Auto merge of #13729 - cynicaldevil:readAsArrayBuffer, r=Ms2ger

Implemented FileReader::readAsArrayBuffer

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---

<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #12555

<!-- Either: -->
- [X] There are tests for these changes

There's still some small issues, but I suppose most of the work is done:
- test-tidy mentions a `method declared in webidl is missing a comment with a specification link` for the `getResult` method.
- I get an 'unused code' warning for code present in `UnionTypes.rs`, which is auto-generated.

Passing tests:
- [x]  `FileAPI/reading-data-section/filereader_result.html`
- [x]  `FileAPI/reading-data-section/filereader_readAsArrayBuffer.html`
- [x]  `FileAPI/idlharness.html`
- [ ]  `FileAPI/reading-data-section/FileReader-multiple-reads.html`

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This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/13729)

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3 files changed, 73 insertions, 23 deletions

diff --git a/components/script/dom/bindings/codegen/CodegenRust.py b/components/script/dom/bindings/codegen/CodegenRust.py
index 4c67f61af2d..b65d2e65cdb 100644
--- a/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/components/script/dom/bindings/codegen/CodegenRust.py
@@ -2237,6 +2237,7 @@ def UnionTypes(descriptors, dictionaries, callbacks, typedefs, config):
         'js::error::throw_type_error',
         'js::jsapi::HandleValue',
         'js::jsapi::JSContext',
+        'js::jsapi::JSObject',
         'js::jsapi::MutableHandleValue',
         'js::jsval::JSVal',
     ]
@@ -4047,6 +4048,9 @@ def getUnionTypeTemplateVars(type, descriptorProvider):
     elif type.isPrimitive():
         name = type.name
         typeName = builtinNames[type.tag()]
+    elif type.isObject():
+        name = type.name
+        typeName = "*mut JSObject"
     else:
         raise TypeError("Can't handle %s in unions yet" % type)
 
@@ -4056,7 +4060,6 @@ def getUnionTypeTemplateVars(type, descriptorProvider):
         isDefinitelyObject=True)
     template = info.template
 
-    assert not type.isObject()
     jsConversion = string.Template(template).substitute({
         "val": "value",
     })
@@ -4176,7 +4179,10 @@ class CGUnionConversionStruct(CGThing):
 
         objectMemberTypes = filter(lambda t: t.isObject(), memberTypes)
         if len(objectMemberTypes) > 0:
-            raise TypeError("Can't handle objects in unions.")
+            assert len(objectMemberTypes) == 1
+            typeName = objectMemberTypes[0].name
+            object = CGGeneric(get_match(typeName))
+            names.append(typeName)
         else:
             object = None
 
@@ -4191,7 +4197,8 @@ class CGUnionConversionStruct(CGThing):
 
         hasObjectTypes = interfaceObject or arrayObject or dateObject or nonPlatformObject or object or mozMapObject
         if hasObjectTypes:
-            assert interfaceObject or arrayObject or mozMapObject
+            # "object" is not distinguishable from other types
+            assert not object or not (interfaceObject or arrayObject or dateObject or callbackObject or mozMapObject)
             templateBody = CGList([], "\n")
             if interfaceObject:
                 templateBody.append(interfaceObject)
diff --git a/components/script/dom/filereader.rs b/components/script/dom/filereader.rs
index 296a6461b55..d9fd00630de 100644
--- a/components/script/dom/filereader.rs
+++ b/components/script/dom/filereader.rs
@@ -6,6 +6,7 @@ use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::BlobBinding::BlobMethods;
 use dom::bindings::codegen::Bindings::EventHandlerBinding::EventHandlerNonNull;
 use dom::bindings::codegen::Bindings::FileReaderBinding::{self, FileReaderConstants, FileReaderMethods};
+use dom::bindings::codegen::UnionTypes::StringOrObject;
 use dom::bindings::error::{Error, ErrorResult, Fallible};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::js::{JS, MutNullableHeap, Root};
@@ -22,9 +23,15 @@ use encoding::all::UTF_8;
 use encoding::label::encoding_from_whatwg_label;
 use encoding::types::{DecoderTrap, EncodingRef};
 use hyper::mime::{Attr, Mime};
+use js::jsapi::Heap;
+use js::jsapi::JSAutoCompartment;
+use js::jsapi::JSContext;
+use js::jsval::{self, JSVal};
+use js::typedarray::Uint8Array;
 use rustc_serialize::base64::{CharacterSet, Config, Newline, ToBase64};
 use script_thread::RunnableWrapper;
 use std::cell::Cell;
+use std::ptr;
 use std::sync::Arc;
 use string_cache::Atom;
 use task_source::TaskSource;
@@ -35,6 +42,7 @@ use util::thread::spawn_named;
 pub enum FileReaderFunction {
     ReadAsText,
     ReadAsDataUrl,
+    ReadAsArrayBuffer,
 }
 
 pub type TrustedFileReader = Trusted<FileReader>;
@@ -68,12 +76,18 @@ pub enum FileReaderReadyState {
     Done = FileReaderConstants::DONE,
 }
 
+#[derive(HeapSizeOf, JSTraceable)]
+pub enum FileReaderResult {
+    ArrayBuffer(Heap<JSVal>),
+    String(DOMString),
+}
+
 #[dom_struct]
 pub struct FileReader {
     eventtarget: EventTarget,
     ready_state: Cell<FileReaderReadyState>,
     error: MutNullableHeap<JS<DOMException>>,
-    result: DOMRefCell<Option<DOMString>>,
+    result: DOMRefCell<Option<FileReaderResult>>,
     generation_id: Cell<GenerationId>,
 }
 
@@ -159,6 +173,7 @@ impl FileReader {
     }
 
     // https://w3c.github.io/FileAPI/#dfn-readAsText
+    #[allow(unsafe_code)]
     pub fn process_read_eof(filereader: TrustedFileReader, gen_id: GenerationId,
                             data: ReadMetaData, blob_contents: Arc<Vec<u8>>) {
         let fr = filereader.root();
@@ -176,15 +191,17 @@ impl FileReader {
         fr.change_ready_state(FileReaderReadyState::Done);
         // Step 8.2
 
-        let output = match data.function {
+        match data.function {
             FileReaderFunction::ReadAsDataUrl =>
-                FileReader::perform_readasdataurl(data, &blob_contents),
+                FileReader::perform_readasdataurl(&fr.result, data, &blob_contents),
             FileReaderFunction::ReadAsText =>
-                FileReader::perform_readastext(data, &blob_contents),
+                FileReader::perform_readastext(&fr.result, data, &blob_contents),
+            FileReaderFunction::ReadAsArrayBuffer => {
+                let _ac = JSAutoCompartment::new(fr.global().get_cx(), *fr.reflector().get_jsobject());
+                FileReader::perform_readasarraybuffer(&fr.result, fr.global().get_cx(), data, &blob_contents)
+            },
         };
 
-        *fr.result.borrow_mut() = Some(output);
-
         // Step 8.3
         fr.dispatch_progress_event(atom!("load"), 0, None);
         return_on_abort!();
@@ -198,8 +215,7 @@ impl FileReader {
     }
 
     // https://w3c.github.io/FileAPI/#dfn-readAsText
-    fn perform_readastext(data: ReadMetaData, blob_bytes: &[u8])
-        -> DOMString {
+    fn perform_readastext(result: &DOMRefCell<Option<FileReaderResult>>, data: ReadMetaData, blob_bytes: &[u8]) {
         let blob_label = &data.label;
         let blob_type = &data.blobtype;
 
@@ -225,12 +241,11 @@ impl FileReader {
         let convert = blob_bytes;
         // Step 7
         let output = enc.decode(convert, DecoderTrap::Replace).unwrap();
-        DOMString::from(output)
+        *result.borrow_mut() = Some(FileReaderResult::String(DOMString::from(output)));
     }
 
     //https://w3c.github.io/FileAPI/#dfn-readAsDataURL
-    fn perform_readasdataurl(data: ReadMetaData, bytes: &[u8])
-        -> DOMString {
+    fn perform_readasdataurl(result: &DOMRefCell<Option<FileReaderResult>>, data: ReadMetaData, bytes: &[u8]) {
         let config = Config {
             char_set: CharacterSet::UrlSafe,
             newline: Newline::LF,
@@ -245,7 +260,23 @@ impl FileReader {
             format!("data:{};base64,{}", data.blobtype, base64)
         };
 
-        DOMString::from(output)
+        *result.borrow_mut() = Some(FileReaderResult::String(DOMString::from(output)));
+    }
+
+    // https://w3c.github.io/FileAPI/#dfn-readAsArrayBuffer
+    #[allow(unsafe_code)]
+    fn perform_readasarraybuffer(result: &DOMRefCell<Option<FileReaderResult>>,
+        cx: *mut JSContext, _: ReadMetaData, bytes: &[u8]) {
+        unsafe {
+            rooted!(in(cx) let mut array_buffer = ptr::null_mut());
+            assert!(Uint8Array::create(cx, bytes.len() as u32, Some(bytes), array_buffer.handle_mut()).is_ok());
+
+            *result.borrow_mut() = Some(FileReaderResult::ArrayBuffer(Heap::default()));
+
+            if let Some(FileReaderResult::ArrayBuffer(ref mut heap)) = *result.borrow_mut() {
+                heap.set(jsval::ObjectValue(&*array_buffer.get()));
+            };
+        }
     }
 }
 
@@ -268,7 +299,11 @@ impl FileReaderMethods for FileReader {
     // https://w3c.github.io/FileAPI/#dfn-onloadend
     event_handler!(loadend, GetOnloadend, SetOnloadend);
 
-    //TODO https://w3c.github.io/FileAPI/#dfn-readAsArrayBuffer
+    // https://w3c.github.io/FileAPI/#dfn-readAsArrayBuffer
+    fn ReadAsArrayBuffer(&self, blob: &Blob) -> ErrorResult {
+        self.read(FileReaderFunction::ReadAsArrayBuffer, blob, None)
+    }
+
     // https://w3c.github.io/FileAPI/#dfn-readAsDataURL
     fn ReadAsDataURL(&self, blob: &Blob) -> ErrorResult {
         self.read(FileReaderFunction::ReadAsDataUrl, blob, None)
@@ -302,9 +337,18 @@ impl FileReaderMethods for FileReader {
         self.error.get()
     }
 
+    #[allow(unsafe_code)]
     // https://w3c.github.io/FileAPI/#dfn-result
-    fn GetResult(&self) -> Option<DOMString> {
-        self.result.borrow().clone()
+    fn GetResult(&self, _: *mut JSContext) -> Option<StringOrObject> {
+        self.result.borrow().as_ref().map(|r| match *r {
+            FileReaderResult::String(ref string) =>
+                StringOrObject::String(string.clone()),
+            FileReaderResult::ArrayBuffer(ref arr_buffer) => {
+                unsafe {
+                    StringOrObject::Object((*arr_buffer.ptr.get()).to_object())
+                }
+            }
+        })
     }
 
     // https://w3c.github.io/FileAPI/#dfn-readyState
diff --git a/components/script/dom/webidls/FileReader.webidl b/components/script/dom/webidls/FileReader.webidl
index 45ae6ea1b2c..be00e39fd77 100644
--- a/components/script/dom/webidls/FileReader.webidl
+++ b/components/script/dom/webidls/FileReader.webidl
@@ -4,13 +4,13 @@
 
  // http://dev.w3.org/2006/webapi/FileAPI/#APIASynch
 
-//typedef (DOMString or ArrayBuffer) FileReaderResult;
+typedef (DOMString or object) FileReaderResult;
 [Constructor, Exposed=(Window,Worker)]
 interface FileReader: EventTarget {
 
   // async read methods
-  //[Throws]
-  //void readAsArrayBuffer(Blob blob);
+  [Throws]
+  void readAsArrayBuffer(Blob blob);
   [Throws]
   void readAsText(Blob blob, optional DOMString label);
   [Throws]
@@ -25,8 +25,7 @@ interface FileReader: EventTarget {
   readonly attribute unsigned short readyState;
 
   // File or Blob data
-  //readonly attribute FileReaderResult? result;
-  readonly attribute DOMString? result;
+  readonly attribute FileReaderResult? result;
 
   readonly attribute DOMException? error;