On Fri, 13 Dec 2019 17:30:21 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@xxxxxxxxx> wrote:
> The ID of the current tracing session is stored in the trace.dat file.
> A new file option is introduced:
> TRACECMD_OPTION_TRACEID
> The data is stored in the file as NULL terminated string:
> "\nTraceID: %llu\n"
If the trace ID is just a 64 bit number, why is it stored in the file
as a string?
-- Steve
> A new libtracecmd API is introduced, to get the ID when the trace.dat file is read:
> unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
>
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
> ---
> include/trace-cmd/trace-cmd.h | 2 ++
> lib/trace-cmd/trace-input.c | 25 +++++++++++++++++++++++++
> tracecmd/trace-record.c | 15 +++++++++++++++
> 3 files changed, 42 insertions(+)
>
> diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
> index ad69313..6cc2913 100644
> --- a/include/trace-cmd/trace-cmd.h
> +++ b/include/trace-cmd/trace-cmd.h
> @@ -86,6 +86,7 @@ enum {
> TRACECMD_OPTION_CPUCOUNT,
> TRACECMD_OPTION_VERSION,
> TRACECMD_OPTION_PROCMAPS,
> + TRACECMD_OPTION_TRACEID,
> };
>
> enum {
> @@ -128,6 +129,7 @@ int tracecmd_copy_headers(struct tracecmd_input *handle, int fd);
> void tracecmd_set_flag(struct tracecmd_input *handle, int flag);
> void tracecmd_clear_flag(struct tracecmd_input *handle, int flag);
> unsigned long tracecmd_get_flags(struct tracecmd_input *handle);
> +unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
>
> void tracecmd_parse_trace_clock(struct tracecmd_input *handle, char *file, int size);
>
> diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
> index 91362f3..40d9825 100644
> --- a/lib/trace-cmd/trace-input.c
> +++ b/lib/trace-cmd/trace-input.c
> @@ -79,6 +79,7 @@ struct tracecmd_input {
> struct tep_plugin_list *plugin_list;
> struct tracecmd_input *parent;
> unsigned long flags;
> + unsigned long long trace_id;
> int fd;
> int long_size;
> int page_size;
> @@ -2169,6 +2170,15 @@ static void procmap_free(struct pid_addr_maps *maps)
> free(maps);
> }
>
> +static int trace_traceid_load(struct tracecmd_input *handle, char *buf)
> +{
> +
> + if (sscanf(buf, "%*s %llu", &handle->trace_id) == 1)
> + return 0;
> +
> + return -1;
> +}
> +
> #define STR_PROCMAP_LINE_MAX (PATH_MAX+22)
> static int trace_pid_map_load(struct tracecmd_input *handle, char *buf)
> {
> @@ -2406,6 +2416,10 @@ static int handle_options(struct tracecmd_input *handle)
> if (buf[size-1] == '\0')
> trace_pid_map_load(handle, buf);
> break;
> + case TRACECMD_OPTION_TRACEID:
> + if (buf[size-1] == '\0')
> + trace_traceid_load(handle, buf);
> + break;
> default:
> warning("unknown option %d", option);
> break;
> @@ -3507,3 +3521,14 @@ void tracecmd_set_show_data_func(struct tracecmd_input *handle,
> {
> handle->show_data_func = func;
> }
> +
> +/**
> + * tracecmd_get_traceid - get the trace id of the session
> + * @handle: input handle for the trace.dat file
> + *
> + * Returns the trace id, written in the trace file
> + */
> +unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle)
> +{
> + return handle->trace_id;
> +}
> diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> index 7089f7b..b65aeb2 100644
> --- a/tracecmd/trace-record.c
> +++ b/tracecmd/trace-record.c
> @@ -3714,6 +3714,19 @@ add_pid_maps(struct tracecmd_output *handle, struct buffer_instance *instance)
> trace_seq_destroy(&s);
> }
>
> +static void
> +add_trace_id(struct tracecmd_output *handle, struct buffer_instance *instance)
> +{
> + char *str = NULL;
> + int len;
> +
> + len = asprintf(&str, "\nTraceID: %llu\n", instance->trace_id);
> + if (len < 1)
> + return;
> + tracecmd_add_option(handle, TRACECMD_OPTION_TRACEID, len + 1, str);
> + free(str);
> +}
> +
> static void
> add_buffer_stat(struct tracecmd_output *handle, struct buffer_instance *instance)
> {
> @@ -3817,6 +3830,8 @@ static void add_options(struct tracecmd_output *handle, struct common_record_con
> add_option_hooks(handle);
> add_uname(handle);
> add_version(handle);
> + if (!no_top_instance())
> + add_trace_id(handle, &top_instance);
> }
>
> static void write_guest_file(struct buffer_instance *instance)
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