feat: works

__wasm/wit-bindgen-sample/engine/getrandom/src/bsd_arandom.rs

@@ -0,0 +1,53 @@
+// Copyright 2018 Developers of the Rand project.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Implementation for FreeBSD and NetBSD
+use crate::{util_libc::sys_fill_exact, Error};
+use core::ptr;
+
+fn kern_arnd(buf: &mut [u8]) -> libc::ssize_t {
+    static MIB: [libc::c_int; 2] = [libc::CTL_KERN, libc::KERN_ARND];
+    let mut len = buf.len();
+    let ret = unsafe {
+        libc::sysctl(
+            MIB.as_ptr(),
+            MIB.len() as libc::c_uint,
+            buf.as_mut_ptr() as *mut _,
+            &mut len,
+            ptr::null(),
+            0,
+        )
+    };
+    if ret == -1 {
+        -1
+    } else {
+        len as libc::ssize_t
+    }
+}
+
+pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
+    // getrandom(2) was introduced in FreeBSD 12.0 and NetBSD 10.0
+    #[cfg(target_os = "freebsd")]
+    {
+        use crate::util_libc::Weak;
+        static GETRANDOM: Weak = unsafe { Weak::new("getrandom\0") };
+        type GetRandomFn =
+            unsafe extern "C" fn(*mut u8, libc::size_t, libc::c_uint) -> libc::ssize_t;
+
+        if let Some(fptr) = GETRANDOM.ptr() {
+            let func: GetRandomFn = unsafe { core::mem::transmute(fptr) };
+            return sys_fill_exact(dest, |buf| unsafe { func(buf.as_mut_ptr(), buf.len(), 0) });
+        }
+    }
+    // Both FreeBSD and NetBSD will only return up to 256 bytes at a time, and
+    // older NetBSD kernels will fail on longer buffers.
+    for chunk in dest.chunks_mut(256) {
+        sys_fill_exact(chunk, kern_arnd)?
+    }
+    Ok(())
+}