Merge pull request #106 from haircommander/write_dev_null

journal logging: write to /dev/null instead of -1

src/ctr_logging.c

@@ -167,6 +167,13 @@ bool write_to_logs(stdpipe_t pipe, char *buf, ssize_t num_read)
  */
 int write_journald(int pipe, char *buf, ssize_t buflen)
 {
+	/* When using writev_buffer_append_segment, we should never approach the number of
+	 * entries necessary to flush the buffer. Therefore, the fd passed in is for /dev/null
+	 */
+	_cleanup_close_ int dev_null = open("/dev/null", O_WRONLY | O_CLOEXEC);
+	if (dev_null < 0)
+		pexit("Failed to open /dev/null");
+
 	/* Since we know the priority values for the journal (6 being log info and 3 being log err
 	 * we can set it statically here. This will also save on runtime, at the expense of needing
 	 * to be changed if this convention is changed.
@@ -188,35 +195,32 @@ int write_journald(int pipe, char *buf, ssize_t buflen)
 		char tmp_line_end = buf[line_len];
 		buf[line_len] = '\0';
 
-		/* When using writev_buffer_append_segment here, we should never approach the number of
-		 * entries necessary to flush the buffer. Therefore, the fd passed in is -1.
-		 */
 		_cleanup_free_ char *message = g_strdup_printf("MESSAGE=%s", buf);
-		if (writev_buffer_append_segment(-1, &bufv, message, line_len + MESSAGE_EQ_LEN) < 0)
+		if (writev_buffer_append_segment(dev_null, &bufv, message, line_len + MESSAGE_EQ_LEN) < 0)
 			return -1;
 
 		/* Restore state of the buffer */
 		buf[line_len] = tmp_line_end;
 
 
-		if (writev_buffer_append_segment(-1, &bufv, container_id_full, cuuid_len + CID_FULL_EQ_LEN) < 0)
+		if (writev_buffer_append_segment(dev_null, &bufv, container_id_full, cuuid_len + CID_FULL_EQ_LEN) < 0)
 			return -1;
 
-		if (writev_buffer_append_segment(-1, &bufv, message_priority, PRIORITY_EQ_LEN) < 0)
+		if (writev_buffer_append_segment(dev_null, &bufv, message_priority, PRIORITY_EQ_LEN) < 0)
 			return -1;
 
-		if (writev_buffer_append_segment(-1, &bufv, container_id, TRUNC_ID_LEN + CID_EQ_LEN) < 0)
+		if (writev_buffer_append_segment(dev_null, &bufv, container_id, TRUNC_ID_LEN + CID_EQ_LEN) < 0)
 			return -1;
 
-		if (container_tag && writev_buffer_append_segment(-1, &bufv, container_tag, container_tag_len) < 0)
+		if (container_tag && writev_buffer_append_segment(dev_null, &bufv, container_tag, container_tag_len) < 0)
 			return -1;
 
 		/* only print the name if we have a name to print */
-		if (name && writev_buffer_append_segment(-1, &bufv, container_name, name_len + CID_FULL_EQ_LEN) < 0)
+		if (name && writev_buffer_append_segment(dev_null, &bufv, container_name, name_len + CID_FULL_EQ_LEN) < 0)
 			return -1;
 
 		/* per docker journald logging format, CONTAINER_PARTIAL_MESSAGE is set to true if it's partial, but otherwise not set. */
-		if (partial && writev_buffer_append_segment(-1, &bufv, "CONTAINER_PARTIAL_MESSAGE=true", PARTIAL_MESSAGE_EQ_LEN) < 0)
+		if (partial && writev_buffer_append_segment(dev_null, &bufv, "CONTAINER_PARTIAL_MESSAGE=true", PARTIAL_MESSAGE_EQ_LEN) < 0)
 			return -1;
 
 		int err = sd_journal_sendv(bufv.iov, bufv.iovcnt);