gecko-dev/dom/filehandle/ActorsParent.cpp

/* 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 "ActorsParent.h"

#include "mozilla/Assertions.h"
#include "mozilla/Atomics.h"
#include "mozilla/Attributes.h"
#include "mozilla/Unused.h"
#include "mozilla/dom/File.h"
#include "mozilla/dom/FileHandleCommon.h"
#include "mozilla/dom/PBackgroundFileHandleParent.h"
#include "mozilla/dom/PBackgroundFileRequestParent.h"
#include "mozilla/dom/indexedDB/ActorsParent.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBDatabaseParent.h"
#include "mozilla/dom/IPCBlobUtils.h"
#include "mozilla/dom/ipc/PendingIPCBlobParent.h"
#include "nsAutoPtr.h"
#include "nsComponentManagerUtils.h"
#include "nsDebug.h"
#include "nsError.h"
#include "nsIEventTarget.h"
#include "nsIFileStreams.h"
#include "nsIInputStream.h"
#include "nsIOutputStream.h"
#include "nsIRunnable.h"
#include "nsISeekableStream.h"
#include "nsIThread.h"
#include "nsIThreadPool.h"
#include "nsNetUtil.h"
#include "nsStreamUtils.h"
#include "nsStringStream.h"
#include "nsTArray.h"
#include "nsThreadPool.h"
#include "nsThreadUtils.h"
#include "nsXPCOMCIDInternal.h"

#define DISABLE_ASSERTS_FOR_FUZZING 0

#if DISABLE_ASSERTS_FOR_FUZZING
#define ASSERT_UNLESS_FUZZING(...) do { } while (0)
#else
#define ASSERT_UNLESS_FUZZING(...) MOZ_ASSERT(false, __VA_ARGS__)
#endif

namespace mozilla {
namespace dom {

using namespace mozilla::ipc;

namespace {

/******************************************************************************
 * Constants
 ******************************************************************************/

const uint32_t kThreadLimit = 5;
const uint32_t kIdleThreadLimit = 1;
const uint32_t kIdleThreadTimeoutMs = 30000;

const uint32_t kStreamCopyBlockSize = 32768;

} // namespace

class FileHandleThreadPool::FileHandleQueue final
  : public Runnable
{
  friend class FileHandleThreadPool;

  RefPtr<FileHandleThreadPool> mOwningFileHandleThreadPool;
  RefPtr<FileHandle> mFileHandle;
  nsTArray<RefPtr<FileHandleOp>> mQueue;
  RefPtr<FileHandleOp> mCurrentOp;
  bool mShouldFinish;

public:
  explicit
  FileHandleQueue(FileHandleThreadPool* aFileHandleThreadPool,
                  FileHandle* aFileHandle);

  void
  Enqueue(FileHandleOp* aFileHandleOp);

  void
  Finish();

  void
  ProcessQueue();

private:
  ~FileHandleQueue() {}

  NS_DECL_NSIRUNNABLE
};

struct FileHandleThreadPool::DelayedEnqueueInfo
{
  RefPtr<FileHandle> mFileHandle;
  RefPtr<FileHandleOp> mFileHandleOp;
  bool mFinish;
};

class FileHandleThreadPool::DirectoryInfo
{
  friend class FileHandleThreadPool;

  RefPtr<FileHandleThreadPool> mOwningFileHandleThreadPool;
  nsTArray<RefPtr<FileHandleQueue>> mFileHandleQueues;
  nsTArray<DelayedEnqueueInfo> mDelayedEnqueueInfos;
  nsTHashtable<nsStringHashKey> mFilesReading;
  nsTHashtable<nsStringHashKey> mFilesWriting;

public:
  FileHandleQueue*
  CreateFileHandleQueue(FileHandle* aFileHandle);

  FileHandleQueue*
  GetFileHandleQueue(FileHandle* aFileHandle);

  void
  RemoveFileHandleQueue(FileHandle* aFileHandle);

  bool
  HasRunningFileHandles()
  {
    return !mFileHandleQueues.IsEmpty();
  }

  DelayedEnqueueInfo*
  CreateDelayedEnqueueInfo(FileHandle* aFileHandle,
                           FileHandleOp* aFileHandleOp,
                           bool aFinish);

  void
  LockFileForReading(const nsAString& aFileName)
  {
    mFilesReading.PutEntry(aFileName);
  }

  void
  LockFileForWriting(const nsAString& aFileName)
  {
    mFilesWriting.PutEntry(aFileName);
  }

  bool
  IsFileLockedForReading(const nsAString& aFileName)
  {
    return mFilesReading.Contains(aFileName);
  }

  bool
  IsFileLockedForWriting(const nsAString& aFileName)
  {
    return mFilesWriting.Contains(aFileName);
  }

private:
  explicit DirectoryInfo(FileHandleThreadPool* aFileHandleThreadPool)
    : mOwningFileHandleThreadPool(aFileHandleThreadPool)
  { }
};

struct FileHandleThreadPool::StoragesCompleteCallback final
{
  friend class nsAutoPtr<StoragesCompleteCallback>;

  nsTArray<nsCString> mDirectoryIds;
  nsCOMPtr<nsIRunnable> mCallback;

  StoragesCompleteCallback(nsTArray<nsCString>&& aDatabaseIds,
                           nsIRunnable* aCallback);

private:
  ~StoragesCompleteCallback();
};

/******************************************************************************
 * Actor class declarations
 ******************************************************************************/

class FileHandle
  : public PBackgroundFileHandleParent
{
  friend class BackgroundMutableFileParentBase;

  class FinishOp;

  RefPtr<BackgroundMutableFileParentBase> mMutableFile;
  nsCOMPtr<nsISupports> mStream;
  uint64_t mActiveRequestCount;
  FileHandleStorage mStorage;
  Atomic<bool> mInvalidatedOnAnyThread;
  FileMode mMode;
  bool mHasBeenActive;
  bool mActorDestroyed;
  bool mInvalidated;
  bool mAborted;
  bool mFinishOrAbortReceived;
  bool mFinishedOrAborted;
  bool mForceAborted;

  DEBUGONLY(nsCOMPtr<nsIEventTarget> mThreadPoolEventTarget;)

public:
  void
  AssertIsOnThreadPool() const;

  bool
  IsActorDestroyed() const
  {
    AssertIsOnBackgroundThread();

    return mActorDestroyed;
  }

  // Must be called on the background thread.
  bool
  IsInvalidated() const
  {
    MOZ_ASSERT(IsOnBackgroundThread(), "Use IsInvalidatedOnAnyThread()");
    MOZ_ASSERT_IF(mInvalidated, mAborted);

    return mInvalidated;
  }

  // May be called on any thread, but is more expensive than IsInvalidated().
  bool
  IsInvalidatedOnAnyThread() const
  {
    return mInvalidatedOnAnyThread;
  }

  void
  SetActive()
  {
    AssertIsOnBackgroundThread();

    mHasBeenActive = true;
  }

  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(mozilla::dom::FileHandle)

  nsresult
  GetOrCreateStream(nsISupports** aStream);

  void
  Abort(bool aForce);

  FileHandleStorage
  Storage() const
  {
    return mStorage;
  }

  FileMode
  Mode() const
  {
    return mMode;
  }

  BackgroundMutableFileParentBase*
  GetMutableFile() const
  {
    AssertIsOnBackgroundThread();
    MOZ_ASSERT(mMutableFile);

    return mMutableFile;
  }

  bool
  IsAborted() const
  {
    AssertIsOnBackgroundThread();

    return mAborted;
  }

  PBackgroundParent*
  GetBackgroundParent() const
  {
    AssertIsOnBackgroundThread();
    MOZ_ASSERT(!IsActorDestroyed());

    return GetMutableFile()->GetBackgroundParent();
  }

  void
  NoteActiveRequest();

  void
  NoteFinishedRequest();

  void
  Invalidate();

private:
  // This constructor is only called by BackgroundMutableFileParentBase.
  FileHandle(BackgroundMutableFileParentBase* aMutableFile,
             FileMode aMode);

  // Reference counted.
  ~FileHandle();

  void
  MaybeFinishOrAbort()
  {
    AssertIsOnBackgroundThread();

    // If we've already finished or aborted then there's nothing else to do.
    if (mFinishedOrAborted) {
      return;
    }

    // If there are active requests then we have to wait for those requests to
    // complete (see NoteFinishedRequest).
    if (mActiveRequestCount) {
      return;
    }

    // If we haven't yet received a finish or abort message then there could be
    // additional requests coming so we should wait unless we're being forced to
    // abort.
    if (!mFinishOrAbortReceived && !mForceAborted) {
      return;
    }

    FinishOrAbort();
  }

  void
  SendCompleteNotification(bool aAborted);

  bool
  VerifyRequestParams(const FileRequestParams& aParams) const;

  bool
  VerifyRequestData(const FileRequestData& aData) const;

  void
  FinishOrAbort();

  // IPDL methods are only called by IPDL.
  virtual void
  ActorDestroy(ActorDestroyReason aWhy) override;

  virtual mozilla::ipc::IPCResult
  RecvDeleteMe() override;

  virtual mozilla::ipc::IPCResult
  RecvFinish() override;

  virtual mozilla::ipc::IPCResult
  RecvAbort() override;

  virtual PBackgroundFileRequestParent*
  AllocPBackgroundFileRequestParent(const FileRequestParams& aParams) override;

  virtual mozilla::ipc::IPCResult
  RecvPBackgroundFileRequestConstructor(PBackgroundFileRequestParent* aActor,
                                        const FileRequestParams& aParams)
                                        override;

  virtual bool
  DeallocPBackgroundFileRequestParent(PBackgroundFileRequestParent* aActor)
                                      override;
};

class FileHandleOp
{
protected:
  nsCOMPtr<nsIEventTarget> mOwningThread;
  RefPtr<FileHandle> mFileHandle;

public:
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(FileHandleOp)

  void
  AssertIsOnOwningThread() const
  {
    AssertIsOnBackgroundThread();
    MOZ_ASSERT(mOwningThread);
    DebugOnly<bool> current;
    MOZ_ASSERT(NS_SUCCEEDED(mOwningThread->IsOnCurrentThread(&current)));
    MOZ_ASSERT(current);
  }

  nsIEventTarget*
  OwningThread() const
  {
    return mOwningThread;
  }

  void
  AssertIsOnThreadPool() const
  {
    MOZ_ASSERT(mFileHandle);
    mFileHandle->AssertIsOnThreadPool();
  }

  void
  Enqueue();

  virtual void
  RunOnThreadPool() = 0;

  virtual void
  RunOnOwningThread() = 0;

protected:
  FileHandleOp(FileHandle* aFileHandle)
    : mOwningThread(NS_GetCurrentThread())
    , mFileHandle(aFileHandle)
  {
    AssertIsOnOwningThread();
    MOZ_ASSERT(aFileHandle);
  }

  virtual
  ~FileHandleOp()
  { }
};

class FileHandle::FinishOp
  : public FileHandleOp
{
  friend class FileHandle;

  bool mAborted;

private:
  FinishOp(FileHandle* aFileHandle,
           bool aAborted)
    : FileHandleOp(aFileHandle)
    , mAborted(aAborted)
  {
    MOZ_ASSERT(aFileHandle);
  }

  ~FinishOp()
  { }

  virtual void
  RunOnThreadPool() override;

  virtual void
  RunOnOwningThread() override;
};

class NormalFileHandleOp
  : public FileHandleOp
  , public PBackgroundFileRequestParent
{
  nsresult mResultCode;
  Atomic<bool> mOperationMayProceed;
  bool mActorDestroyed;
  const bool mFileHandleIsAborted;

  DEBUGONLY(bool mResponseSent;)

protected:
  nsCOMPtr<nsISupports> mFileStream;

public:
  void
  NoteActorDestroyed()
  {
    AssertIsOnOwningThread();

    mActorDestroyed = true;
    mOperationMayProceed = false;
  }

  bool
  IsActorDestroyed() const
  {
    AssertIsOnOwningThread();

    return mActorDestroyed;
  }

  // May be called on any thread, but you should call IsActorDestroyed() if
  // you know you're on the background thread because it is slightly faster.
  bool
  OperationMayProceed() const
  {
    return mOperationMayProceed;
  }

  // May be overridden by subclasses if they need to perform work on the
  // background thread before being enqueued. Returning false will kill the
  // child actors and prevent enqueue.
  virtual bool
  Init(FileHandle* aFileHandle);

  // This callback will be called on the background thread before releasing the
  // final reference to this request object. Subclasses may perform any
  // additional cleanup here but must always call the base class implementation.
  virtual void
  Cleanup();

protected:
  NormalFileHandleOp(FileHandle* aFileHandle)
    : FileHandleOp(aFileHandle)
    , mResultCode(NS_OK)
    , mOperationMayProceed(true)
    , mActorDestroyed(false)
    , mFileHandleIsAborted(aFileHandle->IsAborted())
    DEBUGONLY(, mResponseSent(false))
  {
    MOZ_ASSERT(aFileHandle);
  }

  virtual
  ~NormalFileHandleOp();

  // Must be overridden in subclasses. Called on the target thread to allow the
  // subclass to perform necessary file operations. A successful return value
  // will trigger a SendSuccessResult callback on the background thread while
  // a failure value will trigger a SendFailureResult callback.
  virtual nsresult
  DoFileWork(FileHandle* aFileHandle) = 0;

  // Subclasses use this override to set the IPDL response value.
  virtual void
  GetResponse(FileRequestResponse& aResponse) = 0;

private:
  nsresult
  SendSuccessResult();

  bool
  SendFailureResult(nsresult aResultCode);

  virtual void
  RunOnThreadPool() override;

  virtual void
  RunOnOwningThread() override;

  // IPDL methods.
  virtual void
  ActorDestroy(ActorDestroyReason aWhy) override;
};

class CopyFileHandleOp
  : public NormalFileHandleOp
{
  class ProgressRunnable;

protected:
  nsCOMPtr<nsISupports> mBufferStream;

  uint64_t mOffset;
  uint64_t mSize;

  bool mRead;

protected:
  CopyFileHandleOp(FileHandle* aFileHandle)
    : NormalFileHandleOp(aFileHandle)
    , mOffset(0)
    , mSize(0)
    , mRead(true)
  { }

  virtual nsresult
  DoFileWork(FileHandle* aFileHandle) override;

  virtual void
  Cleanup() override;
};

class CopyFileHandleOp::ProgressRunnable final
  : public Runnable
{
  RefPtr<CopyFileHandleOp> mCopyFileHandleOp;
  uint64_t mProgress;
  uint64_t mProgressMax;

public:
  ProgressRunnable(CopyFileHandleOp* aCopyFileHandleOp,
                   uint64_t aProgress,
                   uint64_t aProgressMax)
    : mCopyFileHandleOp(aCopyFileHandleOp)
    , mProgress(aProgress)
    , mProgressMax(aProgressMax)
  { }

private:
  ~ProgressRunnable() {}

  NS_DECL_NSIRUNNABLE
};

class GetMetadataOp
  : public NormalFileHandleOp
{
  friend class FileHandle;

  const FileRequestGetMetadataParams mParams;

protected:
  FileRequestMetadata mMetadata;

protected:
  // Only created by FileHandle.
  GetMetadataOp(FileHandle* aFileHandle,
                const FileRequestParams& aParams);

  ~GetMetadataOp()
  { }

  virtual nsresult
  DoFileWork(FileHandle* aFileHandle) override;

  virtual void
  GetResponse(FileRequestResponse& aResponse) override;
};

class ReadOp final
  : public CopyFileHandleOp
{
  friend class FileHandle;

  class MemoryOutputStream;

  const FileRequestReadParams mParams;

private:
  // Only created by FileHandle.
  ReadOp(FileHandle* aFileHandle,
         const FileRequestParams& aParams);

  ~ReadOp()
  { }

  virtual bool
  Init(FileHandle* aFileHandle) override;

  virtual void
  GetResponse(FileRequestResponse& aResponse) override;
};

class ReadOp::MemoryOutputStream final
  : public nsIOutputStream
{
  nsCString mData;
  uint64_t mOffset;

public:
  static already_AddRefed<MemoryOutputStream>
  Create(uint64_t aSize);

  const nsCString&
  Data() const
  {
    return mData;
  }

private:
  MemoryOutputStream()
  : mOffset(0)
  { }

  virtual ~MemoryOutputStream()
  { }

  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSIOUTPUTSTREAM
};

class WriteOp final
  : public CopyFileHandleOp
{
  friend class FileHandle;

  const FileRequestWriteParams mParams;

private:
  // Only created by FileHandle.
  WriteOp(FileHandle* aFileHandle,
          const FileRequestParams& aParams);

  ~WriteOp()
  { }

  virtual bool
  Init(FileHandle* aFileHandle) override;

  virtual void
  GetResponse(FileRequestResponse& aResponse) override;
};

class TruncateOp final
  : public NormalFileHandleOp
{
  friend class FileHandle;

  const FileRequestTruncateParams mParams;

private:
  // Only created by FileHandle.
  TruncateOp(FileHandle* aFileHandle,
                        const FileRequestParams& aParams);

  ~TruncateOp()
  { }

  virtual nsresult
  DoFileWork(FileHandle* aFileHandle) override;

  virtual void
  GetResponse(FileRequestResponse& aResponse) override;
};

class FlushOp final
  : public NormalFileHandleOp
{
  friend class FileHandle;

  const FileRequestFlushParams mParams;

private:
  // Only created by FileHandle.
  FlushOp(FileHandle* aFileHandle,
          const FileRequestParams& aParams);

  ~FlushOp()
  { }

  virtual nsresult
  DoFileWork(FileHandle* aFileHandle) override;

  virtual void
  GetResponse(FileRequestResponse& aResponse) override;
};

class GetFileOp final
  : public GetMetadataOp
{
  friend class FileHandle;

  PBackgroundParent* mBackgroundParent;

private:
  // Only created by FileHandle.
  GetFileOp(FileHandle* aFileHandle,
            const FileRequestParams& aParams);

  ~GetFileOp()
  { }

  virtual void
  GetResponse(FileRequestResponse& aResponse) override;
};

namespace {

/*******************************************************************************
 * Helper Functions
 ******************************************************************************/

FileHandleThreadPool*
GetFileHandleThreadPoolFor(FileHandleStorage aStorage)
{
  switch (aStorage) {
    case FILE_HANDLE_STORAGE_IDB:
      return mozilla::dom::indexedDB::GetFileHandleThreadPool();

    default:
      MOZ_CRASH("Bad file handle storage value!");
  }
}

} // namespace

/*******************************************************************************
 * FileHandleThreadPool implementation
 ******************************************************************************/

FileHandleThreadPool::FileHandleThreadPool()
  : mOwningThread(NS_GetCurrentThread())
  , mShutdownRequested(false)
  , mShutdownComplete(false)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(mOwningThread);
  AssertIsOnOwningThread();
}

FileHandleThreadPool::~FileHandleThreadPool()
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(!mDirectoryInfos.Count());
  MOZ_ASSERT(mCompleteCallbacks.IsEmpty());
  MOZ_ASSERT(mShutdownRequested);
  MOZ_ASSERT(mShutdownComplete);
}

// static
already_AddRefed<FileHandleThreadPool>
FileHandleThreadPool::Create()
{
  AssertIsOnBackgroundThread();

  RefPtr<FileHandleThreadPool> fileHandleThreadPool =
    new FileHandleThreadPool();
  fileHandleThreadPool->AssertIsOnOwningThread();

  if (NS_WARN_IF(NS_FAILED(fileHandleThreadPool->Init()))) {
    return nullptr;
  }

  return fileHandleThreadPool.forget();
}

#ifdef DEBUG

void
FileHandleThreadPool::AssertIsOnOwningThread() const
{
  MOZ_ASSERT(mOwningThread);

  bool current;
  MOZ_ALWAYS_SUCCEEDS(mOwningThread->IsOnCurrentThread(&current));
  MOZ_ASSERT(current);
}

nsIEventTarget*
FileHandleThreadPool::GetThreadPoolEventTarget() const
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(mThreadPool);

  return mThreadPool;
}

#endif // DEBUG

void
FileHandleThreadPool::Enqueue(FileHandle* aFileHandle,
                              FileHandleOp* aFileHandleOp,
                              bool aFinish)
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(aFileHandle);
  MOZ_ASSERT(!mShutdownRequested);

  BackgroundMutableFileParentBase* mutableFile = aFileHandle->GetMutableFile();

  const nsACString& directoryId = mutableFile->DirectoryId();
  const nsAString& fileName = mutableFile->FileName();
  bool modeIsWrite = aFileHandle->Mode() == FileMode::Readwrite;

  DirectoryInfo* directoryInfo;
  if (!mDirectoryInfos.Get(directoryId, &directoryInfo)) {
    nsAutoPtr<DirectoryInfo> newDirectoryInfo(new DirectoryInfo(this));

    mDirectoryInfos.Put(directoryId, newDirectoryInfo);

    directoryInfo = newDirectoryInfo.forget();
  }

  FileHandleQueue* existingFileHandleQueue =
    directoryInfo->GetFileHandleQueue(aFileHandle);

  if (existingFileHandleQueue) {
    existingFileHandleQueue->Enqueue(aFileHandleOp);
    if (aFinish) {
      existingFileHandleQueue->Finish();
    }
    return;
  }

  bool lockedForReading = directoryInfo->IsFileLockedForReading(fileName);
  bool lockedForWriting = directoryInfo->IsFileLockedForWriting(fileName);

  if (modeIsWrite) {
    if (!lockedForWriting) {
      directoryInfo->LockFileForWriting(fileName);
    }
  }
  else {
    if (!lockedForReading) {
      directoryInfo->LockFileForReading(fileName);
    }
  }

  if (lockedForWriting || (lockedForReading && modeIsWrite)) {
    directoryInfo->CreateDelayedEnqueueInfo(aFileHandle,
                                            aFileHandleOp,
                                            aFinish);
  }
  else {
    FileHandleQueue* fileHandleQueue =
      directoryInfo->CreateFileHandleQueue(aFileHandle);

    if (aFileHandleOp) {
      fileHandleQueue->Enqueue(aFileHandleOp);
      if (aFinish) {
        fileHandleQueue->Finish();
      }
    }
  }
}

void
FileHandleThreadPool::WaitForDirectoriesToComplete(
                                             nsTArray<nsCString>&& aDirectoryIds,
                                             nsIRunnable* aCallback)
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(!aDirectoryIds.IsEmpty());
  MOZ_ASSERT(aCallback);

  nsAutoPtr<StoragesCompleteCallback> callback(
    new StoragesCompleteCallback(Move(aDirectoryIds), aCallback));

  if (!MaybeFireCallback(callback)) {
    mCompleteCallbacks.AppendElement(callback.forget());
  }
}

void
FileHandleThreadPool::Shutdown()
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(!mShutdownRequested);
  MOZ_ASSERT(!mShutdownComplete);

  mShutdownRequested = true;

  if (!mThreadPool) {
    MOZ_ASSERT(!mDirectoryInfos.Count());
    MOZ_ASSERT(mCompleteCallbacks.IsEmpty());

    mShutdownComplete = true;
    return;
  }

  if (!mDirectoryInfos.Count()) {
    Cleanup();

    MOZ_ASSERT(mShutdownComplete);
    return;
  }

  nsIThread* currentThread = NS_GetCurrentThread();
  MOZ_ASSERT(currentThread);

  while (!mShutdownComplete) {
    MOZ_ALWAYS_TRUE(NS_ProcessNextEvent(currentThread));
  }
}

nsresult
FileHandleThreadPool::Init()
{
  AssertIsOnOwningThread();

  mThreadPool = new nsThreadPool();

  nsresult rv = mThreadPool->SetName(NS_LITERAL_CSTRING("FileHandles"));
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  rv = mThreadPool->SetThreadLimit(kThreadLimit);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  rv = mThreadPool->SetIdleThreadLimit(kIdleThreadLimit);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  rv = mThreadPool->SetIdleThreadTimeout(kIdleThreadTimeoutMs);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  return NS_OK;
}

void
FileHandleThreadPool::Cleanup()
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(mThreadPool);
  MOZ_ASSERT(mShutdownRequested);
  MOZ_ASSERT(!mShutdownComplete);
  MOZ_ASSERT(!mDirectoryInfos.Count());

  MOZ_ALWAYS_SUCCEEDS(mThreadPool->Shutdown());

  if (!mCompleteCallbacks.IsEmpty()) {
    // Run all callbacks manually now.
    for (uint32_t count = mCompleteCallbacks.Length(), index = 0;
         index < count;
         index++) {
      nsAutoPtr<StoragesCompleteCallback> completeCallback(
        mCompleteCallbacks[index].forget());
      MOZ_ASSERT(completeCallback);
      MOZ_ASSERT(completeCallback->mCallback);

      Unused << completeCallback->mCallback->Run();
    }

    mCompleteCallbacks.Clear();

    // And make sure they get processed.
    nsIThread* currentThread = NS_GetCurrentThread();
    MOZ_ASSERT(currentThread);

    MOZ_ALWAYS_SUCCEEDS(NS_ProcessPendingEvents(currentThread));
  }

  mShutdownComplete = true;
}

void
FileHandleThreadPool::FinishFileHandle(FileHandle* aFileHandle)
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(aFileHandle);

  BackgroundMutableFileParentBase* mutableFile = aFileHandle->GetMutableFile();
  const nsACString& directoryId = mutableFile->DirectoryId();

  DirectoryInfo* directoryInfo;
  if (!mDirectoryInfos.Get(directoryId, &directoryInfo)) {
    NS_ERROR("We don't know anyting about this directory?!");
    return;
  }

  directoryInfo->RemoveFileHandleQueue(aFileHandle);

  if (!directoryInfo->HasRunningFileHandles()) {
    mDirectoryInfos.Remove(directoryId);

    // See if we need to fire any complete callbacks.
    uint32_t index = 0;
    while (index < mCompleteCallbacks.Length()) {
      if (MaybeFireCallback(mCompleteCallbacks[index])) {
        mCompleteCallbacks.RemoveElementAt(index);
      }
      else {
        index++;
      }
    }

    if (mShutdownRequested && !mDirectoryInfos.Count()) {
      Cleanup();
    }
  }
}

bool
FileHandleThreadPool::MaybeFireCallback(StoragesCompleteCallback* aCallback)
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(aCallback);
  MOZ_ASSERT(!aCallback->mDirectoryIds.IsEmpty());
  MOZ_ASSERT(aCallback->mCallback);

  for (uint32_t count = aCallback->mDirectoryIds.Length(), index = 0;
       index < count;
       index++) {
    const nsCString& directoryId = aCallback->mDirectoryIds[index];
    MOZ_ASSERT(!directoryId.IsEmpty());

    if (mDirectoryInfos.Get(directoryId, nullptr)) {
      return false;
    }
  }

  aCallback->mCallback->Run();
  return true;
}

FileHandleThreadPool::
FileHandleQueue::FileHandleQueue(FileHandleThreadPool* aFileHandleThreadPool,
                                 FileHandle* aFileHandle)
  : mOwningFileHandleThreadPool(aFileHandleThreadPool)
  , mFileHandle(aFileHandle)
  , mShouldFinish(false)
{
  MOZ_ASSERT(aFileHandleThreadPool);
  aFileHandleThreadPool->AssertIsOnOwningThread();
  MOZ_ASSERT(aFileHandle);
}

void
FileHandleThreadPool::
FileHandleQueue::Enqueue(FileHandleOp* aFileHandleOp)
{
  MOZ_ASSERT(!mShouldFinish, "Enqueue called after Finish!");

  mQueue.AppendElement(aFileHandleOp);

  ProcessQueue();
}

void
FileHandleThreadPool::
FileHandleQueue::Finish()
{
  MOZ_ASSERT(!mShouldFinish, "Finish called more than once!");

  mShouldFinish = true;
}

void
FileHandleThreadPool::
FileHandleQueue::ProcessQueue()
{
  if (mCurrentOp) {
    return;
  }

  if (mQueue.IsEmpty()) {
    if (mShouldFinish) {
      mOwningFileHandleThreadPool->FinishFileHandle(mFileHandle);

      // Make sure this is released on this thread.
      mOwningFileHandleThreadPool = nullptr;
    }

    return;
  }

  mCurrentOp = mQueue[0];
  mQueue.RemoveElementAt(0);

  nsCOMPtr<nsIThreadPool> threadPool = mOwningFileHandleThreadPool->mThreadPool;
  MOZ_ASSERT(threadPool);

  MOZ_ALWAYS_SUCCEEDS(threadPool->Dispatch(this, NS_DISPATCH_NORMAL));
}

NS_IMETHODIMP
FileHandleThreadPool::
FileHandleQueue::Run()
{
  MOZ_ASSERT(mCurrentOp);

  if (IsOnBackgroundThread()) {
    RefPtr<FileHandleOp> currentOp;

    mCurrentOp.swap(currentOp);
    ProcessQueue();

    currentOp->RunOnOwningThread();
  } else {
    mCurrentOp->RunOnThreadPool();

    nsCOMPtr<nsIEventTarget> backgroundThread = mCurrentOp->OwningThread();

    MOZ_ALWAYS_SUCCEEDS(
      backgroundThread->Dispatch(this, NS_DISPATCH_NORMAL));
  }

  return NS_OK;
}

auto
FileHandleThreadPool::
DirectoryInfo::CreateFileHandleQueue(FileHandle* aFileHandle)
  -> FileHandleQueue*
{
  RefPtr<FileHandleQueue>* fileHandleQueue =
    mFileHandleQueues.AppendElement();
  *fileHandleQueue = new FileHandleQueue(mOwningFileHandleThreadPool,
                                         aFileHandle);
  return fileHandleQueue->get();
}

auto
FileHandleThreadPool::
DirectoryInfo::GetFileHandleQueue(FileHandle* aFileHandle) -> FileHandleQueue*
{
  uint32_t count = mFileHandleQueues.Length();
  for (uint32_t index = 0; index < count; index++) {
    RefPtr<FileHandleQueue>& fileHandleQueue = mFileHandleQueues[index];
    if (fileHandleQueue->mFileHandle == aFileHandle) {
      return fileHandleQueue;
    }
  }
  return nullptr;
}

void
FileHandleThreadPool::
DirectoryInfo::RemoveFileHandleQueue(FileHandle* aFileHandle)
{
  for (uint32_t index = 0; index < mDelayedEnqueueInfos.Length(); index++) {
    if (mDelayedEnqueueInfos[index].mFileHandle == aFileHandle) {
      MOZ_ASSERT(!mDelayedEnqueueInfos[index].mFileHandleOp, "Should be null!");
      mDelayedEnqueueInfos.RemoveElementAt(index);
      return;
    }
  }

  uint32_t fileHandleCount = mFileHandleQueues.Length();

  // We can't just remove entries from lock hash tables, we have to rebuild
  // them instead. Multiple FileHandle objects may lock the same file
  // (one entry can represent multiple locks).

  mFilesReading.Clear();
  mFilesWriting.Clear();

  for (uint32_t index = 0, count = fileHandleCount; index < count; index++) {
    FileHandle* fileHandle = mFileHandleQueues[index]->mFileHandle;
    if (fileHandle == aFileHandle) {
      MOZ_ASSERT(count == fileHandleCount, "More than one match?!");

      mFileHandleQueues.RemoveElementAt(index);
      index--;
      count--;

      continue;
    }

    const nsAString& fileName = fileHandle->GetMutableFile()->FileName();

    if (fileHandle->Mode() == FileMode::Readwrite) {
      if (!IsFileLockedForWriting(fileName)) {
        LockFileForWriting(fileName);
      }
    }
    else {
      if (!IsFileLockedForReading(fileName)) {
        LockFileForReading(fileName);
      }
    }
  }

  MOZ_ASSERT(mFileHandleQueues.Length() == fileHandleCount - 1,
             "Didn't find the file handle we were looking for!");

  nsTArray<DelayedEnqueueInfo> delayedEnqueueInfos;
  delayedEnqueueInfos.SwapElements(mDelayedEnqueueInfos);

  for (uint32_t index = 0; index < delayedEnqueueInfos.Length(); index++) {
    DelayedEnqueueInfo& delayedEnqueueInfo = delayedEnqueueInfos[index];
    mOwningFileHandleThreadPool->Enqueue(delayedEnqueueInfo.mFileHandle,
                                         delayedEnqueueInfo.mFileHandleOp,
                                         delayedEnqueueInfo.mFinish);
  }
}

auto
FileHandleThreadPool::
DirectoryInfo::CreateDelayedEnqueueInfo(FileHandle* aFileHandle,
                                        FileHandleOp* aFileHandleOp,
                                        bool aFinish) -> DelayedEnqueueInfo*
{
  DelayedEnqueueInfo* info = mDelayedEnqueueInfos.AppendElement();
  info->mFileHandle = aFileHandle;
  info->mFileHandleOp = aFileHandleOp;
  info->mFinish = aFinish;
  return info;
}

FileHandleThreadPool::
StoragesCompleteCallback::StoragesCompleteCallback(
                                             nsTArray<nsCString>&& aDirectoryIds,
                                             nsIRunnable* aCallback)
  : mDirectoryIds(Move(aDirectoryIds))
  , mCallback(aCallback)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(!mDirectoryIds.IsEmpty());
  MOZ_ASSERT(aCallback);

  MOZ_COUNT_CTOR(FileHandleThreadPool::StoragesCompleteCallback);
}

FileHandleThreadPool::
StoragesCompleteCallback::~StoragesCompleteCallback()
{
  AssertIsOnBackgroundThread();

  MOZ_COUNT_DTOR(FileHandleThreadPool::StoragesCompleteCallback);
}

/*******************************************************************************
 * BackgroundMutableFileParentBase
 ******************************************************************************/

BackgroundMutableFileParentBase::BackgroundMutableFileParentBase(
                                                 FileHandleStorage aStorage,
                                                 const nsACString& aDirectoryId,
                                                 const nsAString& aFileName,
                                                 nsIFile* aFile)
  : mDirectoryId(aDirectoryId)
  , mFileName(aFileName)
  , mStorage(aStorage)
  , mInvalidated(false)
  , mActorWasAlive(false)
  , mActorDestroyed(false)
  , mFile(aFile)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aStorage != FILE_HANDLE_STORAGE_MAX);
  MOZ_ASSERT(!aDirectoryId.IsEmpty());
  MOZ_ASSERT(!aFileName.IsEmpty());
  MOZ_ASSERT(aFile);
}

BackgroundMutableFileParentBase::~BackgroundMutableFileParentBase()
{
  MOZ_ASSERT_IF(mActorWasAlive, mActorDestroyed);
}

void
BackgroundMutableFileParentBase::Invalidate()
{
  AssertIsOnBackgroundThread();

  class MOZ_STACK_CLASS Helper final
  {
  public:
    static bool
    InvalidateFileHandles(nsTHashtable<nsPtrHashKey<FileHandle>>& aTable)
    {
      AssertIsOnBackgroundThread();

      const uint32_t count = aTable.Count();
      if (!count) {
        return true;
      }

      FallibleTArray<RefPtr<FileHandle>> fileHandles;
      if (NS_WARN_IF(!fileHandles.SetCapacity(count, fallible))) {
        return false;
      }

      for (auto iter = aTable.Iter(); !iter.Done(); iter.Next()) {
        if (NS_WARN_IF(!fileHandles.AppendElement(iter.Get()->GetKey(),
                                                  fallible))) {
          return false;
        }
      }

      if (count) {
        for (uint32_t index = 0; index < count; index++) {
          RefPtr<FileHandle> fileHandle = fileHandles[index].forget();
          MOZ_ASSERT(fileHandle);

          fileHandle->Invalidate();
        }
      }

      return true;
    }
  };

  if (mInvalidated) {
    return;
  }

  mInvalidated = true;

  if (!Helper::InvalidateFileHandles(mFileHandles)) {
    NS_WARNING("Failed to abort all file handles!");
  }
}

bool
BackgroundMutableFileParentBase::RegisterFileHandle(FileHandle* aFileHandle)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aFileHandle);
  MOZ_ASSERT(!mFileHandles.GetEntry(aFileHandle));
  MOZ_ASSERT(!mInvalidated);

  if (NS_WARN_IF(!mFileHandles.PutEntry(aFileHandle, fallible))) {
    return false;
  }

  if (mFileHandles.Count() == 1) {
    NoteActiveState();
  }

  return true;
}

void
BackgroundMutableFileParentBase::UnregisterFileHandle(FileHandle* aFileHandle)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aFileHandle);
  MOZ_ASSERT(mFileHandles.GetEntry(aFileHandle));

  mFileHandles.RemoveEntry(aFileHandle);

  if (!mFileHandles.Count()) {
    NoteInactiveState();
  }
}

void
BackgroundMutableFileParentBase::SetActorAlive()
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(!mActorWasAlive);
  MOZ_ASSERT(!mActorDestroyed);

  mActorWasAlive = true;

  // This reference will be absorbed by IPDL and released when the actor is
  // destroyed.
  AddRef();
}

already_AddRefed<nsISupports>
BackgroundMutableFileParentBase::CreateStream(bool aReadOnly)
{
  AssertIsOnBackgroundThread();

  nsresult rv;

  if (aReadOnly) {
    nsCOMPtr<nsIInputStream> stream;
    rv = NS_NewLocalFileInputStream(getter_AddRefs(stream), mFile, -1, -1,
                                    nsIFileInputStream::DEFER_OPEN);
    if (NS_WARN_IF(NS_FAILED(rv))) {
      return nullptr;
    }
    return stream.forget();
  }

  nsCOMPtr<nsIFileStream> stream;
  rv = NS_NewLocalFileStream(getter_AddRefs(stream), mFile, -1, -1,
                             nsIFileStream::DEFER_OPEN);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return nullptr;
  }
  return stream.forget();
}

void
BackgroundMutableFileParentBase::ActorDestroy(ActorDestroyReason aWhy)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(!mActorDestroyed);

  mActorDestroyed = true;

  if (!IsInvalidated()) {
    Invalidate();
  }
}

PBackgroundFileHandleParent*
BackgroundMutableFileParentBase::AllocPBackgroundFileHandleParent(
                                                          const FileMode& aMode)
{
  AssertIsOnBackgroundThread();

  if (NS_WARN_IF(aMode != FileMode::Readonly &&
                 aMode != FileMode::Readwrite)) {
    ASSERT_UNLESS_FUZZING();
    return nullptr;
  }

  RefPtr<FileHandle> fileHandle = new FileHandle(this, aMode);

  return fileHandle.forget().take();
}

mozilla::ipc::IPCResult
BackgroundMutableFileParentBase::RecvPBackgroundFileHandleConstructor(
                                            PBackgroundFileHandleParent* aActor,
                                            const FileMode& aMode)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aActor);
  MOZ_ASSERT(aMode == FileMode::Readonly || aMode == FileMode::Readwrite);

  FileHandleThreadPool* fileHandleThreadPool =
    GetFileHandleThreadPoolFor(mStorage);
  MOZ_ASSERT(fileHandleThreadPool);

  auto* fileHandle = static_cast<FileHandle*>(aActor);

  // Add a placeholder for this file handle immediately.
  fileHandleThreadPool->Enqueue(fileHandle, nullptr, false);

  fileHandle->SetActive();

  if (NS_WARN_IF(!RegisterFileHandle(fileHandle))) {
    fileHandle->Abort(/* aForce */ false);
    return IPC_OK();
  }

  return IPC_OK();
}

bool
BackgroundMutableFileParentBase::DeallocPBackgroundFileHandleParent(
                                            PBackgroundFileHandleParent* aActor)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aActor);

  RefPtr<FileHandle> fileHandle =
    dont_AddRef(static_cast<FileHandle*>(aActor));
  return true;
}

mozilla::ipc::IPCResult
BackgroundMutableFileParentBase::RecvDeleteMe()
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(!mActorDestroyed);

  IProtocol* mgr = Manager();
  if (!PBackgroundMutableFileParent::Send__delete__(this)) {
    return IPC_FAIL_NO_REASON(mgr);
  }
  return IPC_OK();
}

mozilla::ipc::IPCResult
BackgroundMutableFileParentBase::RecvGetFileId(int64_t* aFileId)
{
  AssertIsOnBackgroundThread();

  *aFileId = -1;
  return IPC_OK();
}

/*******************************************************************************
 * FileHandle
 ******************************************************************************/

FileHandle::FileHandle(BackgroundMutableFileParentBase* aMutableFile,
                       FileMode aMode)
  : mMutableFile(aMutableFile)
  , mActiveRequestCount(0)
  , mStorage(aMutableFile->Storage())
  , mInvalidatedOnAnyThread(false)
  , mMode(aMode)
  , mHasBeenActive(false)
  , mActorDestroyed(false)
  , mInvalidated(false)
  , mAborted(false)
  , mFinishOrAbortReceived(false)
  , mFinishedOrAborted(false)
  , mForceAborted(false)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aMutableFile);

#ifdef DEBUG
  FileHandleThreadPool* fileHandleThreadPool =
    GetFileHandleThreadPoolFor(mStorage);
  MOZ_ASSERT(fileHandleThreadPool);

  mThreadPoolEventTarget = fileHandleThreadPool->GetThreadPoolEventTarget();
#endif
}

FileHandle::~FileHandle()
{
  MOZ_ASSERT(!mActiveRequestCount);
  MOZ_ASSERT(mActorDestroyed);
  MOZ_ASSERT_IF(mHasBeenActive, mFinishedOrAborted);
}

void
FileHandle::AssertIsOnThreadPool() const
{
  MOZ_ASSERT(mThreadPoolEventTarget);
  DebugOnly<bool> current;
  MOZ_ASSERT(NS_SUCCEEDED(mThreadPoolEventTarget->IsOnCurrentThread(&current)));
  MOZ_ASSERT(current);
}

nsresult
FileHandle::GetOrCreateStream(nsISupports** aStream)
{
  AssertIsOnBackgroundThread();

  if (!mStream) {
    nsCOMPtr<nsISupports> stream =
      mMutableFile->CreateStream(mMode == FileMode::Readonly);
    if (NS_WARN_IF(!stream)) {
      return NS_ERROR_FAILURE;
    }

    stream.swap(mStream);
  }

  nsCOMPtr<nsISupports> stream(mStream);
  stream.forget(aStream);

  return NS_OK;
}

void
FileHandle::Abort(bool aForce)
{
  AssertIsOnBackgroundThread();

  mAborted = true;

  if (aForce) {
    mForceAborted = true;
  }

  MaybeFinishOrAbort();
}

void
FileHandle::NoteActiveRequest()
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(mActiveRequestCount < UINT64_MAX);

  mActiveRequestCount++;
}

void
FileHandle::NoteFinishedRequest()
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(mActiveRequestCount);

  mActiveRequestCount--;

  MaybeFinishOrAbort();
}

void
FileHandle::Invalidate()
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(mInvalidated == mInvalidatedOnAnyThread);

  if (!mInvalidated) {
    mInvalidated = true;
    mInvalidatedOnAnyThread = true;

    Abort(/* aForce */ true);
  }
}

void
FileHandle::SendCompleteNotification(bool aAborted)
{
  AssertIsOnBackgroundThread();

  if (!IsActorDestroyed()) {
    Unused << SendComplete(aAborted);
  }
}

bool
FileHandle::VerifyRequestParams(const FileRequestParams& aParams) const
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aParams.type() != FileRequestParams::T__None);

  switch (aParams.type()) {
    case FileRequestParams::TFileRequestGetMetadataParams: {
      const FileRequestGetMetadataParams& params =
        aParams.get_FileRequestGetMetadataParams();

      if (NS_WARN_IF(!params.size() && !params.lastModified())) {
        ASSERT_UNLESS_FUZZING();
        return false;
      }

      break;
    }

    case FileRequestParams::TFileRequestReadParams: {
      const FileRequestReadParams& params =
        aParams.get_FileRequestReadParams();

      if (NS_WARN_IF(params.offset() == UINT64_MAX)) {
        ASSERT_UNLESS_FUZZING();
        return false;
      }

      if (NS_WARN_IF(!params.size())) {
        ASSERT_UNLESS_FUZZING();
        return false;
      }

      break;
    }

    case FileRequestParams::TFileRequestWriteParams: {
      if (NS_WARN_IF(mMode != FileMode::Readwrite)) {
        ASSERT_UNLESS_FUZZING();
        return false;
      }

      const FileRequestWriteParams& params =
        aParams.get_FileRequestWriteParams();


      if (NS_WARN_IF(!params.dataLength())) {
        ASSERT_UNLESS_FUZZING();
        return false;
      }

      if (NS_WARN_IF(!VerifyRequestData(params.data()))) {
        ASSERT_UNLESS_FUZZING();
        return false;
      }

      break;
    }

    case FileRequestParams::TFileRequestTruncateParams: {
      if (NS_WARN_IF(mMode != FileMode::Readwrite)) {
        ASSERT_UNLESS_FUZZING();
        return false;
      }

      const FileRequestTruncateParams& params =
        aParams.get_FileRequestTruncateParams();

      if (NS_WARN_IF(params.offset() == UINT64_MAX)) {
        ASSERT_UNLESS_FUZZING();
        return false;
      }

      break;
    }

    case FileRequestParams::TFileRequestFlushParams: {
      if (NS_WARN_IF(mMode != FileMode::Readwrite)) {
        ASSERT_UNLESS_FUZZING();
        return false;
      }

      break;
    }

    case FileRequestParams::TFileRequestGetFileParams: {
      break;
    }

    default:
      MOZ_CRASH("Should never get here!");
  }

  return true;
}

bool
FileHandle::VerifyRequestData(const FileRequestData& aData) const
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aData.type() != FileRequestData::T__None);

  switch (aData.type()) {
    case FileRequestData::TFileRequestStringData: {
      const FileRequestStringData& data =
        aData.get_FileRequestStringData();

      if (NS_WARN_IF(data.string().IsEmpty())) {
        ASSERT_UNLESS_FUZZING();
        return false;
      }

      break;
    }

    case FileRequestData::TFileRequestBlobData: {
      break;
    }

    default:
      MOZ_CRASH("Should never get here!");
  }

  return true;
}

void
FileHandle::FinishOrAbort()
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(!mFinishedOrAborted);

  mFinishedOrAborted = true;

  if (!mHasBeenActive) {
    return;
  }

  RefPtr<FinishOp> finishOp = new FinishOp(this, mAborted);

  FileHandleThreadPool* fileHandleThreadPool =
    GetFileHandleThreadPoolFor(mStorage);
  MOZ_ASSERT(fileHandleThreadPool);

  fileHandleThreadPool->Enqueue(this, finishOp, true);
}

void
FileHandle::ActorDestroy(ActorDestroyReason aWhy)
{
  AssertIsOnBackgroundThread();

  MOZ_ASSERT(!mActorDestroyed);

  mActorDestroyed = true;

  if (!mFinishedOrAborted) {
    mAborted = true;

    mForceAborted = true;

    MaybeFinishOrAbort();
  }
}

mozilla::ipc::IPCResult
FileHandle::RecvDeleteMe()
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(!IsActorDestroyed());

  IProtocol* mgr = Manager();
  if (!PBackgroundFileHandleParent::Send__delete__(this)) {
    return IPC_FAIL_NO_REASON(mgr);
  }
  return IPC_OK();
}

mozilla::ipc::IPCResult
FileHandle::RecvFinish()
{
  AssertIsOnBackgroundThread();

  if (NS_WARN_IF(mFinishOrAbortReceived)) {
    ASSERT_UNLESS_FUZZING();
    return IPC_FAIL_NO_REASON(this);
  }

  mFinishOrAbortReceived = true;

  MaybeFinishOrAbort();
  return IPC_OK();
}

mozilla::ipc::IPCResult
FileHandle::RecvAbort()
{
  AssertIsOnBackgroundThread();

  if (NS_WARN_IF(mFinishOrAbortReceived)) {
    ASSERT_UNLESS_FUZZING();
    return IPC_FAIL_NO_REASON(this);
  }

  mFinishOrAbortReceived = true;

  Abort(/* aForce */ false);
  return IPC_OK();
}

PBackgroundFileRequestParent*
FileHandle::AllocPBackgroundFileRequestParent(const FileRequestParams& aParams)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aParams.type() != FileRequestParams::T__None);

#ifdef DEBUG
  // Always verify parameters in DEBUG builds!
  bool trustParams = false;
#else
  PBackgroundParent* backgroundActor = GetBackgroundParent();
  MOZ_ASSERT(backgroundActor);

  bool trustParams = !BackgroundParent::IsOtherProcessActor(backgroundActor);
#endif

  if (NS_WARN_IF(!trustParams && !VerifyRequestParams(aParams))) {
    ASSERT_UNLESS_FUZZING();
    return nullptr;
  }

  if (NS_WARN_IF(mFinishOrAbortReceived)) {
    ASSERT_UNLESS_FUZZING();
    return nullptr;
  }

  RefPtr<NormalFileHandleOp> actor;

  switch (aParams.type()) {
    case FileRequestParams::TFileRequestGetMetadataParams:
      actor = new GetMetadataOp(this, aParams);
      break;

    case FileRequestParams::TFileRequestReadParams:
      actor = new ReadOp(this, aParams);
      break;

    case FileRequestParams::TFileRequestWriteParams:
      actor = new WriteOp(this, aParams);
      break;

    case FileRequestParams::TFileRequestTruncateParams:
      actor = new TruncateOp(this, aParams);
      break;

    case FileRequestParams::TFileRequestFlushParams:
      actor = new FlushOp(this, aParams);
      break;

    case FileRequestParams::TFileRequestGetFileParams:
      actor = new GetFileOp(this, aParams);
      break;

    default:
      MOZ_CRASH("Should never get here!");
  }

  MOZ_ASSERT(actor);

  // Transfer ownership to IPDL.
  return actor.forget().take();
}

mozilla::ipc::IPCResult
FileHandle::RecvPBackgroundFileRequestConstructor(
                                           PBackgroundFileRequestParent* aActor,
                                           const FileRequestParams& aParams)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aActor);
  MOZ_ASSERT(aParams.type() != FileRequestParams::T__None);

  auto* op = static_cast<NormalFileHandleOp*>(aActor);

  if (NS_WARN_IF(!op->Init(this))) {
    op->Cleanup();
    return IPC_FAIL_NO_REASON(this);
  }

  op->Enqueue();
  return IPC_OK();
}

bool
FileHandle::DeallocPBackgroundFileRequestParent(
                                           PBackgroundFileRequestParent* aActor)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aActor);

  // Transfer ownership back from IPDL.
  RefPtr<NormalFileHandleOp> actor =
    dont_AddRef(static_cast<NormalFileHandleOp*>(aActor));
  return true;
}

/*******************************************************************************
 * Local class implementations
 ******************************************************************************/

void
FileHandleOp::Enqueue()
{
  AssertIsOnOwningThread();

  FileHandleThreadPool* fileHandleThreadPool =
    GetFileHandleThreadPoolFor(mFileHandle->Storage());
  MOZ_ASSERT(fileHandleThreadPool);

  fileHandleThreadPool->Enqueue(mFileHandle, this, false);

  mFileHandle->NoteActiveRequest();
}

void
FileHandle::
FinishOp::RunOnThreadPool()
{
  AssertIsOnThreadPool();
  MOZ_ASSERT(mFileHandle);

  nsCOMPtr<nsISupports>& stream = mFileHandle->mStream;

  if (!stream) {
    return;
  }

  nsCOMPtr<nsIInputStream> inputStream = do_QueryInterface(stream);
  MOZ_ASSERT(inputStream);

  MOZ_ALWAYS_SUCCEEDS(inputStream->Close());

  stream = nullptr;
}

void
FileHandle::
FinishOp::RunOnOwningThread()
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(mFileHandle);

  mFileHandle->SendCompleteNotification(mAborted);

  mFileHandle->GetMutableFile()->UnregisterFileHandle(mFileHandle);

  mFileHandle = nullptr;
}

NormalFileHandleOp::~NormalFileHandleOp()
{
  MOZ_ASSERT(!mFileHandle,
             "NormalFileHandleOp::Cleanup() was not called by a subclass!");
}

bool
NormalFileHandleOp::Init(FileHandle* aFileHandle)
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(aFileHandle);

  nsresult rv = aFileHandle->GetOrCreateStream(getter_AddRefs(mFileStream));
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return false;
  }

  return true;
}

void
NormalFileHandleOp::Cleanup()
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(mFileHandle);
  MOZ_ASSERT_IF(!IsActorDestroyed(), mResponseSent);

  mFileHandle = nullptr;
}

nsresult
NormalFileHandleOp::SendSuccessResult()
{
  AssertIsOnOwningThread();

  if (!IsActorDestroyed()) {
    FileRequestResponse response;
    GetResponse(response);

    MOZ_ASSERT(response.type() != FileRequestResponse::T__None);

    if (response.type() == FileRequestResponse::Tnsresult) {
      MOZ_ASSERT(NS_FAILED(response.get_nsresult()));

      return response.get_nsresult();
    }

    if (NS_WARN_IF(!PBackgroundFileRequestParent::Send__delete__(this,
                                                                 response))) {
      return NS_ERROR_DOM_FILEHANDLE_UNKNOWN_ERR;
    }
  }

  DEBUGONLY(mResponseSent = true;)

  return NS_OK;
}

bool
NormalFileHandleOp::SendFailureResult(nsresult aResultCode)
{
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(NS_FAILED(aResultCode));

  bool result = false;

  if (!IsActorDestroyed()) {
    result =
      PBackgroundFileRequestParent::Send__delete__(this, aResultCode);
  }

  DEBUGONLY(mResponseSent = true;)

  return result;
}

void
NormalFileHandleOp::RunOnThreadPool()
{
  AssertIsOnThreadPool();
  MOZ_ASSERT(mFileHandle);
  MOZ_ASSERT(NS_SUCCEEDED(mResultCode));

  // There are several cases where we don't actually have to to any work here.

  if (mFileHandleIsAborted) {
    // This transaction is already set to be aborted.
    mResultCode = NS_ERROR_DOM_FILEHANDLE_ABORT_ERR;
  } else if (mFileHandle->IsInvalidatedOnAnyThread()) {
    // This file handle is being invalidated.
    mResultCode = NS_ERROR_DOM_FILEHANDLE_UNKNOWN_ERR;
  } else if (!OperationMayProceed()) {
    // The operation was canceled in some way, likely because the child process
    // has crashed.
    mResultCode = NS_ERROR_DOM_FILEHANDLE_UNKNOWN_ERR;
  } else {
    nsresult rv = DoFileWork(mFileHandle);
    if (NS_FAILED(rv)) {
      mResultCode = rv;
    }
  }
}

void
NormalFileHandleOp::RunOnOwningThread()
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(mFileHandle);

  if (NS_WARN_IF(IsActorDestroyed())) {
    // Don't send any notifications if the actor was destroyed already.
    if (NS_SUCCEEDED(mResultCode)) {
      mResultCode = NS_ERROR_DOM_FILEHANDLE_UNKNOWN_ERR;
    }
  } else {
    if (mFileHandle->IsInvalidated()) {
      mResultCode = NS_ERROR_DOM_FILEHANDLE_UNKNOWN_ERR;
    } else if (mFileHandle->IsAborted()) {
      // Aborted file handles always see their requests fail with ABORT_ERR,
      // even if the request succeeded or failed with another error.
      mResultCode = NS_ERROR_DOM_FILEHANDLE_ABORT_ERR;
    } else if (NS_SUCCEEDED(mResultCode)) {
      // This may release the IPDL reference.
      mResultCode = SendSuccessResult();
    }

    if (NS_FAILED(mResultCode)) {
      // This should definitely release the IPDL reference.
      if (!SendFailureResult(mResultCode)) {
        // Abort the file handle.
        mFileHandle->Abort(/* aForce */ false);
      }
    }
  }

  mFileHandle->NoteFinishedRequest();

  Cleanup();
}

void
NormalFileHandleOp::ActorDestroy(ActorDestroyReason aWhy)
{
  AssertIsOnOwningThread();

  NoteActorDestroyed();
}

nsresult
CopyFileHandleOp::DoFileWork(FileHandle* aFileHandle)
{
  AssertIsOnThreadPool();

  nsCOMPtr<nsIInputStream> inputStream;
  nsCOMPtr<nsIOutputStream> outputStream;

  if (mRead) {
    inputStream = do_QueryInterface(mFileStream);
    outputStream = do_QueryInterface(mBufferStream);
  } else {
    inputStream = do_QueryInterface(mBufferStream);
    outputStream = do_QueryInterface(mFileStream);
  }

  MOZ_ASSERT(inputStream);
  MOZ_ASSERT(outputStream);

  nsCOMPtr<nsISeekableStream> seekableStream =
    do_QueryInterface(mFileStream);

  nsresult rv;

  if (seekableStream) {
    if (mOffset == UINT64_MAX) {
      rv = seekableStream->Seek(nsISeekableStream::NS_SEEK_END, 0);
    }
    else {
      rv = seekableStream->Seek(nsISeekableStream::NS_SEEK_SET, mOffset);
    }
    if (NS_WARN_IF(NS_FAILED(rv))) {
      return rv;
    }
  }

  mOffset = 0;

  do {
    char copyBuffer[kStreamCopyBlockSize];

    uint64_t max = mSize - mOffset;
    if (max == 0) {
      break;
    }

    uint32_t count = sizeof(copyBuffer);
    if (count > max) {
      count = max;
    }

    uint32_t numRead;
    rv = inputStream->Read(copyBuffer, count, &numRead);
    if (NS_WARN_IF(NS_FAILED(rv))) {
      return rv;
    }

    if (!numRead) {
      break;
    }

    uint32_t numWrite;
    rv = outputStream->Write(copyBuffer, numRead, &numWrite);
    if (rv == NS_ERROR_FILE_NO_DEVICE_SPACE) {
      rv = NS_ERROR_DOM_FILEHANDLE_QUOTA_ERR;
    }
    if (NS_WARN_IF(NS_FAILED(rv))) {
      return rv;
    }

    if (NS_WARN_IF(numWrite != numRead)) {
      return NS_ERROR_FAILURE;
    }

    mOffset += numWrite;

    nsCOMPtr<nsIRunnable> runnable =
      new ProgressRunnable(this, mOffset, mSize);

    mOwningThread->Dispatch(runnable, NS_DISPATCH_NORMAL);
  } while (true);

  MOZ_ASSERT(mOffset == mSize);

  if (mRead) {
    MOZ_ALWAYS_SUCCEEDS(outputStream->Close());
  } else {
    MOZ_ALWAYS_SUCCEEDS(inputStream->Close());
  }

  return NS_OK;
}

void
CopyFileHandleOp::Cleanup()
{
  AssertIsOnOwningThread();

  mBufferStream = nullptr;

  NormalFileHandleOp::Cleanup();
}

NS_IMETHODIMP
CopyFileHandleOp::
ProgressRunnable::Run()
{
  AssertIsOnBackgroundThread();

  Unused << mCopyFileHandleOp->SendProgress(mProgress, mProgressMax);

  mCopyFileHandleOp = nullptr;

  return NS_OK;
}

GetMetadataOp::GetMetadataOp(FileHandle* aFileHandle,
                             const FileRequestParams& aParams)
  : NormalFileHandleOp(aFileHandle)
  , mParams(aParams.get_FileRequestGetMetadataParams())
{
  MOZ_ASSERT(aParams.type() ==
             FileRequestParams::TFileRequestGetMetadataParams);
}

nsresult
GetMetadataOp::DoFileWork(FileHandle* aFileHandle)
{
  AssertIsOnThreadPool();

  nsresult rv;

  if (mFileHandle->Mode() == FileMode::Readwrite) {
    // Force a flush (so all pending writes are flushed to the disk and file
    // metadata is updated too).

    nsCOMPtr<nsIOutputStream> ostream = do_QueryInterface(mFileStream);
    MOZ_ASSERT(ostream);

    rv = ostream->Flush();
    if (NS_WARN_IF(NS_FAILED(rv))) {
      return rv;
    }
  }

  nsCOMPtr<nsIFileMetadata> metadata = do_QueryInterface(mFileStream);
  MOZ_ASSERT(metadata);

  if (mParams.size()) {
    int64_t size;
    rv = metadata->GetSize(&size);
    if (NS_WARN_IF(NS_FAILED(rv))) {
      return rv;
    }

    if (NS_WARN_IF(size < 0)) {
      return NS_ERROR_FAILURE;
    }

    mMetadata.size() = uint64_t(size);
  } else {
    mMetadata.size() = void_t();
  }

  if (mParams.lastModified()) {
    int64_t lastModified;
    rv = metadata->GetLastModified(&lastModified);
    if (NS_WARN_IF(NS_FAILED(rv))) {
      return rv;
    }

    mMetadata.lastModified() = lastModified;
  } else {
    mMetadata.lastModified() = void_t();
  }

  return NS_OK;
}

void
GetMetadataOp::GetResponse(FileRequestResponse& aResponse)
{
  AssertIsOnOwningThread();

  aResponse = FileRequestGetMetadataResponse(mMetadata);
}

ReadOp::ReadOp(FileHandle* aFileHandle,
               const FileRequestParams& aParams)
  : CopyFileHandleOp(aFileHandle)
  , mParams(aParams.get_FileRequestReadParams())
{
  MOZ_ASSERT(aParams.type() == FileRequestParams::TFileRequestReadParams);
}

bool
ReadOp::Init(FileHandle* aFileHandle)
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(aFileHandle);

  if (NS_WARN_IF(!NormalFileHandleOp::Init(aFileHandle))) {
    return false;
  }

  mBufferStream = MemoryOutputStream::Create(mParams.size());
  if (NS_WARN_IF(!mBufferStream)) {
    return false;
  }

  mOffset = mParams.offset();
  mSize = mParams.size();
  mRead = true;

  return true;
}

void
ReadOp::GetResponse(FileRequestResponse& aResponse)
{
  AssertIsOnOwningThread();

  auto* stream = static_cast<MemoryOutputStream*>(mBufferStream.get());

  aResponse = FileRequestReadResponse(stream->Data());
}

// static
already_AddRefed<ReadOp::MemoryOutputStream>
ReadOp::
MemoryOutputStream::Create(uint64_t aSize)
{
  MOZ_ASSERT(aSize, "Passed zero size!");

  if (NS_WARN_IF(aSize > UINT32_MAX)) {
    return nullptr;
  }

  RefPtr<MemoryOutputStream> stream = new MemoryOutputStream();

  char* dummy;
  uint32_t length = stream->mData.GetMutableData(&dummy, aSize, fallible);
  if (NS_WARN_IF(length != aSize)) {
    return nullptr;
  }

  return stream.forget();
}

NS_IMPL_ISUPPORTS(ReadOp::MemoryOutputStream, nsIOutputStream)

NS_IMETHODIMP
ReadOp::
MemoryOutputStream::Close()
{
  mData.Truncate(mOffset);
  return NS_OK;
}

NS_IMETHODIMP
ReadOp::
MemoryOutputStream::Write(const char* aBuf, uint32_t aCount, uint32_t* _retval)
{
  return WriteSegments(NS_CopySegmentToBuffer, (char*)aBuf, aCount, _retval);
}

NS_IMETHODIMP
ReadOp::
MemoryOutputStream::Flush()
{
  return NS_OK;
}

NS_IMETHODIMP
ReadOp::
MemoryOutputStream::WriteFrom(nsIInputStream* aFromStream, uint32_t aCount,
                              uint32_t* _retval)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
ReadOp::
MemoryOutputStream::WriteSegments(nsReadSegmentFun aReader, void* aClosure,
                                  uint32_t aCount, uint32_t* _retval)
{
  NS_ASSERTION(mData.Length() >= mOffset, "Bad stream state!");

  uint32_t maxCount = mData.Length() - mOffset;
  if (maxCount == 0) {
    *_retval = 0;
    return NS_OK;
  }

  if (aCount > maxCount) {
    aCount = maxCount;
  }

  nsresult rv = aReader(this, aClosure, mData.BeginWriting() + mOffset, 0,
                        aCount, _retval);
  if (NS_SUCCEEDED(rv)) {
    NS_ASSERTION(*_retval <= aCount,
                 "Reader should not read more than we asked it to read!");
    mOffset += *_retval;
  }

  return NS_OK;
}

NS_IMETHODIMP
ReadOp::
MemoryOutputStream::IsNonBlocking(bool* _retval)
{
  *_retval = false;
  return NS_OK;
}

WriteOp::WriteOp(FileHandle* aFileHandle,
                 const FileRequestParams& aParams)
  : CopyFileHandleOp(aFileHandle)
  , mParams(aParams.get_FileRequestWriteParams())
{
  MOZ_ASSERT(aParams.type() == FileRequestParams::TFileRequestWriteParams);
}

bool
WriteOp::Init(FileHandle* aFileHandle)
{
  AssertIsOnOwningThread();
  MOZ_ASSERT(aFileHandle);

  if (NS_WARN_IF(!NormalFileHandleOp::Init(aFileHandle))) {
    return false;
  }

  nsCOMPtr<nsIInputStream> inputStream;

  const FileRequestData& data = mParams.data();
  switch (data.type()) {
    case FileRequestData::TFileRequestStringData: {
      const FileRequestStringData& stringData =
        data.get_FileRequestStringData();

      const nsCString& string = stringData.string();

      nsresult rv =
        NS_NewCStringInputStream(getter_AddRefs(inputStream), string);
      if (NS_WARN_IF(NS_FAILED(rv))) {
        return false;
      }

      break;
    }
    case FileRequestData::TFileRequestBlobData: {
      const FileRequestBlobData& blobData =
        data.get_FileRequestBlobData();

      RefPtr<BlobImpl> blobImpl = IPCBlobUtils::Deserialize(blobData.blob());
      if (NS_WARN_IF(!blobImpl)) {
        return false;
      }

      IgnoredErrorResult rv;
      blobImpl->GetInternalStream(getter_AddRefs(inputStream), rv);
      if (NS_WARN_IF(rv.Failed())) {
        return false;
      }

      break;
    }

    default:
      MOZ_CRASH("Should never get here!");
  }

  mBufferStream = inputStream;
  mOffset = mParams.offset();
  mSize = mParams.dataLength();
  mRead = false;

  return true;
}

void
WriteOp::GetResponse(FileRequestResponse& aResponse)
{
  AssertIsOnOwningThread();
  aResponse = FileRequestWriteResponse();
}

TruncateOp::TruncateOp(FileHandle* aFileHandle,
                       const FileRequestParams& aParams)
  : NormalFileHandleOp(aFileHandle)
  , mParams(aParams.get_FileRequestTruncateParams())
{
  MOZ_ASSERT(aParams.type() == FileRequestParams::TFileRequestTruncateParams);
}

nsresult
TruncateOp::DoFileWork(FileHandle* aFileHandle)
{
  AssertIsOnThreadPool();

  nsCOMPtr<nsISeekableStream> sstream = do_QueryInterface(mFileStream);
  MOZ_ASSERT(sstream);

  nsresult rv = sstream->Seek(nsISeekableStream::NS_SEEK_SET, mParams.offset());
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  rv = sstream->SetEOF();
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  return NS_OK;
}

void
TruncateOp::GetResponse(FileRequestResponse& aResponse)
{
  AssertIsOnOwningThread();
  aResponse = FileRequestTruncateResponse();
}

FlushOp::FlushOp(FileHandle* aFileHandle,
                 const FileRequestParams& aParams)
  : NormalFileHandleOp(aFileHandle)
  , mParams(aParams.get_FileRequestFlushParams())
{
  MOZ_ASSERT(aParams.type() == FileRequestParams::TFileRequestFlushParams);
}

nsresult
FlushOp::DoFileWork(FileHandle* aFileHandle)
{
  AssertIsOnThreadPool();

  nsCOMPtr<nsIOutputStream> ostream = do_QueryInterface(mFileStream);
  MOZ_ASSERT(ostream);

  nsresult rv = ostream->Flush();
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  return NS_OK;
}

void
FlushOp::GetResponse(FileRequestResponse& aResponse)
{
  AssertIsOnOwningThread();
  aResponse = FileRequestFlushResponse();
}

GetFileOp::GetFileOp(FileHandle* aFileHandle,
                     const FileRequestParams& aParams)
  : GetMetadataOp(aFileHandle,
                  FileRequestGetMetadataParams(true, true))
  , mBackgroundParent(aFileHandle->GetBackgroundParent())
{
  MOZ_ASSERT(aParams.type() == FileRequestParams::TFileRequestGetFileParams);
  MOZ_ASSERT(mBackgroundParent);
}

void
GetFileOp::GetResponse(FileRequestResponse& aResponse)
{
  AssertIsOnOwningThread();

  RefPtr<BlobImpl> blobImpl = mFileHandle->GetMutableFile()->CreateBlobImpl();
  MOZ_ASSERT(blobImpl);

  PendingIPCBlobParent* actor =
    PendingIPCBlobParent::Create(mBackgroundParent, blobImpl);
  if (NS_WARN_IF(!actor)) {
    // This can only fail if the child has crashed.
    aResponse = NS_ERROR_DOM_FILEHANDLE_UNKNOWN_ERR;
    return;
  }

  FileRequestGetFileResponse response;
  response.fileParent() = actor;
  response.metadata() = mMetadata;

  aResponse = response;
}

} // namespace dom
} // namespace mozilla