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LibWeb: Implement FileAPI::Blob::get_stream()

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This is used internally in many Blob algorithms, such as Blob::stream(),
Blob::text() and Blob::array_buffer().
This commit is contained in:
Shannon Booth 2023-06-13 07:31:06 +12:00 • committed by Andreas Kling
parent 94883866f5
commit 9f39be6e23
2 changed files with 62 additions and 0 deletions
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60
Userland/Libraries/LibWeb/FileAPI/Blob.cpp
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@ -1,5 +1,6 @@
/*
* Copyright (c) 2022-2023, Kenneth Myhra <kennethmyhra@serenityos.org>
* Copyright (c) 2023, Shannon Booth <shannon.ml.booth@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -7,11 +8,13 @@
#include <AK/GenericLexer.h>
#include <LibJS/Runtime/ArrayBuffer.h>
#include <LibJS/Runtime/Completion.h>
#include <LibJS/Runtime/TypedArray.h>
#include <LibWeb/Bindings/BlobPrototype.h>
#include <LibWeb/Bindings/ExceptionOrUtils.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/FileAPI/Blob.h>
#include <LibWeb/Infra/Strings.h>
#include <LibWeb/Streams/AbstractOperations.h>
#include <LibWeb/WebIDL/AbstractOperations.h>
namespace Web::FileAPI {
@ -249,6 +252,63 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> Blob::slice(Optional<i64> start, Opt
return MUST_OR_THROW_OOM(heap().allocate<Blob>(realm(), realm(), move(byte_buffer), move(relative_content_type)));
}
// https://w3c.github.io/FileAPI/#blob-get-stream
WebIDL::ExceptionOr<JS::NonnullGCPtr<Streams::ReadableStream>> Blob::get_stream()
{
auto& realm = this->realm();
// 1. Let stream be a new ReadableStream created in blob’s relevant Realm.
auto stream = MUST_OR_THROW_OOM(realm.heap().allocate<Streams::ReadableStream>(realm, realm));
// 2. Set up stream with byte reading support.
TRY(set_up_readable_stream_controller_with_byte_reading_support(stream));
// FIXME: 3. Run the following steps in parallel:
{
// 1. While not all bytes of blob have been read:
// NOTE: for simplicity the chunk is the entire buffer for now.
{
// 1. Let bytes be the byte sequence that results from reading a chunk from blob, or failure if a chunk cannot be read.
auto bytes = m_byte_buffer;
// 2. Queue a global task on the file reading task source given blob’s relevant global object to perform the following steps:
HTML::queue_global_task(HTML::Task::Source::FileReading, realm.global_object(), [stream, bytes = move(bytes)]() {
// NOTE: Not part of the spec, but we need to have an execution context on the stack to call native functions.
auto& environment_settings_object = Bindings::host_defined_environment_settings_object(stream->realm());
environment_settings_object.prepare_to_run_script();
ScopeGuard guard = [&]() {
// See above NOTE.
environment_settings_object.clean_up_after_running_script();
};
// 1. If bytes is failure, then error stream with a failure reason and abort these steps.
// 2. Let chunk be a new Uint8Array wrapping an ArrayBuffer containing bytes. If creating the ArrayBuffer throws an exception, then error stream with that exception and abort these steps.
auto array_buffer = JS::ArrayBuffer::create(stream->realm(), bytes);
auto chunk = JS::Uint8Array::create(stream->realm(), bytes.size(), *array_buffer);
// 3. Enqueue chunk in stream.
auto maybe_error = Bindings::throw_dom_exception_if_needed(stream->realm().vm(), [&]() {
return readable_stream_enqueue(*stream->controller(), chunk);
});
if (maybe_error.is_error()) {
readable_stream_error(*stream, maybe_error.release_error().value().value());
return;
}
// FIXME: Close the stream now that we have finished enqueuing all chunks to the stream. Without this, ReadableStream.read will never resolve the second time around with 'done' set.
// Nowhere in the spec seems to mention this - but testing against other implementations the stream does appear to be closed after reading all data (closed callback is fired).
// Probably there is a better way of doing this.
readable_stream_close(*stream);
});
}
}
// 4. Return stream.
return stream;
}
// https://w3c.github.io/FileAPI/#dom-blob-text
WebIDL::ExceptionOr<JS::NonnullGCPtr<JS::Promise>> Blob::text()
{