bpo-26439 Fix ctypes.util.find_library failure on AIX (#4507)

Implement find_library() support in ctypes/util for AIX.

Add some AIX specific tests.

.gitignore

+# added for local development
+.buildaix/
+Modules/python.exp
+buildaix/
+installp/
+.gitignore
+
 # Two-trick pony for OSX and other case insensitive file systems:
 # Ignore ./python binary on Unix but still look into ./Python/ directory.
 /python

Lib/ctypes/__init__.py

@@ -338,6 +338,14 @@ class CDLL(object):
             flags |= _FUNCFLAG_USE_ERRNO
         if use_last_error:
             flags |= _FUNCFLAG_USE_LASTERROR
+        if _sys.platform.startswith("aix"):
+            """When the name contains ".a(" and ends with ")",
+               e.g., "libFOO.a(libFOO.so)" - this is taken to be an
+               archive(member) syntax for dlopen(), and the mode is adjusted.
+               Otherwise, name is presented to dlopen() as a file argument.
+            """
+            if name and name.endswith(")") and ".a(" in name:
+                mode |= ( _os.RTLD_MEMBER | _os.RTLD_NOW )
 
         class _FuncPtr(_CFuncPtr):
             _flags_ = flags

Lib/ctypes/util.py

@@ -80,6 +80,15 @@ if os.name == "posix" and sys.platform == "darwin":
                 continue
         return None
 
+if sys.platform.startswith("aix"):
+    # AIX has two styles of storing shared libraries
+    # GNU auto_tools refer to these as svr4 and aix
+    # svr4 (System V Release 4) is a regular file, often with .so as suffix
+    # AIX style uses an archive (suffix .a) with members (e.g., shr.o, libssl.so)
+    # see issue#26439 and _aix.py for more details
+
+    from ctypes._aix import find_library
+
 elif os.name == "posix":
     # Andreas Degert's find functions, using gcc, /sbin/ldconfig, objdump
     import re, tempfile
@@ -324,6 +333,22 @@ def test():
             print(cdll.LoadLibrary("libcrypto.dylib"))
             print(cdll.LoadLibrary("libSystem.dylib"))
             print(cdll.LoadLibrary("System.framework/System"))
+        # issue-26439 - fix broken test call for AIX
+        elif sys.platform.startswith("aix"):
+            from ctypes import CDLL
+            if sys.maxsize < 2**32:
+                print("Using CDLL(name, os.RTLD_MEMBER): %s" % CDLL("libc.a(shr.o)", os.RTLD_MEMBER))
+                print("Using cdll.LoadLibrary(): %s" % cdll.LoadLibrary("libc.a(shr.o)"))
+                # librpm.so is only available as 32-bit shared library
+                print(find_library("rpm"))
+                print(cdll.LoadLibrary("librpm.so"))
+            else:
+                print("Using CDLL(name, os.RTLD_MEMBER): %s" % CDLL("libc.a(shr_64.o)", os.RTLD_MEMBER))
+                print("Using cdll.LoadLibrary(): %s" % cdll.LoadLibrary("libc.a(shr_64.o)"))
+            print("crypt\t:: %s" % find_library("crypt"))
+            print("crypt\t:: %s" % cdll.LoadLibrary(find_library("crypt")))
+            print("crypto\t:: %s" % find_library("crypto"))
+            print("crypto\t:: %s" % cdll.LoadLibrary(find_library("crypto")))
         else:
             print(cdll.LoadLibrary("libm.so"))
             print(cdll.LoadLibrary("libcrypt.so"))

Misc/NEWS.d/next/Library/2017-11-24-08-35-43.bpo-26439.IC45_f.rst

+Fix ctypes.util.find_library() for AIX
+by implementing ctypes._aix.find_library()
+Patch by: Michael Felt aka aixtools
+
+ctypes.util.find_library has always returned None on a standard AIX.
+With this patch there is support for both AIX and svr4 shared libraries.
+None is returned only when there is nothinbg found. Normal behavior is now:
+on AIX find_library("FOO") returns either libFOO.a(libFOO.so) or libFOO.so
+while legacy names e.g., find_library("c") returns libc.a(shr.o)
+or libc.a(shr_64.o) - depending on 32 or 64-bit operations.
+Include RTLD_MEMBER to mode to support AIX legacy library(member) names
+(Modules/_ctype/posixmodule.c), ctypes/__init__.py and configure.ac)

Modules/posixmodule.c

@@ -13007,6 +13007,9 @@ all_ins(PyObject *m)
 #if HAVE_DECL_RTLD_DEEPBIND
     if (PyModule_AddIntMacro(m, RTLD_DEEPBIND)) return -1;
 #endif
+#if HAVE_DECL_RTLD_MEMBER
+    if (PyModule_AddIntMacro(m, RTLD_MEMBER)) return -1;
+#endif
 
 #ifdef HAVE_GETRANDOM_SYSCALL
     if (PyModule_AddIntMacro(m, GRND_RANDOM)) return -1;

configure

@@ -9872,7 +9872,6 @@ fi
 
 
 
-
 if test "x$ac_cv_env_PKG_CONFIG_set" != "xset"; then
 	if test -n "$ac_tool_prefix"; then
   # Extract the first word of "${ac_tool_prefix}pkg-config", so it can be a program name with args.
@@ -14360,6 +14359,17 @@ fi
 cat >>confdefs.h <<_ACEOF
 #define HAVE_DECL_RTLD_DEEPBIND $ac_have_decl
 _ACEOF
+ac_fn_c_check_decl "$LINENO" "RTLD_MEMBER" "ac_cv_have_decl_RTLD_MEMBER" "#include <dlfcn.h>
+"
+if test "x$ac_cv_have_decl_RTLD_MEMBER" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_RTLD_MEMBER $ac_have_decl
+_ACEOF
 
 
 # determine what size digit to use for Python's longs

configure.ac

@@ -4480,7 +4480,7 @@ then
   [define to 1 if your sem_getvalue is broken.])
 fi
 
-AC_CHECK_DECLS([RTLD_LAZY, RTLD_NOW, RTLD_GLOBAL, RTLD_LOCAL, RTLD_NODELETE, RTLD_NOLOAD, RTLD_DEEPBIND], [], [], [[#include <dlfcn.h>]])
+AC_CHECK_DECLS([RTLD_LAZY, RTLD_NOW, RTLD_GLOBAL, RTLD_LOCAL, RTLD_NODELETE, RTLD_NOLOAD, RTLD_DEEPBIND, RTLD_MEMBER], [], [], [[#include <dlfcn.h>]])
 
 # determine what size digit to use for Python's longs
 AC_MSG_CHECKING([digit size for Python's longs])

pyconfig.h.in

@@ -210,6 +210,10 @@
    don't. */
 #undef HAVE_DECL_RTLD_LOCAL
 
+/* Define to 1 if you have the declaration of `RTLD_MEMBER', and to 0 if you
+   don't. */
+#undef HAVE_DECL_RTLD_MEMBER
+
 /* Define to 1 if you have the declaration of `RTLD_NODELETE', and to 0 if you
    don't. */
 #undef HAVE_DECL_RTLD_NODELETE