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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(): | |
| # type: () -> 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(): | |
| # type: () -> 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(): | |
| # type: () -> 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(): | |
| # type: () -> 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) | |