Fix: relayd stream.c: LTTNG_OPTIONAL_GET address confusion
authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Wed, 18 Dec 2019 15:56:29 +0000 (10:56 -0500)
committerJérémie Galarneau <jeremie.galarneau@efficios.com>
Thu, 19 Dec 2019 22:07:20 +0000 (17:07 -0500)
The lack of proper care around use of macro arguments in LTTNG_OPTIONAL_GET
allowed this code to compile, but caused the following issue (manually
replacing "optional" argument with the a

Using LTTNG_OPTIONAL_GET(&stream->ongoing_rotation)->next_trace_chunk

with:

 #define LTTNG_OPTIONAL_GET(optional)                   \
         ({                                             \
               assert(optional.is_set);                 \
               optional.value;                          \
         })

translates to:

         ({
               assert(&stream->ongoing_rotation.is_set);
               &stream->ongoing_rotation.value;
         })->next_trace_chunk

The issue here is the assert(), which just checks that the address
is not NULL, when it should actually check that the value is set.

The prior commit fixing optional.h to add proper parentheses to the
macro rightfully fails to compile this code. Fix the erroneous user.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I0dd45fb60573cae6ae3e831e24266aff4406f57f
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
src/bin/lttng-relayd/stream.c

index 4c97a609e98323927532e92ee54402dbc7319cb1..755fb6734072113af804e59f6e1e81089adb6b1f 100644 (file)
@@ -209,7 +209,7 @@ static int rotate_truncate_stream(struct relay_stream *stream)
        struct stream_fd *previous_stream_fd = NULL;
        struct lttng_trace_chunk *previous_chunk = NULL;
 
        struct stream_fd *previous_stream_fd = NULL;
        struct lttng_trace_chunk *previous_chunk = NULL;
 
-       if (!LTTNG_OPTIONAL_GET(&stream->ongoing_rotation)->next_trace_chunk) {
+       if (!LTTNG_OPTIONAL_GET(stream->ongoing_rotation).next_trace_chunk) {
                ERR("Protocol error encoutered in %s(): stream rotation "
                        "sequence number is before the current sequence number "
                        "and the next trace chunk is unset. Honoring this "
                ERR("Protocol error encoutered in %s(): stream rotation "
                        "sequence number is before the current sequence number "
                        "and the next trace chunk is unset. Honoring this "
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