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/Misc/ACKS b/Misc/ACKS
index 357ce02..239d06f 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -733,6 +733,7 @@
Chiu-Hsiang Hsu
Chih-Hao Huang
Christian Hudon
+Benoît Hudson
Lawrence Hudson
Michael Hudson
Jim Hugunin
diff --git a/Misc/NEWS.d/next/macOS/2019-08-23-12-14-34.bpo-37931.goYgQj.rst b/Misc/NEWS.d/next/macOS/2019-08-23-12-14-34.bpo-37931.goYgQj.rst
new file mode 100644
index 0000000..45b54e8
--- /dev/null
+++ b/Misc/NEWS.d/next/macOS/2019-08-23-12-14-34.bpo-37931.goYgQj.rst
@@ -0,0 +1,3 @@
+Fixed a crash on OSX dynamic builds that occurred when re-initializing the
+posix module after a Py_Finalize if the environment had changed since the
+previous `import posix`. Patch by Benoît Hudson.
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