view hgext/logtoprocess.py @ 29630:67b180c0e263 stable

extdiff: escape path for docstring (issue5301)

The existing code (a) assumed path would be specified in
encoding.encoding and (b) assumed unicode() objects wouldn't cause
other parts of Mercurial to blow up. Both are dangerous assumptions.

Since we don't know the encoding of path and can't pass non-ASCII
through docstrings, just escape the path and drop the early _(). Will
have to suffice until we can teach docstrings to handle UTF-8b
escaping.

This has the side-effect that the line containing the path is now
variable by the time it reaches _() and thus can't be translated.

# logtoprocess.py - send ui.log() data to a subprocess
#
# Copyright 2016 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""Send ui.log() data to a subprocess (EXPERIMENTAL)

This extension lets you specify a shell command per ui.log() event,
sending all remaining arguments to as environment variables to that command.

Each positional argument to the method results in a `MSG[N]` key in the
environment, starting at 1 (so `MSG1`, `MSG2`, etc.). Each keyword argument
is set as a `OPT_UPPERCASE_KEY` variable (so the key is uppercased, and
prefixed with `OPT_`). The original event name is passed in the `EVENT`
environment variable, and the process ID of mercurial is given in `HGPID`.

So given a call `ui.log('foo', 'bar', 'baz', spam='eggs'), a script configured
for the `foo` event can expect an environment with `MSG1=bar`, `MSG2=baz`, and
`OPT_SPAM=eggs`.

Scripts are configured in the `[logtoprocess]` section, each key an event name.
For example::

  [logtoprocess]
  commandexception = echo "$MSG2$MSG3" > /var/log/mercurial_exceptions.log

would log the warning message and traceback of any failed command dispatch.

Scripts are run asychronously as detached daemon processes; mercurial will
not ensure that they exit cleanly.

"""

from __future__ import absolute_import

import itertools
import os
import platform
import subprocess
import sys

# 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 uisetup(ui):
    if platform.system() == 'Windows':
        # no fork on Windows, but we can create a detached process
        # https://msdn.microsoft.com/en-us/library/windows/desktop/ms684863.aspx
        # No stdlib constant exists for this value
        DETACHED_PROCESS = 0x00000008
        _creationflags = DETACHED_PROCESS | subprocess.CREATE_NEW_PROCESS_GROUP

        def runshellcommand(script, env):
            # we can't use close_fds *and* redirect stdin. I'm not sure that we
            # need to because the detached process has no console connection.
            subprocess.Popen(
                script, shell=True, env=env, close_fds=True,
                creationflags=_creationflags)
    else:
        def runshellcommand(script, env):
            # double-fork to completely detach from the parent process
            # based on http://code.activestate.com/recipes/278731
            pid = os.fork()
            if pid:
                # parent
                return
            # subprocess.Popen() forks again, all we need to add is
            # flag the new process as a new session.
            if sys.version_info < (3, 2):
                newsession = {'preexec_fn': os.setsid}
            else:
                newsession = {'start_new_session': True}
            try:
                # connect stdin to devnull to make sure the subprocess can't
                # muck up that stream for mercurial.
                subprocess.Popen(
                    script, shell=True, stdin=open(os.devnull, 'r'), env=env,
                    close_fds=True, **newsession)
            finally:
                # mission accomplished, this child needs to exit and not
                # continue the hg process here.
                os._exit(0)

    class logtoprocessui(ui.__class__):
        def log(self, event, *msg, **opts):
            """Map log events to external commands

            Arguments are passed on as environment variables.

            """
            script = self.config('logtoprocess', event)
            if script:
                if msg:
                    # try to format the log message given the remaining
                    # arguments
                    try:
                        # Python string formatting with % either uses a
                        # dictionary *or* tuple, but not both. If we have
                        # keyword options, assume we need a mapping.
                        formatted = msg[0] % (opts or msg[1:])
                    except (TypeError, KeyError):
                        # Failed to apply the arguments, ignore
                        formatted = msg[0]
                    messages = (formatted,) + msg[1:]
                else:
                    messages = msg
                # positional arguments are listed as MSG[N] keys in the
                # environment
                msgpairs = (
                    ('MSG{0:d}'.format(i), str(m))
                    for i, m in enumerate(messages, 1))
                # keyword arguments get prefixed with OPT_ and uppercased
                optpairs = (
                    ('OPT_{0}'.format(key.upper()), str(value))
                    for key, value in opts.iteritems())
                env = dict(itertools.chain(os.environ.items(),
                                           msgpairs, optpairs),
                           EVENT=event, HGPID=str(os.getpid()))
                # Connect stdin to /dev/null to prevent child processes messing
                # with mercurial's stdin.
                runshellcommand(script, env)
            return super(logtoprocessui, self).log(event, *msg, **opts)

    # Replace the class for this instance and all clones created from it:
    ui.__class__ = logtoprocessui