mercurial/rcutil.py

sharesafe: introduce functionality to automatically upgrade shares

In past few months, we have developed a `share-safe` mode for sharing repository
in which share source requirements and config values are shared with the shares.

To get it rolling, an important task is to get these shares automatically
upgraded. We are focusing on an installation where shares are created by scripts
and test jobs. It will be difficult to manually upgrade these and we need some
functionality to do so automatically.

This patch introduces a config option to deal with it. If all of the following
conditions are met, we upgrade the share repository automatically:

* If the config option is enabled
* Share source repository is share-safe enabled
* Share is not share-safe enabled
* Any command is run in the share

Upgrading the share is pretty easy as it involves only editing the requirements
file.

Differential Revision: https://phab.mercurial-scm.org/D9679

# rcutil.py - utilities about config paths, special config sections etc.
#
#  Copyright Mercurial Contributors
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import os

from . import (
    encoding,
    pycompat,
    util,
)

from .utils import resourceutil

if pycompat.iswindows:
    from . import scmwindows as scmplatform
else:
    from . import scmposix as scmplatform

fallbackpager = scmplatform.fallbackpager
systemrcpath = scmplatform.systemrcpath
userrcpath = scmplatform.userrcpath


def _expandrcpath(path):
    '''path could be a file or a directory. return a list of file paths'''
    p = util.expandpath(path)
    if os.path.isdir(p):
        join = os.path.join
        return sorted(
            join(p, f) for f, k in util.listdir(p) if f.endswith(b'.rc')
        )
    return [p]


def envrcitems(env=None):
    """Return [(section, name, value, source)] config items.

    The config items are extracted from environment variables specified by env,
    used to override systemrc, but not userrc.

    If env is not provided, encoding.environ will be used.
    """
    if env is None:
        env = encoding.environ
    checklist = [
        (b'EDITOR', b'ui', b'editor'),
        (b'VISUAL', b'ui', b'editor'),
        (b'PAGER', b'pager', b'pager'),
    ]
    result = []
    for envname, section, configname in checklist:
        if envname not in env:
            continue
        result.append((section, configname, env[envname], b'$%s' % envname))
    return result


def default_rc_resources():
    """return rc resource IDs in defaultrc"""
    rsrcs = resourceutil.contents(b'mercurial.defaultrc')
    return [
        (b'mercurial.defaultrc', r)
        for r in sorted(rsrcs)
        if resourceutil.is_resource(b'mercurial.defaultrc', r)
        and r.endswith(b'.rc')
    ]


def rccomponents():
    """return an ordered [(type, obj)] about where to load configs.

    respect $HGRCPATH. if $HGRCPATH is empty, only .hg/hgrc of current repo is
    used. if $HGRCPATH is not set, the platform default will be used.

    if a directory is provided, *.rc files under it will be used.

    type could be either 'path', 'items' or 'resource'. If type is 'path',
    obj is a string, and is the config file path. if type is 'items', obj is a
    list of (section, name, value, source) that should fill the config directly.
    If type is 'resource', obj is a tuple of (package name, resource name).
    """
    envrc = (b'items', envrcitems())

    if b'HGRCPATH' in encoding.environ:
        # assume HGRCPATH is all about user configs so environments can be
        # overridden.
        _rccomponents = [envrc]
        for p in encoding.environ[b'HGRCPATH'].split(pycompat.ospathsep):
            if not p:
                continue
            _rccomponents.extend((b'path', p) for p in _expandrcpath(p))
    else:
        _rccomponents = [(b'resource', r) for r in default_rc_resources()]

        normpaths = lambda paths: [
            (b'path', os.path.normpath(p)) for p in paths
        ]
        _rccomponents.extend(normpaths(systemrcpath()))
        _rccomponents.append(envrc)
        _rccomponents.extend(normpaths(userrcpath()))
    return _rccomponents


def defaultpagerenv():
    """return a dict of default environment variables and their values,
    intended to be set before starting a pager.
    """
    return {b'LESS': b'FRX', b'LV': b'-c'}


def use_repo_hgrc():
    """True if repositories `.hg/hgrc` config should be read"""
    return b'HGRCSKIPREPO' not in encoding.environ