[PATCH v3 20/25] trace-cmd library: Track the offset in the option section in the trace file

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

When reading / writing trace file, store the offset of the option
section in the file. A new internal API is added, to get the offset of
the option section from an input file handler:
 tracecmd_get_options_offset()

These changes are needed for compression of the option section from
the trace file.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 lib/trace-cmd/include/private/trace-cmd-private.h |  1 +
 lib/trace-cmd/trace-input.c                       | 11 +++++++++++
 lib/trace-cmd/trace-output.c                      |  2 ++
 3 files changed, 14 insertions(+)

diff --git a/lib/trace-cmd/include/private/trace-cmd-private.h b/lib/trace-cmd/include/private/trace-cmd-private.h
index d7488346..a9b66736 100644
--- a/lib/trace-cmd/include/private/trace-cmd-private.h
+++ b/lib/trace-cmd/include/private/trace-cmd-private.h
@@ -239,6 +239,7 @@ tracecmd_get_cursor(struct tracecmd_input *handle, int cpu);
 unsigned long tracecmd_get_file_version(struct tracecmd_input *handle);
 int tracecmd_get_file_compress_proto(struct tracecmd_input *handle,
 				     const char **name, const char **version);
+size_t tracecmd_get_options_offset(struct tracecmd_input *handle);
 
 int tracecmd_ftrace_overrides(struct tracecmd_input *handle, struct tracecmd_ftrace *finfo);
 bool tracecmd_get_use_trace_clock(struct tracecmd_input *handle);
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 5088a059..78581789 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -157,6 +157,7 @@ struct tracecmd_input {
 	size_t			header_files_start;
 	size_t			ftrace_files_start;
 	size_t			event_files_start;
+	size_t			options_start;
 	size_t			total_file_size;
 
 	/* For custom profilers. */
@@ -2759,6 +2760,7 @@ static int handle_options(struct tracecmd_input *handle)
 
 	/* By default, use usecs, unless told otherwise */
 	handle->flags |= TRACECMD_FL_IN_USECS;
+	handle->options_start = lseek64(handle->fd, 0, SEEK_CUR);
 
 	for (;;) {
 		if (do_read_check(handle, &option, 2))
@@ -4215,6 +4217,15 @@ bool tracecmd_get_use_trace_clock(struct tracecmd_input *handle)
 	return handle->use_trace_clock;
 }
 
+/**
+ * tracecmd_get_options_offset - get offset of the options sections in the file
+ * @handle: input handle for the trace.dat file
+ */
+size_t tracecmd_get_options_offset(struct tracecmd_input *handle)
+{
+	return handle->options_start;
+}
+
 /**
  * tracecmd_get_show_data_func - return the show data func
  * @handle: input handle for the trace.dat file
diff --git a/lib/trace-cmd/trace-output.c b/lib/trace-cmd/trace-output.c
index 57b11493..1bd2351f 100644
--- a/lib/trace-cmd/trace-output.c
+++ b/lib/trace-cmd/trace-output.c
@@ -66,6 +66,7 @@ struct tracecmd_output {
 	bool			quiet;
 	unsigned long		file_state;
 	unsigned long		file_version;
+	size_t			options_start;
 
 	bool			do_compress;
 	struct tracecmd_compression *compress;
@@ -1854,6 +1855,7 @@ struct tracecmd_output *tracecmd_get_output_handle_fd(int fd)
 	tep_ref(handle->pevent);
 	handle->page_size = tracecmd_page_size(ihandle);
 	handle->file_version = tracecmd_get_file_version(ihandle);
+	handle->options_start = tracecmd_get_options_offset(ihandle);
 	list_head_init(&handle->options);
 	list_head_init(&handle->buffers);
 
-- 
2.31.1