Source code for pex.glibc

# This file was copied from the pip project master branch on 2016/12/05
from __future__ import absolute_import

import ctypes
import platform
import re
import warnings


def glibc_version_string():
  "Returns glibc version string, or None if not using glibc."

  # 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


# Separated out from have_compatible_glibc for easier unit testing
def check_glibc_version(version_str, required_major, minimum_minor):
  # Parse string and check against requested version.
  #
  # We use a regexp instead of str.split because we want to discard any
  # random junk that might come after the minor version -- this might happen
  # in patched/forked versions of glibc (e.g. Linaro's version of glibc
  # uses version strings like "2.20-2014.11"). See gh-3588.
  m = re.match(r"(?P<major>[0-9]+)\.(?P<minor>[0-9]+)", version_str)
  if not m:
    warnings.warn("Expected glibc version with 2 components major.minor,"
                  " got: %s" % version_str, RuntimeWarning)
    return False
  return (int(m.group("major")) == required_major and
          int(m.group("minor")) >= minimum_minor)


def have_compatible_glibc(required_major, minimum_minor):
  version_str = glibc_version_string()
  if version_str is None:
    return False
  return check_glibc_version(version_str, required_major, minimum_minor)


# 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():
  glibc_version = glibc_version_string()
  if glibc_version is None:
    # For non-glibc platforms, fall back on platform.libc_ver
    return platform.libc_ver()
  else:
    return ("glibc", glibc_version)