Re: [PATCH] elf: Restore how vDSO dependency is printed with LD_TRACE_LOADED_OBJECTS (BZ #29539)

[Florian Weimer <fweimer@redhat.com>]

* Adhemerval Zanella via Libc-alpha:

> The d7703d3176d225d5743b21811d888619eba39e82 changed how vDSO like
> dependencies are printed, instead of just the name and address it
> follows other libraries mode and prints 'name => path'.
>
> Unfortunately, this broke some ldd consumer that uses the output to
> filter out the program's dependencies.  For instance CMake
> bundleutilities module [1], where GetPrequirite uses the regex to filter
> out 'name => path' [2].
>
> This patch restore the previous way to print just the name and the
> mapping address.
>
> Checked on x86_64-linux-gnu.
>
> [1] https://github.com/Kitware/CMake/tree/master/Tests/BundleUtilities
> [2] https://github.com/Kitware/CMake/blob/master/Modules/GetPrerequisites.cmake#L733
> ---
>  elf/rtld.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/elf/rtld.c b/elf/rtld.c
> index cbbaf4a331..3e771a93d8 100644
> --- a/elf/rtld.c
> +++ b/elf/rtld.c
> @@ -2122,6 +2122,12 @@ dl_main (const ElfW(Phdr) *phdr,
>  	    if (l->l_faked)
>  	      /* The library was not found.  */
>  	      _dl_printf ("\t%s => not found\n",  l->l_libname->name);
> +	    else if (strcmp (l->l_libname->name, l->l_name) == 0)
> +	      /* Print vDSO like libraries without duplicate name.  Some
> +		 consumers depend of this format.  */
> +	      _dl_printf ("\t%s (0x%0*Zx)\n", l->l_libname->name,
> +			  (int) sizeof l->l_map_start * 2,
> +			  (size_t) l->l_map_start);
>  	    else
>  	      _dl_printf ("\t%s => %s (0x%0*Zx)\n",
>  			  DSO_FILENAME (l->l_libname->name),

Looks okay, thanks.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

Florian