Function pio_package_validate 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn pio_package_validate(
    pkg: *mut PioPackage,
    errbuf: *mut c_char,
    errlen: usize,
) -> i32

Run the package semantic validation profile in place. Returns 0 on success, -1 on error.

Unlike the read-only accessors, this rewrites the handle’s diagnostics and validation (the payload is untouched), so it takes the handle non-const and needs exclusive access: no other call may touch the same handle concurrently. This is the one exception to the header’s blanket concurrent-read guarantee.