[PATCH v3 22/23] trace-cmd: Save the trace clocks in TRACECLOCK option

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

Save the content of the trace_clock file in the TRACECLOCK option in
the trace.dat file. The clocks can be printed with "trace-cmd dump
--options" command.
These clocks were saved right before the tracing data in the file, but
this patch set changed that logic. Now only the selected clock is saved
in the file before the tracing data.
Having all supported trace clocks in the file is useful for debug
purposes. Adding clocks in the existing TRACECLOCK option is save and
will not break the older versions of trace-cmd.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 tracecmd/trace-record.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 2fc6723a..f4c27ef1 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -4138,6 +4138,7 @@ enum {
 static void add_options(struct tracecmd_output *handle, struct common_record_context *ctx)
 {
 	int type = 0;
+	char *clocks;
 
 	if (ctx->date2ts) {
 		if (ctx->data_flags & DATA_FL_DATE)
@@ -4149,12 +4150,15 @@ static void add_options(struct tracecmd_output *handle, struct common_record_con
 	if (type)
 		tracecmd_add_option(handle, type, strlen(ctx->date2ts)+1, ctx->date2ts);
 
-	tracecmd_add_option(handle, TRACECMD_OPTION_TRACECLOCK, 0, NULL);
+	clocks = tracefs_instance_file_read(NULL, "trace_clock", NULL);
+	tracecmd_add_option(handle, TRACECMD_OPTION_TRACECLOCK,
+			    clocks ? strlen(clocks)+1 : 0, clocks);
 	add_option_hooks(handle);
 	add_uname(handle);
 	add_version(handle);
 	if (!no_top_instance())
 		add_trace_id(handle, &top_instance);
+	free(clocks);
 }
 
 static void write_guest_file(struct buffer_instance *instance)
-- 
2.30.2