Re: [PATCH v3 3/5] trace-cmd: Load libtraceevent plugins from build folder, if exists.

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

On Thu, Oct 3, 2019 at 2:49 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Wed,  2 Oct 2019 14:41:50 +0300
> "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 drierctories.
> > 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
> >   pluigins will be loaded last, so in case of duplication the "development"
> >   plugins win.
> >
> > Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> > ---
> >  lib/traceevent/event-plugin.c | 28 ++++++++++++++++++++++++++++
> >  1 file changed, 28 insertions(+)
> >
> > diff --git a/lib/traceevent/event-plugin.c b/lib/traceevent/event-plugin.c
> > index bc10205..4fc4ee3 100644
> > --- a/lib/traceevent/event-plugin.c
> > +++ b/lib/traceevent/event-plugin.c
> > @@ -14,6 +14,7 @@
> >  #include <unistd.h>
> >  #include <dirent.h>
> >  #include <errno.h>
> > +#include <libgen.h>
> >  #include "event-parse.h"
> >  #include "event-parse-local.h"
> >  #include "event-utils.h"
> > @@ -538,6 +539,27 @@ load_plugins_dir(struct tep_handle *tep, const char *suffix,
> >       closedir(dir);
> >  }
> >
> > +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)
>
> Hmm, this is in the lib/libtraceevent directory. We shouldn't be
> referencing trace-cmd code here. We should have a way to override the
> plugins from the trace-cmd side, perhaps after tep_load_plugins_hook()
> gets called?
>

I agree, we should move this check outside of the library.
I'll expose the functionality of load_plugins_dir() as a library API.
Thanks !

> -- Steve
>
>
> > +             return NULL;
> > +
> > +     strcpy(p, "/lib/traceevent/plugins");
> > +     return strdup(path);
> > +}
> > +
> >  void tep_load_plugins_hook(struct tep_handle *tep, const char *suffix,
> >                          void (*load_plugin)(struct tep_handle *tep,
> >                                              const char *path,
> > @@ -588,6 +610,12 @@ void tep_load_plugins_hook(struct tep_handle *tep, const char *suffix,
> >       load_plugins_dir(tep, suffix, path, load_plugin, data);
> >
> >       free(path);
> > +
> > +     path = get_source_plugins_dir();
> > +     if (path) {
> > +             load_plugins_dir(tep, suffix, path, load_plugin, data);
> > +             free(path);
> > +     }
> >  }
> >
> >  struct tep_plugin_list*
>


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