Re: [PATCH v7] usertools: rewrite pmdinfo

[Thomas Monjalon <thomas@monjalon.net>]

12/10/2022 17:16, Olivier Matz:
> On Tue, Oct 11, 2022 at 12:44:56AM +0200, Thomas Monjalon wrote:
> As discussed off-list with Robin, it appears that "ldd" is not available
> on buildroot-based images. See:
> http://lists.busybox.net/pipermail/buildroot/2013-July/074927.html
> 
> The link is quite old but it seems it's still true today if we don't
> build the toolchain.
> 
> Robin suggested this patch:
> 
> --- a/usertools/dpdk-pmdinfo.py
> +++ b/usertools/dpdk-pmdinfo.py
> @@ -290,8 +290,10 @@ def get_needed_libs(path: Path) -> Iterator[Path]:
>      """
>      Extract the dynamic library dependencies from an ELF executable.
>      """
> +    env = os.environ.copy()
> +    env["LD_TRACE_LOADED_OBJECTS"] = "1"
>      with subprocess.Popen(
> -        ["ldd", str(path)], stdout=subprocess.PIPE, stderr=subprocess.PIPE
> +        [str(path)], stdout=subprocess.PIPE, stderr=subprocess.PIPE, env=env
>      ) as proc:
>          out, err = proc.communicate()
>          if proc.returncode != 0:
> 
> One subtle difference is that the patched version won't work on
> non-executable files, but I don't think it can happen in real-life.
> 
> An alternative for us is to provide a simple "ldd" shell script in our
> buildroot-based images.
> 
> I don't have a strong opinion, I'll tend to say that the patch is a
> better option. Any comment?

What about implementing both?
If ldd is available, use it,
otherwise use LD_TRACE_LOADED_OBJECTS variable.