Fix: load: incomplete error handling for load_session_from_file

This fix is adapted from a fix against the stable-2.11 branch.  The
commit message of the stable-2.11 branch follows.

An equivalent fix was already in place in `load_session_from_path()`,
but the same problem as the stable-2.11 branch is present in
`load_session_from_file()`.

Original message:

Observed issue
==============

lttng-ivc test fails to fail.

test_save_load_blocking_timeout[lttng-tools-2.12-lttng-tools-2.11-False]

Here we load a xml created by lttng-tools-2.12 and try to load it using
lttng-tools 2.11. We expect this to fail on the load.

The command report an error on the stderr but the command return code
value is zero.

From lttng-ivc test runtime.log:
Command #0
  Return value: 0
  Command: lttng load --input-path=/home/joraj/lttng/lttng-ivc/.tox/py3/tmp/test_save_load_blocking_timeou0/save_load saved_trace
  STDOUT:
      Session saved_trace has been loaded successfully
  STDERR:
      XML Error: Element 'process_attr_trackers': This element is not expected.
      Error: Session configuration file validation failed

Cause
=====

The error coming from load_session_from_file is not handled correctly.

Solution
========

Rework error handling in load_session_from_path and
load_session_from_file.

LTTNG_ERR_LOAD_SESSION_NOENT is NOT an error when session_name is
specified in load_session_from_path. In this scenario, we are actively
looking for the configuration of the session.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: Ic68c253aa194bf8ab72c3c271f10d443118bdeee

diff --git a/src/common/config/session-config.c b/src/common/config/session-config.c
index a8ea68eda42fdb92fc0177d02a6c239d6d281bd4..e893c129863fe5a2d593226f85922f349c2f985c 100644 (file)
--- a/src/common/config/session-config.c
+++ b/src/common/config/session-config.c
@@ -3767,10 +3767,24 @@ int load_session_from_file(const char *path, const char *session_name,
                        xmlNextElementSibling(session_node)) {
                ret = process_session_node(session_node,
                        session_name, overwrite, overrides);
-               if (session_name && ret == 0) {
-                       /* Target session found and loaded */
-                       session_found = 1;
-                       break;
+               if (!session_name && ret) {
+                       /* Loading error occurred. */
+                       goto end;
+               } else if (session_name) {
+                       if (ret == 0) {
+                               /* Target session found and loaded */
+                               session_found = 1;
+                               break;
+                       } else if (ret == -LTTNG_ERR_NO_SESSION) {
+                               /*
+                                * Ignore this error, we are looking for a
+                                * specific session.
+                                */
+                               ret = 0;
+                       } else {
+                               /* Loading error occurred. */
+                               goto end;
+                       }
                }
        }
 end:
@@ -3778,9 +3792,6 @@ end:
        if (!ret) {
                ret = session_found ? 0 : -LTTNG_ERR_LOAD_SESSION_NOENT;
        }
-       if (ret == -LTTNG_ERR_NO_SESSION) {
-               ret = -LTTNG_ERR_LOAD_SESSION_NOENT;
-       }
        return ret;
 }