1 files changed, 333 insertions, 0 deletions
diff --git a/xpcom/io/nsInputStreamTee.cpp b/xpcom/io/nsInputStreamTee.cpp
new file mode 100644
index 0000000000..3f2db549c3
--- /dev/null
+++ b/xpcom/io/nsInputStreamTee.cpp
@@ -0,0 +1,333 @@
+/* -*- 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 <stdlib.h>
+#include "mozilla/Logging.h"
+
+#include "mozilla/Maybe.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/Attributes.h"
+#include "nsIInputStreamTee.h"
+#include "nsIInputStream.h"
+#include "nsIOutputStream.h"
+#include "nsCOMPtr.h"
+#include "nsIEventTarget.h"
+#include "nsThreadUtils.h"
+
+using namespace mozilla;
+
+#ifdef LOG
+#  undef LOG
+#endif
+
+static LazyLogModule sTeeLog("nsInputStreamTee");
+#define LOG(args) MOZ_LOG(sTeeLog, mozilla::LogLevel::Debug, args)
+
+class nsInputStreamTee final : public nsIInputStreamTee {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIINPUTSTREAMTEE
+
+  nsInputStreamTee();
+  bool SinkIsValid();
+  void InvalidateSink();
+
+ private:
+  ~nsInputStreamTee() = default;
+
+  nsresult TeeSegment(const char* aBuf, uint32_t aCount);
+
+  static nsresult 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
+  Maybe<Mutex> mLock;         // synchronize access to mSinkIsValid
+  bool mSinkIsValid;          // False if TeeWriteEvent fails
+};
+
+class nsInputStreamTeeWriteEvent : public Runnable {
+ public:
+  // aTee's lock is held across construction of this object
+  nsInputStreamTeeWriteEvent(const char* aBuf, uint32_t aCount,
+                             nsIOutputStream* aSink, nsInputStreamTee* aTee)
+      : mozilla::Runnable("nsInputStreamTeeWriteEvent") {
+    // 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() override {
+    if (!mBuf) {
+      NS_WARNING(
+          "nsInputStreamTeeWriteEvent::Run() "
+          "memory not allocated\n");
+      return NS_OK;
+    }
+    MOZ_ASSERT(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 %" PRIx32 " in writing",
+             this, static_cast<uint32_t>(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
+  RefPtr<nsInputStreamTee> mTee;
+};
+
+nsInputStreamTee::nsInputStreamTee()
+    : mWriter(nullptr), mClosure(nullptr), mLock(), mSinkIsValid(true) {}
+
+bool nsInputStreamTee::SinkIsValid() {
+  MutexAutoLock lock(*mLock);
+  return mSinkIsValid;
+}
+
+void nsInputStreamTee::InvalidateSink() {
+  MutexAutoLock lock(*mLock);
+  mSinkIsValid = false;
+}
+
+nsresult nsInputStreamTee::TeeSegment(const char* aBuf, uint32_t aCount) {
+  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
+    }
+    nsCOMPtr<nsIRunnable> event =
+        new nsInputStreamTeeWriteEvent(aBuf, aCount, mSink, this);
+    LOG(("nsInputStreamTee::TeeSegment [%p] dispatching write %u bytes\n", this,
+         aCount));
+    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 (aCount) {
+      uint32_t bytesWritten = 0;
+      rv = mSink->Write(aBuf + totalBytesWritten, aCount, &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 = nullptr;
+        break;
+      }
+      totalBytesWritten += bytesWritten;
+      NS_ASSERTION(bytesWritten <= aCount, "wrote too much");
+      aCount -= bytesWritten;
+    }
+    return NS_OK;
+  }
+}
+
+nsresult nsInputStreamTee::WriteSegmentFun(nsIInputStream* aIn, void* aClosure,
+                                           const char* aFromSegment,
+                                           uint32_t aOffset, uint32_t aCount,
+                                           uint32_t* aWriteCount) {
+  nsInputStreamTee* tee = reinterpret_cast<nsInputStreamTee*>(aClosure);
+  nsresult rv = tee->mWriter(aIn, tee->mClosure, aFromSegment, aOffset, aCount,
+                             aWriteCount);
+  if (NS_FAILED(rv) || (*aWriteCount == 0)) {
+    NS_ASSERTION((NS_FAILED(rv) ? (*aWriteCount == 0) : true),
+                 "writer returned an error with non-zero writeCount");
+    return rv;
+  }
+
+  return tee->TeeSegment(aFromSegment, *aWriteCount);
+}
+
+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 = nullptr;
+  mSink = nullptr;
+  return rv;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::Available(uint64_t* aAvail) {
+  if (NS_WARN_IF(!mSource)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return mSource->Available(aAvail);
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::Read(char* aBuf, uint32_t aCount, uint32_t* aBytesRead) {
+  if (NS_WARN_IF(!mSource)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  nsresult rv = mSource->Read(aBuf, aCount, aBytesRead);
+  if (NS_FAILED(rv) || (*aBytesRead == 0)) {
+    return rv;
+  }
+
+  return TeeSegment(aBuf, *aBytesRead);
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                               uint32_t aCount, uint32_t* aBytesRead) {
+  if (NS_WARN_IF(!mSource)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  mWriter = aWriter;
+  mClosure = aClosure;
+
+  return mSource->ReadSegments(WriteSegmentFun, this, aCount, aBytesRead);
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::IsNonBlocking(bool* aResult) {
+  if (NS_WARN_IF(!mSource)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return mSource->IsNonBlocking(aResult);
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::SetSource(nsIInputStream* aSource) {
+  mSource = aSource;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::GetSource(nsIInputStream** aSource) {
+  NS_IF_ADDREF(*aSource = mSource);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::SetSink(nsIOutputStream* aSink) {
+#ifdef DEBUG
+  if (aSink) {
+    bool nonBlocking;
+    nsresult rv = aSink->IsNonBlocking(&nonBlocking);
+    if (NS_FAILED(rv) || nonBlocking) {
+      NS_ERROR("aSink should be a blocking stream");
+    }
+  }
+#endif
+  mSink = aSink;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::GetSink(nsIOutputStream** aSink) {
+  NS_IF_ADDREF(*aSink = mSink);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::SetEventTarget(nsIEventTarget* aEventTarget) {
+  mEventTarget = aEventTarget;
+  if (mEventTarget) {
+    // Only need synchronization if this is an async tee
+    mLock.emplace("nsInputStreamTee.mLock");
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::GetEventTarget(nsIEventTarget** aEventTarget) {
+  NS_IF_ADDREF(*aEventTarget = mEventTarget);
+  return NS_OK;
+}
+
+nsresult NS_NewInputStreamTeeAsync(nsIInputStream** aResult,
+                                   nsIInputStream* aSource,
+                                   nsIOutputStream* aSink,
+                                   nsIEventTarget* aEventTarget) {
+  nsresult rv;
+
+  nsCOMPtr<nsIInputStreamTee> tee = new nsInputStreamTee();
+  rv = tee->SetSource(aSource);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  rv = tee->SetSink(aSink);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  rv = tee->SetEventTarget(aEventTarget);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  tee.forget(aResult);
+  return rv;
+}
+
+nsresult NS_NewInputStreamTee(nsIInputStream** aResult, nsIInputStream* aSource,
+                              nsIOutputStream* aSink) {
+  return NS_NewInputStreamTeeAsync(aResult, aSource, aSink, nullptr);
+}
+
+#undef LOG