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std: Use getexecpath() for current_exe() on OpenBSD #163393

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std: Use getexecpath() for current_exe() on OpenBSD #163393

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1 change: 0 additions & 1 deletion library/std/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -287,7 +287,6 @@
#![feature(doc_masked)]
#![feature(doc_notable_trait)]
#![feature(dropck_eyepatch)]
#![feature(exact_div)]
#![feature(f16)]
#![feature(f128)]
#![feature(ffi_const)]
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35 changes: 6 additions & 29 deletions library/std/src/sys/paths/unix.rs
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Expand Up @@ -253,37 +253,14 @@ pub fn current_exe() -> io::Result<PathBuf> {

#[cfg(target_os = "openbsd")]
pub fn current_exe() -> io::Result<PathBuf> {
let mut path = vec![0u8; 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();

// Determine the required size (in bytes) for the argument array ...
let mut argv_size = 0;
cvt(libc::sysctl(mib, 4, ptr::null_mut(), &mut argv_size, ptr::null_mut(), 0))?;

// ... allocate a buffer for it ...
let argc = argv_size.div_exact(size_of::<*const libc::c_char>()).unwrap();
let mut argv = Vec::<*const libc::c_char>::with_capacity(argc);

// ... and retrieve the argument array.
cvt(libc::sysctl(mib, 4, argv.as_mut_ptr() as *mut _, &mut argv_size, ptr::null_mut(), 0))?;
let argc = argv_size.div_exact(size_of::<*const libc::c_char>()).unwrap();
argv.set_len(argc);

if argv[0].is_null() {
return Err(io::const_error!(io::ErrorKind::Uncategorized, "no current exe available"));
}
let argv0 = CStr::from_ptr(argv[0]).to_bytes();
if argv0.iter().any(|b| *b == b'/') {
// The program name is path-like, so try to canonicalize it.
crate::fs::canonicalize(OsStr::from_bytes(argv0))
} else {
// The program was probably found in the PATH. Instead of trying to
// find it again (which might not succeed if PATH has changed), just
// return the program name – this function is best-effort anyway.
Ok(PathBuf::from(OsStr::from_bytes(argv0)))
}
cvt(libc::getexecpath(path.as_mut_ptr().cast(), path.len()))?;
// SAFETY: getexecpath(3) NUL-terminates the buffer on success.
let len = CStr::from_ptr(path.as_ptr().cast()).count_bytes();
path.truncate(len);
}
Ok(PathBuf::from(OsString::from_vec(path)))

@catap catap Oct 19, 2026 •
edited by rustbot
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Probably I've missed why do we need truncate here. I think it should be as simple as:

    let mut path = vec![0; libc::PATH_MAX as usize];
    unsafe {
        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)))
    }

View changes since the review

@kpcyrd kpcyrd Oct 20, 2026

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This code does two heap allocations instead of just one, see this comment: #163393 (comment)

}

#[cfg(any(
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