[PATCH 13/28] elf: Add library search path information to ld.so --help

[Adhemerval Zanella]

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

On 01/10/2020 13:32, Florian Weimer via Libc-alpha wrote:
> ---
>  elf/dl-usage.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 56 insertions(+)
> 
> diff --git a/elf/dl-usage.c b/elf/dl-usage.c
> index 0a62e8f7cf..20aa715cb1 100644
> --- a/elf/dl-usage.c
> +++ b/elf/dl-usage.c
> @@ -46,6 +46,61 @@ PARTICULAR PURPOSE.\n\
>    _exit (0);
>  }
>  
> +/* Print part of the library search path (from a single source).  */
> +static void
> +print_search_path_for_help_1 (struct r_search_path_elem **list)
> +{
> +  if (list == NULL || list == (void *) -1)
> +    /* Path is missing or marked as inactive.  */
> +    return;
> +
> +  for (; *list != NULL; ++list)
> +    {
> +      (void) _dl_write (STDOUT_FILENO, "  ", 2);
> +      const char *name = (*list)->dirname;
> +      size_t namelen = (*list)->dirnamelen;
> +      if (namelen == 0)
> +        {
> +          /* The empty string denotes the current directory.  */
> +          name = ".";
> +          namelen = 1;
> +        }
> +      else if (namelen > 1)
> +        /* Remove the trailing slash.  */
> +        --namelen;
> +      (void) _dl_write (STDOUT_FILENO, name, namelen);
> +      _dl_printf (" (%s)\n", (*list)->what);
> +    }
> +}
> +

Do we need the (void) casts? 

> +/* Prints the library search path.  See _dl_init_paths in dl-load.c
> +   how this information is populated.  */
> +static void
> +print_search_path_for_help (struct dl_main_state *state)
> +{
> +  if (__rtld_search_dirs.dirs == NULL)
> +    /* The run-time search paths have not yet been initialized.  */
> +    _dl_init_paths (state->library_path, state->library_path_source);
> +
> +  _dl_printf ("\nShared library search path:\n");
> +
> +  /* The print order should reflect the processing in
> +     _dl_map_object.  */
> +
> +  struct link_map *map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
> +  if (map != NULL)
> +    print_search_path_for_help_1 (map->l_rpath_dirs.dirs);
> +
> +  print_search_path_for_help_1 (__rtld_env_path_list.dirs);
> +
> +  if (map != NULL)
> +    print_search_path_for_help_1 (map->l_runpath_dirs.dirs);
> +
> +  _dl_printf ("  (libraries located via %s)\n", LD_SO_CACHE);
> +
> +  print_search_path_for_help_1 (__rtld_search_dirs.dirs);
> +}
> +
>  void
>  _dl_help (const char *argv0, struct dl_main_state *state)
>  {
> @@ -80,5 +135,6 @@ setting environment variables (which would be inherted by subprocesses).\n\
>  This program interpreter self-identifies as: " RTLD "\n\
>  ",
>                argv0);
> +  print_search_path_for_help (state);
>    _exit (0);
>  }
> 

Ok.