hgext/logtoprocess.py

sslutil: add support for clients to set TLSv1.3 as the minimum protocol

AFAICT, all of the TLS versions are supported by the server without doing any
explicit work, and there's only a `devel` config to specify an exact version on
the server side.  Clients would also use TLSv1.3 if available, but this prevents
the server from negotiating down.  This also causes "tls1.3" to be listed in
`hg debuginstall`, even though it was previously supported (if the Python
intepreter supported it- IDK if there's a good way to proactively test for and
show future protocols without requiring manual updates like this).

The v1.3 tests are nested inside the v1.2 tests for simplicity.  The v1.2 blocks
already assume v1.0 and v1.1 support, so this seems reasonable for now.  If/when
the older protocols start getting dropped, this will have to be reworked anyway.

# 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.

Positional arguments construct a log message, which is passed in the `MSG1`
environment variables. 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 %s\n', 'baz', spam='eggs'), a script
configured for the `foo` event can expect an environment with `MSG1=bar baz`,
and `OPT_SPAM=eggs`.

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

  [logtoprocess]
  commandexception = echo "$MSG1" > /var/log/mercurial_exceptions.log

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

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

"""

from __future__ import annotations

import os

from mercurial.utils import procutil

# 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'


class processlogger:
    """Map log events to external commands

    Arguments are passed on as environment variables.
    """

    def __init__(self, ui):
        self._scripts = dict(ui.configitems(b'logtoprocess'))

    def tracked(self, event):
        return bool(self._scripts.get(event))

    def log(self, ui, event, msg, opts):
        script = self._scripts[event]
        maxmsg = 100000
        if len(msg) > maxmsg:
            # Each env var has a 128KiB limit on linux. msg can be long, in
            # particular for command event, where it's the full command line.
            # Prefer truncating the message than raising "Argument list too
            # long" error.
            msg = msg[:maxmsg] + b' (truncated)'
        env = {
            b'EVENT': event,
            b'HGPID': os.getpid(),
            b'MSG1': msg,
        }
        # keyword arguments get prefixed with OPT_ and uppercased
        env.update(
            (b'OPT_%s' % key.upper(), value) for key, value in opts.items()
        )
        fullenv = procutil.shellenviron(env)
        procutil.runbgcommand(script, fullenv, shell=True)


def uipopulate(ui):
    ui.setlogger(b'logtoprocess', processlogger(ui))