[PATCH v3 21/25] trace-cmd library: Handle latency trace in version 7 files

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

Latency trace data is saved the same was as flyrecord buffer data
in trace files version 7. There is a BUFFER_TEXT option which holds the
latency specific trace metadata and points to the section in the file
with the trace data. A new API is added to read latency data:
 tracecmd_latency_data_read()

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 .../include/private/trace-cmd-private.h       |  5 +++-
 lib/trace-cmd/trace-input.c                   | 29 ++++++++++++++++++-
 lib/trace-cmd/trace-output.c                  |  5 +++-
 tracecmd/trace-record.c                       |  3 +-
 4 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/lib/trace-cmd/include/private/trace-cmd-private.h b/lib/trace-cmd/include/private/trace-cmd-private.h
index a08890df..045fd5a1 100644
--- a/lib/trace-cmd/include/private/trace-cmd-private.h
+++ b/lib/trace-cmd/include/private/trace-cmd-private.h
@@ -221,6 +221,8 @@ tracecmd_peek_data_ref(struct tracecmd_input *handle, int cpu)
 	return rec;
 }
 
+int tracecmd_latency_data_read(struct tracecmd_input *handle, char **buf, size_t *size);
+
 struct tep_record *
 tracecmd_read_prev(struct tracecmd_input *handle, struct tep_record *record);
 
@@ -295,7 +297,8 @@ int tracecmd_output_write_init(struct tracecmd_output *handler);
 int tracecmd_output_write_headers(struct tracecmd_output *handler,
 				  struct tracecmd_event_list *list);
 
-struct tracecmd_output *tracecmd_create_file_latency(const char *output_file, int cpus);
+struct tracecmd_output *tracecmd_create_file_latency(const char *output_file, int cpus,
+						     int file_version);
 struct tracecmd_output *tracecmd_create_init_fd(int fd);
 
 struct tracecmd_output *tracecmd_create_init_file(const char *output_file);
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 87c33423..1b4a4d6b 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -3203,6 +3203,24 @@ static int read_options_type(struct tracecmd_input *handle)
 	return 0;
 }
 
+int tracecmd_latency_data_read(struct tracecmd_input *handle, char **buf, size_t *size)
+{
+	if (!handle || !buf || !size)
+		return -1;
+	if (handle->file_state != TRACECMD_FILE_CPU_LATENCY)
+		return -1;
+
+	/* Read data from a file */
+	if (!(*buf)) {
+		*size = BUFSIZ;
+		*buf = malloc(*size);
+		if (!(*buf))
+			return -1;
+	}
+
+	return do_read(handle, *buf, *size);
+}
+
 static int init_cpu_data(struct tracecmd_input *handle)
 {
 	enum kbuffer_long_size long_size;
@@ -3265,6 +3283,12 @@ static int init_cpu_data(struct tracecmd_input *handle)
 	return -1;
 }
 
+int init_latency_data(struct tracecmd_input *handle)
+{
+	/* To do */
+	return 0;
+}
+
 static int init_buffer_cpu_data(struct tracecmd_input *handle, struct input_buffer_instance *buffer)
 {
 	unsigned long long offset;
@@ -3279,7 +3303,10 @@ static int init_buffer_cpu_data(struct tracecmd_input *handle, struct input_buff
 		return -1;
 	if (read_section_header(handle, &id, &flags, NULL, NULL))
 		return -1;
-
+	if (buffer->latency) {
+		handle->file_state = TRACECMD_FILE_CPU_LATENCY;
+		return init_latency_data(handle) == 0 ? 1 : -1;
+	}
 	handle->file_state = TRACECMD_FILE_CPU_FLYRECORD;
 	handle->cpus = buffer->cpus;
 	if (handle->max_cpu < handle->cpus)
diff --git a/lib/trace-cmd/trace-output.c b/lib/trace-cmd/trace-output.c
index b3904204..645a8ab7 100644
--- a/lib/trace-cmd/trace-output.c
+++ b/lib/trace-cmd/trace-output.c
@@ -1786,7 +1786,8 @@ out_add_buffer_option_v7(struct tracecmd_output *handle, const char *name,
 	return option;
 }
 
-struct tracecmd_output *tracecmd_create_file_latency(const char *output_file, int cpus)
+struct tracecmd_output *tracecmd_create_file_latency(const char *output_file, int cpus,
+						     int file_version)
 {
 	enum tracecmd_section_flags flags = 0;
 	struct tracecmd_output *handle;
@@ -1801,6 +1802,8 @@ struct tracecmd_output *tracecmd_create_file_latency(const char *output_file, in
 	handle = tracecmd_output_allocate(fd);
 	if (!handle)
 		goto out_free;
+	if (file_version && tracecmd_output_set_version(handle, file_version))
+		goto out_free;
 	if (tracecmd_output_write_init(handle))
 		goto out_free;
 	if (tracecmd_output_write_headers(handle, NULL))
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 879acb7c..af7f332c 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -4505,7 +4505,8 @@ static void record_data(struct common_record_context *ctx)
 		return;
 
 	if (latency) {
-		handle = tracecmd_create_file_latency(ctx->output, local_cpu_count);
+		handle = tracecmd_create_file_latency(ctx->output, local_cpu_count,
+						      ctx->file_version);
 		tracecmd_set_quiet(handle, quiet);
 	} else {
 		if (!local_cpu_count)
-- 
2.31.1