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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mozilla/css/StreamLoader.h"
#include "mozilla/Encoding.h"
#include "mozilla/TaskQueue.h"
#include "nsContentUtils.h"
#include "nsIChannel.h"
#include "nsIInputStream.h"
#include "nsIThreadRetargetableRequest.h"
#include "nsIStreamTransportService.h"
#include "nsNetCID.h"
#include "nsServiceManagerUtils.h"
namespace mozilla::css {
StreamLoader::StreamLoader(SheetLoadData& aSheetLoadData)
: mSheetLoadData(&aSheetLoadData), mStatus(NS_OK) {}
StreamLoader::~StreamLoader() {
#ifdef NIGHTLY_BUILD
MOZ_RELEASE_ASSERT(mOnStopRequestCalled || mChannelOpenFailed);
#endif
}
NS_IMPL_ISUPPORTS(StreamLoader, nsIStreamListener,
nsIThreadRetargetableStreamListener)
/* nsIRequestObserver implementation */
NS_IMETHODIMP
StreamLoader::OnStartRequest(nsIRequest* aRequest) {
MOZ_ASSERT(aRequest);
mSheetLoadData->NotifyStart(aRequest);
// It's kinda bad to let Web content send a number that results
// in a potentially large allocation directly, but efficiency of
// compression bombs is so great that it doesn't make much sense
// to require a site to send one before going ahead and allocating.
if (nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest)) {
int64_t length;
nsresult rv = channel->GetContentLength(&length);
if (NS_SUCCEEDED(rv) && length > 0) {
CheckedInt<nsACString::size_type> checkedLength(length);
if (!checkedLength.isValid()) {
return (mStatus = NS_ERROR_OUT_OF_MEMORY);
}
if (!mBytes.SetCapacity(checkedLength.value(), fallible)) {
return (mStatus = NS_ERROR_OUT_OF_MEMORY);
}
}
}
if (nsCOMPtr<nsIThreadRetargetableRequest> rr = do_QueryInterface(aRequest)) {
nsCOMPtr<nsIEventTarget> sts =
do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID);
RefPtr queue =
TaskQueue::Create(sts.forget(), "css::StreamLoader Delivery Queue");
rr->RetargetDeliveryTo(queue);
}
mSheetLoadData->mExpirationTime = [&] {
auto info = nsContentUtils::GetSubresourceCacheValidationInfo(
aRequest, mSheetLoadData->mURI);
// For now, we never cache entries that we have to revalidate, or whose
// channel don't support caching.
if (info.mMustRevalidate || !info.mExpirationTime) {
return nsContentUtils::SecondsFromPRTime(PR_Now()) - 1;
}
return *info.mExpirationTime;
}();
return NS_OK;
}
NS_IMETHODIMP
StreamLoader::CheckListenerChain() { return NS_OK; }
NS_IMETHODIMP
StreamLoader::OnStopRequest(nsIRequest* aRequest, nsresult aStatus) {
#ifdef NIGHTLY_BUILD
MOZ_RELEASE_ASSERT(!mOnStopRequestCalled);
mOnStopRequestCalled = true;
#endif
nsresult rv = mStatus;
// Decoded data
nsCString utf8String;
{
// Hold the nsStringBuffer for the bytes from the stack to ensure release
// no matter which return branch is taken.
nsCString bytes = std::move(mBytes);
nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
if (NS_FAILED(mStatus)) {
mSheetLoadData->VerifySheetReadyToParse(mStatus, ""_ns, ""_ns, channel);
return mStatus;
}
rv = mSheetLoadData->VerifySheetReadyToParse(aStatus, mBOMBytes, bytes,
channel);
if (rv != NS_OK_PARSE_SHEET) {
return rv;
}
// BOM detection generally happens during the write callback, but that won't
// have happened if fewer than three bytes were received.
if (mEncodingFromBOM.isNothing()) {
HandleBOM();
MOZ_ASSERT(mEncodingFromBOM.isSome());
}
// The BOM handling has happened, but we still may not have an encoding if
// there was no BOM. Ensure we have one.
const Encoding* encoding = mEncodingFromBOM.value();
if (!encoding) {
// No BOM
encoding = mSheetLoadData->DetermineNonBOMEncoding(bytes, channel);
}
mSheetLoadData->mEncoding = encoding;
size_t validated = 0;
if (encoding == UTF_8_ENCODING) {
validated = Encoding::UTF8ValidUpTo(bytes);
}
if (validated == bytes.Length()) {
// Either this is UTF-8 and all valid, or it's not UTF-8 but is an empty
// string. This assumes that an empty string in any encoding decodes to
// empty string, which seems like a plausible assumption.
utf8String = std::move(bytes);
} else {
rv = encoding->DecodeWithoutBOMHandling(bytes, utf8String, validated);
NS_ENSURE_SUCCESS(rv, rv);
}
} // run destructor for `bytes`
// For reasons I don't understand, factoring the below lines into
// a method on SheetLoadData resulted in a linker error. Hence,
// accessing fields of mSheetLoadData from here.
mSheetLoadData->mLoader->ParseSheet(utf8String, *mSheetLoadData,
Loader::AllowAsyncParse::Yes);
return NS_OK;
}
/* nsIStreamListener implementation */
NS_IMETHODIMP
StreamLoader::OnDataAvailable(nsIRequest*, nsIInputStream* aInputStream,
uint64_t, uint32_t aCount) {
if (NS_FAILED(mStatus)) {
return mStatus;
}
uint32_t dummy;
return aInputStream->ReadSegments(WriteSegmentFun, this, aCount, &dummy);
}
NS_IMETHODIMP
StreamLoader::OnDataFinished(nsresult aStatus) { return NS_OK; }
void StreamLoader::HandleBOM() {
MOZ_ASSERT(mEncodingFromBOM.isNothing());
MOZ_ASSERT(mBytes.IsEmpty());
auto [encoding, bomLength] = Encoding::ForBOM(mBOMBytes);
mEncodingFromBOM.emplace(encoding); // Null means no BOM.
// BOMs are three bytes at most, but may be fewer. Copy over anything
// that wasn't part of the BOM to mBytes. Note that we need to track
// any BOM bytes as well for SRI handling.
mBytes.Append(Substring(mBOMBytes, bomLength));
mBOMBytes.Truncate(bomLength);
}
nsresult StreamLoader::WriteSegmentFun(nsIInputStream*, void* aClosure,
const char* aSegment, uint32_t,
uint32_t aCount, uint32_t* aWriteCount) {
*aWriteCount = 0;
StreamLoader* self = static_cast<StreamLoader*>(aClosure);
if (NS_FAILED(self->mStatus)) {
return self->mStatus;
}
// If we haven't done BOM detection yet, divert bytes into the special buffer.
if (self->mEncodingFromBOM.isNothing()) {
size_t bytesToCopy = std::min<size_t>(3 - self->mBOMBytes.Length(), aCount);
self->mBOMBytes.Append(aSegment, bytesToCopy);
aSegment += bytesToCopy;
*aWriteCount += bytesToCopy;
aCount -= bytesToCopy;
if (self->mBOMBytes.Length() == 3) {
self->HandleBOM();
} else {
return NS_OK;
}
}
if (!self->mBytes.Append(aSegment, aCount, fallible)) {
self->mBytes.Truncate();
return (self->mStatus = NS_ERROR_OUT_OF_MEMORY);
}
*aWriteCount += aCount;
return NS_OK;
}
} // namespace mozilla::css
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