libc: add execvpe to weak symbol as gnu libc does

[imp]

Why? Why does glibc do this?

[emaste]

See https://github.com/rizsotto/Bear/issues/557 for the issue that prompted this and particularly the comment https://github.com/rizsotto/Bear/issues/557#issuecomment-2776259708

[kib]

I think that the proper fix in line with the existing code is to use namespace.h to mangle execvpe reference in libc.

[aokblast]

Use namespace.h instead of waek alias

[aokblast]

fix indent

[aokblast]

The bear problem still fixed but we are unable to intercept the execvpe call as it is replaced with _execvpe.

In D49733#1134224, @kib wrote:

I think that the proper fix in line with the existing code is to use namespace.h to mangle execvpe reference in libc.

[brooks]

I think you need to bring the __weak_reference line back from the original change.

Using _execvpe is consistent, but perhaps it should be __libc_execvpe. The general _<foo> model is a remnant of libc_r and should perhaps be removed at some point.

lib/libc/gen/Symbol.map

460 ↗

(On Diff #153445)

You can't remove previously exported public symbols.

lib/libc/gen/exec.c

301

Remove

lib/libc/include/libc_private.h

357 ↗

(On Diff #153445)

Should not be required.

lib/libc/include/namespace.h

64–66

White space is wrong and touching the execve line is bug.

More importantly, you're missing a matching un-namespace.h change.

[aokblast]

Use weak alias also

[aokblast]

Bring back namespace

[brooks]

You still need to add a an #undef execvpe line to un-namespace.h and then you shouldn't need the libc_private.h entry. The point of namespace.h/un-namespace.h is that the declarations are impacted by the macro so the execvpe declaration in unistd.h becomes an __libc_execvpe declaration which you can then use.

[aokblast]

fix missed un-namespace.h

[brooks]

This seems alright.

[kib]

lib/libc/include/namespace.h

65

If you changed the original symbol name, why the namespacing is still kept in the patch?