custom: Add RNG for CPU-based randomness

Signed-off-by: Joe Richey <[email protected]>

Author: josephlr

Cargo.toml

@@ -16,6 +16,7 @@ appveyor = { repository = "rust-random/getrandom" }
 
 [workspace]
 members = [
+    "custom/cpurand",
     "custom/stdweb",
     "custom/wasm-bindgen",
 ]

custom/cpurand/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "cpurand-getrandom"
+version = "0.1.0"
+edition = "2018"
+authors = ["The Rand Project Developers"]
+license = "MIT OR Apache-2.0"
+description = "Custom shim for using getrandom with CPU RNG instructions"
+documentation = "https://docs.rs/cpurand-getrandom"
+repository = "https://github.com/rust-random/getrandom"
+categories = ["hardware-support", "no-std"]
+
+[dependencies]
+cfg-if = "0.1.2"
+getrandom = { path = "../..", version = "0.2", features = ["custom"] }
+
+[[test]]
+name = "common"
+path = "../../tests/common.rs"
+
+[package.metadata.docs.rs]
+default-target = "x86_64-unknown-linux"

custom/cpurand/src/lib.rs

@@ -0,0 +1,24 @@
+// 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.
+#![no_std]
+
+#[macro_use]
+extern crate cfg_if;
+
+use getrandom::{register_custom_getrandom, Error};
+
+cfg_if! {
+    if #[cfg(target_arch = "x86_64")] {
+        #[path = "../../../src/util.rs"] mod util;
+        #[path = "../../../src/rdrand.rs"] mod imp;
+    } else {
+        compile_error!("CPU-based randomness is not supported for this arch");
+    }
+}
+
+register_custom_getrandom!(imp::getrandom_inner);

src/custom.rs

@@ -23,7 +23,7 @@ macro_rules! register_custom_getrandom {
         // We use an extern "C" function to get the guarantees of a stable ABI.
         #[no_mangle]
         extern "C" fn __getrandom_custom(dest: *mut u8, len: usize) -> u32 {
-            let slice = unsafe { ::std::slice::from_raw_parts_mut(dest, len) };
+            let slice = unsafe { ::core::slice::from_raw_parts_mut(dest, len) };
             match $path(slice) {
                 Ok(()) => 0,
                 Err(e) => e.code().get(),

src/lib.rs

@@ -183,12 +183,7 @@ cfg_if! {
         #[path = "windows_uwp.rs"] mod imp;
     } else if #[cfg(windows)] {
         #[path = "windows.rs"] mod imp;
-    } else if #[cfg(all(target_arch = "x86_64", any(
-                  target_os = "hermit",
-                  target_os = "l4re",
-                  target_os = "uefi",
-                  target_env = "sgx",
-              )))] {
+    } else if #[cfg(all(target_arch = "x86_64", target_env = "sgx"))] {
         #[path = "rdrand.rs"] mod imp;
     } else if #[cfg(feature = "custom")] {
         use custom as imp;