Fix: compare write() return value to size

[lttng-tools.git] / src / common / consumer.c

diff --git a/src/common/consumer.c b/src/common/consumer.c
index be984a49270fefbba0b55bccd8ebf897ceea4ce7..1e710ab3d9b80fefbbfe2aad58fd050e50d03444 100644 (file)
--- a/src/common/consumer.c
+++ b/src/common/consumer.c
@@ -782,6 +782,13 @@ static int write_relayd_stream_header(struct lttng_consumer_stream *stream,
                data_hdr.stream_id = htobe64(stream->relayd_stream_id);
                data_hdr.data_size = htobe32(data_size);
                data_hdr.padding_size = htobe32(padding);
+               /*
+                * Note that net_seq_num below is assigned with the *current* value of
+                * next_net_seq_num and only after that the next_net_seq_num will be
+                * increment. This is why when issuing a command on the relayd using
+                * this next value, 1 should always be substracted in order to compare
+                * the last seen sequence number on the relayd side to the last sent.
+                */
                data_hdr.net_seq_num = htobe64(stream->next_net_seq_num++);
                /* Other fields are zeroed previously */
 
@@ -1099,7 +1106,7 @@ void lttng_consumer_should_exit(struct lttng_consumer_local_data *ctx)
        do {
                ret = write(ctx->consumer_should_quit[1], "4", 1);
        } while (ret < 0 && errno == EINTR);
-       if (ret < 0) {
+       if (ret < 0 || ret != 1) {
                PERROR("write consumer quit");
        }
 
@@ -1317,8 +1324,16 @@ static int write_relayd_metadata_id(int fd,
        do {
                ret = write(fd, (void *) &hdr, sizeof(hdr));
        } while (ret < 0 && errno == EINTR);
-       if (ret < 0) {
-               PERROR("write metadata stream id");
+       if (ret < 0 || ret != sizeof(hdr)) {
+               /*
+                * This error means that the fd's end is closed so ignore the perror
+                * not to clubber the error output since this can happen in a normal
+                * code path.
+                */
+               if (errno != EPIPE) {
+                       PERROR("write metadata stream id");
+               }
+               DBG3("Consumer failed to write relayd metadata id (errno: %d)", errno);
                goto end;
        }
        DBG("Metadata stream id %" PRIu64 " with padding %lu written before data",
@@ -3021,7 +3036,8 @@ int consumer_data_pending(uint64_t id)
                                                stream->relayd_stream_id);
                        } else {
                                ret = relayd_data_pending(&relayd->control_sock,
-                                               stream->relayd_stream_id, stream->next_net_seq_num);
+                                               stream->relayd_stream_id,
+                                               stream->next_net_seq_num - 1);
                        }
                        pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
                        if (ret == 1) {