diff mbox series

[v2,5/7] trace-cmd library: Select the file version when writing trace file

Message ID 20210429040119.843617-6-tz.stoyanov@gmail.com (mailing list archive)
State Superseded
Headers show
Series Bump trace file version | expand

Commit Message

Tzvetomir Stoyanov (VMware) April 29, 2021, 4:01 a.m. UTC
When a new output handler to trace file is allocated, select the proper
file version. If this output handler is based on an existing input trace
file handler, inherit the trace file version.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 lib/trace-cmd/trace-output.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

Comments

Steven Rostedt April 29, 2021, 1:42 p.m. UTC | #1
On Thu, 29 Apr 2021 07:01:17 +0300
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> index 9231c319..f36718f1 100644
> --- a/lib/trace-cmd/trace-output.c
> +++ b/lib/trace-cmd/trace-output.c
> @@ -57,6 +57,7 @@ struct tracecmd_output {
>  	int			nr_options;
>  	bool			quiet;
>  	unsigned long		file_state;
> +	unsigned long		file_version;
>  	struct list_head	options;
>  	struct tracecmd_msg_handle *msg_handle;
>  	char			*trace_clock;
> @@ -907,6 +908,17 @@ out_free:
>  	return ret;
>  }
>  
> +static int select_file_version(struct tracecmd_output *handle,
> +				struct tracecmd_input *ihandle)
> +{
> +	if (ihandle)
> +		handle->file_version = tracecmd_get_file_version(ihandle);
> +	else
> +		handle->file_version = FILE_VERSION;
> +
> +	return 0;
> +}
> +

This is where we should have the logic for what we write.

We save a string where the version is going to be located. We default it to
the lowest level (6), and then if a feature is recorded that is of a higher
version, we up it, and change the number of disk as well.

If there's a case where we get to two digit strings, we should have it be:

  "6 \0"

which should still work. Then if we use a feature that requires version 10,
it would be updated to:

  "10\0"

We can do this at the end of recording.

-- Steve
diff mbox series

Patch

diff --git a/lib/trace-cmd/trace-output.c b/lib/trace-cmd/trace-output.c
index 9231c319..f36718f1 100644
--- a/lib/trace-cmd/trace-output.c
+++ b/lib/trace-cmd/trace-output.c
@@ -57,6 +57,7 @@  struct tracecmd_output {
 	int			nr_options;
 	bool			quiet;
 	unsigned long		file_state;
+	unsigned long		file_version;
 	struct list_head	options;
 	struct tracecmd_msg_handle *msg_handle;
 	char			*trace_clock;
@@ -907,6 +908,17 @@  out_free:
 	return ret;
 }
 
+static int select_file_version(struct tracecmd_output *handle,
+				struct tracecmd_input *ihandle)
+{
+	if (ihandle)
+		handle->file_version = tracecmd_get_file_version(ihandle);
+	else
+		handle->file_version = FILE_VERSION;
+
+	return 0;
+}
+
 static struct tracecmd_output *
 create_file_fd(int fd, struct tracecmd_input *ihandle,
 	       const char *tracing_dir,
@@ -933,6 +945,9 @@  create_file_fd(int fd, struct tracecmd_input *ihandle,
 
 	handle->msg_handle = msg_handle;
 
+	if (select_file_version(handle, ihandle))
+		goto out_free;
+
 	list_head_init(&handle->options);
 
 	buf[0] = 23;
@@ -943,7 +958,8 @@  create_file_fd(int fd, struct tracecmd_input *ihandle,
 	if (do_write_check(handle, buf, 10))
 		goto out_free;
 
-	if (do_write_check(handle, FILE_VERSION_STRING, strlen(FILE_VERSION_STRING) + 1))
+	sprintf(buf, "%lu", handle->file_version);
+	if (do_write_check(handle, buf, strlen(buf) + 1))
 		goto out_free;
 
 	/* get endian and page size */
@@ -1602,6 +1618,7 @@  struct tracecmd_output *tracecmd_get_output_handle_fd(int fd)
 	handle->pevent = tracecmd_get_tep(ihandle);
 	tep_ref(handle->pevent);
 	handle->page_size = tracecmd_page_size(ihandle);
+	handle->file_version = tracecmd_get_file_version(ihandle);
 	list_head_init(&handle->options);
 
 	tracecmd_close(ihandle);