file.
The --pager=... option can also be used to control when the pager is
used. Use a boolean value like yes, no, on, off, or use auto for
normal behavior.
'''
import atexit, sys, os, signal, subprocess
from mercurial import commands, dispatch, util, extensions, cmdutil
from mercurial.i18n import _
# Note for extension authors: ONLY specify testedwith = 'internal' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'internal'
def _runpager(ui, p):
pager = subprocess.Popen(p, shell=True, bufsize=-1,
close_fds=util.closefds, stdin=subprocess.PIPE,
stdout=sys.stdout, stderr=sys.stderr)
# back up original file objects and descriptors
olduifout = ui.fout
oldstdout = sys.stdout
stdoutfd = os.dup(sys.stdout.fileno())
stderrfd = os.dup(sys.stderr.fileno())
# create new line-buffered stdout so that output can show up immediately
ui.fout = sys.stdout = newstdout = os.fdopen(sys.stdout.fileno(), 'wb', 1)
os.dup2(pager.stdin.fileno(), sys.stdout.fileno())
if ui._isatty(sys.stderr):
os.dup2(pager.stdin.fileno(), sys.stderr.fileno())
@atexit.register
def killpager():
if util.safehasattr(signal, "SIGINT"):
signal.signal(signal.SIGINT, signal.SIG_IGN)
pager.stdin.close()
ui.fout = olduifout
sys.stdout = oldstdout
# close new stdout while it's associated with pager; otherwise stdout
# fd would be closed when newstdout is deleted
newstdout.close()
# restore original fds: stdout is open again
os.dup2(stdoutfd, sys.stdout.fileno())
os.dup2(stderrfd, sys.stderr.fileno())
pager.wait()
def uisetup(ui):
if '--debugger' in sys.argv or not ui.formatted():
return
def pagecmd(orig, ui, options, cmd, cmdfunc):
p = ui.config("pager", "pager", os.environ.get("PAGER"))
usepager = False
always = util.parsebool(options['pager'])
auto = options['pager'] == 'auto'
if not p:
pass
elif always:
usepager = True
elif not auto:
usepager = False
else:
attend = ui.configlist('pager', 'attend', attended)
ignore = ui.configlist('pager', 'ignore')
cmds, _ = cmdutil.findcmd(cmd, commands.table)
for cmd in cmds:
var = 'attend-%s' % cmd
if ui.config('pager', var):
usepager = ui.configbool('pager', var)
break
if (cmd in attend or
(cmd not in ignore and not attend)):
usepager = True
break
setattr(ui, 'pageractive', usepager)
if usepager:
ui.setconfig('ui', 'formatted', ui.formatted(), 'pager')
ui.setconfig('ui', 'interactive', False, 'pager')
if util.safehasattr(signal, "SIGPIPE"):
signal.signal(signal.SIGPIPE, signal.SIG_DFL)
_runpager(ui, p)
return orig(ui, options, cmd, cmdfunc)
# Wrap dispatch._runcommand after color is loaded so color can see
# ui.pageractive. Otherwise, if we loaded first, color's wrapped
# dispatch._runcommand would run without having access to ui.pageractive.
def afterloaded(loaded):
extensions.wrapfunction(dispatch, '_runcommand', pagecmd)
extensions.afterloaded('color', afterloaded)
def extsetup(ui):
commands.globalopts.append(
('', 'pager', 'auto',
_("when to paginate (boolean, always, auto, or never)"),
_('TYPE')))
attended = ['annotate', 'cat', 'diff', 'export', 'glog', 'log', 'qdiff']