From: Sebastien Marie <semarie@kapouay.eu.org>
Subject: Re: lang/rust: migrate to getexecpath()
To: "Kirill A. Korinsky" <kirill@korins.ky>, OpenBSD ports <ports@openbsd.org>
Date: Fri, 04 Sep 2026 08:17:19 +0200

Kirill A. Korinsky <kirill@korins.ky> writes:

> Sebastien,
>
> I'd like to migrate our rust to use of getexecpath(), it should allow to
> drop a lot of patches to remove usage of current_exe()
>
> I plan to upstream it as soon as 8.0 is released.
>
> Briefly tested on -current/amd64
>
> Ok?

Several comments:

- the diff is almost fine for ports (it would also need
  _SYSTEM_VERSION-rust bump too, as it modifies libstd which is
  statically compiled in all rust ports)

- but the diff is *not* fine for upstream. getexecpath() should be
  introduced via libc rust crate.

Please also note it would be fine if we synchronize as 1.98.1 has been
released and I would like to commit it soon. I would permit to avoid
bumping twice in a row the whole rust ecosystem in ports.

Regards.

> Index: Makefile
> ===================================================================
> RCS file: /home/cvs/ports/lang/rust/Makefile,v
> diff -u -p -r1.252 Makefile
> --- Makefile	26 Aug 2026 17:25:14 -0000	1.252
> +++ Makefile	3 Sep 2026 20:49:45 -0000
> @@ -13,6 +13,7 @@ COMMENT-bootstrap =	Rust binary bootstra
>  COMMENT-src =		Rust source component
>  
>  V =			1.98.0
> +REVISION =		0
>  DISTNAME =		rustc-${V}-src
>  
>  # always keep REVISION-bootstrap in sync with REVISION-main (if defined)
> Index: patches/patch-library_std_src_sys_paths_unix_rs
> ===================================================================
> RCS file: /home/cvs/ports/lang/rust/patches/patch-library_std_src_sys_paths_unix_rs,v
> diff -u -p -r1.1 patch-library_std_src_sys_paths_unix_rs
> --- patches/patch-library_std_src_sys_paths_unix_rs	3 Jun 2026 11:15:20 -0000	1.1
> +++ patches/patch-library_std_src_sys_paths_unix_rs	3 Sep 2026 20:48:28 -0000
> @@ -1,21 +1,37 @@
> -argv0 isn't suitable as current_exe() in all cases.
> +Implement support of getexecpath()
>  
>  Index: library/std/src/sys/paths/unix.rs
>  --- library/std/src/sys/paths/unix.rs.orig
>  +++ library/std/src/sys/paths/unix.rs
> -@@ -240,13 +240,13 @@ pub fn current_exe() -> io::Result<PathBuf> {
> -         cvt(libc::sysctl(mib, 4, argv.as_mut_ptr() as *mut _, &mut argv_len, ptr::null_mut(), 0))?;
> -         argv.set_len(argv_len as usize);
> -         if argv[0].is_null() {
> +@@ -231,23 +231,15 @@ pub fn current_exe() -> io::Result<PathBuf> {
> + 
> + #[cfg(target_os = "openbsd")]
> + pub fn current_exe() -> io::Result<PathBuf> {
> ++    unsafe extern "C" {
> ++        fn getexecpath(buf: *mut c_char, bufsize: libc::size_t) -> c_int;
> ++    }
> ++
> ++    let mut path = vec![0; libc::PATH_MAX as usize];
> +     unsafe {
> +-        let mut mib = [libc::CTL_KERN, libc::KERN_PROC_ARGS, libc::getpid(), libc::KERN_PROC_ARGV];
> +-        let mib = mib.as_mut_ptr();
> +-        let mut argv_len = 0;
> +-        cvt(libc::sysctl(mib, 4, ptr::null_mut(), &mut argv_len, ptr::null_mut(), 0))?;
> +-        let mut argv = Vec::<*const libc::c_char>::with_capacity(argv_len as usize);
> +-        cvt(libc::sysctl(mib, 4, argv.as_mut_ptr() as *mut _, &mut argv_len, ptr::null_mut(), 0))?;
> +-        argv.set_len(argv_len as usize);
> +-        if argv[0].is_null() {
>  -            return Err(io::const_error!(io::ErrorKind::Uncategorized, "no current exe available"));
> -+            return Err(io::const_error!(io::ErrorKind::Uncategorized, "no current exe available (null)"));
> -         }
> -         let argv0 = CStr::from_ptr(argv[0]).to_bytes();
> -         if argv0[0] == b'.' || argv0.iter().any(|b| *b == b'/') {
> -             crate::fs::canonicalize(OsStr::from_bytes(argv0))
> -         } else {
> +-        }
> +-        let argv0 = CStr::from_ptr(argv[0]).to_bytes();
> +-        if argv0[0] == b'.' || argv0.iter().any(|b| *b == b'/') {
> +-            crate::fs::canonicalize(OsStr::from_bytes(argv0))
> +-        } else {
>  -            Ok(PathBuf::from(OsStr::from_bytes(argv0)))
> -+            Err(io::const_error!(io::ErrorKind::Uncategorized, "no current exe available (short)"))
> -         }
> +-        }
> ++        cvt(getexecpath(path.as_mut_ptr(), path.len()))?;
> ++        let path = CStr::from_ptr(path.as_ptr()).to_bytes();
> ++        Ok(PathBuf::from(OsStr::from_bytes(path)))
>       }
>   }
> + 
-- 
Sebastien Marie