Source code for ctypes.util
From Get docs
< Source code for ctypesPython/docs/3.6/ modules/ctypes/util
Source code for ctypes.util
import os
import shutil
import subprocess
import sys
# find_library(name) returns the pathname of a library, or None.
if os.name == "nt":
def _get_build_version():
"""Return the version of MSVC that was used to build Python.
For Python 2.3 and up, the version number is included in
sys.version. For earlier versions, assume the compiler is MSVC 6.
"""
# This function was copied from Lib/distutils/msvccompiler.py
prefix = "MSC v."
i = sys.version.find(prefix)
if i == -1:
return 6
i = i + len(prefix)
s, rest = sys.version[i:].split(" ", 1)
majorVersion = int(s[:-2]) - 6
if majorVersion >= 13:
majorVersion += 1
minorVersion = int(s[2:3]) / 10.0
# I don't think paths are affected by minor version in version 6
if majorVersion == 6:
minorVersion = 0
if majorVersion >= 6:
return majorVersion + minorVersion
# else we don't know what version of the compiler this is
return None
def find_msvcrt():
"""Return the name of the VC runtime dll"""
version = _get_build_version()
if version is None:
# better be safe than sorry
return None
if version <= 6:
clibname = 'msvcrt'
elif version <= 13:
clibname = 'msvcr%d' % (version * 10)
else:
# CRT is no longer directly loadable. See issue23606 for the
# discussion about alternative approaches.
return None
# If python was built with in debug mode
import importlib.machinery
if '_d.pyd' in importlib.machinery.EXTENSION_SUFFIXES:
clibname += 'd'
return clibname+'.dll'
def find_library(name):
if name in ('c', 'm'):
return find_msvcrt()
# See MSDN for the REAL search order.
for directory in os.environ['PATH'].split(os.pathsep):
fname = os.path.join(directory, name)
if os.path.isfile(fname):
return fname
if fname.lower().endswith(".dll"):
continue
fname = fname + ".dll"
if os.path.isfile(fname):
return fname
return None
elif os.name == "posix" and sys.platform == "darwin":
from ctypes.macholib.dyld import dyld_find as _dyld_find
def find_library(name):
possible = ['lib%s.dylib' % name,
'%s.dylib' % name,
'%s.framework/%s' % (name, name)]
for name in possible:
try:
return _dyld_find(name)
except ValueError:
continue
return None
elif sys.platform.startswith("aix"):
# AIX has two styles of storing shared libraries
# GNU auto_tools refer to these as svr4 and aix
# svr4 (System V Release 4) is a regular file, often with .so as suffix
# AIX style uses an archive (suffix .a) with members (e.g., shr.o, libssl.so)
# see issue#26439 and _aix.py for more details
from ctypes._aix import find_library
elif os.name == "posix":
# Andreas Degert's find functions, using gcc, /sbin/ldconfig, objdump
import re, tempfile
def _is_elf(filename):
"Return True if the given file is an ELF file"
elf_header = b'\x7fELF'
with open(filename, 'br') as thefile:
return thefile.read(4) == elf_header
def _findLib_gcc(name):
# Run GCC's linker with the -t (aka --trace) option and examine the
# library name it prints out. The GCC command will fail because we
# haven't supplied a proper program with main(), but that does not
# matter.
expr = os.fsencode(r'[^\(\)\s]*lib%s\.[^\(\)\s]*' % re.escape(name))
c_compiler = shutil.which('gcc')
if not c_compiler:
c_compiler = shutil.which('cc')
if not c_compiler:
# No C compiler available, give up
return None
temp = tempfile.NamedTemporaryFile()
try:
args = [c_compiler, '-Wl,-t', '-o', temp.name, '-l' + name]
env = dict(os.environ)
env['LC_ALL'] = 'C'
env['LANG'] = 'C'
try:
proc = subprocess.Popen(args,
stdout=subprocess.PIPE,
stderr=subprocess.STDOUT,
env=env)
except OSError: # E.g. bad executable
return None
with proc:
trace = proc.stdout.read()
finally:
try:
temp.close()
except FileNotFoundError:
# Raised if the file was already removed, which is the normal
# behaviour of GCC if linking fails
pass
res = re.findall(expr, trace)
if not res:
return None
for file in res:
# Check if the given file is an elf file: gcc can report
# some files that are linker scripts and not actual
# shared objects. See bpo-41976 for more details
if not _is_elf(file):
continue
return os.fsdecode(file)
if sys.platform == "sunos5":
# use /usr/ccs/bin/dump on solaris
def _get_soname(f):
if not f:
return None
try:
proc = subprocess.Popen(("/usr/ccs/bin/dump", "-Lpv", f),
stdout=subprocess.PIPE,
stderr=subprocess.DEVNULL)
except OSError: # E.g. command not found
return None
with proc:
data = proc.stdout.read()
res = re.search(br'\[.*\]\sSONAME\s+([^\s]+)', data)
if not res:
return None
return os.fsdecode(res.group(1))
else:
def _get_soname(f):
# assuming GNU binutils / ELF
if not f:
return None
objdump = shutil.which('objdump')
if not objdump:
# objdump is not available, give up
return None
try:
proc = subprocess.Popen((objdump, '-p', '-j', '.dynamic', f),
stdout=subprocess.PIPE,
stderr=subprocess.DEVNULL)
except OSError: # E.g. bad executable
return None
with proc:
dump = proc.stdout.read()
res = re.search(br'\sSONAME\s+([^\s]+)', dump)
if not res:
return None
return os.fsdecode(res.group(1))
if sys.platform.startswith(("freebsd", "openbsd", "dragonfly")):
def _num_version(libname):
# "libxyz.so.MAJOR.MINOR" => [ MAJOR, MINOR ]
parts = libname.split(b".")
nums = []
try:
while parts:
nums.insert(0, int(parts.pop()))
except ValueError:
pass
return nums or [sys.maxsize]
def find_library(name):
ename = re.escape(name)
expr = r':-l%s\.\S+ => \S*/(lib%s\.\S+)' % (ename, ename)
expr = os.fsencode(expr)
try:
proc = subprocess.Popen(('/sbin/ldconfig', '-r'),
stdout=subprocess.PIPE,
stderr=subprocess.DEVNULL)
except OSError: # E.g. command not found
data = b''
else:
with proc:
data = proc.stdout.read()
res = re.findall(expr, data)
if not res:
return _get_soname(_findLib_gcc(name))
res.sort(key=_num_version)
return os.fsdecode(res[-1])
elif sys.platform == "sunos5":
def _findLib_crle(name, is64):
if not os.path.exists('/usr/bin/crle'):
return None
env = dict(os.environ)
env['LC_ALL'] = 'C'
if is64:
args = ('/usr/bin/crle', '-64')
else:
args = ('/usr/bin/crle',)
paths = None
try:
proc = subprocess.Popen(args,
stdout=subprocess.PIPE,
stderr=subprocess.DEVNULL,
env=env)
except OSError: # E.g. bad executable
return None
with proc:
for line in proc.stdout:
line = line.strip()
if line.startswith(b'Default Library Path (ELF):'):
paths = os.fsdecode(line).split()[4]
if not paths:
return None
for dir in paths.split(":"):
libfile = os.path.join(dir, "lib%s.so" % name)
if os.path.exists(libfile):
return libfile
return None
def find_library(name, is64 = False):
return _get_soname(_findLib_crle(name, is64) or _findLib_gcc(name))
else:
def _findSoname_ldconfig(name):
import struct
if struct.calcsize('l') == 4:
machine = os.uname().machine + '-32'
else:
machine = os.uname().machine + '-64'
mach_map = {
'x86_64-64': 'libc6,x86-64',
'ppc64-64': 'libc6,64bit',
'sparc64-64': 'libc6,64bit',
's390x-64': 'libc6,64bit',
'ia64-64': 'libc6,IA-64',
}
abi_type = mach_map.get(machine, 'libc6')
# XXX assuming GLIBC's ldconfig (with option -p)
regex = r'\s+(lib%s\.[^\s]+)\s+\(%s'
regex = os.fsencode(regex % (re.escape(name), abi_type))
try:
with subprocess.Popen(['/sbin/ldconfig', '-p'],
stdin=subprocess.DEVNULL,
stderr=subprocess.DEVNULL,
stdout=subprocess.PIPE,
env={'LC_ALL': 'C', 'LANG': 'C'}) as p:
res = re.search(regex, p.stdout.read())
if res:
return os.fsdecode(res.group(1))
except OSError:
pass
def _findLib_ld(name):
# See issue #9998 for why this is needed
expr = r'[^\(\)\s]*lib%s\.[^\(\)\s]*' % re.escape(name)
cmd = ['ld', '-t']
libpath = os.environ.get('LD_LIBRARY_PATH')
if libpath:
for d in libpath.split(':'):
cmd.extend(['-L', d])
cmd.extend(['-o', os.devnull, '-l%s' % name])
result = None
try:
p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
universal_newlines=True)
out, _ = p.communicate()
res = re.findall(expr, os.fsdecode(out))
for file in res:
# Check if the given file is an elf file: gcc can report
# some files that are linker scripts and not actual
# shared objects. See bpo-41976 for more details
if not _is_elf(file):
continue
return os.fsdecode(file)
except Exception:
pass # result will be None
return result
[docs] def find_library(name):
# See issue #9998
return _findSoname_ldconfig(name) or \
_get_soname(_findLib_gcc(name)) or _get_soname(_findLib_ld(name))
################################################################
# test code
def test():
from ctypes import cdll
if os.name == "nt":
print(cdll.msvcrt)
print(cdll.load("msvcrt"))
print(find_library("msvcrt"))
if os.name == "posix":
# find and load_version
print(find_library("m"))
print(find_library("c"))
print(find_library("bz2"))
# load
if sys.platform == "darwin":
print(cdll.LoadLibrary("libm.dylib"))
print(cdll.LoadLibrary("libcrypto.dylib"))
print(cdll.LoadLibrary("libSystem.dylib"))
print(cdll.LoadLibrary("System.framework/System"))
# issue-26439 - fix broken test call for AIX
elif sys.platform.startswith("aix"):
from ctypes import CDLL
if sys.maxsize < 2**32:
print(f"Using CDLL(name, os.RTLD_MEMBER): {CDLL('libc.a(shr.o)', os.RTLD_MEMBER)}")
print(f"Using cdll.LoadLibrary(): {cdll.LoadLibrary('libc.a(shr.o)')}")
# librpm.so is only available as 32-bit shared library
print(find_library("rpm"))
print(cdll.LoadLibrary("librpm.so"))
else:
print(f"Using CDLL(name, os.RTLD_MEMBER): {CDLL('libc.a(shr_64.o)', os.RTLD_MEMBER)}")
print(f"Using cdll.LoadLibrary(): {cdll.LoadLibrary('libc.a(shr_64.o)')}")
print(f"crypt\t:: {find_library('crypt')}")
print(f"crypt\t:: {cdll.LoadLibrary(find_library('crypt'))}")
print(f"crypto\t:: {find_library('crypto')}")
print(f"crypto\t:: {cdll.LoadLibrary(find_library('crypto'))}")
else:
print(cdll.LoadLibrary("libm.so"))
print(cdll.LoadLibrary("libcrypt.so"))
print(find_library("crypt"))
if __name__ == "__main__":
test()
