1 files changed, 61 insertions, 0 deletions
diff --git a/nearby/crypto/rand_core_05_adapter/src/lib.rs b/nearby/crypto/rand_core_05_adapter/src/lib.rs
new file mode 100644
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+++ b/nearby/crypto/rand_core_05_adapter/src/lib.rs
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+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Adapter for using rand_core 0.5 RNGs with code that expects rand_core 0.5 RNGs.
+#![no_std]
+#![forbid(unsafe_code)]
+#![deny(
+    missing_docs,
+    clippy::indexing_slicing,
+    clippy::unwrap_used,
+    clippy::panic,
+    clippy::expect_used
+)]
+
+/// A trivial adapter to expose rand 1.0/rand_core 0.6 rngs to ed25519-dalek's rand_core 0.5 types,
+/// which we import under a separate name so there's no clash.
+pub struct RandWrapper<'r, R: rand::RngCore + rand::CryptoRng> {
+    rng: &'r mut R,
+}
+
+impl<'r, R: rand::RngCore + rand::CryptoRng> RandWrapper<'r, R> {
+    /// Build a rand_core 0.5 compatible wrapper around the provided rng.
+    pub fn from(rng: &'r mut R) -> RandWrapper<'r, R> {
+        RandWrapper { rng }
+    }
+}
+
+impl<'r, R: rand::RngCore + rand::CryptoRng> rand_core05::RngCore for RandWrapper<'r, R> {
+    fn next_u32(&mut self) -> u32 {
+        self.rng.next_u32()
+    }
+
+    fn next_u64(&mut self) -> u64 {
+        self.rng.next_u64()
+    }
+
+    fn fill_bytes(&mut self, dest: &mut [u8]) {
+        self.rng.fill_bytes(dest)
+    }
+
+    fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), rand_core05::Error> {
+        self.rng
+            .try_fill_bytes(dest)
+            .map_err(|e| rand_core05::Error::new(e.take_inner()))
+    }
+}
+
+impl<'r, R: rand::RngCore + rand::CryptoRng> rand_core05::CryptoRng for RandWrapper<'r, R> {
+    // marker trait
+}