diff options
Diffstat (limited to 'xpcom/io/nsStreamUtils.cpp')
| -rw-r--r-- | xpcom/io/nsStreamUtils.cpp | 957 |
1 files changed, 957 insertions, 0 deletions
diff --git a/xpcom/io/nsStreamUtils.cpp b/xpcom/io/nsStreamUtils.cpp new file mode 100644 index 000000000..891dad59f --- /dev/null +++ b/xpcom/io/nsStreamUtils.cpp @@ -0,0 +1,957 @@ +/* -*- 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/Mutex.h" +#include "mozilla/Attributes.h" +#include "nsStreamUtils.h" +#include "nsAutoPtr.h" +#include "nsCOMPtr.h" +#include "nsIPipe.h" +#include "nsICloneableInputStream.h" +#include "nsIEventTarget.h" +#include "nsICancelableRunnable.h" +#include "nsISafeOutputStream.h" +#include "nsString.h" +#include "nsIAsyncInputStream.h" +#include "nsIAsyncOutputStream.h" +#include "nsIBufferedStreams.h" +#include "nsNetCID.h" +#include "nsServiceManagerUtils.h" +#include "nsThreadUtils.h" + +using namespace mozilla; + +//----------------------------------------------------------------------------- + +// This is a nsICancelableRunnable because we can dispatch it to Workers and +// those can be shut down at any time, and in these cases, Cancel() is called +// instead of Run(). +class nsInputStreamReadyEvent final + : public CancelableRunnable + , public nsIInputStreamCallback +{ +public: + NS_DECL_ISUPPORTS_INHERITED + + nsInputStreamReadyEvent(nsIInputStreamCallback* aCallback, + nsIEventTarget* aTarget) + : mCallback(aCallback) + , mTarget(aTarget) + { + } + +private: + ~nsInputStreamReadyEvent() + { + if (!mCallback) { + return; + } + // + // whoa!! looks like we never posted this event. take care to + // release mCallback on the correct thread. if mTarget lives on the + // calling thread, then we are ok. otherwise, we have to try to + // proxy the Release over the right thread. if that thread is dead, + // then there's nothing we can do... better to leak than crash. + // + bool val; + nsresult rv = mTarget->IsOnCurrentThread(&val); + if (NS_FAILED(rv) || !val) { + nsCOMPtr<nsIInputStreamCallback> event = + NS_NewInputStreamReadyEvent(mCallback, mTarget); + mCallback = nullptr; + if (event) { + rv = event->OnInputStreamReady(nullptr); + if (NS_FAILED(rv)) { + NS_NOTREACHED("leaking stream event"); + nsISupports* sup = event; + NS_ADDREF(sup); + } + } + } + } + +public: + NS_IMETHOD OnInputStreamReady(nsIAsyncInputStream* aStream) override + { + mStream = aStream; + + nsresult rv = + mTarget->Dispatch(this, NS_DISPATCH_NORMAL); + if (NS_FAILED(rv)) { + NS_WARNING("Dispatch failed"); + return NS_ERROR_FAILURE; + } + + return NS_OK; + } + + NS_IMETHOD Run() override + { + if (mCallback) { + if (mStream) { + mCallback->OnInputStreamReady(mStream); + } + mCallback = nullptr; + } + return NS_OK; + } + + nsresult Cancel() override + { + mCallback = nullptr; + return NS_OK; + } + +private: + nsCOMPtr<nsIAsyncInputStream> mStream; + nsCOMPtr<nsIInputStreamCallback> mCallback; + nsCOMPtr<nsIEventTarget> mTarget; +}; + +NS_IMPL_ISUPPORTS_INHERITED(nsInputStreamReadyEvent, CancelableRunnable, + nsIInputStreamCallback) + +//----------------------------------------------------------------------------- + +// This is a nsICancelableRunnable because we can dispatch it to Workers and +// those can be shut down at any time, and in these cases, Cancel() is called +// instead of Run(). +class nsOutputStreamReadyEvent final + : public CancelableRunnable + , public nsIOutputStreamCallback +{ +public: + NS_DECL_ISUPPORTS_INHERITED + + nsOutputStreamReadyEvent(nsIOutputStreamCallback* aCallback, + nsIEventTarget* aTarget) + : mCallback(aCallback) + , mTarget(aTarget) + { + } + +private: + ~nsOutputStreamReadyEvent() + { + if (!mCallback) { + return; + } + // + // whoa!! looks like we never posted this event. take care to + // release mCallback on the correct thread. if mTarget lives on the + // calling thread, then we are ok. otherwise, we have to try to + // proxy the Release over the right thread. if that thread is dead, + // then there's nothing we can do... better to leak than crash. + // + bool val; + nsresult rv = mTarget->IsOnCurrentThread(&val); + if (NS_FAILED(rv) || !val) { + nsCOMPtr<nsIOutputStreamCallback> event = + NS_NewOutputStreamReadyEvent(mCallback, mTarget); + mCallback = nullptr; + if (event) { + rv = event->OnOutputStreamReady(nullptr); + if (NS_FAILED(rv)) { + NS_NOTREACHED("leaking stream event"); + nsISupports* sup = event; + NS_ADDREF(sup); + } + } + } + } + +public: + NS_IMETHOD OnOutputStreamReady(nsIAsyncOutputStream* aStream) override + { + mStream = aStream; + + nsresult rv = + mTarget->Dispatch(this, NS_DISPATCH_NORMAL); + if (NS_FAILED(rv)) { + NS_WARNING("PostEvent failed"); + return NS_ERROR_FAILURE; + } + + return NS_OK; + } + + NS_IMETHOD Run() override + { + if (mCallback) { + if (mStream) { + mCallback->OnOutputStreamReady(mStream); + } + mCallback = nullptr; + } + return NS_OK; + } + + nsresult Cancel() override + { + mCallback = nullptr; + return NS_OK; + } + +private: + nsCOMPtr<nsIAsyncOutputStream> mStream; + nsCOMPtr<nsIOutputStreamCallback> mCallback; + nsCOMPtr<nsIEventTarget> mTarget; +}; + +NS_IMPL_ISUPPORTS_INHERITED(nsOutputStreamReadyEvent, CancelableRunnable, + nsIOutputStreamCallback) + +//----------------------------------------------------------------------------- + +already_AddRefed<nsIInputStreamCallback> +NS_NewInputStreamReadyEvent(nsIInputStreamCallback* aCallback, + nsIEventTarget* aTarget) +{ + NS_ASSERTION(aCallback, "null callback"); + NS_ASSERTION(aTarget, "null target"); + RefPtr<nsInputStreamReadyEvent> ev = + new nsInputStreamReadyEvent(aCallback, aTarget); + return ev.forget(); +} + +already_AddRefed<nsIOutputStreamCallback> +NS_NewOutputStreamReadyEvent(nsIOutputStreamCallback* aCallback, + nsIEventTarget* aTarget) +{ + NS_ASSERTION(aCallback, "null callback"); + NS_ASSERTION(aTarget, "null target"); + RefPtr<nsOutputStreamReadyEvent> ev = + new nsOutputStreamReadyEvent(aCallback, aTarget); + return ev.forget(); +} + +//----------------------------------------------------------------------------- +// NS_AsyncCopy implementation + +// abstract stream copier... +class nsAStreamCopier + : public nsIInputStreamCallback + , public nsIOutputStreamCallback + , public CancelableRunnable +{ +public: + NS_DECL_ISUPPORTS_INHERITED + + nsAStreamCopier() + : mLock("nsAStreamCopier.mLock") + , mCallback(nullptr) + , mProgressCallback(nullptr) + , mClosure(nullptr) + , mChunkSize(0) + , mEventInProcess(false) + , mEventIsPending(false) + , mCloseSource(true) + , mCloseSink(true) + , mCanceled(false) + , mCancelStatus(NS_OK) + { + } + + // kick off the async copy... + nsresult Start(nsIInputStream* aSource, + nsIOutputStream* aSink, + nsIEventTarget* aTarget, + nsAsyncCopyCallbackFun aCallback, + void* aClosure, + uint32_t aChunksize, + bool aCloseSource, + bool aCloseSink, + nsAsyncCopyProgressFun aProgressCallback) + { + mSource = aSource; + mSink = aSink; + mTarget = aTarget; + mCallback = aCallback; + mClosure = aClosure; + mChunkSize = aChunksize; + mCloseSource = aCloseSource; + mCloseSink = aCloseSink; + mProgressCallback = aProgressCallback; + + mAsyncSource = do_QueryInterface(mSource); + mAsyncSink = do_QueryInterface(mSink); + + return PostContinuationEvent(); + } + + // implemented by subclasses, returns number of bytes copied and + // sets source and sink condition before returning. + virtual uint32_t DoCopy(nsresult* aSourceCondition, + nsresult* aSinkCondition) = 0; + + void Process() + { + if (!mSource || !mSink) { + return; + } + + nsresult cancelStatus; + bool canceled; + { + MutexAutoLock lock(mLock); + canceled = mCanceled; + cancelStatus = mCancelStatus; + } + + // If the copy was canceled before Process() was even called, then + // sourceCondition and sinkCondition should be set to error results to + // ensure we don't call Finish() on a canceled nsISafeOutputStream. + MOZ_ASSERT(NS_FAILED(cancelStatus) == canceled, "cancel needs an error"); + nsresult sourceCondition = cancelStatus; + nsresult sinkCondition = cancelStatus; + + // Copy data from the source to the sink until we hit failure or have + // copied all the data. + for (;;) { + // Note: copyFailed will be true if the source or the sink have + // reported an error, or if we failed to write any bytes + // because we have consumed all of our data. + bool copyFailed = false; + if (!canceled) { + uint32_t n = DoCopy(&sourceCondition, &sinkCondition); + if (n > 0 && mProgressCallback) { + mProgressCallback(mClosure, n); + } + copyFailed = NS_FAILED(sourceCondition) || + NS_FAILED(sinkCondition) || n == 0; + + MutexAutoLock lock(mLock); + canceled = mCanceled; + cancelStatus = mCancelStatus; + } + if (copyFailed && !canceled) { + if (sourceCondition == NS_BASE_STREAM_WOULD_BLOCK && mAsyncSource) { + // need to wait for more data from source. while waiting for + // more source data, be sure to observe failures on output end. + mAsyncSource->AsyncWait(this, 0, 0, nullptr); + + if (mAsyncSink) + mAsyncSink->AsyncWait(this, + nsIAsyncOutputStream::WAIT_CLOSURE_ONLY, + 0, nullptr); + break; + } else if (sinkCondition == NS_BASE_STREAM_WOULD_BLOCK && mAsyncSink) { + // need to wait for more room in the sink. while waiting for + // more room in the sink, be sure to observer failures on the + // input end. + mAsyncSink->AsyncWait(this, 0, 0, nullptr); + + if (mAsyncSource) + mAsyncSource->AsyncWait(this, + nsIAsyncInputStream::WAIT_CLOSURE_ONLY, + 0, nullptr); + break; + } + } + if (copyFailed || canceled) { + if (mCloseSource) { + // close source + if (mAsyncSource) + mAsyncSource->CloseWithStatus( + canceled ? cancelStatus : sinkCondition); + else { + mSource->Close(); + } + } + mAsyncSource = nullptr; + mSource = nullptr; + + if (mCloseSink) { + // close sink + if (mAsyncSink) + mAsyncSink->CloseWithStatus( + canceled ? cancelStatus : sourceCondition); + else { + // If we have an nsISafeOutputStream, and our + // sourceCondition and sinkCondition are not set to a + // failure state, finish writing. + nsCOMPtr<nsISafeOutputStream> sostream = + do_QueryInterface(mSink); + if (sostream && NS_SUCCEEDED(sourceCondition) && + NS_SUCCEEDED(sinkCondition)) { + sostream->Finish(); + } else { + mSink->Close(); + } + } + } + mAsyncSink = nullptr; + mSink = nullptr; + + // notify state complete... + if (mCallback) { + nsresult status; + if (!canceled) { + status = sourceCondition; + if (NS_SUCCEEDED(status)) { + status = sinkCondition; + } + if (status == NS_BASE_STREAM_CLOSED) { + status = NS_OK; + } + } else { + status = cancelStatus; + } + mCallback(mClosure, status); + } + break; + } + } + } + + nsresult Cancel(nsresult aReason) + { + MutexAutoLock lock(mLock); + if (mCanceled) { + return NS_ERROR_FAILURE; + } + + if (NS_SUCCEEDED(aReason)) { + NS_WARNING("cancel with non-failure status code"); + aReason = NS_BASE_STREAM_CLOSED; + } + + mCanceled = true; + mCancelStatus = aReason; + return NS_OK; + } + + NS_IMETHOD OnInputStreamReady(nsIAsyncInputStream* aSource) override + { + PostContinuationEvent(); + return NS_OK; + } + + NS_IMETHOD OnOutputStreamReady(nsIAsyncOutputStream* aSink) override + { + PostContinuationEvent(); + return NS_OK; + } + + // continuation event handler + NS_IMETHOD Run() override + { + Process(); + + // clear "in process" flag and post any pending continuation event + MutexAutoLock lock(mLock); + mEventInProcess = false; + if (mEventIsPending) { + mEventIsPending = false; + PostContinuationEvent_Locked(); + } + + return NS_OK; + } + + nsresult Cancel() MOZ_MUST_OVERRIDE override = 0; + + nsresult PostContinuationEvent() + { + // we cannot post a continuation event if there is currently + // an event in process. doing so could result in Process being + // run simultaneously on multiple threads, so we mark the event + // as pending, and if an event is already in process then we + // just let that existing event take care of posting the real + // continuation event. + + MutexAutoLock lock(mLock); + return PostContinuationEvent_Locked(); + } + + nsresult PostContinuationEvent_Locked() + { + nsresult rv = NS_OK; + if (mEventInProcess) { + mEventIsPending = true; + } else { + rv = mTarget->Dispatch(this, NS_DISPATCH_NORMAL); + if (NS_SUCCEEDED(rv)) { + mEventInProcess = true; + } else { + NS_WARNING("unable to post continuation event"); + } + } + return rv; + } + +protected: + nsCOMPtr<nsIInputStream> mSource; + nsCOMPtr<nsIOutputStream> mSink; + nsCOMPtr<nsIAsyncInputStream> mAsyncSource; + nsCOMPtr<nsIAsyncOutputStream> mAsyncSink; + nsCOMPtr<nsIEventTarget> mTarget; + Mutex mLock; + nsAsyncCopyCallbackFun mCallback; + nsAsyncCopyProgressFun mProgressCallback; + void* mClosure; + uint32_t mChunkSize; + bool mEventInProcess; + bool mEventIsPending; + bool mCloseSource; + bool mCloseSink; + bool mCanceled; + nsresult mCancelStatus; + + // virtual since subclasses call superclass Release() + virtual ~nsAStreamCopier() + { + } +}; + +NS_IMPL_ISUPPORTS_INHERITED(nsAStreamCopier, + CancelableRunnable, + nsIInputStreamCallback, + nsIOutputStreamCallback) + +class nsStreamCopierIB final : public nsAStreamCopier +{ +public: + nsStreamCopierIB() : nsAStreamCopier() + { + } + virtual ~nsStreamCopierIB() + { + } + + struct MOZ_STACK_CLASS ReadSegmentsState + { + // the nsIOutputStream will outlive the ReadSegmentsState on the stack + nsIOutputStream* MOZ_NON_OWNING_REF mSink; + nsresult mSinkCondition; + }; + + static nsresult ConsumeInputBuffer(nsIInputStream* aInStr, + void* aClosure, + const char* aBuffer, + uint32_t aOffset, + uint32_t aCount, + uint32_t* aCountWritten) + { + ReadSegmentsState* state = (ReadSegmentsState*)aClosure; + + nsresult rv = state->mSink->Write(aBuffer, aCount, aCountWritten); + if (NS_FAILED(rv)) { + state->mSinkCondition = rv; + } else if (*aCountWritten == 0) { + state->mSinkCondition = NS_BASE_STREAM_CLOSED; + } + + return state->mSinkCondition; + } + + uint32_t DoCopy(nsresult* aSourceCondition, + nsresult* aSinkCondition) override + { + ReadSegmentsState state; + state.mSink = mSink; + state.mSinkCondition = NS_OK; + + uint32_t n; + *aSourceCondition = + mSource->ReadSegments(ConsumeInputBuffer, &state, mChunkSize, &n); + *aSinkCondition = state.mSinkCondition; + return n; + } + + nsresult Cancel() override + { + return NS_OK; + } +}; + +class nsStreamCopierOB final : public nsAStreamCopier +{ +public: + nsStreamCopierOB() : nsAStreamCopier() + { + } + virtual ~nsStreamCopierOB() + { + } + + struct MOZ_STACK_CLASS WriteSegmentsState + { + // the nsIInputStream will outlive the WriteSegmentsState on the stack + nsIInputStream* MOZ_NON_OWNING_REF mSource; + nsresult mSourceCondition; + }; + + static nsresult FillOutputBuffer(nsIOutputStream* aOutStr, + void* aClosure, + char* aBuffer, + uint32_t aOffset, + uint32_t aCount, + uint32_t* aCountRead) + { + WriteSegmentsState* state = (WriteSegmentsState*)aClosure; + + nsresult rv = state->mSource->Read(aBuffer, aCount, aCountRead); + if (NS_FAILED(rv)) { + state->mSourceCondition = rv; + } else if (*aCountRead == 0) { + state->mSourceCondition = NS_BASE_STREAM_CLOSED; + } + + return state->mSourceCondition; + } + + uint32_t DoCopy(nsresult* aSourceCondition, + nsresult* aSinkCondition) override + { + WriteSegmentsState state; + state.mSource = mSource; + state.mSourceCondition = NS_OK; + + uint32_t n; + *aSinkCondition = + mSink->WriteSegments(FillOutputBuffer, &state, mChunkSize, &n); + *aSourceCondition = state.mSourceCondition; + return n; + } + + nsresult Cancel() override + { + return NS_OK; + } +}; + +//----------------------------------------------------------------------------- + +nsresult +NS_AsyncCopy(nsIInputStream* aSource, + nsIOutputStream* aSink, + nsIEventTarget* aTarget, + nsAsyncCopyMode aMode, + uint32_t aChunkSize, + nsAsyncCopyCallbackFun aCallback, + void* aClosure, + bool aCloseSource, + bool aCloseSink, + nsISupports** aCopierCtx, + nsAsyncCopyProgressFun aProgressCallback) +{ + NS_ASSERTION(aTarget, "non-null target required"); + + nsresult rv; + nsAStreamCopier* copier; + + if (aMode == NS_ASYNCCOPY_VIA_READSEGMENTS) { + copier = new nsStreamCopierIB(); + } else { + copier = new nsStreamCopierOB(); + } + + // Start() takes an owning ref to the copier... + NS_ADDREF(copier); + rv = copier->Start(aSource, aSink, aTarget, aCallback, aClosure, aChunkSize, + aCloseSource, aCloseSink, aProgressCallback); + + if (aCopierCtx) { + *aCopierCtx = static_cast<nsISupports*>(static_cast<nsIRunnable*>(copier)); + NS_ADDREF(*aCopierCtx); + } + NS_RELEASE(copier); + + return rv; +} + +//----------------------------------------------------------------------------- + +nsresult +NS_CancelAsyncCopy(nsISupports* aCopierCtx, nsresult aReason) +{ + nsAStreamCopier* copier = + static_cast<nsAStreamCopier*>(static_cast<nsIRunnable *>(aCopierCtx)); + return copier->Cancel(aReason); +} + +//----------------------------------------------------------------------------- + +nsresult +NS_ConsumeStream(nsIInputStream* aStream, uint32_t aMaxCount, + nsACString& aResult) +{ + nsresult rv = NS_OK; + aResult.Truncate(); + + while (aMaxCount) { + uint64_t avail64; + rv = aStream->Available(&avail64); + if (NS_FAILED(rv)) { + if (rv == NS_BASE_STREAM_CLOSED) { + rv = NS_OK; + } + break; + } + if (avail64 == 0) { + break; + } + + uint32_t avail = (uint32_t)XPCOM_MIN<uint64_t>(avail64, aMaxCount); + + // resize aResult buffer + uint32_t length = aResult.Length(); + if (avail > UINT32_MAX - length) { + return NS_ERROR_FILE_TOO_BIG; + } + + aResult.SetLength(length + avail); + if (aResult.Length() != (length + avail)) { + return NS_ERROR_OUT_OF_MEMORY; + } + char* buf = aResult.BeginWriting() + length; + + uint32_t n; + rv = aStream->Read(buf, avail, &n); + if (NS_FAILED(rv)) { + break; + } + if (n != avail) { + aResult.SetLength(length + n); + } + if (n == 0) { + break; + } + aMaxCount -= n; + } + + return rv; +} + +//----------------------------------------------------------------------------- + +static nsresult +TestInputStream(nsIInputStream* aInStr, + void* aClosure, + const char* aBuffer, + uint32_t aOffset, + uint32_t aCount, + uint32_t* aCountWritten) +{ + bool* result = static_cast<bool*>(aClosure); + *result = true; + return NS_ERROR_ABORT; // don't call me anymore +} + +bool +NS_InputStreamIsBuffered(nsIInputStream* aStream) +{ + nsCOMPtr<nsIBufferedInputStream> bufferedIn = do_QueryInterface(aStream); + if (bufferedIn) { + return true; + } + + bool result = false; + uint32_t n; + nsresult rv = aStream->ReadSegments(TestInputStream, &result, 1, &n); + return result || NS_SUCCEEDED(rv); +} + +static nsresult +TestOutputStream(nsIOutputStream* aOutStr, + void* aClosure, + char* aBuffer, + uint32_t aOffset, + uint32_t aCount, + uint32_t* aCountRead) +{ + bool* result = static_cast<bool*>(aClosure); + *result = true; + return NS_ERROR_ABORT; // don't call me anymore +} + +bool +NS_OutputStreamIsBuffered(nsIOutputStream* aStream) +{ + nsCOMPtr<nsIBufferedOutputStream> bufferedOut = do_QueryInterface(aStream); + if (bufferedOut) { + return true; + } + + bool result = false; + uint32_t n; + aStream->WriteSegments(TestOutputStream, &result, 1, &n); + return result; +} + +//----------------------------------------------------------------------------- + +nsresult +NS_CopySegmentToStream(nsIInputStream* aInStr, + void* aClosure, + const char* aBuffer, + uint32_t aOffset, + uint32_t aCount, + uint32_t* aCountWritten) +{ + nsIOutputStream* outStr = static_cast<nsIOutputStream*>(aClosure); + *aCountWritten = 0; + while (aCount) { + uint32_t n; + nsresult rv = outStr->Write(aBuffer, aCount, &n); + if (NS_FAILED(rv)) { + return rv; + } + aBuffer += n; + aCount -= n; + *aCountWritten += n; + } + return NS_OK; +} + +nsresult +NS_CopySegmentToBuffer(nsIInputStream* aInStr, + void* aClosure, + const char* aBuffer, + uint32_t aOffset, + uint32_t aCount, + uint32_t* aCountWritten) +{ + char* toBuf = static_cast<char*>(aClosure); + memcpy(&toBuf[aOffset], aBuffer, aCount); + *aCountWritten = aCount; + return NS_OK; +} + +nsresult +NS_CopySegmentToBuffer(nsIOutputStream* aOutStr, + void* aClosure, + char* aBuffer, + uint32_t aOffset, + uint32_t aCount, + uint32_t* aCountRead) +{ + const char* fromBuf = static_cast<const char*>(aClosure); + memcpy(aBuffer, &fromBuf[aOffset], aCount); + *aCountRead = aCount; + return NS_OK; +} + +nsresult +NS_DiscardSegment(nsIInputStream* aInStr, + void* aClosure, + const char* aBuffer, + uint32_t aOffset, + uint32_t aCount, + uint32_t* aCountWritten) +{ + *aCountWritten = aCount; + return NS_OK; +} + +//----------------------------------------------------------------------------- + +nsresult +NS_WriteSegmentThunk(nsIInputStream* aInStr, + void* aClosure, + const char* aBuffer, + uint32_t aOffset, + uint32_t aCount, + uint32_t* aCountWritten) +{ + nsWriteSegmentThunk* thunk = static_cast<nsWriteSegmentThunk*>(aClosure); + return thunk->mFun(thunk->mStream, thunk->mClosure, aBuffer, aOffset, aCount, + aCountWritten); +} + +nsresult +NS_FillArray(FallibleTArray<char>& aDest, nsIInputStream* aInput, + uint32_t aKeep, uint32_t* aNewBytes) +{ + MOZ_ASSERT(aInput, "null stream"); + MOZ_ASSERT(aKeep <= aDest.Length(), "illegal keep count"); + + char* aBuffer = aDest.Elements(); + int64_t keepOffset = int64_t(aDest.Length()) - aKeep; + if (aKeep != 0 && keepOffset > 0) { + memmove(aBuffer, aBuffer + keepOffset, aKeep); + } + + nsresult rv = + aInput->Read(aBuffer + aKeep, aDest.Capacity() - aKeep, aNewBytes); + if (NS_FAILED(rv)) { + *aNewBytes = 0; + } + // NOTE: we rely on the fact that the new slots are NOT initialized by + // SetLengthAndRetainStorage here, see nsTArrayElementTraits::Construct() + // in nsTArray.h: + aDest.SetLengthAndRetainStorage(aKeep + *aNewBytes); + + MOZ_ASSERT(aDest.Length() <= aDest.Capacity(), "buffer overflow"); + return rv; +} + +bool +NS_InputStreamIsCloneable(nsIInputStream* aSource) +{ + if (!aSource) { + return false; + } + + nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(aSource); + return cloneable && cloneable->GetCloneable(); +} + +nsresult +NS_CloneInputStream(nsIInputStream* aSource, nsIInputStream** aCloneOut, + nsIInputStream** aReplacementOut) +{ + if (NS_WARN_IF(!aSource)) { + return NS_ERROR_FAILURE; + } + + // Attempt to perform the clone directly on the source stream + nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(aSource); + if (cloneable && cloneable->GetCloneable()) { + if (aReplacementOut) { + *aReplacementOut = nullptr; + } + return cloneable->Clone(aCloneOut); + } + + // If we failed the clone and the caller does not want to replace their + // original stream, then we are done. Return error. + if (!aReplacementOut) { + return NS_ERROR_FAILURE; + } + + // The caller has opted-in to the fallback clone support that replaces + // the original stream. Copy the data to a pipe and return two cloned + // input streams. + + nsCOMPtr<nsIInputStream> reader; + nsCOMPtr<nsIInputStream> readerClone; + nsCOMPtr<nsIOutputStream> writer; + + nsresult rv = NS_NewPipe(getter_AddRefs(reader), getter_AddRefs(writer), + 0, 0, // default segment size and max size + true, true); // non-blocking + if (NS_WARN_IF(NS_FAILED(rv))) { return rv; } + + cloneable = do_QueryInterface(reader); + MOZ_ASSERT(cloneable && cloneable->GetCloneable()); + + rv = cloneable->Clone(getter_AddRefs(readerClone)); + if (NS_WARN_IF(NS_FAILED(rv))) { return rv; } + + nsCOMPtr<nsIEventTarget> target = + do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID, &rv); + if (NS_WARN_IF(NS_FAILED(rv))) { return rv; } + + rv = NS_AsyncCopy(aSource, writer, target, NS_ASYNCCOPY_VIA_WRITESEGMENTS); + if (NS_WARN_IF(NS_FAILED(rv))) { return rv; } + + readerClone.forget(aCloneOut); + reader.forget(aReplacementOut); + + return NS_OK; +} |