Issue #12124: zipimport doesn't keep a reference to zlib.decompress() anymore

to be able to unload the module.

Lib/test/test_zipimport.py

@@ -19,11 +19,6 @@ import io
 from traceback import extract_tb, extract_stack, print_tb
 raise_src = 'def do_raise(): raise TypeError\n'
 
-# so we only run testAFakeZlib once if this test is run repeatedly
-# which happens when we look for ref leaks
-test_imported = False
-
-
 def make_pyc(co, mtime):
     data = marshal.dumps(co)
     if type(mtime) is type(0.0):
@@ -453,19 +448,7 @@ class BadFileZipImportTestCase(unittest.TestCase):
             zipimport._zip_directory_cache.clear()
 
 
-def cleanup():
-    # this is necessary if test is run repeated (like when finding leaks)
-    global test_imported
-    if test_imported:
-        zipimport._zip_directory_cache.clear()
-        if hasattr(UncompressedZipImportTestCase, 'testAFakeZlib'):
-            delattr(UncompressedZipImportTestCase, 'testAFakeZlib')
-        if hasattr(CompressedZipImportTestCase, 'testAFakeZlib'):
-            delattr(CompressedZipImportTestCase, 'testAFakeZlib')
-    test_imported = True
-
 def test_main():
-    cleanup()
     try:
         support.run_unittest(
               UncompressedZipImportTestCase,

Misc/NEWS

@@ -72,6 +72,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #12124: zipimport doesn't keep a reference to zlib.decompress() anymore
+  to be able to unload the module.
+
 - Issue #10801: In zipfile, support different encodings for the header and
   the filenames.
 

Modules/zipimport.c

@@ -785,16 +785,13 @@ error:
 
 /* Return the zlib.decompress function object, or NULL if zlib couldn't
    be imported. The function is cached when found, so subsequent calls
-   don't import zlib again. Returns a *borrowed* reference.
-   XXX This makes zlib.decompress immortal. */
+   don't import zlib again. */
 static PyObject *
 get_decompress_func(void)
 {
-    static PyObject *decompress = NULL;
-
-    if (decompress == NULL) {
-        PyObject *zlib;
     static int importing_zlib = 0;
+    PyObject *zlib;
+    PyObject *decompress;
 
     if (importing_zlib != 0)
         /* Someone has a zlib.py[co] in their Zip file;
@@ -808,12 +805,13 @@ get_decompress_func(void)
                                             "decompress");
         Py_DECREF(zlib);
     }
-        else
+    else {
         PyErr_Clear();
+        decompress = NULL;
+    }
     if (Py_VerboseFlag)
         PySys_WriteStderr("# zipimport: zlib %s\n",
             zlib != NULL ? "available": "UNAVAILABLE");
-    }
     return decompress;
 }
 
@@ -904,6 +902,7 @@ get_data(char *archive, PyObject *toc_entry)
         goto error;
     }
     data = PyObject_CallFunction(decompress, "Oi", raw_data, -15);
+    Py_DECREF(decompress);
 error:
     Py_DECREF(raw_data);
     return data;