Fix Access to be reloaded if the python interpreter is restarted when…

… embedded. Fixes python-pillow#2268.

Tests/test_image_access.py

@@ -7,7 +7,7 @@
     pass
 
 from PIL import Image
-
+import sys
 
 class AccessTest(PillowTestCase):
     # initial value
@@ -246,5 +246,37 @@ def test_reference_counting(self):
                 self.assertEqual(px[i, 0], 0)
 
 
+class TestEmbeddable(unittest.TestCase):
+    @unittest.skipIf(not sys.platform.startswith('win32'), "requires Windows")
+    def test_embeddable(self):
+        import subprocess
+        from distutils import ccompiler
+
+        with open('embed_pil.c', 'w') as fh:
+            fh.write("""
+#include "Python.h"
+
+int main(int argc, char* argv[])
+{
+    Py_SetPythonHome( "%s" );
+
+    Py_InitializeEx( 0 );
+    Py_DECREF(PyImport_ImportModule( "PIL.Image" ));
+    Py_Finalize();
+
+    Py_InitializeEx( 0 );
+    Py_DECREF(PyImport_ImportModule( "PIL.Image" ));
+    Py_Finalize();
+
+    return 0;
+}    
+        """ % sys.prefix.replace('\\', '\\\\'))
+
+        compiler = ccompiler.new_compiler()
+        objects = compiler.compile(['embed_pil.c'])
+        compiler.link_executable(objects, 'embed_pil')
+
+        subprocess.call(['embed_pil.exe'])  
+
 if __name__ == '__main__':
     unittest.main()

libImaging/Access.c

@@ -32,7 +32,7 @@ add_item(const char* mode)
 {
     UINT32 i = hash(mode);
     /* printf("hash %s => %d\n", mode, i); */
-    if (access_table[i].mode) {
+    if (access_table[i].mode && strcmp(access_table[i].mode, mode) != 0) {
         fprintf(stderr, "AccessInit: hash collision: %d for both %s and %s\n",
                 i, mode, access_table[i].mode);
         exit(1);