From: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Date: Tue, 14 Sep 2021 20:10:36 +0000 (-0400)
Subject: Fix: common: error query for trigger action protocol error
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=a2fc020ee1251a8edee4a20f4107116605a29896;p=lttng-tools.git

Fix: common: error query for trigger action protocol error

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

When listing a trigger with a single non-list action the CLI reports an
error in the protocol resulting in an output with no error accounting
for the action.

 $ lttng list-triggers
  - name: trigger0
    owner uid: 1000
    condition: session rotation ongoing
      session name: test
      errors: none
   action:notify
  Error: Failed to query errors of trigger 'trigger0' (owner uid: 1000): Protocol error occurred

Cause
=====

The `action_path` associated with the query has an index count of 0 as
it should considering that the single root element action element is not
a `list` object.

Inside `lttng_action_path_create_from_payload` a payload view is
initialized with a `len` of 0 since `header->index_count` is 0 as it
should.

The payload view is then validated and is considered invalid since the
validation check for `len` > 0. The error then bubbles up.

Solution
========

Since that the payload view is considered invalid when it is equal to
zero simply handle this special case and call directly
`lttng_action_path_create` with the appropriate parameter.

Known drawbacks
=========

None.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I8f302c3aa78835342c665793908dc02f0a9dece4
---

diff --git a/src/common/actions/path.c b/src/common/actions/path.c
index 7f4955475..4ee649928 100644
--- a/src/common/actions/path.c
+++ b/src/common/actions/path.c
@@ -143,6 +143,13 @@ ssize_t lttng_action_path_create_from_payload(
 
 	header = (typeof(header)) header_view.buffer.data;
 	consumed_size += header_view.buffer.size;
+
+	/*
+	 * An action path of size 0 can exist and represents a trigger with a
+	 * single non-list action. Handle it differently since a payload view of
+	 * size 0 is considered invalid.
+	 */
+	if (header->index_count != 0)
 	{
 		const struct lttng_payload_view indexes_view =
 				lttng_payload_view_from_view(view,
@@ -161,6 +168,11 @@ ssize_t lttng_action_path_create_from_payload(
 		if (!action_path) {
 			goto end;
 		}
+	} else {
+		action_path = lttng_action_path_create(NULL, 0);
+		if (!action_path) {
+			goto end;
+		}
 	}
 
 	ret = consumed_size;