1 files changed, 34 insertions, 0 deletions
diff --git a/getrandom/src/macos.rs b/getrandom/src/macos.rs
new file mode 100644
index 0000000..c3bc533
--- /dev/null
+++ b/getrandom/src/macos.rs
@@ -0,0 +1,34 @@
+// Copyright 2019 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 macOS
+use crate::util_libc::{last_os_error, Weak};
+use crate::{use_file, Error};
+use core::mem;
+
+type GetEntropyFn = unsafe extern "C" fn(*mut u8, libc::size_t) -> libc::c_int;
+
+pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
+    static GETENTROPY: Weak = unsafe { Weak::new("getentropy\0") };
+    if let Some(fptr) = GETENTROPY.ptr() {
+        let func: GetEntropyFn = unsafe { mem::transmute(fptr) };
+        for chunk in dest.chunks_mut(256) {
+            let ret = unsafe { func(chunk.as_mut_ptr(), chunk.len()) };
+            if ret != 0 {
+                let err = last_os_error();
+                error!("getentropy syscall failed");
+                return Err(err);
+            }
+        }
+        Ok(())
+    } else {
+        // We fallback to reading from /dev/random instead of SecRandomCopyBytes
+        // to avoid high startup costs and linking the Security framework.
+        use_file::getrandom_inner(dest)
+    }
+}