1 files changed, 77 insertions, 0 deletions
diff --git a/third_party/rust/cubeb-coreaudio/src/backend/auto_release.rs b/third_party/rust/cubeb-coreaudio/src/backend/auto_release.rs
new file mode 100644
index 0000000000..97e091a497
--- /dev/null
+++ b/third_party/rust/cubeb-coreaudio/src/backend/auto_release.rs
@@ -0,0 +1,77 @@
+use std::fmt;
+
+pub struct AutoRelease<T> {
+    ptr: *mut T,
+    release_func: unsafe extern "C" fn(*mut T),
+}
+
+impl<T> AutoRelease<T> {
+    pub fn new(ptr: *mut T, release_func: unsafe extern "C" fn(*mut T)) -> Self {
+        Self { ptr, release_func }
+    }
+
+    pub fn reset(&mut self, ptr: *mut T) {
+        self.release();
+        self.ptr = ptr;
+    }
+
+    pub fn as_ref(&self) -> &T {
+        assert!(!self.ptr.is_null());
+        unsafe { &*self.ptr }
+    }
+
+    pub fn as_mut(&mut self) -> &mut T {
+        assert!(!self.ptr.is_null());
+        unsafe { &mut *self.ptr }
+    }
+
+    pub fn as_ptr(&self) -> *const T {
+        self.ptr
+    }
+
+    fn release(&self) {
+        if !self.ptr.is_null() {
+            unsafe {
+                (self.release_func)(self.ptr);
+            }
+        }
+    }
+}
+
+impl<T> Drop for AutoRelease<T> {
+    fn drop(&mut self) {
+        self.release();
+    }
+}
+
+// Explicit Debug impl to work for the type T
+// that doesn't implement Debug trait.
+impl<T> fmt::Debug for AutoRelease<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("AutoRelease")
+            .field("ptr", &self.ptr)
+            .field("release_func", &self.release_func)
+            .finish()
+    }
+}
+
+#[test]
+fn test_auto_release() {
+    use std::mem;
+    use std::ptr;
+
+    unsafe extern "C" fn allocate() -> *mut libc::c_void {
+        // println!("Allocate!");
+        libc::calloc(1, mem::size_of::<u32>())
+    }
+
+    unsafe extern "C" fn deallocate(ptr: *mut libc::c_void) {
+        // println!("Deallocate!");
+        libc::free(ptr);
+    }
+
+    let mut auto_release = AutoRelease::new(ptr::null_mut(), deallocate);
+    let ptr = unsafe { allocate() };
+    auto_release.reset(ptr);
+    assert_eq!(auto_release.as_ptr(), ptr);
+}