From 39de561b86bdab6e85f1c26080590f37ccd36b62 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sosth=C3=A8ne=20Gu=C3=A9don?= <sosthene@nitrokey.com>
Date: Thu, 10 Apr 2025 15:35:43 +0200
Subject: [PATCH] Implement the bytes traits

---
 Cargo.toml          |  2 ++
 src/bytes_traits.rs | 74 +++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs          |  3 ++
 3 files changed, 79 insertions(+)
 create mode 100644 src/bytes_traits.rs

diff --git a/Cargo.toml b/Cargo.toml
index d24a804..b96b1ce 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,6 +13,7 @@ edition = "2021"
 
 [dependencies]
 heapless = { version = "0.9.1", default-features = false }
+bytes = { version = "1.10.1", default-features = false, optional = true }
 serde = { version = "1.0", default-features = false }
 
 [dev-dependencies]
@@ -20,3 +21,4 @@ serde_test = "1.0.176"
 
 [features]
 "heapless-0.9" = []
+bytes = ["dep:bytes"]
diff --git a/src/bytes_traits.rs b/src/bytes_traits.rs
new file mode 100644
index 0000000..31b9817
--- /dev/null
+++ b/src/bytes_traits.rs
@@ -0,0 +1,74 @@
+use crate::storage::BytesStorage;
+use bytes::{buf::UninitSlice, BufMut};
+use heapless::LenType;
+
+unsafe impl<S: BytesStorage + ?Sized, LenT: LenType> BufMut for crate::BytesInner<LenT, S> {
+    fn remaining_mut(&self) -> usize {
+        self.capacity() - self.len()
+    }
+    unsafe fn advance_mut(&mut self, cnt: usize) {
+        self.set_len(cnt);
+    }
+    fn chunk_mut(&mut self) -> &mut UninitSlice {
+        // SAFETY: add is safe because once the length is added is less than the buffer and therefore
+        // always in the "allocation" bounds
+        let ptr = unsafe { self.bytes.as_mut_ptr().add(self.len()) };
+        let len = self.capacity() - self.len();
+        unsafe { UninitSlice::from_raw_parts_mut(ptr, len) }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{Bytes, BytesView};
+    use bytes::BufMut;
+
+    #[test]
+    #[should_panic]
+    fn buf_mut_advance_mut_out_of_bounds() {
+        let mut bytes: Bytes<8> = Bytes::new();
+        unsafe { bytes.advance_mut(9) };
+    }
+
+    #[test]
+    fn buf_mut_remaining_mut() {
+        let mut bytes: Bytes<8> = Bytes::new();
+        assert_eq!(bytes.remaining_mut(), 8);
+        bytes.push(42).unwrap();
+        assert_eq!(bytes.remaining_mut(), 7);
+    }
+
+    #[test]
+    fn buf_mut_chunk_mut() {
+        let mut bytes: Bytes<8> = Bytes::new();
+        assert_eq!(bytes.chunk_mut().len(), 8);
+        unsafe { bytes.advance_mut(1) };
+        assert_eq!(bytes.chunk_mut().len(), 7);
+    }
+
+    #[test]
+    #[should_panic]
+    fn view_buf_mut_advance_mut_out_of_bounds() {
+        let mut bytes: Bytes<8> = Bytes::new();
+        let bytes: &mut BytesView = &mut bytes;
+        unsafe { bytes.advance_mut(9) };
+    }
+
+    #[test]
+    fn view_buf_mut_remaining_mut() {
+        let mut bytes: Bytes<8> = Bytes::new();
+        let bytes: &mut BytesView = &mut bytes;
+        assert_eq!(bytes.remaining_mut(), 8);
+        bytes.push(42).unwrap();
+        assert_eq!(bytes.remaining_mut(), 7);
+    }
+
+    #[test]
+    fn view_buf_mut_chunk_mut() {
+        let mut bytes: Bytes<8> = Bytes::new();
+        let bytes: &mut BytesView = &mut bytes;
+        assert_eq!(bytes.chunk_mut().len(), 8);
+        unsafe { bytes.advance_mut(1) };
+        assert_eq!(bytes.chunk_mut().len(), 7);
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 5f09b0c..3fdb4d5 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,6 +5,9 @@
 #![cfg_attr(not(test), no_std)]
 #![allow(clippy::result_unit_err)]
 
+#[cfg(feature = "bytes")]
+mod bytes_traits;
+
 use core::{
     cmp::Ordering,
     fmt::{self, Debug},