LibWeb: Implement the DecompressionStream interface

Author: https://github.com/trflynn89
Commit: https://github.com/LadybirdBrowser/ladybird/commit/5bcba896c2d
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2370

Libraries/LibWeb/CMakeLists.txt

@@ -29,6 +29,7 @@ set(SOURCES
     Clipboard/Clipboard.cpp
     Clipboard/ClipboardEvent.cpp
     Compression/CompressionStream.cpp
+    Compression/DecompressionStream.cpp
     Crypto/Crypto.cpp
     Crypto/CryptoAlgorithms.cpp
     Crypto/CryptoBindings.cpp

Libraries/LibWeb/Compression/DecompressionStream.cpp

@@ -0,0 +1,177 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibCompress/Deflate.h>
+#include <LibCompress/Gzip.h>
+#include <LibCompress/Zlib.h>
+#include <LibJS/Runtime/ArrayBuffer.h>
+#include <LibJS/Runtime/Realm.h>
+#include <LibJS/Runtime/TypedArray.h>
+#include <LibWeb/Bindings/DecompressionStreamPrototype.h>
+#include <LibWeb/Bindings/ExceptionOrUtils.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/Compression/DecompressionStream.h>
+#include <LibWeb/Streams/AbstractOperations.h>
+#include <LibWeb/Streams/TransformStream.h>
+#include <LibWeb/WebIDL/AbstractOperations.h>
+
+namespace Web::Compression {
+
+GC_DEFINE_ALLOCATOR(DecompressionStream);
+
+// https://compression.spec.whatwg.org/#dom-decompressionstream-decompressionstream
+WebIDL::ExceptionOr<GC::Ref<DecompressionStream>> DecompressionStream::construct_impl(JS::Realm& realm, Bindings::CompressionFormat format)
+{
+    // 1. If format is unsupported in DecompressionStream, then throw a TypeError.
+    // 2. Set this's format to format.
+    auto input_stream = make<AllocatingMemoryStream>();
+
+    auto decompressor = [&, input_stream = MaybeOwned<Stream> { *input_stream }]() mutable -> ErrorOr<Decompressor> {
+        switch (format) {
+        case Bindings::CompressionFormat::Deflate:
+            // FIXME: Our zlib decompressor assumes the initial data contains the zlib header. We don't have any data yet,
+            //        so this will always fail.
+            return TRY(Compress::ZlibDecompressor::create(move(input_stream)));
+        case Bindings::CompressionFormat::DeflateRaw:
+            return TRY(Compress::DeflateDecompressor::construct(make<LittleEndianInputBitStream>(move(input_stream))));
+        case Bindings::CompressionFormat::Gzip:
+            return make<Compress::GzipDecompressor>(move(input_stream));
+        }
+
+        VERIFY_NOT_REACHED();
+    }();
+
+    if (decompressor.is_error())
+        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, MUST(String::formatted("Unable to create decompressor: {}", decompressor.error())) };
+
+    // 5. Set this's transform to a new TransformStream.
+    // NOTE: We do this first so that we may store it as nonnull in the GenericTransformStream.
+    auto stream = realm.create<DecompressionStream>(realm, realm.create<Streams::TransformStream>(realm), decompressor.release_value(), move(input_stream));
+
+    // 3. Let transformAlgorithm be an algorithm which takes a chunk argument and runs the decompress and enqueue a chunk
+    //    algorithm with this and chunk.
+    auto transform_algorithm = GC::create_function(realm.heap(), [stream](JS::Value chunk) -> GC::Ref<WebIDL::Promise> {
+        auto& realm = stream->realm();
+        auto& vm = realm.vm();
+
+        if (auto result = stream->decompress_and_enqueue_chunk(chunk); result.is_error()) {
+            auto throw_completion = Bindings::dom_exception_to_throw_completion(vm, result.exception());
+            return WebIDL::create_rejected_promise(realm, *throw_completion.release_value());
+        }
+
+        return WebIDL::create_resolved_promise(realm, JS::js_undefined());
+    });
+
+    // 4. Let flushAlgorithm be an algorithm which takes no argument and runs the decompress flush and enqueue algorithm with this.
+    auto flush_algorithm = GC::create_function(realm.heap(), [stream]() -> GC::Ref<WebIDL::Promise> {
+        auto& realm = stream->realm();
+        auto& vm = realm.vm();
+
+        if (auto result = stream->decompress_flush_and_enqueue(); result.is_error()) {
+            auto throw_completion = Bindings::dom_exception_to_throw_completion(vm, result.exception());
+            return WebIDL::create_rejected_promise(realm, *throw_completion.release_value());
+        }
+
+        return WebIDL::create_resolved_promise(realm, JS::js_undefined());
+    });
+
+    // 6. Set up this's transform with transformAlgorithm set to transformAlgorithm and flushAlgorithm set to flushAlgorithm.
+    Streams::transform_stream_set_up(stream->m_transform, transform_algorithm, flush_algorithm);
+
+    return stream;
+}
+
+DecompressionStream::DecompressionStream(JS::Realm& realm, GC::Ref<Streams::TransformStream> transform, Decompressor decompressor, NonnullOwnPtr<AllocatingMemoryStream> input_stream)
+    : Bindings::PlatformObject(realm)
+    , Streams::GenericTransformStreamMixin(transform)
+    , m_decompressor(move(decompressor))
+    , m_input_stream(move(input_stream))
+{
+}
+
+DecompressionStream::~DecompressionStream() = default;
+
+void DecompressionStream::initialize(JS::Realm& realm)
+{
+    Base::initialize(realm);
+    WEB_SET_PROTOTYPE_FOR_INTERFACE(DecompressionStream);
+}
+
+void DecompressionStream::visit_edges(JS::Cell::Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    Streams::GenericTransformStreamMixin::visit_edges(visitor);
+}
+
+// https://compression.spec.whatwg.org/#decompress-and-enqueue-a-chunk
+WebIDL::ExceptionOr<void> DecompressionStream::decompress_and_enqueue_chunk(JS::Value chunk)
+{
+    auto& realm = this->realm();
+
+    // 1. If chunk is not a BufferSource type, then throw a TypeError.
+    if (!WebIDL::is_buffer_source_type(chunk))
+        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, "Chunk is not a BufferSource type"sv };
+
+    // 2. Let buffer be the result of decompressing chunk with ds's format and context. If this results in an error,
+    //    then throw a TypeError.
+    auto buffer = [&]() -> ErrorOr<ByteBuffer> {
+        if (auto buffer = WebIDL::underlying_buffer_source(chunk.as_object()))
+            return decompress(buffer->buffer());
+        return ByteBuffer {};
+    }();
+
+    if (buffer.is_error())
+        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, MUST(String::formatted("Unable to decompress chunk: {}", buffer.error())) };
+
+    // 3. If buffer is empty, return.
+    if (buffer.value().is_empty())
+        return {};
+
+    // 4. Split buffer into one or more non-empty pieces and convert them into Uint8Arrays.
+    auto array_buffer = JS::ArrayBuffer::create(realm, buffer.release_value());
+    auto array = JS::Uint8Array::create(realm, array_buffer->byte_length(), *array_buffer);
+
+    // 5. For each Uint8Array array, enqueue array in ds's transform.
+    TRY(Streams::transform_stream_default_controller_enqueue(*m_transform->controller(), array));
+    return {};
+}
+
+// https://compression.spec.whatwg.org/#decompress-flush-and-enqueue
+WebIDL::ExceptionOr<void> DecompressionStream::decompress_flush_and_enqueue()
+{
+    auto& realm = this->realm();
+
+    // 1. Let buffer be the result of decompressing an empty input with ds's format and context, with the finish flag.
+    auto buffer = decompress({});
+
+    if (buffer.is_error())
+        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, MUST(String::formatted("Unable to compress flush: {}", buffer.error())) };
+
+    // FIXME: 2. If the end of the compressed input has not been reached, then throw a TypeError.
+
+    // 3. If buffer is empty, return.
+    if (buffer.value().is_empty())
+        return {};
+
+    // 4. Split buffer into one or more non-empty pieces and convert them into Uint8Arrays.
+    auto array_buffer = JS::ArrayBuffer::create(realm, buffer.release_value());
+    auto array = JS::Uint8Array::create(realm, array_buffer->byte_length(), *array_buffer);
+
+    // 5. For each Uint8Array array, enqueue array in ds's transform.
+    TRY(Streams::transform_stream_default_controller_enqueue(*m_transform->controller(), array));
+    return {};
+}
+
+ErrorOr<ByteBuffer> DecompressionStream::decompress(ReadonlyBytes bytes)
+{
+    TRY(m_input_stream->write_until_depleted(bytes));
+
+    return TRY(m_decompressor.visit([&](auto const& decompressor) {
+        return decompressor->read_until_eof();
+    }));
+}
+
+}

Libraries/LibWeb/Compression/DecompressionStream.h

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/MemoryStream.h>
+#include <AK/NonnullOwnPtr.h>
+#include <AK/Variant.h>
+#include <LibCompress/Forward.h>
+#include <LibGC/Ptr.h>
+#include <LibJS/Forward.h>
+#include <LibWeb/Bindings/PlatformObject.h>
+#include <LibWeb/Compression/CompressionStream.h>
+#include <LibWeb/Streams/GenericTransformStream.h>
+#include <LibWeb/WebIDL/ExceptionOr.h>
+
+namespace Web::Compression {
+
+using Decompressor = Variant<
+    NonnullOwnPtr<Compress::ZlibDecompressor>,
+    NonnullOwnPtr<Compress::DeflateDecompressor>,
+    NonnullOwnPtr<Compress::GzipDecompressor>>;
+
+// https://compression.spec.whatwg.org/#decompressionstream
+class DecompressionStream final
+    : public Bindings::PlatformObject
+    , public Streams::GenericTransformStreamMixin {
+    WEB_PLATFORM_OBJECT(DecompressionStream, Bindings::PlatformObject);
+    GC_DECLARE_ALLOCATOR(DecompressionStream);
+
+public:
+    static WebIDL::ExceptionOr<GC::Ref<DecompressionStream>> construct_impl(JS::Realm&, Bindings::CompressionFormat);
+    virtual ~DecompressionStream() override;
+
+private:
+    DecompressionStream(JS::Realm&, GC::Ref<Streams::TransformStream>, Decompressor, NonnullOwnPtr<AllocatingMemoryStream>);
+
+    virtual void initialize(JS::Realm&) override;
+    virtual void visit_edges(Cell::Visitor&) override;
+
+    WebIDL::ExceptionOr<void> decompress_and_enqueue_chunk(JS::Value);
+    WebIDL::ExceptionOr<void> decompress_flush_and_enqueue();
+
+    ErrorOr<ByteBuffer> decompress(ReadonlyBytes);
+
+    Decompressor m_decompressor;
+    NonnullOwnPtr<AllocatingMemoryStream> m_input_stream;
+};
+
+}

Libraries/LibWeb/Compression/DecompressionStream.idl

@@ -0,0 +1,10 @@
+#import <Compression/CompressionStream.idl>
+#import <Streams/GenericTransformStream.idl>
+
+// https://compression.spec.whatwg.org/#decompressionstream
+[Exposed=*]
+interface DecompressionStream {
+    constructor(CompressionFormat format);
+};
+
+DecompressionStream includes GenericTransformStream;

Libraries/LibWeb/Forward.h

@@ -88,6 +88,7 @@ class Clipboard;
 
 namespace Web::Compression {
 class CompressionStream;
+class DecompressionStream;
 }
 
 namespace Web::Cookie {

Libraries/LibWeb/idl_files.cmake

@@ -10,6 +10,7 @@ libweb_js_bindings(Animations/KeyframeEffect)
 libweb_js_bindings(Clipboard/Clipboard)
 libweb_js_bindings(Clipboard/ClipboardEvent)
 libweb_js_bindings(Compression/CompressionStream)
+libweb_js_bindings(Compression/DecompressionStream)
 libweb_js_bindings(Crypto/Crypto)
 libweb_js_bindings(Crypto/CryptoKey)
 libweb_js_bindings(Crypto/SubtleCrypto)

Tests/LibWeb/Text/expected/Compression/DecompressionStream.txt

@@ -0,0 +1,2 @@
+format=deflate-raw: Well hello friends!
+format=gzip: Well hello friends!

Tests/LibWeb/Text/expected/all-window-properties.txt

@@ -88,6 +88,7 @@ DataTransferItem
 DataTransferItemList
 DataView
 Date
+DecompressionStream
 DisposableStack
 Document
 DocumentFragment

Tests/LibWeb/Text/input/Compression/DecompressionStream.html

@@ -0,0 +1,37 @@
+<script src="../include.js"></script>
+<script>
+    asyncTest(async done => {
+        const data = [
+            // FIXME: Enable this case when our DecompressionStream is functioning with the zlib format.
+            // { format: "deflate", text: "eJwLT83JUchIzcnJV0grykzNSylWBABGEQb1" },
+            { format: "deflate-raw", text: "C0/NyVHISM3JyVdIK8pMzUspVgQA" },
+            { format: "gzip", text: "H4sIAAAAAAADAwtPzclRyEjNyclXSCvKTM1LKVYEAHN0w4sTAAAA" },
+        ];
+
+        for (const test of data) {
+            const text = Uint8Array.fromBase64(test.text);
+            let stream = new Blob([text]).stream();
+
+            let decompressor = stream.pipeThrough(new DecompressionStream(test.format));
+            let reader = decompressor.getReader();
+
+            let buffer = new ArrayBuffer(256);
+            let offset = 0;
+
+            while (true) {
+                let result = await reader.read();
+                if (result.done) {
+                    break;
+                }
+
+                new Uint8Array(buffer).set(result.value, offset);
+                offset += result.value.byteLength;
+            }
+
+            let result = String.fromCharCode.apply(null, new Uint8Array(buffer, 0, offset));
+            println(`format=${test.format}: ${result}`);
+        }
+
+        done();
+    });
+</script>