[PATCH v5 37/40] trace-cmd library: Refactor the logic for writing CPU instance trace data

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

Added a helper function, internal to the library, for updating CPU
instance offset in the trace file. This allows to reuse the logic inside
the library, will be used in the tracecmd_copy API.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 lib/trace-cmd/include/trace-cmd-local.h |  2 ++
 lib/trace-cmd/trace-output.c            | 11 +++++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/trace-cmd/include/trace-cmd-local.h b/lib/trace-cmd/include/trace-cmd-local.h
index e8c7968f..14908f3c 100644
--- a/lib/trace-cmd/include/trace-cmd-local.h
+++ b/lib/trace-cmd/include/trace-cmd-local.h
@@ -72,4 +72,6 @@ struct cpu_data_source {
 int out_write_cpu_data(struct tracecmd_output *handle, int cpus,
 		       struct cpu_data_source *data);
 
+int out_update_buffer_cpu_offset(struct tracecmd_output *handle, const char *name);
+
 #endif /* _TRACE_CMD_LOCAL_H */
diff --git a/lib/trace-cmd/trace-output.c b/lib/trace-cmd/trace-output.c
index a3ccfba5..9933224c 100644
--- a/lib/trace-cmd/trace-output.c
+++ b/lib/trace-cmd/trace-output.c
@@ -1853,8 +1853,7 @@ int tracecmd_append_cpu_data(struct tracecmd_output *handle,
 	return tracecmd_write_cpu_data(handle, cpus, cpu_data_files);
 }
 
-int tracecmd_append_buffer_cpu_data(struct tracecmd_output *handle,
-				    const char *name, int cpus, char * const *cpu_data_files)
+__hidden int out_update_buffer_cpu_offset(struct tracecmd_output *handle, const char *name)
 {
 	tsize_t b_offset;
 	tsize_t offset;
@@ -1883,6 +1882,14 @@ int tracecmd_append_buffer_cpu_data(struct tracecmd_output *handle,
 		tracecmd_warning("could not seek to %lld\n", offset);
 		return -1;
 	}
+	return 0;
+}
+
+int tracecmd_append_buffer_cpu_data(struct tracecmd_output *handle,
+				    const char *name, int cpus, char * const *cpu_data_files)
+{
+	if (out_update_buffer_cpu_offset(handle, name))
+		return -1;
 
 	return tracecmd_write_cpu_data(handle, cpus, cpu_data_files);
 }
-- 
2.31.1