bpo-35389: platform.libc_ver() uses os.confstr() (GH-10891)
platform.libc_ver() now uses os.confstr('CS_GNU_LIBC_VERSION') if available and the *executable* parameter is not set. The default value of the libc_ver() *executable* parameter becomes None. Quick benchmark on Fedora 29: python3 -m perf command ./python -S -c 'import platform; platform.libc_ver()' 94.9 ms +- 4.3 ms -> 33.2 ms +- 1.4 ms: 2.86x faster (-65%)
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@ -169,7 +169,7 @@ _libc_search = re.compile(b'(__libc_init)'
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b'|'
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br'(libc(_\w+)?\.so(?:\.(\d[0-9.]*))?)', re.ASCII)
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def libc_ver(executable=sys.executable, lib='', version='', chunksize=16384):
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def libc_ver(executable=None, lib='', version='', chunksize=16384):
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""" Tries to determine the libc version that the file executable
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(which defaults to the Python interpreter) is linked against.
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@ -184,6 +184,19 @@ def libc_ver(executable=sys.executable, lib='', version='', chunksize=16384):
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The file is read and scanned in chunks of chunksize bytes.
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"""
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if executable is None:
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try:
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ver = os.confstr('CS_GNU_LIBC_VERSION')
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# parse 'glibc 2.28' as ('glibc', '2.28')
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parts = ver.split(maxsplit=1)
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if len(parts) == 2:
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return tuple(parts)
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except (AttributeError, ValueError, OSError):
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# os.confstr() or CS_GNU_LIBC_VERSION value not available
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pass
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executable = sys.executable
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V = _comparable_version
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if hasattr(os.path, 'realpath'):
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# Python 2.2 introduced os.path.realpath(); it is used
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@ -3,7 +3,9 @@ import platform
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import subprocess
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import sys
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import sysconfig
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import tempfile
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import unittest
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from unittest import mock
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from test import support
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@ -263,19 +265,46 @@ class PlatformTest(unittest.TestCase):
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self.assertEqual(sts, 0)
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def test_libc_ver(self):
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# check that libc_ver(executable) doesn't raise an exception
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if os.path.isdir(sys.executable) and \
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os.path.exists(sys.executable+'.exe'):
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# Cygwin horror
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executable = sys.executable + '.exe'
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else:
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executable = sys.executable
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res = platform.libc_ver(executable)
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platform.libc_ver(executable)
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self.addCleanup(support.unlink, support.TESTFN)
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with open(support.TESTFN, 'wb') as f:
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f.write(b'x'*(16384-10))
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filename = support.TESTFN
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self.addCleanup(support.unlink, filename)
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with mock.patch('os.confstr', create=True, return_value='mock 1.0'):
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# test os.confstr() code path
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self.assertEqual(platform.libc_ver(), ('mock', '1.0'))
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# test the different regular expressions
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for data, expected in (
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(b'__libc_init', ('libc', '')),
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(b'GLIBC_2.9', ('glibc', '2.9')),
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(b'libc.so.1.2.5', ('libc', '1.2.5')),
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(b'libc_pthread.so.1.2.5', ('libc', '1.2.5_pthread')),
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(b'', ('', '')),
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):
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with open(filename, 'wb') as fp:
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fp.write(b'[xxx%sxxx]' % data)
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fp.flush()
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# os.confstr() must not be used if executable is set
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self.assertEqual(platform.libc_ver(executable=filename),
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expected)
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# binary containing multiple versions: get the most recent,
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# make sure that 1.9 is seen as older than 1.23.4
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chunksize = 16384
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with open(filename, 'wb') as f:
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# test match at chunk boundary
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f.write(b'x'*(chunksize - 10))
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f.write(b'GLIBC_1.23.4\0GLIBC_1.9\0GLIBC_1.21\0')
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self.assertEqual(platform.libc_ver(support.TESTFN),
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self.assertEqual(platform.libc_ver(filename, chunksize=chunksize),
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('glibc', '1.23.4'))
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@support.cpython_only
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@ -0,0 +1,2 @@
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:func:`platform.libc_ver` now uses ``os.confstr('CS_GNU_LIBC_VERSION')`` if
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available and the *executable* parameter is not set.
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