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gecko-dev/xpcom/io/nsStreamUtils.cpp

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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/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"
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 nsICancelableRunnable
, public nsIInputStreamCallback
{
public:
NS_DECL_THREADSAFE_ISUPPORTS
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;
}
NS_IMETHOD Cancel() override
{
mCallback = nullptr;
return NS_OK;
}
private:
nsCOMPtr<nsIAsyncInputStream> mStream;
nsCOMPtr<nsIInputStreamCallback> mCallback;
nsCOMPtr<nsIEventTarget> mTarget;
};
NS_IMPL_ISUPPORTS(nsInputStreamReadyEvent, nsICancelableRunnable,
nsIRunnable, 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 nsICancelableRunnable
, public nsIOutputStreamCallback
{
public:
NS_DECL_THREADSAFE_ISUPPORTS
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;
}
NS_IMETHOD Cancel() override
{
mCallback = nullptr;
return NS_OK;
}
private:
nsCOMPtr<nsIAsyncOutputStream> mStream;
nsCOMPtr<nsIOutputStreamCallback> mCallback;
nsCOMPtr<nsIEventTarget> mTarget;
};
NS_IMPL_ISUPPORTS(nsOutputStreamReadyEvent, nsICancelableRunnable,
nsIRunnable, 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 nsICancelableRunnable
{
public:
NS_DECL_THREADSAFE_ISUPPORTS
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;
}
NS_IMETHOD 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(nsAStreamCopier,
nsIInputStreamCallback,
nsIOutputStreamCallback,
nsICancelableRunnable,
nsIRunnable)
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 NS_METHOD 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;
}
NS_IMETHOD 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 NS_METHOD 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;
}
NS_IMETHOD 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 NS_METHOD
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 NS_METHOD
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;
}
//-----------------------------------------------------------------------------
NS_METHOD
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;
}
NS_METHOD
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;
}
NS_METHOD
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;
}
NS_METHOD
NS_DiscardSegment(nsIInputStream* aInStr,
void* aClosure,
const char* aBuffer,
uint32_t aOffset,
uint32_t aCount,
uint32_t* aCountWritten)
{
*aCountWritten = aCount;
return NS_OK;
}
//-----------------------------------------------------------------------------
NS_METHOD
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);
}
NS_METHOD
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;
}
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