Re: [PATCH v6 2/3] trace-cmd: Load libtraceevent plugins from build folder, if exists.

[Tzvetomir Stoyanov <tz.stoyanov@gmail.com>]

Ping.

I think this will be useful in avoiding problems like
https://bugzilla.kernel.org/show_bug.cgi?id=205643

-- 
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center



On Mon, Oct 7, 2019 at 2:49 PM Tzvetomir Stoyanov (VMware)
<tz.stoyanov@gmail.com> wrote:
>
> When a development version of trace-cmd is built and run on the machine,
> by default it loads only installed plugins, from system directories.
> Thus, the development plugins will not be loaded. To simplify the development
> process, a new logic is added:
>   At plugins load time, check the location of trace-cmd application and look
>   for "plugins" directory around it. If found, load plugins from it. Those
>   plugins will be loaded last, so in case of duplication the "development"
>   plugins win.
> A two new APIs are introduced to libtraceevent, in order to accomplish this
> logic:
>  tep_load_plugins_dir() - loads tep plugins from a specific directory.
>  tep_plugins_append() - Append two plugin lists.
>
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>  include/trace-cmd/trace-cmd.h |  2 ++
>  lib/trace-cmd/trace-input.c   |  7 +-----
>  lib/trace-cmd/trace-util.c    | 42 +++++++++++++++++++++++++++++++++++
>  tracecmd/trace-check-events.c |  7 +-----
>  tracecmd/trace-list.c         | 14 ++----------
>  5 files changed, 48 insertions(+), 24 deletions(-)
>
> diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
> index 4090eba..d1aaef8 100644
> --- a/include/trace-cmd/trace-cmd.h
> +++ b/include/trace-cmd/trace-cmd.h
> @@ -24,6 +24,8 @@ void tracecmd_parse_ftrace_printk(struct tep_handle *pevent, char *file, unsigne
>  extern int tracecmd_disable_sys_plugins;
>  extern int tracecmd_disable_plugins;
>
> +struct tep_plugin_list *trace_load_plugins(struct tep_handle *tep);
> +
>  char **tracecmd_event_systems(const char *tracing_dir);
>  char **tracecmd_system_events(const char *tracing_dir, const char *system);
>  struct tep_handle *tracecmd_local_events(const char *tracing_dir);
> diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
> index 6102eb3..28da455 100644
> --- a/lib/trace-cmd/trace-input.c
> +++ b/lib/trace-cmd/trace-input.c
> @@ -2886,15 +2886,10 @@ struct tracecmd_input *tracecmd_alloc_fd(int fd)
>         if (!handle->pevent)
>                 goto failed_read;
>
> -       if (tracecmd_disable_plugins)
> -               tep_set_flag(handle->pevent, TEP_DISABLE_PLUGINS);
> -       if (tracecmd_disable_sys_plugins)
> -               tep_set_flag(handle->pevent, TEP_DISABLE_SYS_PLUGINS);
> -
>         /* register default ftrace functions first */
>         tracecmd_ftrace_overrides(handle, &handle->finfo);
>
> -       handle->plugin_list = tep_load_plugins(handle->pevent);
> +       handle->plugin_list = trace_load_plugins(handle->pevent);
>
>         tep_set_file_bigendian(handle->pevent, buf[0]);
>         tep_set_local_bigendian(handle->pevent, tracecmd_host_bigendian());
> diff --git a/lib/trace-cmd/trace-util.c b/lib/trace-cmd/trace-util.c
> index 8aa3b6c..690a135 100644
> --- a/lib/trace-cmd/trace-util.c
> +++ b/lib/trace-cmd/trace-util.c
> @@ -860,6 +860,48 @@ void trace_util_free_plugin_files(char **files)
>         free(files);
>  }
>
> +static char *get_source_plugins_dir(void)
> +{
> +       char *p, path[PATH_MAX+1];
> +       int ret;
> +
> +       ret = readlink("/proc/self/exe", path, PATH_MAX);
> +       if (ret > PATH_MAX || ret < 0)
> +               return NULL;
> +
> +       dirname(path);
> +       p = strrchr(path, '/');
> +       if (!p)
> +               return NULL;
> +       /* Check if we are in the the source tree */
> +       if (strcmp(p, "/tracecmd") != 0)
> +               return NULL;
> +
> +       strcpy(p, "/lib/traceevent/plugins");
> +       return strdup(path);
> +}
> +
> +struct tep_plugin_list*
> +trace_load_plugins(struct tep_handle *tep)
> +{
> +       struct tep_plugin_list *list;
> +       char *path;
> +
> +       if (tracecmd_disable_plugins)
> +               tep_set_flag(tep, TEP_DISABLE_PLUGINS);
> +       if (tracecmd_disable_sys_plugins)
> +               tep_set_flag(tep, TEP_DISABLE_SYS_PLUGINS);
> +
> +       path = get_source_plugins_dir();
> +       if (path)
> +               tep_add_plugin_path(tep, path, TEP_PLUGIN_LAST);
> +       free(path);
> +
> +       list = tep_load_plugins(tep);
> +
> +       return list;
> +}
> +
>  char *tracecmd_get_tracing_file(const char *name)
>  {
>         static const char *tracing;
> diff --git a/tracecmd/trace-check-events.c b/tracecmd/trace-check-events.c
> index b09fcd0..ffaae27 100644
> --- a/tracecmd/trace-check-events.c
> +++ b/tracecmd/trace-check-events.c
> @@ -43,12 +43,7 @@ void trace_check_events(int argc, char **argv)
>         if (!pevent)
>                 exit(EINVAL);
>
> -       if (tracecmd_disable_plugins)
> -               tep_set_flag(pevent, TEP_DISABLE_PLUGINS);
> -       if (tracecmd_disable_sys_plugins)
> -               tep_set_flag(pevent, TEP_DISABLE_SYS_PLUGINS);
> -
> -       list = tep_load_plugins(pevent);
> +       list = trace_load_plugins(pevent);
>         ret = tracecmd_fill_local_events(tracing, pevent, &parsing_failures);
>         if (ret || parsing_failures)
>                 ret = EINVAL;
> diff --git a/tracecmd/trace-list.c b/tracecmd/trace-list.c
> index 65099a5..6b59117 100644
> --- a/tracecmd/trace-list.c
> +++ b/tracecmd/trace-list.c
> @@ -317,14 +317,9 @@ static void show_plugin_options(void)
>         if (!pevent)
>                 die("Can not allocate pevent\n");
>
> -       if (tracecmd_disable_plugins)
> -               tep_set_flag(pevent, TEP_DISABLE_PLUGINS);
> -       if (tracecmd_disable_sys_plugins)
> -               tep_set_flag(pevent, TEP_DISABLE_SYS_PLUGINS);
> -
>         trace_seq_init(&s);
>
> -       list = tep_load_plugins(pevent);
> +       list = trace_load_plugins(pevent);
>         tep_plugin_print_options(&s);
>         trace_seq_do_printf(&s);
>         tep_unload_plugins(list, pevent);
> @@ -348,14 +343,9 @@ static void show_plugins(void)
>         if (!pevent)
>                 die("Can not allocate pevent\n");
>
> -       if (tracecmd_disable_plugins)
> -               tep_set_flag(pevent, TEP_DISABLE_PLUGINS);
> -       if (tracecmd_disable_sys_plugins)
> -               tep_set_flag(pevent, TEP_DISABLE_SYS_PLUGINS);
> -
>         trace_seq_init(&s);
>
> -       list = tep_load_plugins(pevent);
> +       list = trace_load_plugins(pevent);
>         tep_print_plugins(&s, "  ", "\n", list);
>
>         trace_seq_do_printf(&s);
> --
> 2.21.0
>


--
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center