bpo-37931: Fix crash on OSX re-initializing os.environ (GH-15428)
On most platforms, the `environ` symbol is accessible everywhere.
In a dylib on OSX, it's not easily accessible, you need to find it with
_NSGetEnviron.
The code was caching the *value* of environ. But a setenv() can change the value,
leaving garbage at the old value. Fix: don't cache the value of environ, just
read it every time.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 8985471..322c215 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -1402,7 +1402,6 @@
** man environ(7).
*/
#include <crt_externs.h>
-static char **environ;
#elif !defined(_MSC_VER) && (!defined(__WATCOMC__) || defined(__QNX__) || defined(__VXWORKS__))
extern char **environ;
#endif /* !_MSC_VER */
@@ -1420,15 +1419,16 @@
d = PyDict_New();
if (d == NULL)
return NULL;
-#if defined(WITH_NEXT_FRAMEWORK) || (defined(__APPLE__) && defined(Py_ENABLE_SHARED))
- if (environ == NULL)
- environ = *_NSGetEnviron();
-#endif
#ifdef MS_WINDOWS
/* _wenviron must be initialized in this way if the program is started
through main() instead of wmain(). */
_wgetenv(L"");
e = _wenviron;
+#elif defined(WITH_NEXT_FRAMEWORK) || (defined(__APPLE__) && defined(Py_ENABLE_SHARED))
+ /* environ is not accessible as an extern in a shared object on OSX; use
+ _NSGetEnviron to resolve it. The value changes if you add environment
+ variables between calls to Py_Initialize, so don't cache the value. */
+ e = *_NSGetEnviron();
#else
e = environ;
#endif