Fix as_slice and as_mut_slice for empty Buffers and ArrayBuffers

src/types/binary.rs

@@ -138,9 +138,13 @@ impl<'a> BinaryData<'a> {
     /// # }
     /// ```
     pub fn as_slice<T: BinaryViewType>(self) -> &'a [T] {
-        let base = unsafe { mem::transmute(self.base) };
-        let len = self.size / mem::size_of::<T>();
-        unsafe { slice::from_raw_parts(base, len) }
+        if self.size == 0 {
+            &[]
+        } else {
+            let base = unsafe { mem::transmute(self.base) };
+            let len = self.size / mem::size_of::<T>();
+            unsafe { slice::from_raw_parts(base, len) }
+        }
     }
 
     /// Produces a mutable slice as a view into the contents of this buffer.
@@ -160,9 +164,13 @@ impl<'a> BinaryData<'a> {
     /// # }
     /// ```
     pub fn as_mut_slice<T: BinaryViewType>(self) -> &'a mut [T] {
-        let base = unsafe { mem::transmute(self.base) };
-        let len = self.size / mem::size_of::<T>();
-        unsafe { slice::from_raw_parts_mut(base, len) }
+        if self.size == 0 {
+            &mut []
+        } else {
+            let base = unsafe { mem::transmute(self.base) };
+            let len = self.size / mem::size_of::<T>();
+            unsafe { slice::from_raw_parts_mut(base, len) }
+        }
     }
 
     /// Produces the length of the buffer, in bytes.

test/dynamic/lib/objects.js

@@ -57,6 +57,14 @@ describe('JsObject', function() {
     assert.equal(addon.read_array_buffer_with_borrow(b, 3), 89898989);
   });
 
+  it('correctly reads an empty ArrayBuffer using the borrow API', function() {
+    let nonempty = Uint8Array.from([1, 2, 3]);
+    assert.equal(addon.sum_array_buffer_with_borrow(nonempty.buffer), 6);
+
+    let empty = Uint8Array.from([]);
+    assert.equal(addon.sum_array_buffer_with_borrow(empty.buffer), 0);
+  });
+
   it('correctly writes to an ArrayBuffer using the lock API', function() {
     var b = new ArrayBuffer(16);
     addon.write_array_buffer_with_lock(b, 0, 999);
@@ -81,6 +89,16 @@ describe('JsObject', function() {
     assert.equal((new Uint32Array(b))[3], 400100);
   });
 
+  it('correctly writes to an empty ArrayBuffer using the borrow API', function() {
+    let nonempty = Uint8Array.from([1, 2, 3]);
+    addon.increment_array_buffer_with_borrow_mut(nonempty.buffer);
+    assert.deepEqual(Array.from(nonempty), [2, 3, 4]);
+
+    let empty = Uint8Array.from([]);
+    addon.increment_array_buffer_with_borrow_mut(empty.buffer);
+    assert.deepEqual(Array.from(empty), []);
+  });
+
   it('gets a 16-byte, zeroed Buffer', function() {
     var b = addon.return_buffer();
     assert.ok(b.equals(Buffer.alloc(16)));
@@ -110,6 +128,14 @@ describe('JsObject', function() {
     assert.equal(addon.read_buffer_with_borrow(b, 3), 22914478);
   });
 
+  it('correctly reads an empty Buffer using the borrow API', function() {
+    let nonempty = Buffer.from([1, 2, 3]);
+    assert.equal(addon.sum_buffer_with_borrow(nonempty), 6);
+
+    let empty = Buffer.from([]);
+    assert.equal(addon.sum_buffer_with_borrow(empty), 0);
+  });
+
   it('correctly writes to a Buffer using the lock API', function() {
     var b = Buffer.allocUnsafe(16);
     b.fill(0);
@@ -135,4 +161,14 @@ describe('JsObject', function() {
     addon.write_buffer_with_borrow_mut(b, 3, 66012);
     assert.equal(b.readUInt32LE(12), 66012);
   });
+
+  it('correctly writes to an empty Buffer using the borrow API', function() {
+    let nonempty = Buffer.from([1, 2, 3]);
+    addon.increment_buffer_with_borrow_mut(nonempty);
+    assert.deepEqual(Array.from(nonempty), [2, 3, 4]);
+
+    let empty = Buffer.from([]);
+    addon.increment_buffer_with_borrow_mut(empty);
+    assert.deepEqual(Array.from(empty), []);
+  });
 });

test/dynamic/native/src/js/objects.rs

@@ -55,6 +55,12 @@ pub fn read_array_buffer_with_borrow(mut cx: FunctionContext) -> JsResult<JsNumb
     Ok(cx.number(x))
 }
 
+pub fn sum_array_buffer_with_borrow(mut cx: FunctionContext) -> JsResult<JsNumber> {
+    let b: Handle<JsArrayBuffer> = cx.argument(0)?;
+    let x: u8 = cx.borrow(&b, |data| { data.as_slice::<u8>().iter().sum() });
+    Ok(cx.number(x))
+}
+
 pub fn write_array_buffer_with_lock(mut cx: FunctionContext) -> JsResult<JsUndefined> {
     let mut b: Handle<JsArrayBuffer> = cx.argument(0)?;
     let i = cx.argument::<JsNumber>(1)?.value() as u32 as usize;
@@ -76,6 +82,12 @@ pub fn write_array_buffer_with_borrow_mut(mut cx: FunctionContext) -> JsResult<J
     Ok(cx.undefined())
 }
 
+pub fn increment_array_buffer_with_borrow_mut(mut cx: FunctionContext) -> JsResult<JsUndefined> {
+    let mut b: Handle<JsArrayBuffer> = cx.argument(0)?;
+    cx.borrow_mut(&mut b, |data| { data.as_mut_slice::<i8>().iter_mut().for_each(|x| *x += 1); });
+    Ok(cx.undefined())
+}
+
 pub fn return_buffer(mut cx: FunctionContext) -> JsResult<JsBuffer> {
     let b: Handle<JsBuffer> = cx.buffer(16)?;
     Ok(b)
@@ -100,6 +112,12 @@ pub fn read_buffer_with_borrow(mut cx: FunctionContext) -> JsResult<JsNumber> {
     Ok(cx.number(x))
 }
 
+pub fn sum_buffer_with_borrow(mut cx: FunctionContext) -> JsResult<JsNumber> {
+    let b: Handle<JsBuffer> = cx.argument(0)?;
+    let x: u8 = cx.borrow(&b, |data| { data.as_slice::<u8>().iter().sum() });
+    Ok(cx.number(x))
+}
+
 pub fn write_buffer_with_lock(mut cx: FunctionContext) -> JsResult<JsUndefined> {
     let mut b: Handle<JsBuffer> = cx.argument(0)?;
     let i = cx.argument::<JsNumber>(1)?.value() as u32 as usize;
@@ -120,3 +138,9 @@ pub fn write_buffer_with_borrow_mut(mut cx: FunctionContext) -> JsResult<JsUndef
     cx.borrow_mut(&mut b, |data| { data.as_mut_slice::<u32>()[i] = x; });
     Ok(cx.undefined())
 }
+
+pub fn increment_buffer_with_borrow_mut(mut cx: FunctionContext) -> JsResult<JsUndefined> {
+    let mut b: Handle<JsBuffer> = cx.argument(0)?;
+    cx.borrow_mut(&mut b, |data| { data.as_mut_slice::<i8>().iter_mut().for_each(|x| *x += 1); });
+    Ok(cx.undefined())
+}

test/dynamic/native/src/lib.rs

@@ -46,13 +46,17 @@ fn main(mut cx: ModuleContext) -> NeonResult<()> {
     cx.export_function("return_array_buffer", return_array_buffer)?;
     cx.export_function("read_array_buffer_with_lock", read_array_buffer_with_lock)?;
     cx.export_function("read_array_buffer_with_borrow", read_array_buffer_with_borrow)?;
+    cx.export_function("sum_array_buffer_with_borrow", sum_array_buffer_with_borrow)?;
     cx.export_function("write_array_buffer_with_lock", write_array_buffer_with_lock)?;
     cx.export_function("write_array_buffer_with_borrow_mut", write_array_buffer_with_borrow_mut)?;
+    cx.export_function("increment_array_buffer_with_borrow_mut", increment_array_buffer_with_borrow_mut)?;
     cx.export_function("return_buffer", return_buffer)?;
     cx.export_function("read_buffer_with_lock", read_buffer_with_lock)?;
     cx.export_function("read_buffer_with_borrow", read_buffer_with_borrow)?;
+    cx.export_function("sum_buffer_with_borrow", sum_buffer_with_borrow)?;
     cx.export_function("write_buffer_with_lock", write_buffer_with_lock)?;
     cx.export_function("write_buffer_with_borrow_mut", write_buffer_with_borrow_mut)?;
+    cx.export_function("increment_buffer_with_borrow_mut", increment_buffer_with_borrow_mut)?;
 
     cx.export_function("return_js_function", return_js_function)?;
     cx.export_function("call_js_function", call_js_function)?;

test/napi/src/js/objects.rs

@@ -55,6 +55,12 @@ pub fn read_array_buffer_with_borrow(mut cx: FunctionContext) -> JsResult<JsNumb
     Ok(cx.number(x))
 }
 
+pub fn sum_array_buffer_with_borrow(mut cx: FunctionContext) -> JsResult<JsNumber> {
+    let b: Handle<JsArrayBuffer> = cx.argument(0)?;
+    let x: u8 = cx.borrow(&b, |data| { data.as_slice::<u8>().iter().sum() });
+    Ok(cx.number(x))
+}
+
 pub fn write_array_buffer_with_lock(mut cx: FunctionContext) -> JsResult<JsUndefined> {
     let mut b: Handle<JsArrayBuffer> = cx.argument(0)?;
     let i = cx.argument::<JsNumber>(1)?.value(&mut cx) as u32 as usize;
@@ -76,6 +82,12 @@ pub fn write_array_buffer_with_borrow_mut(mut cx: FunctionContext) -> JsResult<J
     Ok(cx.undefined())
 }
 
+pub fn increment_array_buffer_with_borrow_mut(mut cx: FunctionContext) -> JsResult<JsUndefined> {
+    let mut b: Handle<JsArrayBuffer> = cx.argument(0)?;
+    cx.borrow_mut(&mut b, |data| { data.as_mut_slice::<i8>().iter_mut().for_each(|x| *x += 1); });
+    Ok(cx.undefined())
+}
+
 pub fn return_uninitialized_buffer(mut cx: FunctionContext) -> JsResult<JsBuffer> {
     let b: Handle<JsBuffer> = unsafe { JsBuffer::uninitialized(&mut cx, 16)? };
     Ok(b)
@@ -105,6 +117,12 @@ pub fn read_buffer_with_borrow(mut cx: FunctionContext) -> JsResult<JsNumber> {
     Ok(cx.number(x))
 }
 
+pub fn sum_buffer_with_borrow(mut cx: FunctionContext) -> JsResult<JsNumber> {
+    let b: Handle<JsBuffer> = cx.argument(0)?;
+    let x: u8 = cx.borrow(&b, |data| { data.as_slice::<u8>().iter().sum() });
+    Ok(cx.number(x))
+}
+
 pub fn write_buffer_with_lock(mut cx: FunctionContext) -> JsResult<JsUndefined> {
     let mut b: Handle<JsBuffer> = cx.argument(0)?;
     let i = cx.argument::<JsNumber>(1)?.value(&mut cx) as u32 as usize;
@@ -125,3 +143,9 @@ pub fn write_buffer_with_borrow_mut(mut cx: FunctionContext) -> JsResult<JsUndef
     cx.borrow_mut(&mut b, |data| { data.as_mut_slice::<u32>()[i] = x; });
     Ok(cx.undefined())
 }
+
+pub fn increment_buffer_with_borrow_mut(mut cx: FunctionContext) -> JsResult<JsUndefined> {
+    let mut b: Handle<JsBuffer> = cx.argument(0)?;
+    cx.borrow_mut(&mut b, |data| { data.as_mut_slice::<i8>().iter_mut().for_each(|x| *x += 1); });
+    Ok(cx.undefined())
+}

test/napi/src/lib.rs

@@ -142,14 +142,18 @@ fn main(mut cx: ModuleContext) -> NeonResult<()> {
     cx.export_function("return_array_buffer", return_array_buffer)?;
     cx.export_function("read_array_buffer_with_lock", read_array_buffer_with_lock)?;
     cx.export_function("read_array_buffer_with_borrow", read_array_buffer_with_borrow)?;
+    cx.export_function("sum_array_buffer_with_borrow", sum_array_buffer_with_borrow)?;
     cx.export_function("write_array_buffer_with_lock", write_array_buffer_with_lock)?;
     cx.export_function("write_array_buffer_with_borrow_mut", write_array_buffer_with_borrow_mut)?;
+    cx.export_function("increment_array_buffer_with_borrow_mut", increment_array_buffer_with_borrow_mut)?;
     cx.export_function("return_uninitialized_buffer", return_uninitialized_buffer)?;
     cx.export_function("return_buffer", return_buffer)?;
     cx.export_function("read_buffer_with_lock", read_buffer_with_lock)?;
     cx.export_function("read_buffer_with_borrow", read_buffer_with_borrow)?;
+    cx.export_function("sum_buffer_with_borrow", sum_buffer_with_borrow)?;
     cx.export_function("write_buffer_with_lock", write_buffer_with_lock)?;
     cx.export_function("write_buffer_with_borrow_mut", write_buffer_with_borrow_mut)?;
+    cx.export_function("increment_buffer_with_borrow_mut", increment_buffer_with_borrow_mut)?;
 
     cx.export_function("create_date", create_date)?;
     cx.export_function("get_date_value", get_date_value)?;