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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=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/. */
+
+/**
+ * This file defines two implementations of the nsIBackgroundFileSaver
+ * interface. See the "test_backgroundfilesaver.js" file for usage examples.
+ */
+
+#ifndef BackgroundFileSaver_h__
+#define BackgroundFileSaver_h__
+
+#include "ScopedNSSTypes.h"
+#include "mozilla/Mutex.h"
+#include "nsCOMArray.h"
+#include "nsCOMPtr.h"
+#include "nsIAsyncOutputStream.h"
+#include "nsIBackgroundFileSaver.h"
+#include "nsIStreamListener.h"
+#include "nsNSSShutDown.h"
+#include "nsStreamUtils.h"
+#include "nsString.h"
+
+class nsIAsyncInputStream;
+class nsIThread;
+class nsIX509CertList;
+
+namespace mozilla {
+namespace net {
+
+class DigestOutputStream;
+
+////////////////////////////////////////////////////////////////////////////////
+//// BackgroundFileSaver
+
+class BackgroundFileSaver : public nsIBackgroundFileSaver,
+ public nsNSSShutDownObject
+{
+public:
+ NS_DECL_NSIBACKGROUNDFILESAVER
+
+ BackgroundFileSaver();
+
+ /**
+ * Initializes the pipe and the worker thread on XPCOM construction.
+ *
+ * This is called automatically by the XPCOM infrastructure, and if this
+ * fails, the factory will delete this object without returning a reference.
+ */
+ nsresult Init();
+
+ /**
+ * Used by nsNSSShutDownList to manage nsNSSShutDownObjects.
+ */
+ void virtualDestroyNSSReference() override;
+
+ /**
+ * Number of worker threads that are currently running.
+ */
+ static uint32_t sThreadCount;
+
+ /**
+ * Maximum number of worker threads reached during the current download session,
+ * used for telemetry.
+ *
+ * When there are no more worker threads running, we consider the download
+ * session finished, and this counter is reset.
+ */
+ static uint32_t sTelemetryMaxThreadCount;
+
+
+protected:
+ virtual ~BackgroundFileSaver();
+
+ /**
+ * Helper function for managing NSS objects (mDigestContext).
+ */
+ void destructorSafeDestroyNSSReference();
+
+ /**
+ * Thread that constructed this object.
+ */
+ nsCOMPtr<nsIThread> mControlThread;
+
+ /**
+ * Thread to which the actual input/output is delegated.
+ */
+ nsCOMPtr<nsIThread> mWorkerThread;
+
+ /**
+ * Stream that receives data from derived classes. The received data will be
+ * available to the worker thread through mPipeInputStream. This is an
+ * instance of nsPipeOutputStream, not BackgroundFileSaverOutputStream.
+ */
+ nsCOMPtr<nsIAsyncOutputStream> mPipeOutputStream;
+
+ /**
+ * Used during initialization, determines if the pipe is created with an
+ * infinite buffer. An infinite buffer is required if the derived class
+ * implements nsIStreamListener, because this interface requires all the
+ * provided data to be consumed synchronously.
+ */
+ virtual bool HasInfiniteBuffer() = 0;
+
+ /**
+ * Used by derived classes if they need to be called back while copying.
+ */
+ virtual nsAsyncCopyProgressFun GetProgressCallback() = 0;
+
+ /**
+ * Stream used by the worker thread to read the data to be saved.
+ */
+ nsCOMPtr<nsIAsyncInputStream> mPipeInputStream;
+
+private:
+ friend class NotifyTargetChangeRunnable;
+
+ /**
+ * Matches the nsIBackgroundFileSaver::observer property.
+ *
+ * @remarks This is a strong reference so that JavaScript callers don't need
+ * to worry about keeping another reference to the observer.
+ */
+ nsCOMPtr<nsIBackgroundFileSaverObserver> mObserver;
+
+ //////////////////////////////////////////////////////////////////////////////
+ //// Shared state between control and worker threads
+
+ /**
+ * Protects the shared state between control and worker threads. This mutex
+ * is always locked for a very short time, never during input/output.
+ */
+ mozilla::Mutex mLock;
+
+ /**
+ * True if the worker thread is already waiting to process a change in state.
+ */
+ bool mWorkerThreadAttentionRequested;
+
+ /**
+ * True if the operation should finish as soon as possibile.
+ */
+ bool mFinishRequested;
+
+ /**
+ * True if the operation completed, with either success or failure.
+ */
+ bool mComplete;
+
+ /**
+ * Holds the current file saver status. This is a success status while the
+ * object is working correctly, and remains such if the operation completes
+ * successfully. This becomes an error status when an error occurs on the
+ * worker thread, or when the operation is canceled.
+ */
+ nsresult mStatus;
+
+ /**
+ * True if we should append data to the initial target file, instead of
+ * overwriting it.
+ */
+ bool mAppend;
+
+ /**
+ * This is set by the first SetTarget call on the control thread, and contains
+ * the target file name that will be used by the worker thread, as soon as it
+ * is possible to update mActualTarget and open the file. This is null if no
+ * target was ever assigned to this object.
+ */
+ nsCOMPtr<nsIFile> mInitialTarget;
+
+ /**
+ * This is set by the first SetTarget call on the control thread, and
+ * indicates whether mInitialTarget should be kept as partially completed,
+ * rather than deleted, if the operation fails or is canceled.
+ */
+ bool mInitialTargetKeepPartial;
+
+ /**
+ * This is set by subsequent SetTarget calls on the control thread, and
+ * contains the new target file name to which the worker thread will move the
+ * target file, as soon as it can be done. This is null if SetTarget was
+ * called only once, or no target was ever assigned to this object.
+ *
+ * The target file can be renamed multiple times, though only the most recent
+ * rename is guaranteed to be processed by the worker thread.
+ */
+ nsCOMPtr<nsIFile> mRenamedTarget;
+
+ /**
+ * This is set by subsequent SetTarget calls on the control thread, and
+ * indicates whether mRenamedTarget should be kept as partially completed,
+ * rather than deleted, if the operation fails or is canceled.
+ */
+ bool mRenamedTargetKeepPartial;
+
+ /**
+ * While NS_AsyncCopy is in progress, allows canceling it. Null otherwise.
+ * This is read by both threads but only written by the worker thread.
+ */
+ nsCOMPtr<nsISupports> mAsyncCopyContext;
+
+ /**
+ * The SHA 256 hash in raw bytes of the downloaded file. This is written
+ * by the worker thread but can be read on the main thread.
+ */
+ nsCString mSha256;
+
+ /**
+ * Whether or not to compute the hash. Must be set on the main thread before
+ * setTarget is called.
+ */
+ bool mSha256Enabled;
+
+ /**
+ * Store the signature info.
+ */
+ nsCOMArray<nsIX509CertList> mSignatureInfo;
+
+ /**
+ * Whether or not to extract the signature. Must be set on the main thread
+ * before setTarget is called.
+ */
+ bool mSignatureInfoEnabled;
+
+ //////////////////////////////////////////////////////////////////////////////
+ //// State handled exclusively by the worker thread
+
+ /**
+ * Current target file associated to the input and output streams.
+ */
+ nsCOMPtr<nsIFile> mActualTarget;
+
+ /**
+ * Indicates whether mActualTarget should be kept as partially completed,
+ * rather than deleted, if the operation fails or is canceled.
+ */
+ bool mActualTargetKeepPartial;
+
+ /**
+ * Used to calculate the file hash. This keeps state across file renames and
+ * is lazily initialized in ProcessStateChange.
+ */
+ UniquePK11Context mDigestContext;
+
+ //////////////////////////////////////////////////////////////////////////////
+ //// Private methods
+
+ /**
+ * Called when NS_AsyncCopy completes.
+ *
+ * @param aClosure
+ * Populated with a raw pointer to the BackgroundFileSaver object.
+ * @param aStatus
+ * Success or failure status specified when the copy was interrupted.
+ */
+ static void AsyncCopyCallback(void *aClosure, nsresult aStatus);
+
+ /**
+ * Called on the control thread after state changes, to ensure that the worker
+ * thread will process the state change appropriately.
+ *
+ * @param aShouldInterruptCopy
+ * If true, the current NS_AsyncCopy, if any, is canceled.
+ */
+ nsresult GetWorkerThreadAttention(bool aShouldInterruptCopy);
+
+ /**
+ * Event called on the worker thread to begin processing a state change.
+ */
+ nsresult ProcessAttention();
+
+ /**
+ * Called by ProcessAttention to execute the operations corresponding to the
+ * state change. If this results in an error, ProcessAttention will force the
+ * entire operation to be aborted.
+ */
+ nsresult ProcessStateChange();
+
+ /**
+ * Returns true if completion conditions are met on the worker thread. The
+ * first time this happens, posts the completion event to the control thread.
+ */
+ bool CheckCompletion();
+
+ /**
+ * Event called on the control thread to indicate that file contents will now
+ * be saved to the specified file.
+ */
+ nsresult NotifyTargetChange(nsIFile *aTarget);
+
+ /**
+ * Event called on the control thread to send the final notification.
+ */
+ nsresult NotifySaveComplete();
+
+ /**
+ * Verifies the signature of the binary at the specified file path and stores
+ * the signature data in mSignatureInfo. We extract only X.509 certificates,
+ * since that is what Google's Safebrowsing protocol specifies.
+ */
+ nsresult ExtractSignatureInfo(const nsAString& filePath);
+};
+
+////////////////////////////////////////////////////////////////////////////////
+//// BackgroundFileSaverOutputStream
+
+class BackgroundFileSaverOutputStream : public BackgroundFileSaver
+ , public nsIAsyncOutputStream
+ , public nsIOutputStreamCallback
+{
+public:
+ NS_DECL_THREADSAFE_ISUPPORTS
+ NS_DECL_NSIOUTPUTSTREAM
+ NS_DECL_NSIASYNCOUTPUTSTREAM
+ NS_DECL_NSIOUTPUTSTREAMCALLBACK
+
+ BackgroundFileSaverOutputStream();
+
+protected:
+ virtual bool HasInfiniteBuffer() override;
+ virtual nsAsyncCopyProgressFun GetProgressCallback() override;
+
+private:
+ ~BackgroundFileSaverOutputStream();
+
+ /**
+ * Original callback provided to our AsyncWait wrapper.
+ */
+ nsCOMPtr<nsIOutputStreamCallback> mAsyncWaitCallback;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+//// BackgroundFileSaverStreamListener. This class is instantiated by
+// nsExternalHelperAppService, DownloadCore.jsm, and possibly others.
+
+class BackgroundFileSaverStreamListener final : public BackgroundFileSaver
+ , public nsIStreamListener
+{
+public:
+ NS_DECL_THREADSAFE_ISUPPORTS
+ NS_DECL_NSIREQUESTOBSERVER
+ NS_DECL_NSISTREAMLISTENER
+
+ BackgroundFileSaverStreamListener();
+
+protected:
+ virtual bool HasInfiniteBuffer() override;
+ virtual nsAsyncCopyProgressFun GetProgressCallback() override;
+
+private:
+ ~BackgroundFileSaverStreamListener();
+
+ /**
+ * Protects the state related to whether the request should be suspended.
+ */
+ mozilla::Mutex mSuspensionLock;
+
+ /**
+ * Whether we should suspend the request because we received too much data.
+ */
+ bool mReceivedTooMuchData;
+
+ /**
+ * Request for which we received too much data. This is populated when
+ * mReceivedTooMuchData becomes true for the first time.
+ */
+ nsCOMPtr<nsIRequest> mRequest;
+
+ /**
+ * Whether mRequest is currently suspended.
+ */
+ bool mRequestSuspended;
+
+ /**
+ * Called while NS_AsyncCopy is copying data.
+ */
+ static void AsyncCopyProgressCallback(void *aClosure, uint32_t aCount);
+
+ /**
+ * Called on the control thread to suspend or resume the request.
+ */
+ nsresult NotifySuspendOrResume();
+};
+
+// A wrapper around nsIOutputStream, so that we can compute hashes on the
+// stream without copying and without polluting pristine NSS code with XPCOM
+// interfaces.
+class DigestOutputStream : public nsNSSShutDownObject,
+ public nsIOutputStream
+{
+public:
+ NS_DECL_THREADSAFE_ISUPPORTS
+ NS_DECL_NSIOUTPUTSTREAM
+ // Constructor. Neither parameter may be null. The caller owns both.
+ DigestOutputStream(nsIOutputStream* outputStream, PK11Context* aContext);
+
+ // We don't own any NSS objects here, so no need to clean up
+ void virtualDestroyNSSReference() override { }
+
+private:
+ ~DigestOutputStream();
+
+ // Calls to write are passed to this stream.
+ nsCOMPtr<nsIOutputStream> mOutputStream;
+ // Digest context used to compute the hash, owned by the caller.
+ PK11Context* mDigestContext;
+
+ // Don't accidentally copy construct.
+ DigestOutputStream(const DigestOutputStream& d);
+};
+
+} // namespace net
+} // namespace mozilla
+
+#endif