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# The following comment should be removed at some point in the future. | |
# mypy: strict-optional=False | |
import os | |
import sys | |
from typing import Optional, Tuple | |
def glibc_version_string() -> Optional[str]: | |
"Returns glibc version string, or None if not using glibc." | |
return glibc_version_string_confstr() or glibc_version_string_ctypes() | |
def glibc_version_string_confstr() -> Optional[str]: | |
"Primary implementation of glibc_version_string using os.confstr." | |
# os.confstr is quite a bit faster than ctypes.DLL. It's also less likely | |
# to be broken or missing. This strategy is used in the standard library | |
# platform module: | |
# https://github.com/python/cpython/blob/fcf1d003bf4f0100c9d0921ff3d70e1127ca1b71/Lib/platform.py#L175-L183 | |
if sys.platform == "win32": | |
return None | |
try: | |
# os.confstr("CS_GNU_LIBC_VERSION") returns a string like "glibc 2.17": | |
_, version = os.confstr("CS_GNU_LIBC_VERSION").split() | |
except (AttributeError, OSError, ValueError): | |
# os.confstr() or CS_GNU_LIBC_VERSION not available (or a bad value)... | |
return None | |
return version | |
def glibc_version_string_ctypes() -> Optional[str]: | |
"Fallback implementation of glibc_version_string using ctypes." | |
try: | |
import ctypes | |
except ImportError: | |
return None | |
# ctypes.CDLL(None) internally calls dlopen(NULL), and as the dlopen | |
# manpage says, "If filename is NULL, then the returned handle is for the | |
# main program". This way we can let the linker do the work to figure out | |
# which libc our process is actually using. | |
process_namespace = ctypes.CDLL(None) | |
try: | |
gnu_get_libc_version = process_namespace.gnu_get_libc_version | |
except AttributeError: | |
# Symbol doesn't exist -> therefore, we are not linked to | |
# glibc. | |
return None | |
# Call gnu_get_libc_version, which returns a string like "2.5" | |
gnu_get_libc_version.restype = ctypes.c_char_p | |
version_str = gnu_get_libc_version() | |
# py2 / py3 compatibility: | |
if not isinstance(version_str, str): | |
version_str = version_str.decode("ascii") | |
return version_str | |
# platform.libc_ver regularly returns completely nonsensical glibc | |
# versions. E.g. on my computer, platform says: | |
# | |
# ~$ python2.7 -c 'import platform; print(platform.libc_ver())' | |
# ('glibc', '2.7') | |
# ~$ python3.5 -c 'import platform; print(platform.libc_ver())' | |
# ('glibc', '2.9') | |
# | |
# But the truth is: | |
# | |
# ~$ ldd --version | |
# ldd (Debian GLIBC 2.22-11) 2.22 | |
# | |
# This is unfortunate, because it means that the linehaul data on libc | |
# versions that was generated by pip 8.1.2 and earlier is useless and | |
# misleading. Solution: instead of using platform, use our code that actually | |
# works. | |
def libc_ver() -> Tuple[str, str]: | |
"""Try to determine the glibc version | |
Returns a tuple of strings (lib, version) which default to empty strings | |
in case the lookup fails. | |
""" | |
glibc_version = glibc_version_string() | |
if glibc_version is None: | |
return ("", "") | |
else: | |
return ("glibc", glibc_version) | |