Issue #17633: Improve support for namespace packages with zipimport.

Previously zipimport mistakenly limited namespace support to only the
top-level of the zipfile when it should have supported an arbitrary
depth.

Thanks to Phil Connel for the bug report and initial patch and Mike
Romberg for the final patch.

1 files changed, 32 insertions, 16 deletions

diff --git a/Modules/zipimport.c b/Modules/zipimport.c
index 7220faf..b978f26 100644
--- a/Modules/zipimport.c
+++ b/Modules/zipimport.c
@@ -324,17 +324,14 @@ get_module_info(ZipImporter *self, PyObject *fullname)
 }
 
 typedef enum {
-    FL_ERROR,
-    FL_NOT_FOUND,
-    FL_MODULE_FOUND,
-    FL_NS_FOUND
+    FL_ERROR = -1,       /* error */
+    FL_NOT_FOUND,        /* no loader or namespace portions found */
+    FL_MODULE_FOUND,     /* module/package found */
+    FL_NS_FOUND          /* namespace portion found: */
+                         /* *namespace_portion will point to the name */
 } find_loader_result;
 
-/* The guts of "find_loader" and "find_module". Return values:
-   -1: error
-    0: no loader or namespace portions found
-    1: module/package found
-    2: namespace portion found: *namespace_portion will point to the name
+/* The guts of "find_loader" and "find_module".
 */
 static find_loader_result
 find_loader(ZipImporter *self, PyObject *fullname, PyObject **namespace_portion)
@@ -349,21 +346,34 @@ find_loader(ZipImporter *self, PyObject *fullname, PyObject **namespace_portion)
     if (mi == MI_NOT_FOUND) {
         /* Not a module or regular package. See if this is a directory, and
            therefore possibly a portion of a namespace package. */
-        int is_dir = check_is_directory(self, self->prefix, fullname);
+        find_loader_result result = FL_NOT_FOUND;
+        PyObject *subname;
+        int is_dir;
+
+        /* We're only interested in the last path component of fullname;
+           earlier components are recorded in self->prefix. */
+        subname = get_subname(fullname);
+        if (subname == NULL) {
+            return FL_ERROR;
+        }
+
+        is_dir = check_is_directory(self, self->prefix, subname);
         if (is_dir < 0)
-            return -1;
-        if (is_dir) {
+            result = FL_ERROR;
+        else if (is_dir) {
             /* This is possibly a portion of a namespace
                package. Return the string representing its path,
                without a trailing separator. */
             *namespace_portion = PyUnicode_FromFormat("%U%c%U%U",
                                                       self->archive, SEP,
-                                                      self->prefix, fullname);
+                                                      self->prefix, subname);
             if (*namespace_portion == NULL)
-                return FL_ERROR;
-            return FL_NS_FOUND;
+                result = FL_ERROR;
+            else
+                result = FL_NS_FOUND;
         }
-        return FL_NOT_FOUND;
+        Py_DECREF(subname);
+        return result;
     }
     /* This is a module or package. */
     return FL_MODULE_FOUND;
@@ -397,6 +407,9 @@ zipimporter_find_module(PyObject *obj, PyObject *args)
     case FL_MODULE_FOUND:
         result = (PyObject *)self;
         break;
+    default:
+        PyErr_BadInternalCall();
+        return NULL;
     }
     Py_INCREF(result);
     return result;
@@ -433,6 +446,9 @@ zipimporter_find_loader(PyObject *obj, PyObject *args)
         result = Py_BuildValue("O[O]", Py_None, namespace_portion);
         Py_DECREF(namespace_portion);
         return result;
+    default:
+        PyErr_BadInternalCall();
+        return NULL;
     }
     return result;
 }