[PATCH v20 06/15] trace-cmd: Store the session tracing ID in the trace.dat file

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

The ID of the current tracing session is stored in the trace.dat file.
A new file option is introduced:
	TRACECMD_OPTION_TRACEID
The data is stored in the file as unsigned long long integer
A new libtracecmd API is introduced, to get the ID when the trace.dat file is read:
	unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/trace-cmd/trace-cmd.h |  2 ++
 lib/trace-cmd/trace-input.c   | 16 ++++++++++++++++
 tracecmd/trace-dump.c         | 11 +++++++++++
 tracecmd/trace-record.c       |  9 +++++++++
 4 files changed, 38 insertions(+)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index 7519e82a..6075a37e 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -109,6 +109,7 @@ enum {
 	TRACECMD_OPTION_CPUCOUNT,
 	TRACECMD_OPTION_VERSION,
 	TRACECMD_OPTION_PROCMAPS,
+	TRACECMD_OPTION_TRACEID,
 };
 
 enum {
@@ -151,6 +152,7 @@ int tracecmd_copy_headers(struct tracecmd_input *handle, int fd);
 void tracecmd_set_flag(struct tracecmd_input *handle, int flag);
 void tracecmd_clear_flag(struct tracecmd_input *handle, int flag);
 unsigned long tracecmd_get_flags(struct tracecmd_input *handle);
+unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
 
 void tracecmd_parse_trace_clock(struct tracecmd_input *handle, char *file, int size);
 
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 842a4c3b..aca13c4e 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -82,6 +82,7 @@ struct tracecmd_input {
 	struct tep_plugin_list	*plugin_list;
 	struct tracecmd_input	*parent;
 	unsigned long		flags;
+	unsigned long long	trace_id;
 	int			fd;
 	int			long_size;
 	int			page_size;
@@ -2316,6 +2317,10 @@ static int handle_options(struct tracecmd_input *handle)
 			if (buf[size-1] == '\0')
 				trace_pid_map_load(handle, buf);
 			break;
+		case TRACECMD_OPTION_TRACEID:
+			handle->trace_id = tep_read_number(handle->pevent,
+							   &cpus, 8);
+			break;
 		default:
 			warning("unknown option %d", option);
 			break;
@@ -3419,3 +3424,14 @@ void tracecmd_set_show_data_func(struct tracecmd_input *handle,
 {
 	handle->show_data_func = func;
 }
+
+/**
+ * tracecmd_get_traceid - get the trace id of the session
+ * @handle: input handle for the trace.dat file
+ *
+ * Returns the trace id, written in the trace file
+ */
+unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle)
+{
+	return handle->trace_id;
+}
diff --git a/tracecmd/trace-dump.c b/tracecmd/trace-dump.c
index 415e9138..2dfeaa0f 100644
--- a/tracecmd/trace-dump.c
+++ b/tracecmd/trace-dump.c
@@ -358,6 +358,14 @@ static void dump_option_int(int fd, int size, char *desc)
 	do_print(OPTIONS, "%d\n", val);
 }
 
+static void dump_option_xlong(int fd, int size, char *desc)
+{
+	long long val;
+
+	do_print(OPTIONS, "\t\t[Option %s, %d bytes]\n", desc, size);
+	read_file_number(fd, &val, size);
+	do_print(OPTIONS, "0x%llX\n", val);
+}
 static void dump_options(int fd)
 {
 	unsigned short option;
@@ -408,6 +416,9 @@ static void dump_options(int fd)
 		case TRACECMD_OPTION_PROCMAPS:
 			dump_option_string(fd, size, "PROCMAPS");
 			break;
+		case TRACECMD_OPTION_TRACEID:
+			dump_option_xlong(fd, size, "TRACEID");
+			break;
 		default:
 			do_print(OPTIONS, " %d %d\t[Unknown option, size - skipping]\n",
 				 option, size);
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 5d31cad8..3e24eb43 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -3895,6 +3895,13 @@ add_pid_maps(struct tracecmd_output *handle, struct buffer_instance *instance)
 	trace_seq_destroy(&s);
 }
 
+static void
+add_trace_id(struct tracecmd_output *handle, struct buffer_instance *instance)
+{
+	tracecmd_add_option(handle, TRACECMD_OPTION_TRACEID,
+			    sizeof(long long), &instance->trace_id);
+}
+
 static void
 add_buffer_stat(struct tracecmd_output *handle, struct buffer_instance *instance)
 {
@@ -4000,6 +4007,8 @@ static void add_options(struct tracecmd_output *handle, struct common_record_con
 	add_option_hooks(handle);
 	add_uname(handle);
 	add_version(handle);
+	if (!no_top_instance())
+		add_trace_id(handle, &top_instance);
 }
 
 static void write_guest_file(struct buffer_instance *instance)
-- 
2.24.1