1 files changed, 54 insertions, 0 deletions
diff --git a/third_party/rust/getrandom/src/bsd_arandom.rs b/third_party/rust/getrandom/src/bsd_arandom.rs
new file mode 100644
index 0000000000..5314c48f19
--- /dev/null
+++ b/third_party/rust/getrandom/src/bsd_arandom.rs
@@ -0,0 +1,54 @@
+// 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, Weak},
+    Error,
+};
+use core::{mem::MaybeUninit, ptr};
+
+fn kern_arnd(buf: &mut [MaybeUninit<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
+    }
+}
+
+type GetRandomFn = unsafe extern "C" fn(*mut u8, libc::size_t, libc::c_uint) -> libc::ssize_t;
+
+pub fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
+    // getrandom(2) was introduced in FreeBSD 12.0 and NetBSD 10.0
+    static GETRANDOM: Weak = unsafe { Weak::new("getrandom\0") };
+    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() as *mut u8, 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(())
+}