On Mon, Jan 06, 2025 at 06:50:25PM +0100, Jean-Yves Migeon (NetBSD) wrote: > > For the sake of argument, I wrote the code, stuck it in /usr/local/bin, > > and ran it in various ways, first from sh: > > This is not a shell matter.
It absolutely is. argv[0] is provided by the program that calls execve, which for ordinary 3rd-party application software that wants this feature is either the shell or a shell substitute (such as a window manager, desktop start button, etc.) There is no reason to care about what an "uncooperative" caller does. Furthermore, as I've already pointed out a couple times, a hostile caller can confuse any of these schemes. The simplest method (assuming for the sake of argument we're trying to run /usr/pkg/bin/qemu and convince it its $PREFIX is /tmp/confusion) is as follows: % mkdir /tmp/confusion /tmp/confusion/bin % ln /usr/pkg/bin/qemu . % ./qemu Then the path to the executable _is_ /tmp/confusion/bin, and you're done. You can't do it that way if /usr/pkg isn't on the same volume as /tmp, at which point things become more complicated, but configs where it is are quite common. -- David A. Holland dholl...@netbsd.org
