# -*- coding: utf-8 -*-
# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
""" This module compiles the intercept library. """
import sys
import os
import os.path
import re
import tempfile
import shutil
import contextlib
import logging
__all__ = ['build_libear']
def build_libear(compiler, dst_dir):
""" Returns the full path to the 'libear' library. """
try:
src_dir = os.path.dirname(os.path.realpath(__file__))
toolset = make_toolset(src_dir)
toolset.set_compiler(compiler)
toolset.set_language_standard('c99')
toolset.add_definitions(['-D_GNU_SOURCE'])
configure = do_configure(toolset)
configure.check_function_exists('execve', 'HAVE_EXECVE')
configure.check_function_exists('execv', 'HAVE_EXECV')
configure.check_function_exists('execvpe', 'HAVE_EXECVPE')
configure.check_function_exists('execvp', 'HAVE_EXECVP')
configure.check_function_exists('execvP', 'HAVE_EXECVP2')
configure.check_function_exists('exect', 'HAVE_EXECT')
configure.check_function_exists('execl', 'HAVE_EXECL')
configure.check_function_exists('execlp', 'HAVE_EXECLP')
configure.check_function_exists('execle', 'HAVE_EXECLE')
configure.check_function_exists('posix_spawn', 'HAVE_POSIX_SPAWN')
configure.check_function_exists('posix_spawnp', 'HAVE_POSIX_SPAWNP')
configure.check_symbol_exists('_NSGetEnviron', 'crt_externs.h',
'HAVE_NSGETENVIRON')
configure.write_by_template(
os.path.join(src_dir, 'config.h.in'),
os.path.join(dst_dir, 'config.h'))
target = create_shared_library('ear', toolset)
target.add_include(dst_dir)
target.add_sources('ear.c')
target.link_against(toolset.dl_libraries())
target.link_against(['pthread'])
target.build_release(dst_dir)
return os.path.join(dst_dir, target.name)
except Exception:
logging.info("Could not build interception library.", exc_info=True)
return None
def execute(cmd, *args, **kwargs):
""" Make subprocess execution silent. """
import subprocess
kwargs.update({'stdout': subprocess.PIPE, 'stderr': subprocess.STDOUT})
return subprocess.check_call(cmd, *args, **kwargs)
@contextlib.contextmanager
def TemporaryDirectory(**kwargs):
name = tempfile.mkdtemp(**kwargs)
try:
yield name
finally:
shutil.rmtree(name)
class Toolset(object):
""" Abstract class to represent different toolset. """
def __init__(self, src_dir):
self.src_dir = src_dir
self.compiler = None
self.c_flags = []
def set_compiler(self, compiler):
""" part of public interface """
self.compiler = compiler
def set_language_standard(self, standard):
""" part of public interface """
self.c_flags.append('-std=' + standard)
def add_definitions(self, defines):
""" part of public interface """
self.c_flags.extend(defines)
def dl_libraries(self):
raise NotImplementedError()
def shared_library_name(self, name):
raise NotImplementedError()
def shared_library_c_flags(self, release):
extra = ['-DNDEBUG', '-O3'] if release else []
return extra + ['-fPIC'] + self.c_flags
def shared_library_ld_flags(self, release, name):
raise NotImplementedError()
class DarwinToolset(Toolset):
def __init__(self, src_dir):
Toolset.__init__(self, src_dir)
def dl_libraries(self):
return []
def shared_library_name(self, name):
return 'lib' + name + '.dylib'
def shared_library_ld_flags(self, release, name):
extra = ['-dead_strip'] if release else []
return extra + ['-dynamiclib', '-install_name', '@rpath/' + name]
class UnixToolset(Toolset):
def __init__(self, src_dir):
Toolset.__init__(self, src_dir)
def dl_libraries(self):
return []
def shared_library_name(self, name):
return 'lib' + name + '.so'
def shared_library_ld_flags(self, release, name):
extra = [] if release else []
return extra + ['-shared', '-Wl,-soname,' + name]
class LinuxToolset(UnixToolset):
def __init__(self, src_dir):
UnixToolset.__init__(self, src_dir)
def dl_libraries(self):
return ['dl']
def make_toolset(src_dir):
platform = sys.platform
if platform in {'win32', 'cygwin'}:
raise RuntimeError('not implemented on this platform')
elif platform == 'darwin':
return DarwinToolset(src_dir)
elif platform in {'linux', 'linux2'}:
return LinuxToolset(src_dir)
else:
return UnixToolset(src_dir)
class Configure(object):
def __init__(self, toolset):
self.ctx = toolset
self.results = {'APPLE': sys.platform == 'darwin'}
def _try_to_compile_and_link(self, source):
try:
with TemporaryDirectory() as work_dir:
src_file = 'check.c'
with open(os.path.join(work_dir, src_file), 'w') as handle:
handle.write(source)
execute([self.ctx.compiler, src_file] + self.ctx.c_flags,
cwd=work_dir)
return True
except Exception:
return False
def check_function_exists(self, function, name):
template = "int FUNCTION(); int main() { return FUNCTION(); }"
source = template.replace("FUNCTION", function)
logging.debug('Checking function %s', function)
found = self._try_to_compile_and_link(source)
logging.debug('Checking function %s -- %s', function,
'found' if found else 'not found')
self.results.update({name: found})
def check_symbol_exists(self, symbol, include, name):
template = """#include <INCLUDE>
int main() { return ((int*)(&SYMBOL))[0]; }"""
source = template.replace('INCLUDE', include).replace("SYMBOL", symbol)
logging.debug('Checking symbol %s', symbol)
found = self._try_to_compile_and_link(source)
logging.debug('Checking symbol %s -- %s', symbol,
'found' if found else 'not found')
self.results.update({name: found})
def write_by_template(self, template, output):
def transform(line, definitions):
pattern = re.compile(r'^#cmakedefine\s+(\S+)')
m = pattern.match(line)
if m:
key = m.group(1)
if key not in definitions or not definitions[key]:
return '/* #undef {0} */{1}'.format(key, os.linesep)
else:
return '#define {0}{1}'.format(key, os.linesep)
return line
with open(template, 'r') as src_handle:
logging.debug('Writing config to %s', output)
with open(output, 'w') as dst_handle:
for line in src_handle:
dst_handle.write(transform(line, self.results))
def do_configure(toolset):
return Configure(toolset)
class SharedLibrary(object):
def __init__(self, name, toolset):
self.name = toolset.shared_library_name(name)
self.ctx = toolset
self.inc = []
self.src = []
self.lib = []
def add_include(self, directory):
self.inc.extend(['-I', directory])
def add_sources(self, source):
self.src.append(source)
def link_against(self, libraries):
self.lib.extend(['-l' + lib for lib in libraries])
def build_release(self, directory):
for src in self.src:
logging.debug('Compiling %s', src)
execute(
[self.ctx.compiler, '-c', os.path.join(self.ctx.src_dir, src),
'-o', src + '.o'] + self.inc +
self.ctx.shared_library_c_flags(True),
cwd=directory)
logging.debug('Linking %s', self.name)
execute(
[self.ctx.compiler] + [src + '.o' for src in self.src] +
['-o', self.name] + self.lib +
self.ctx.shared_library_ld_flags(True, self.name),
cwd=directory)
def create_shared_library(name, toolset):
return SharedLibrary(name, toolset)