From 9b5a023a5dc3127da15253f7acad71019395ebe1 Mon Sep 17 00:00:00 2001 From: Pablo Galindo Date: Thu, 8 Oct 2020 19:50:37 +0100 Subject: [PATCH] [3.7] bpo-41976: Fix the fallback to gcc of ctypes.util.find_library when using gcc>9 (GH-22598). (GH-22601) (cherry picked from commit 27ac19cca2c639caaf6fedf3632fe6beb265f24f) Co-authored-by: Pablo Galindo --- Lib/ctypes/test/test_find.py | 12 ++++++- Lib/ctypes/util.py | 32 +++++++++++++++---- .../2020-10-08-18-22-28.bpo-41976.Svm0wb.rst | 3 ++ 3 files changed, 39 insertions(+), 8 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2020-10-08-18-22-28.bpo-41976.Svm0wb.rst diff --git a/Lib/ctypes/test/test_find.py b/Lib/ctypes/test/test_find.py index b99fdcba7b28f..92ac1840ad7d4 100644 --- a/Lib/ctypes/test/test_find.py +++ b/Lib/ctypes/test/test_find.py @@ -1,4 +1,5 @@ import unittest +import unittest.mock import os.path import sys import test.support @@ -72,7 +73,7 @@ def test_shell_injection(self): @unittest.skipUnless(sys.platform.startswith('linux'), 'Test only valid for Linux') -class LibPathFindTest(unittest.TestCase): +class FindLibraryLinux(unittest.TestCase): def test_find_on_libpath(self): import subprocess import tempfile @@ -111,6 +112,15 @@ def test_find_on_libpath(self): # LD_LIBRARY_PATH) self.assertEqual(find_library(libname), 'lib%s.so' % libname) + def test_find_library_with_gcc(self): + with unittest.mock.patch("ctypes.util._findSoname_ldconfig", lambda *args: None): + self.assertNotEqual(find_library('c'), None) + + def test_find_library_with_ld(self): + with unittest.mock.patch("ctypes.util._findSoname_ldconfig", lambda *args: None), \ + unittest.mock.patch("ctypes.util._findLib_gcc", lambda *args: None): + self.assertNotEqual(find_library('c'), None) + if __name__ == "__main__": unittest.main() diff --git a/Lib/ctypes/util.py b/Lib/ctypes/util.py index 97973bce001d9..0c2510e1619c8 100644 --- a/Lib/ctypes/util.py +++ b/Lib/ctypes/util.py @@ -93,6 +93,12 @@ def find_library(name): # Andreas Degert's find functions, using gcc, /sbin/ldconfig, objdump import re, tempfile + def _is_elf(filename): + "Return True if the given file is an ELF file" + elf_header = b'\x7fELF' + with open(filename, 'br') as thefile: + return thefile.read(4) == elf_header + def _findLib_gcc(name): # Run GCC's linker with the -t (aka --trace) option and examine the # library name it prints out. The GCC command will fail because we @@ -299,17 +312,22 @@ def _findLib_ld(name): stderr=subprocess.PIPE, universal_newlines=True) out, _ = p.communicate() - res = re.search(expr, os.fsdecode(out)) - if res: - result = res.group(0) - except Exception as e: + res = re.findall(expr, os.fsdecode(out)) + for file in res: + # Check if the given file is an elf file: gcc can report + # some files that are linker scripts and not actual + # shared objects. See bpo-41976 for more details + if not _is_elf(file): + continue + return os.fsdecode(file) + except Exception: pass # result will be None return result def find_library(name): # See issue #9998 return _findSoname_ldconfig(name) or \ - _get_soname(_findLib_gcc(name) or _findLib_ld(name)) + _get_soname(_findLib_gcc(name)) or _get_soname(_findLib_ld(name)) ################################################################ # test code diff --git a/Misc/NEWS.d/next/Library/2020-10-08-18-22-28.bpo-41976.Svm0wb.rst b/Misc/NEWS.d/next/Library/2020-10-08-18-22-28.bpo-41976.Svm0wb.rst new file mode 100644 index 0000000000000..c8b3fc771845e --- /dev/null +++ b/Misc/NEWS.d/next/Library/2020-10-08-18-22-28.bpo-41976.Svm0wb.rst @@ -0,0 +1,3 @@ +Fixed a bug that was causing :func:`ctypes.util.find_library` to return +``None`` when triying to locate a library in an environment when gcc>=9 is +available and ``ldconfig`` is not. Patch by Pablo Galindo