PyImport_ExecCodeModuleEx(): remove module from sys.modules in error cases.

PyImport_ReloadModule():  restore the module to sys.modules in error cases.
load_package():  semantic-neutral refactoring from an earlier stab at
                 this patch; giving it a common error exit made the code
                 easier to follow, so retaining that part.
_RemoveModule():  new little utility to delete a key from sys.modules.

diff --git a/Python/import.c b/Python/import.c
index aa0b5c2824878354bffdfb61834538c14d76b698..80427f8e1c8e54e850919fa56c753e30038d3d50 100644 (file)
--- a/Python/import.c
+++ b/Python/import.c
@@ -557,10 +557,25 @@ PyImport_AddModule(char *name)
        return m;
 }
 
+/* Remove name from sys.modules, if it's there. */
+static void
+_RemoveModule(const char *name)
+{
+       PyObject *modules = PyImport_GetModuleDict();
+       if (PyDict_GetItemString(modules, name) == NULL)
+               return;
+       if (PyDict_DelItemString(modules, name) < 0)
+               Py_FatalError("import:  deleting existing key in"
+                             "sys.modules failed");
+}
 
 /* Execute a code object in a module and return the module object
-   WITH INCREMENTED REFERENCE COUNT */
-
+ * WITH INCREMENTED REFERENCE COUNT.  If an error occurs, name is
+ * removed from sys.modules, to avoid leaving damaged module objects
+ * in sys.modules.  The caller may wish to restore the original
+ * module object (if any) in this case; PyImport_ReloadModule is an
+ * example.
+ */
 PyObject *
 PyImport_ExecCodeModule(char *name, PyObject *co)
 {
@@ -582,7 +597,7 @@ PyImport_ExecCodeModuleEx(char *name, PyObject *co, char *pathname)
        if (PyDict_GetItemString(d, "__builtins__") == NULL) {
                if (PyDict_SetItemString(d, "__builtins__",
                                         PyEval_GetBuiltins()) != 0)
-                       return NULL;
+                       goto error;
        }
        /* Remember the filename as the __file__ attribute */
        v = NULL;
@@ -601,7 +616,7 @@ PyImport_ExecCodeModuleEx(char *name, PyObject *co, char *pathname)
 
        v = PyEval_EvalCode((PyCodeObject *)co, d, d);
        if (v == NULL)
-               return NULL;
+               goto error;
        Py_DECREF(v);
 
        if ((m = PyDict_GetItemString(modules, name)) == NULL) {
@@ -614,6 +629,10 @@ PyImport_ExecCodeModuleEx(char *name, PyObject *co, char *pathname)
        Py_INCREF(m);
 
        return m;
+
+  error:
+       _RemoveModule(name);
+       return NULL;
 }
 
 
@@ -888,7 +907,9 @@ static struct _frozen *find_frozen(char *name);
 static PyObject *
 load_package(char *name, char *pathname)
 {
-       PyObject *m, *d, *file, *path;
+       PyObject *m, *d;
+       PyObject *file = NULL;
+       PyObject *path = NULL;
        int err;
        char buf[MAXPATHLEN+1];
        FILE *fp = NULL;
@@ -903,19 +924,15 @@ load_package(char *name, char *pathname)
        d = PyModule_GetDict(m);
        file = PyString_FromString(pathname);
        if (file == NULL)
-               return NULL;
+               goto error;
        path = Py_BuildValue("[O]", file);
-       if (path == NULL) {
-               Py_DECREF(file);
-               return NULL;
-       }
+       if (path == NULL)
+               goto error;
        err = PyDict_SetItemString(d, "__file__", file);
        if (err == 0)
                err = PyDict_SetItemString(d, "__path__", path);
-       if (err != 0) {
-               m = NULL;
-               goto cleanup;
-       }
+       if (err != 0)
+               goto error;
        buf[0] = '\0';
        fdp = find_module(name, "__init__", path, buf, sizeof(buf), &fp, NULL);
        if (fdp == NULL) {
@@ -930,6 +947,10 @@ load_package(char *name, char *pathname)
        m = load_module(name, fp, buf, fdp->type, NULL);
        if (fp != NULL)
                fclose(fp);
+       goto cleanup;
+
+  error:
+       m = NULL;
   cleanup:
        Py_XDECREF(path);
        Py_XDECREF(file);
@@ -2234,6 +2255,7 @@ PyImport_ReloadModule(PyObject *m)
        char buf[MAXPATHLEN+1];
        struct filedescr *fdp;
        FILE *fp = NULL;
+       PyObject *newm;
 
        if (m == NULL || !PyModule_Check(m)) {
                PyErr_SetString(PyExc_TypeError,
@@ -2275,10 +2297,18 @@ PyImport_ReloadModule(PyObject *m)
        Py_XDECREF(path);
        if (fdp == NULL)
                return NULL;
-       m = load_module(name, fp, buf, fdp->type, NULL);
+       newm = load_module(name, fp, buf, fdp->type, NULL);
        if (fp)
                fclose(fp);
-       return m;
+       if (newm == NULL) {
+               /* load_module probably removed name from modules because of
+                * the error.  Put back the original module object.  We're
+                * going to return NULL in this case regardless of whether
+                * replacing name succeeds, so the return value is ignored.
+                */
+               PyDict_SetItemString(modules, name, m);
+       }
+       return newm;
 }