1 files changed, 114 insertions, 0 deletions
diff --git a/tracecmd/trace-snapshot.c b/tracecmd/trace-snapshot.c
new file mode 100644
index 00000000..34630b4f
--- /dev/null
+++ b/tracecmd/trace-snapshot.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "tracefs.h"
+#include "trace-local.h"
+
+static void write_file(const char *name, char *val)
+{
+	char *path;
+	int fd;
+	ssize_t n;
+
+	path = tracefs_get_tracing_file(name);
+	fd = open(path, O_WRONLY);
+	if (fd < 0)
+		die("writing %s", path);
+
+	n = write(fd, val, strlen(val));
+	if (n < 0)
+		die("failed to write to %s\n", path);
+
+	tracefs_put_tracing_file(path);
+	close(fd);
+}
+
+void trace_snapshot (int argc, char **argv)
+{
+	const char *buffer = NULL;
+	const char *file = "snapshot";
+	struct stat st;
+	char *name;
+	char cpu_path[128];
+	int take_snap = 0;
+	int reset_snap = 0;
+	int free_snap = 0;
+	int cpu = -1;
+	int ret;
+	int c;
+
+	if (argc < 2)
+		usage(argv);
+
+	if (strcmp(argv[1], "snapshot") != 0)
+		usage(argv);
+
+	while ((c = getopt(argc-1, argv+1, "srfB:c:")) >= 0) {
+		switch (c) {
+		case 'h':
+			usage(argv);
+			break;
+		case 's':
+			take_snap = 1;
+			if (free_snap)
+				die("can't take snapshot and free it at the same time");
+			break;
+		case 'f':
+			free_snap = 1;
+			if (take_snap)
+				die("can't take snapshot and free it at the same time");
+			break;
+		case 'r':
+			reset_snap = 1;
+			break;
+		case 'B':
+			if (buffer)
+				die("Can only do one buffer at a time");
+			buffer = optarg;
+			break;
+		case 'c':
+			if (cpu >= 0)
+				die("Can only do one CPU (or all) at a time");
+			cpu = atoi(optarg);
+			break;
+		default:
+			usage(argv);
+		}
+	}
+
+	if (cpu >= 0) {
+		snprintf(cpu_path, 128, "per_cpu/cpu%d/%s", cpu, file);
+		file = cpu_path;
+	}
+
+	name = tracefs_get_tracing_file(file);
+	ret = stat(name, &st);
+	if (ret < 0)
+		die("Snapshot feature is not supported by this kernel");
+	tracefs_put_tracing_file(name);
+
+	if (!reset_snap && !take_snap && !free_snap) {
+		show_file(file);
+		exit(0);
+	}
+
+	if (reset_snap)
+		write_file(file, "2");
+
+	if (free_snap)
+		write_file(file, "0");
+
+	if (take_snap)
+		write_file(file, "1");
+}