[PATCH] ld/Linux: determine program name in a more reliable manner

[Collin Funk]

Jan Beulich <jbeulich@suse.com> writes:

> What argv[0] holds can be pretty arbitrary. As long as it's used for just
> diagnostics, that may be pretty okay to go from, but ld also uses it to
> find linker scripts. For that we want to be sure we start from the real
> executable name. Which on Linux we can determine from the /proc/self/exe
> symbolic link target (provided of course procfs is mounted).
>
> While there constify program_name as well.
> ---
> Question is whether we should split program_name: Continue using argv[0]
> for diagnostics (invokees may deliberately use more readable names there),
> while using the /proc/self/exe target only for passing to
> make_relative_prefix().
>
> Further, to become independent of the ldscripts symlink placed (too late,
> see PR ld/33629) in .libs when --enable-shared is in use, should we check
> for .libs as the last path component, i.e. retry invoking
> make_relative_prefix() with that path component removed?

FWIW, my preference is using the last component of argv[0] for
diagnostics. That is what we do in coreutils:

    $ mkdir -p a && ln -s /bin/ls a/gls
    $ ./a/gls b
    gls: cannot access 'b': No such file or directory

Otherwise the diagnostics don't match the name of the program if
--program-suffix or similar are used when configuring.

Collin