src: monotonic-ts: Monotonic timestamp logging

Introduce a new utility which prefixes a monotonic timestamp rendered in the
same format as the kernel logs to all lines fed in through stdin.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/src/monotonic-ts.c b/src/monotonic-ts.c
new file mode 100644
index 0000000..69a1809
--- /dev/null
+++ b/src/monotonic-ts.c
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* SPDX-FileCopyrightText: 2020 Kieran Bingham <kieran.bingham@ideasonboard.com> */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+int main(int argc, char ** argv)
+{
+	struct timespec tp;
+	char *line = NULL;
+	size_t size = 0;
+	const char *label = "";
+
+	if (argc > 1)
+		label = argv[1];
+
+	/*
+	 * Explicitly set line buffering on stdin to be sure it is delivered
+	 * in a timely fashion for our timestamping purposes when data is fed
+	 * through a pipe.
+	 */
+	setlinebuf(stdin);
+
+	do {
+		if (getline(&line, &size, stdin) <= 0)
+			break;
+
+		clock_gettime(CLOCK_MONOTONIC, &tp);
+		printf("[%ld.%.9ld]%s %s", tp.tv_sec, tp.tv_nsec, label, line);
+	} while (!feof(stdin));
+
+	free(line);
+
+	return 0;
+}