view contrib/python-zstandard/make_cffi.py @ 31987:8823daaf4665

obsolescence: add test for the "branch replacement" logic during push, case D2

Mercurial checks for the introduction of new heads on push. Evolution comes
into play to detect if existing branches on the server are being replaced by
some of the new one we push.

The current code for this logic is very basic (eg: issue4354) and was poorly
tested. We have a better implementation coming in the evolve extension fixing
these issues and with more serious tests coverage. In the process of upstreaming
this improved logic, we start with adding the test case that are already passing
with the current implementation. Once they are all in, we'll upstream the better
implementation and the extra test cases.

See inline documentation for details about the test case added in this
changeset.

# 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/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/huf_compress.c',
    'compress/zstd_compress.c',
    'compress/zstdmt_compress.c',
    'decompress/huf_decompress.c',
    'decompress/zstd_decompress.c',
    'dictBuilder/cover.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',),
    ('compress', 'zstdmt_compress.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 = []
        for l in fh:
            # 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:
        process = subprocess.Popen(args + [input_file], stdout=subprocess.PIPE)
        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()
# *_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', '''
#include "mem.h"
#define ZSTD_STATIC_LINKING_ONLY
#include "zstd.h"
#define ZDICT_STATIC_LINKING_ONLY
#define ZDICT_DISABLE_DEPRECATE_WARNINGS
#include "zdict.h"
#include "zstdmt_compress.h"
''', sources=SOURCES, include_dirs=INCLUDE_DIRS)

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()