Bug Fix: Segfault in H5CX_get_vol_wrap_ctx when H5VLwrap_register is called from an application (#2248)

* Jira HDFFV-10881: Segfault in H5CX_get_vol_wrap_ctx when H5VLwrap_register is called from an application.  A quick and simple fix to make it fail with a relevant error message.

* Format changes.

* Committing clang-format changes

* Minor change: split one condition check into two for clarity.

* Adding doxygen comment for H5VLwrap_register.

* Minor change: adding a little more detail to the Doxygen comment for H5VLwrap_register.

src/H5CX.c

@@ -1621,12 +1621,20 @@ H5CX_get_vol_wrap_ctx(void **vol_wrap_ctx)
     H5CX_node_t **head      = NULL;    /* Pointer to head of API context list */
     herr_t        ret_value = SUCCEED; /* Return value */
 
-    FUNC_ENTER_NOAPI_NOERR
+    FUNC_ENTER_NOAPI(FAIL)
 
     /* Sanity check */
     HDassert(vol_wrap_ctx);
     head = H5CX_get_my_context(); /* Get the pointer to the head of the API context, for this thread */
-    HDassert(head && *head);
+
+    /* No error is expected at this point.  But in case an application calls H5VLwrap_register
+     * which doesn't reset the API context and there is no context, returns a relevant error here
+     */
+    if (!head)
+        HGOTO_ERROR(H5E_CONTEXT, H5E_UNINITIALIZED, FAIL, "the API context isn't available")
+
+    if (!(*head))
+        HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "unable to get the current API context")
 
     /* Check for value that was set */
     if ((*head)->ctx.vol_wrap_ctx_valid)
@@ -1635,6 +1643,7 @@ H5CX_get_vol_wrap_ctx(void **vol_wrap_ctx)
     else
         *vol_wrap_ctx = NULL;
 
+done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5CX_get_vol_wrap_ctx() */
 

src/H5VLconnector_passthru.h

@@ -56,6 +56,30 @@ extern "C" {
 
 /* Helper routines for VOL connector authors */
 H5_DLL herr_t H5VLcmp_connector_cls(int *cmp, hid_t connector_id1, hid_t connector_id2);
+/**
+ * \ingroup H5VL
+ *
+ * \brief Wrap an internal object with a "wrap context" and register an
+ *        hid_t for the resulting object.
+ *
+ * \param[in] obj  VOL object.
+ * \param[in] type VOL-managed object class. Allowable values are:
+ *                 - #H5I_FILE
+ *                 - #H5I_GROUP
+ *                 - #H5I_DATATYPE
+ *                 - #H5I_DATASET
+ *                 - #H5I_MAP
+ *                 - #H5I_ATTR
+ *
+ * \return \hid_t
+ *
+ * \note This routine is mainly targeted toward wrapping objects for
+ *       iteration routine callbacks (i.e. the callbacks from H5Aiterate*,
+ *       H5Literate* / H5Lvisit*, and H5Ovisit* ). Using it in an application
+ *       will return an error indicating the API context isn't available or
+ *       can't be retrieved.
+ *
+ */
 H5_DLL hid_t  H5VLwrap_register(void *obj, H5I_type_t type);
 H5_DLL herr_t H5VLretrieve_lib_state(void **state);
 H5_DLL herr_t H5VLstart_lib_state(void);

test/vol.c

@@ -2289,6 +2289,81 @@ error:
     return FAIL;
 } /* end test_vol_cap_flags() */
 
+/*-------------------------------------------------------------------------
+ * Function:    test_wrap_register()
+ *
+ * Purpose:     Tests the failure of calling H5VLwrap_register in application
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+test_wrap_register(void)
+{
+    hid_t fapl_id  = H5I_INVALID_HID;
+    hid_t file_id  = H5I_INVALID_HID;
+    hid_t group_id = H5I_INVALID_HID;
+    hid_t wrap_id  = H5I_INVALID_HID;
+    char  filename[NAME_LEN];
+    void *vol_obj;
+
+    TESTING("failure of calling H5VLwrap_register");
+
+    /* Retrieve the file access property for testing */
+    fapl_id = h5_fileaccess();
+
+    h5_fixname(FILENAME[0], fapl_id, filename, sizeof filename);
+
+    if ((file_id = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id)) < 0)
+        TEST_ERROR;
+
+    if ((group_id = H5Gcreate2(file_id, "test", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0)
+        TEST_ERROR;
+
+    /* Retrieve the VOL object for the group */
+    if (!(vol_obj = H5VLobject(group_id)))
+        TEST_ERROR;
+
+    /* Try to register a second ID for the group.  It should fail because this routine is mainly
+     * targeted toward wrapping objects for iteration routine callbacks, not for application use
+     */
+    H5E_BEGIN_TRY
+    {
+        wrap_id = H5VLwrap_register(vol_obj, H5I_GROUP);
+    }
+    H5E_END_TRY;
+
+    if (H5I_INVALID_HID != wrap_id)
+        FAIL_PUTS_ERROR("should not be able to call H5VLwrap_register in an application");
+
+    if (H5Gclose(group_id) < 0)
+        TEST_ERROR;
+
+    if (H5Fclose(file_id) < 0)
+        TEST_ERROR;
+
+    h5_delete_test_file(FILENAME[0], fapl_id);
+
+    if (H5Pclose(fapl_id) < 0)
+        TEST_ERROR;
+
+    PASSED();
+
+    return SUCCEED;
+
+error:
+    H5E_BEGIN_TRY
+    {
+        H5Gclose(group_id);
+        H5Fclose(file_id);
+        H5Pclose(fapl_id);
+    }
+    H5E_END_TRY;
+
+    return FAIL;
+} /* end test_wrap_register() */
+
 /*-------------------------------------------------------------------------
  * Function:    main
  *
@@ -2326,6 +2401,7 @@ main(void)
     nerrors += test_async_vol_props() < 0 ? 1 : 0;
     nerrors += test_vol_cap_flags() < 0 ? 1 : 0;
     nerrors += test_get_vol_name() < 0 ? 1 : 0;
+    nerrors += test_wrap_register() < 0 ? 1 : 0;
 
     if (nerrors) {
         HDprintf("***** %d Virtual Object Layer TEST%s FAILED! *****\n", nerrors, nerrors > 1 ? "S" : "");