procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
# 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 (DEPRECATED)
Forcibly enable paging for individual commands that don't typically
request pagination with the attend-<command> option. This setting
takes precedence over ignore options and defaults::
[pager]
attend-cat = false
'''
from mercurial import (
cmdutil,
commands,
dispatch,
extensions,
registrar,
)
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' 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 = b'ships-with-hg-core'
configtable = {}
configitem = registrar.configitem(configtable)
configitem(
b'pager',
b'attend',
default=lambda: attended,
)
def uisetup(ui):
def pagecmd(orig, ui, options, cmd, cmdfunc):
auto = options[b'pager'] == b'auto'
if auto and not ui.pageractive:
usepager = False
attend = ui.configlist(b'pager', b'attend')
ignore = ui.configlist(b'pager', b'ignore')
cmds, _ = cmdutil.findcmd(cmd, commands.table)
for cmd in cmds:
var = b'attend-%s' % cmd
if ui.config(b'pager', var, None):
usepager = ui.configbool(b'pager', var, True)
break
if cmd in attend or (cmd not in ignore and not attend):
usepager = True
break
if usepager:
# Slight hack: the attend list is supposed to override
# the ignore list for the pager extension, but the
# core code doesn't know about attend, so we have to
# lobotomize the ignore list so that the extension's
# behavior is preserved.
ui.setconfig(b'pager', b'ignore', b'', b'pager')
ui.pager(b'extension-via-attend-' + cmd)
else:
ui.disablepager()
return orig(ui, options, cmd, cmdfunc)
extensions.wrapfunction(dispatch, b'_runcommand', pagecmd)
attended = [b'annotate', b'cat', b'diff', b'export', b'glog', b'log', b'qdiff']