Re: [PATCH v4l-utils v1] v4l2-tracer: fix trace path name creation

[Deborah Brouwer <deborah.brouwer@collabora.com>]

On Thu, Mar 30, 2023 at 04:36:35PM +0200, Peter Seiderer wrote:
> Fix trace path name creation for poor man's development boards
> (e.g. Raspberry Pi) without RTC (starting at unix epoche aka time 0)
> by forcing initial trace_id creation with 6 valid digits.
> 
> Fixes:
> 
>   terminate called after throwing an instance of 'std::out_of_range'
>     what():  basic_string::substr: __pos (which is 5) > this->size() (which is 3)
>   Aborted
> 
> Signed-off-by: Peter Seiderer <ps.report@gmx.net>
> ---
>  utils/v4l2-tracer/v4l2-tracer.cpp | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/utils/v4l2-tracer/v4l2-tracer.cpp b/utils/v4l2-tracer/v4l2-tracer.cpp
> index cb873d83..1a9a7d75 100644
> --- a/utils/v4l2-tracer/v4l2-tracer.cpp
> +++ b/utils/v4l2-tracer/v4l2-tracer.cpp
> @@ -241,11 +241,9 @@ int tracer(int argc, char *argv[], bool retrace)
>  		trace_id = json_file_name.substr(0, json_file_name.find(".json"));
>  		trace_id += "_retrace";
>  	} else {
> -		const int timestamp_start_pos = 5;
> -		trace_id = std::to_string(time(nullptr));
> -		// trace_id = trace_id.substr(timestamp_start_pos, std::string::npos) + "_trace";
> +		const int timestamp_start_pos = 1;
> +		trace_id = std::to_string(100000 + time(nullptr) % 100000);
>  		trace_id = trace_id.substr(timestamp_start_pos) + "_trace";
> -
Thanks for this patch, I checked and the file names are still working as
expected for traced, retraced and cleaned files, so looks good to me.

>  	}
>  	setenv("TRACE_ID", trace_id.c_str(), 0);
>  	std::string trace_filename = trace_id + ".json";
> -- 
> 2.40.0
>