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Differential D8338

hook: move stdio redirection to context manager
ClosedPublic

Authored by indygreg on Mar 29 2020, 4:31 PM.

Details

Reviewers
Alphare
Group Reviewers
hg-reviewers
Commits
rHG3cbbfd0bfc17: hook: move stdio redirection to context manager
Summary

The old code was checking stdio redirection in a loop.
This didn't make sense. The pattern is better expressed
as a context manager IMO, so this commit refactors it
to be one.

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

indygreg created this revision.Mar 29 2020, 4:31 PM
indygreg added a comment.Mar 29 2020, 4:33 PM

This commit isn't strictly required. I performed this refactoring anticipating needing to add sys.std* fixups as part of this function. But it turns out that the SSH protocol server handles I/O redirection via a different mechanism. There actually appear to be redundant mechanisms for intercepting stdio as part of the wire protocol. This is potentially an area that we could clean up. But I'm not inclined to do so at this time.

Anyway, I feel the cleanup here improves readability, so I sent it along.

Alphare accepted this revision.Mar 31 2020, 5:08 AM
indygreg added a commit: rHG3cbbfd0bfc17: hook: move stdio redirection to context manager.Apr 1 2020, 3:09 PM
This revision was not accepted when it landed; it landed in state Needs Review.
Closed by commit rHG3cbbfd0bfc17: hook: move stdio redirection to context manager (authored by indygreg). · Explain Why
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

PathPackages
Mmercurial/hook.py (60 lines)

Diff 20949

mercurial/hook.py

# hook.py - hook support for mercurial # hook.py - hook support for mercurial
# #
# Copyright 2007 Matt Mackall <mpm@selenic.com> # Copyright 2007 Matt Mackall <mpm@selenic.com>
# #
# This software may be used and distributed according to the terms of the # This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version. # GNU General Public License version 2 or any later version.
from __future__ import absolute_import from __future__ import absolute_import
import contextlib
import os import os
import sys import sys
from .i18n import _ from .i18n import _
from .pycompat import getattr from .pycompat import getattr
from . import ( from . import (
demandimport, demandimport,
encoding, encoding,
res = runhooks(ui, repo, htype, hooks, throw=throw, **args) res = runhooks(ui, repo, htype, hooks, throw=throw, **args)
r = False r = False
for hname, cmd in hooks: for hname, cmd in hooks:
r = res[hname][0] or r r = res[hname][0] or r
return r return r
def runhooks(ui, repo, htype, hooks, throw=False, **args): @contextlib.contextmanager
args = pycompat.byteskwargs(args) def redirect_stdio():
res = {} """Redirects stdout to stderr, if possible."""
oldstdout = -1
oldstdout = -1
try: try:
for hname, cmd in hooks: if _redirect:
if oldstdout == -1 and _redirect:
try: try:
stdoutno = procutil.stdout.fileno() stdoutno = procutil.stdout.fileno()
stderrno = procutil.stderr.fileno() stderrno = procutil.stderr.fileno()
# temporarily redirect stdout to stderr, if possible # temporarily redirect stdout to stderr, if possible
if stdoutno >= 0 and stderrno >= 0: if stdoutno >= 0 and stderrno >= 0:
procutil.stdout.flush() procutil.stdout.flush()
oldstdout = os.dup(stdoutno) oldstdout = os.dup(stdoutno)
os.dup2(stderrno, stdoutno) os.dup2(stderrno, stdoutno)
except (OSError, AttributeError): except (OSError, AttributeError):
# files seem to be bogus, give up on redirecting (WSGI, etc) # files seem to be bogus, give up on redirecting (WSGI, etc)
pass pass
yield
finally:
# The stderr is fully buffered on Windows when connected to a pipe.
# A forcible flush is required to make small stderr data in the
# remote side available to the client immediately.
procutil.stderr.flush()
if _redirect and oldstdout >= 0:
procutil.stdout.flush() # write hook output to stderr fd
os.dup2(oldstdout, stdoutno)
os.close(oldstdout)
def runhooks(ui, repo, htype, hooks, throw=False, **args):
args = pycompat.byteskwargs(args)
res = {}
with redirect_stdio():
for hname, cmd in hooks:
if cmd is _fromuntrusted: if cmd is _fromuntrusted:
if throw: if throw:
raise error.HookAbort( raise error.HookAbort(
_(b'untrusted hook %s not executed') % hname, _(b'untrusted hook %s not executed') % hname,
hint=_(b"see 'hg help config.trusted'"), hint=_(b"see 'hg help config.trusted'"),
) )
ui.warn(_(b'warning: untrusted hook %s not executed\n') % hname) ui.warn(_(b'warning: untrusted hook %s not executed\n') % hname)
r = 1 r = 1
r, raised = pythonhook( r, raised = pythonhook(
ui, repo, htype, hname, hookfn, args, throw ui, repo, htype, hname, hookfn, args, throw
) )
else: else:
r = _exthook(ui, repo, htype, hname, cmd, args, throw) r = _exthook(ui, repo, htype, hname, cmd, args, throw)
raised = False raised = False
res[hname] = r, raised res[hname] = r, raised
finally:
# The stderr is fully buffered on Windows when connected to a pipe.
# A forcible flush is required to make small stderr data in the
# remote side available to the client immediately.
procutil.stderr.flush()
if _redirect and oldstdout >= 0:
procutil.stdout.flush() # write hook output to stderr fd
os.dup2(oldstdout, stdoutno)
os.close(oldstdout)
return res return res