policy.py
157 lines
| 4.7 KiB
| text/x-python
|
PythonLexer
/ mercurial / policy.py
|
r29266 | # policy.py - module policy logic for Mercurial. | ||
# | ||||
# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com> | ||||
# | ||||
# 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 | ||||
import sys | ||||
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r43359 | from .pycompat import getattr | ||
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r29266 | # Rules for how modules can be loaded. Values are: | ||
# | ||||
# c - require C extensions | ||||
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r42651 | # rust+c - require Rust and C extensions | ||
# rust+c-allow - allow Rust and C extensions with fallback to pure Python | ||||
# for each | ||||
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r29266 | # allow - allow pure Python implementation when C loading fails | ||
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r29490 | # cffi - required cffi versions (implemented within pure module) | ||
# cffi-allow - allow pure Python implementation if cffi version is missing | ||||
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r29266 | # py - only load pure Python modules | ||
# | ||||
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r32251 | # By default, fall back to the pure modules so the in-place build can | ||
# run without recompiling the C extensions. This will be overridden by | ||||
# __modulepolicy__ generated by setup.py. | ||||
policy = b'allow' | ||||
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r32366 | _packageprefs = { | ||
# policy: (versioned package, pure package) | ||||
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r43812 | b'c': ('cext', None), | ||
b'allow': ('cext', 'pure'), | ||||
b'cffi': ('cffi', None), | ||||
b'cffi-allow': ('cffi', 'pure'), | ||||
b'py': (None, 'pure'), | ||||
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r42651 | # For now, rust policies impact importrust only | ||
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r43812 | b'rust+c': ('cext', None), | ||
b'rust+c-allow': ('cext', 'pure'), | ||||
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r32366 | } | ||
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r29490 | |||
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r29266 | try: | ||
from . import __modulepolicy__ | ||||
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r43345 | |||
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r29266 | policy = __modulepolicy__.modulepolicy | ||
except ImportError: | ||||
pass | ||||
# PyPy doesn't load C extensions. | ||||
# | ||||
# The canonical way to do this is to test platform.python_implementation(). | ||||
# But we don't import platform and don't bloat for it here. | ||||
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r43812 | if '__pypy__' in sys.builtin_module_names: | ||
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r32205 | policy = b'cffi' | ||
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r29266 | |||
# Environment variable can always force settings. | ||||
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r31361 | if sys.version_info[0] >= 3: | ||
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r43812 | if 'HGMODULEPOLICY' in os.environ: | ||
policy = os.environ['HGMODULEPOLICY'].encode('utf-8') | ||||
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r31361 | else: | ||
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r43812 | policy = os.environ.get('HGMODULEPOLICY', policy) | ||
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r32366 | |||
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r43345 | |||
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r32366 | def _importfrom(pkgname, modname): | ||
# from .<pkgname> import <modname> (where . is looked through this module) | ||||
fakelocals = {} | ||||
pkg = __import__(pkgname, globals(), fakelocals, [modname], level=1) | ||||
try: | ||||
fakelocals[modname] = mod = getattr(pkg, modname) | ||||
except AttributeError: | ||||
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r43812 | raise ImportError('cannot import name %s' % modname) | ||
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r32366 | # force import; fakelocals[modname] may be replaced with the real module | ||
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r43373 | getattr(mod, '__doc__', None) | ||
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r32366 | return fakelocals[modname] | ||
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r43345 | |||
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r32428 | # keep in sync with "version" in C modules | ||
_cextversions = { | ||||
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r43812 | ('cext', 'base85'): 1, | ||
('cext', 'bdiff'): 3, | ||||
('cext', 'mpatch'): 1, | ||||
('cext', 'osutil'): 4, | ||||
r43859 | ('cext', 'parsers'): 15, | |||
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r32428 | } | ||
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r33755 | # map import request to other package or module | ||
_modredirects = { | ||||
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r43812 | ('cext', 'charencode'): ('cext', 'parsers'), | ||
('cffi', 'base85'): ('pure', 'base85'), | ||||
('cffi', 'charencode'): ('pure', 'charencode'), | ||||
('cffi', 'parsers'): ('pure', 'parsers'), | ||||
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r33755 | } | ||
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r43345 | |||
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r32366 | def _checkmod(pkgname, modname, mod): | ||
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r32511 | expected = _cextversions.get((pkgname, modname)) | ||
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r43373 | actual = getattr(mod, 'version', None) | ||
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r32366 | if actual != expected: | ||
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r43345 | raise ImportError( | ||
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r43812 | 'cannot import module %s.%s ' | ||
'(expected version: %d, actual: %r)' | ||||
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r43345 | % (pkgname, modname, expected, actual) | ||
) | ||||
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r32366 | |||
def importmod(modname): | ||||
"""Import module according to policy and check API version""" | ||||
try: | ||||
verpkg, purepkg = _packageprefs[policy] | ||||
except KeyError: | ||||
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r43812 | raise ImportError('invalid HGMODULEPOLICY %r' % policy) | ||
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r32366 | assert verpkg or purepkg | ||
if verpkg: | ||||
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r33755 | pn, mn = _modredirects.get((verpkg, modname), (verpkg, modname)) | ||
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r32366 | try: | ||
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r33755 | mod = _importfrom(pn, mn) | ||
if pn == verpkg: | ||||
_checkmod(pn, mn, mod) | ||||
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r32366 | return mod | ||
except ImportError: | ||||
if not purepkg: | ||||
raise | ||||
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r33755 | pn, mn = _modredirects.get((purepkg, modname), (purepkg, modname)) | ||
return _importfrom(pn, mn) | ||||
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r42651 | |||
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r43345 | |||
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r42651 | def _isrustpermissive(): | ||
"""Assuming the policy is a Rust one, tell if it's permissive.""" | ||||
return policy.endswith(b'-allow') | ||||
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r43345 | |||
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r42651 | def importrust(modname, member=None, default=None): | ||
"""Import Rust module according to policy and availability. | ||||
If policy isn't a Rust one, this returns `default`. | ||||
If either the module or its member is not available, this returns `default` | ||||
if policy is permissive and raises `ImportError` if not. | ||||
""" | ||||
if not policy.startswith(b'rust'): | ||||
return default | ||||
try: | ||||
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r43812 | mod = _importfrom('rustext', modname) | ||
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r42651 | except ImportError: | ||
if _isrustpermissive(): | ||||
return default | ||||
raise | ||||
if member is None: | ||||
return mod | ||||
try: | ||||
return getattr(mod, member) | ||||
except AttributeError: | ||||
if _isrustpermissive(): | ||||
return default | ||||
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r43809 | raise ImportError("Cannot import name %s" % member) | ||