Implement the StableDeref trait

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "memmap"
 # NB: When modifying, also modify html_root_url in lib.rs
-version = "0.7.0"
+version = "0.7.1"
 authors = ["Dan Burkert <[email protected]>"]
 license = "MIT/Apache-2.0"
 repository = "https://github.com/danburkert/memmap-rs"
@@ -13,6 +13,9 @@ keywords = ["mmap", "memory-map", "io", "file"]
 travis-ci = { repository = "danburkert/memmap-rs" }
 appveyor = { repository = "danburkert/mmap" }
 
+[dependencies]
+stable_deref_trait = "1.2.0"
+
 [target.'cfg(unix)'.dependencies]
 libc = "0.2"
 
@@ -21,3 +24,4 @@ winapi = { version = "0.3", features = ["basetsd", "handleapi", "memoryapi", "mi
 
 [dev-dependencies]
 tempdir = "0.3"
+owning_ref = "0.4.1"

src/lib.rs

@@ -1,6 +1,6 @@
 //! A cross-platform Rust API for memory mapped buffers.
 
-#![doc(html_root_url = "https://docs.rs/memmap/0.7.0")]
+#![doc(html_root_url = "https://docs.rs/memmap/0.7.1")]
 
 #[cfg(windows)]
 extern crate winapi;
@@ -21,6 +21,9 @@ use std::ops::{Deref, DerefMut};
 use std::slice;
 use std::usize;
 
+extern crate stable_deref_trait;
+use stable_deref_trait::StableDeref;
+
 /// A memory map builder, providing advanced options and flags for specifying memory map behavior.
 ///
 /// `MmapOptions` can be used to create an anonymous memory map using [`map_anon()`], or a
@@ -411,6 +414,8 @@ impl Mmap {
     }
 }
 
+unsafe impl StableDeref for Mmap {}
+
 impl Deref for Mmap {
     type Target = [u8];
 
@@ -640,6 +645,8 @@ impl MmapMut {
     }
 }
 
+unsafe impl StableDeref for MmapMut {}
+
 impl Deref for MmapMut {
     type Target = [u8];
 
@@ -1057,4 +1064,21 @@ mod test {
         let mmap = mmap.make_exec().expect("make_exec");
         drop(mmap);
     }
+
+    /// Something that relies on StableDeref
+    #[test]
+    fn owning_ref() {
+        extern crate owning_ref;
+
+        let mut map = MmapMut::map_anon(128).unwrap();
+        map[10] = 42;
+        let owning = owning_ref::OwningRef::new(map);
+        let sliced = owning.map(|map| &map[10..20]);
+        assert_eq!(42, sliced[0]);
+
+        let map = sliced.into_owner().make_read_only().unwrap();
+        let owning = owning_ref::OwningRef::new(map);
+        let sliced = owning.map(|map| &map[10..20]);
+        assert_eq!(42, sliced[0]);
+    }
 }