Re: [PATCH] libsemanage: define basename macro for non-glibc systems

["Rahul Sandhu" <nvraxn@gmail.com>]

> What system are you on where you run libsemange without glibc, just curious?

All Gentoo machines, Gentoo musl. :)

> I am not opposed to adding an implementation for basename where the
> input can be read only for non-glibc, but this patch doesn't work:
> Per the man page, https://man7.org/linux/man-pages/man3/basename.3.html,
> basename("/") should return "/", this one return "\0"
> basename("/usr/"); should return "usr", this returns "\0".

> There are two ways you could approach this:
> 1. If you wanted to do an implementation, I would add it to
> utilities.c/h and call it something other than basename so we don't
> get any odd issues with it choosing the one from the headers over the
> macro. Perhaps libsemange_basename(). On glibc systems this would just
> call basename directly and on non-glibc systems do the implementation
> with your own logic.
> 2. Just copy the path into a modifiable buffer on non-glibc systems
>
> I would do both approaches. Create a utility routine that calls
> basename for glibc and for non-glibc just copies it to a modifiable
> buffer and then calls basename over rolling our own and the bugs
> associated with it, also add a unit test for this. This would keep the
> logic in one place and be dirt simple.

FWIW, glibc's basename appears to be really trivial:

char *
__basename (const char *filename)
{
  char *p = strrchr (filename, '/');
  return p ? p + 1 : (char *) filename;
}

> selinux_policy_root() returns a const char *,
> the usage in direct_api.c path is a char *, so we only need one spot
> changed and that can just be a simple
> copy to an intermediate buffer or am I missing something else here
> you're pointing out?

Oh good point, we're just missing a header (libgen.h).

I suppose then it is just a simple copy to an intermediate buffer, I'll
send an updated patch shortly.

Thanks,
Rahul