The Tor Browser: xpcom/io/nsInputStreamTee.cpp@97036ab72558 (annotated)

xpcom/io/nsInputStreamTee.cpp@97036ab72558 (annotated)

xpcom/io/nsInputStreamTee.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* 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 <stdlib.h>
 #include "prlog.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/Attributes.h"
 #include "nsIInputStreamTee.h"
 #include "nsIInputStream.h"
 #include "nsIOutputStream.h"
 #include "nsCOMPtr.h"
 #include "nsAutoPtr.h"
 #include "nsIEventTarget.h"
 #include "nsThreadUtils.h"
 using namespace mozilla;
 #ifdef LOG
 #undef LOG
 #endif
 #ifdef PR_LOGGING
 static PRLogModuleInfo*
 GetTeeLog()
 {
     static PRLogModuleInfo *sLog;
     if (!sLog)
         sLog = PR_NewLogModule("nsInputStreamTee");
     return sLog;
 }
 #define LOG(args) PR_LOG(GetTeeLog(), PR_LOG_DEBUG, args)
 #else
 #define LOG(args)
 #endif
 class nsInputStreamTee MOZ_FINAL : public nsIInputStreamTee
 {
 public:
     NS_DECL_THREADSAFE_ISUPPORTS
     NS_DECL_NSIINPUTSTREAM
     NS_DECL_NSIINPUTSTREAMTEE
     nsInputStreamTee();
     bool SinkIsValid();
     void InvalidateSink();
 private:
     ~nsInputStreamTee() {}
     nsresult TeeSegment(const char *buf, uint32_t count);
     static NS_METHOD WriteSegmentFun(nsIInputStream *, void *, const char *,
                                      uint32_t, uint32_t, uint32_t *);
 private:
     nsCOMPtr<nsIInputStream>  mSource;
     nsCOMPtr<nsIOutputStream> mSink;
     nsCOMPtr<nsIEventTarget>  mEventTarget;
     nsWriteSegmentFun         mWriter;  // for implementing ReadSegments
     void                      *mClosure; // for implementing ReadSegments
     nsAutoPtr<Mutex>          mLock; // synchronize access to mSinkIsValid
     bool                      mSinkIsValid; // False if TeeWriteEvent fails
 };
 class nsInputStreamTeeWriteEvent : public nsRunnable {
 public:
     // aTee's lock is held across construction of this object
     nsInputStreamTeeWriteEvent(const char *aBuf, uint32_t aCount,
                                nsIOutputStream  *aSink,
                                nsInputStreamTee *aTee)
     {
         // copy the buffer - will be free'd by dtor
         mBuf = (char *)malloc(aCount);
         if (mBuf) memcpy(mBuf, (char *)aBuf, aCount);
         mCount = aCount;
         mSink = aSink;
         bool isNonBlocking;
         mSink->IsNonBlocking(&isNonBlocking);
         NS_ASSERTION(isNonBlocking == false, "mSink is nonblocking");
         mTee = aTee;
     }
     NS_IMETHOD Run()
     {
         if (!mBuf) {
             NS_WARNING("nsInputStreamTeeWriteEvent::Run() "
                        "memory not allocated\n");
             return NS_OK;
         }
         NS_ABORT_IF_FALSE(mSink, "mSink is null!");
         //  The output stream could have been invalidated between when
         //  this event was dispatched and now, so check before writing.
         if (!mTee->SinkIsValid()) {
             return NS_OK;
         }
         LOG(("nsInputStreamTeeWriteEvent::Run() [%p]"
              "will write %u bytes to %p\n",
               this, mCount, mSink.get()));
         uint32_t totalBytesWritten = 0;
         while (mCount) {
             nsresult rv;
             uint32_t bytesWritten = 0;
             rv = mSink->Write(mBuf + totalBytesWritten, mCount, &bytesWritten);
             if (NS_FAILED(rv)) {
                 LOG(("nsInputStreamTeeWriteEvent::Run[%p] error %x in writing",
                      this,rv));
                 mTee->InvalidateSink();
                 break;
             }
             totalBytesWritten += bytesWritten;
             NS_ASSERTION(bytesWritten <= mCount, "wrote too much");
             mCount -= bytesWritten;
         }
         return NS_OK;
     }
 protected:
     virtual ~nsInputStreamTeeWriteEvent()
     {
         if (mBuf) free(mBuf);
         mBuf = nullptr;
     }
 private:
     char *mBuf;
     uint32_t mCount;
     nsCOMPtr<nsIOutputStream> mSink;
     // back pointer to the tee that created this runnable
     nsRefPtr<nsInputStreamTee> mTee;
 };
 nsInputStreamTee::nsInputStreamTee(): mLock(nullptr)
                                     , mSinkIsValid(true)
 {
 }
 bool
 nsInputStreamTee::SinkIsValid()
 {
     MutexAutoLock lock(*mLock);
     return mSinkIsValid;
 }
 void
 nsInputStreamTee::InvalidateSink()
 {
     MutexAutoLock lock(*mLock);
     mSinkIsValid = false;
 }
 nsresult
 nsInputStreamTee::TeeSegment(const char *buf, uint32_t count)
 {
     if (!mSink) return NS_OK; // nothing to do
     if (mLock) { // asynchronous case
         NS_ASSERTION(mEventTarget, "mEventTarget is null, mLock is not null.");
         if (!SinkIsValid()) {
             return NS_OK; // nothing to do
         }
         nsRefPtr<nsIRunnable> event =
             new nsInputStreamTeeWriteEvent(buf, count, mSink, this);
         LOG(("nsInputStreamTee::TeeSegment [%p] dispatching write %u bytes\n",
               this, count));
         return mEventTarget->Dispatch(event, NS_DISPATCH_NORMAL);
     } else { // synchronous case
         NS_ASSERTION(!mEventTarget, "mEventTarget is not null, mLock is null.");
         nsresult rv;
         uint32_t totalBytesWritten = 0;
         while (count) {
             uint32_t bytesWritten = 0;
             rv = mSink->Write(buf + totalBytesWritten, count, &bytesWritten);
             if (NS_FAILED(rv)) {
                 // ok, this is not a fatal error... just drop our reference to mSink
                 // and continue on as if nothing happened.
                 NS_WARNING("Write failed (non-fatal)");
                 // catch possible misuse of the input stream tee
                 NS_ASSERTION(rv != NS_BASE_STREAM_WOULD_BLOCK, "sink must be a blocking stream");
                 mSink = 0;
                 break;
             }
             totalBytesWritten += bytesWritten;
             NS_ASSERTION(bytesWritten <= count, "wrote too much");
             count -= bytesWritten;
         }
         return NS_OK;
     }
 }
 NS_METHOD
 nsInputStreamTee::WriteSegmentFun(nsIInputStream *in, void *closure, const char *fromSegment,
                                   uint32_t offset, uint32_t count, uint32_t *writeCount)
 {
     nsInputStreamTee *tee = reinterpret_cast<nsInputStreamTee *>(closure);
     nsresult rv = tee->mWriter(in, tee->mClosure, fromSegment, offset, count, writeCount);
     if (NS_FAILED(rv) || (*writeCount == 0)) {
         NS_ASSERTION((NS_FAILED(rv) ? (*writeCount == 0) : true),
                 "writer returned an error with non-zero writeCount");
         return rv;
     }
     return tee->TeeSegment(fromSegment, *writeCount);
 }
 NS_IMPL_ISUPPORTS(nsInputStreamTee,
                   nsIInputStreamTee,
                   nsIInputStream)
 NS_IMETHODIMP
 nsInputStreamTee::Close()
 {
     if (NS_WARN_IF(!mSource))
         return NS_ERROR_NOT_INITIALIZED;
     nsresult rv = mSource->Close();
     mSource = 0;
     mSink = 0;
     return rv;
 }
 NS_IMETHODIMP
 nsInputStreamTee::Available(uint64_t *avail)
 {
     if (NS_WARN_IF(!mSource))
         return NS_ERROR_NOT_INITIALIZED;
     return mSource->Available(avail);
 }
 NS_IMETHODIMP
 nsInputStreamTee::Read(char *buf, uint32_t count, uint32_t *bytesRead)
 {
     if (NS_WARN_IF(!mSource))
         return NS_ERROR_NOT_INITIALIZED;
     nsresult rv = mSource->Read(buf, count, bytesRead);
     if (NS_FAILED(rv) || (*bytesRead == 0))
         return rv;
     return TeeSegment(buf, *bytesRead);
 }
 NS_IMETHODIMP
 nsInputStreamTee::ReadSegments(nsWriteSegmentFun writer,
                                void *closure,
                                uint32_t count,
                                uint32_t *bytesRead)
 {
     if (NS_WARN_IF(!mSource))
         return NS_ERROR_NOT_INITIALIZED;
     mWriter = writer;
     mClosure = closure;
     return mSource->ReadSegments(WriteSegmentFun, this, count, bytesRead);
 }
 NS_IMETHODIMP
 nsInputStreamTee::IsNonBlocking(bool *result)
 {
     if (NS_WARN_IF(!mSource))
         return NS_ERROR_NOT_INITIALIZED;
     return mSource->IsNonBlocking(result);
 }
 NS_IMETHODIMP
 nsInputStreamTee::SetSource(nsIInputStream *source)
 {
     mSource = source;
     return NS_OK;
 }
 NS_IMETHODIMP
 nsInputStreamTee::GetSource(nsIInputStream **source)
 {
     NS_IF_ADDREF(*source = mSource);
     return NS_OK;
 }
 NS_IMETHODIMP
 nsInputStreamTee::SetSink(nsIOutputStream *sink)
 {
 #ifdef DEBUG
     if (sink) {
         bool nonBlocking;
         nsresult rv = sink->IsNonBlocking(&nonBlocking);
         if (NS_FAILED(rv) || nonBlocking)
             NS_ERROR("sink should be a blocking stream");
     }
 #endif
     mSink = sink;
     return NS_OK;
 }
 NS_IMETHODIMP
 nsInputStreamTee::GetSink(nsIOutputStream **sink)
 {
     NS_IF_ADDREF(*sink = mSink);
     return NS_OK;
 }
 NS_IMETHODIMP
 nsInputStreamTee::SetEventTarget(nsIEventTarget *anEventTarget)
 {
     mEventTarget = anEventTarget;
     if (mEventTarget) {
         // Only need synchronization if this is an async tee
         mLock = new Mutex("nsInputStreamTee.mLock");
     }
     return NS_OK;
 }
 NS_IMETHODIMP
 nsInputStreamTee::GetEventTarget(nsIEventTarget **anEventTarget)
 {
     NS_IF_ADDREF(*anEventTarget = mEventTarget);
     return NS_OK;
 }
 nsresult
 NS_NewInputStreamTeeAsync(nsIInputStream **result,
                           nsIInputStream *source,
                           nsIOutputStream *sink,
                           nsIEventTarget *anEventTarget)
 {
     nsresult rv;
     nsCOMPtr<nsIInputStreamTee> tee = new nsInputStreamTee();
     if (!tee)
         return NS_ERROR_OUT_OF_MEMORY;
     rv = tee->SetSource(source);
     if (NS_FAILED(rv)) return rv;
     rv = tee->SetSink(sink);
     if (NS_FAILED(rv)) return rv;
     rv = tee->SetEventTarget(anEventTarget);
     if (NS_FAILED(rv)) return rv;
     NS_ADDREF(*result = tee);
     return rv;
 }
 nsresult
 NS_NewInputStreamTee(nsIInputStream **result,
                      nsIInputStream *source,
                      nsIOutputStream *sink)
 {
     return NS_NewInputStreamTeeAsync(result, source, sink, nullptr);
 }
 #undef LOG

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xpcom/io/nsInputStreamTee.cpp@97036ab72558 (annotated)

xpcom/io/nsInputStreamTee.cpp