import-checker: allow all absolute imports of stdlib modules
Before this patch, we didn't allow imports like
from importlib import resources
(That's the reason I used `import importlib.resources` in D7629.)
I think that form is still an absolute import, so I don't think we
forbade on purpose.
Differential Revision: https://phab.mercurial-scm.org/D7700
# Copyright (c) 2016-present, Gregory Szorc
# All rights reserved.
#
# This software may be modified and distributed under the terms
# of the BSD license. See the LICENSE file for details.
from __future__ import absolute_import
import cffi
import distutils.ccompiler
import os
import re
import subprocess
import tempfile
HERE = os.path.abspath(os.path.dirname(__file__))
SOURCES = ['zstd/%s' % p for p in (
'common/debug.c',
'common/entropy_common.c',
'common/error_private.c',
'common/fse_decompress.c',
'common/pool.c',
'common/threading.c',
'common/xxhash.c',
'common/zstd_common.c',
'compress/fse_compress.c',
'compress/hist.c',
'compress/huf_compress.c',
'compress/zstd_compress.c',
'compress/zstd_compress_literals.c',
'compress/zstd_compress_sequences.c',
'compress/zstd_double_fast.c',
'compress/zstd_fast.c',
'compress/zstd_lazy.c',
'compress/zstd_ldm.c',
'compress/zstd_opt.c',
'compress/zstdmt_compress.c',
'decompress/huf_decompress.c',
'decompress/zstd_ddict.c',
'decompress/zstd_decompress.c',
'decompress/zstd_decompress_block.c',
'dictBuilder/cover.c',
'dictBuilder/fastcover.c',
'dictBuilder/divsufsort.c',
'dictBuilder/zdict.c',
)]
# Headers whose preprocessed output will be fed into cdef().
HEADERS = [os.path.join(HERE, 'zstd', *p) for p in (
('zstd.h',),
('dictBuilder', 'zdict.h'),
)]
INCLUDE_DIRS = [os.path.join(HERE, d) for d in (
'zstd',
'zstd/common',
'zstd/compress',
'zstd/decompress',
'zstd/dictBuilder',
)]
# cffi can't parse some of the primitives in zstd.h. So we invoke the
# preprocessor and feed its output into cffi.
compiler = distutils.ccompiler.new_compiler()
# Needed for MSVC.
if hasattr(compiler, 'initialize'):
compiler.initialize()
# Distutils doesn't set compiler.preprocessor, so invoke the preprocessor
# manually.
if compiler.compiler_type == 'unix':
args = list(compiler.executables['compiler'])
args.extend([
'-E',
'-DZSTD_STATIC_LINKING_ONLY',
'-DZDICT_STATIC_LINKING_ONLY',
])
elif compiler.compiler_type == 'msvc':
args = [compiler.cc]
args.extend([
'/EP',
'/DZSTD_STATIC_LINKING_ONLY',
'/DZDICT_STATIC_LINKING_ONLY',
])
else:
raise Exception('unsupported compiler type: %s' % compiler.compiler_type)
def preprocess(path):
with open(path, 'rb') as fh:
lines = []
it = iter(fh)
for l in it:
# zstd.h includes <stddef.h>, which is also included by cffi's
# boilerplate. This can lead to duplicate declarations. So we strip
# this include from the preprocessor invocation.
#
# The same things happens for including zstd.h, so give it the same
# treatment.
#
# We define ZSTD_STATIC_LINKING_ONLY, which is redundant with the inline
# #define in zstdmt_compress.h and results in a compiler warning. So drop
# the inline #define.
if l.startswith((b'#include <stddef.h>',
b'#include "zstd.h"',
b'#define ZSTD_STATIC_LINKING_ONLY')):
continue
# ZSTDLIB_API may not be defined if we dropped zstd.h. It isn't
# important so just filter it out.
if l.startswith(b'ZSTDLIB_API'):
l = l[len(b'ZSTDLIB_API '):]
lines.append(l)
fd, input_file = tempfile.mkstemp(suffix='.h')
os.write(fd, b''.join(lines))
os.close(fd)
try:
env = dict(os.environ)
if getattr(compiler, '_paths', None):
env['PATH'] = compiler._paths
process = subprocess.Popen(args + [input_file], stdout=subprocess.PIPE,
env=env)
output = process.communicate()[0]
ret = process.poll()
if ret:
raise Exception('preprocessor exited with error')
return output
finally:
os.unlink(input_file)
def normalize_output(output):
lines = []
for line in output.splitlines():
# CFFI's parser doesn't like __attribute__ on UNIX compilers.
if line.startswith(b'__attribute__ ((visibility ("default"))) '):
line = line[len(b'__attribute__ ((visibility ("default"))) '):]
if line.startswith(b'__attribute__((deprecated('):
continue
elif b'__declspec(deprecated(' in line:
continue
lines.append(line)
return b'\n'.join(lines)
ffi = cffi.FFI()
# zstd.h uses a possible undefined MIN(). Define it until
# https://github.com/facebook/zstd/issues/976 is fixed.
# *_DISABLE_DEPRECATE_WARNINGS prevents the compiler from emitting a warning
# when cffi uses the function. Since we statically link against zstd, even
# if we use the deprecated functions it shouldn't be a huge problem.
ffi.set_source('_zstd_cffi', '''
#define MIN(a,b) ((a)<(b) ? (a) : (b))
#define ZSTD_STATIC_LINKING_ONLY
#include <zstd.h>
#define ZDICT_STATIC_LINKING_ONLY
#define ZDICT_DISABLE_DEPRECATE_WARNINGS
#include <zdict.h>
''', sources=SOURCES,
include_dirs=INCLUDE_DIRS,
extra_compile_args=['-DZSTD_MULTITHREAD'])
DEFINE = re.compile(b'^\\#define ([a-zA-Z0-9_]+) ')
sources = []
# Feed normalized preprocessor output for headers into the cdef parser.
for header in HEADERS:
preprocessed = preprocess(header)
sources.append(normalize_output(preprocessed))
# #define's are effectively erased as part of going through preprocessor.
# So perform a manual pass to re-add those to the cdef source.
with open(header, 'rb') as fh:
for line in fh:
line = line.strip()
m = DEFINE.match(line)
if not m:
continue
if m.group(1) == b'ZSTD_STATIC_LINKING_ONLY':
continue
# The parser doesn't like some constants with complex values.
if m.group(1) in (b'ZSTD_LIB_VERSION', b'ZSTD_VERSION_STRING'):
continue
# The ... is magic syntax by the cdef parser to resolve the
# value at compile time.
sources.append(m.group(0) + b' ...')
cdeflines = b'\n'.join(sources).splitlines()
cdeflines = [l for l in cdeflines if l.strip()]
ffi.cdef(b'\n'.join(cdeflines).decode('latin1'))
if __name__ == '__main__':
ffi.compile()