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