1 files changed, 1007 insertions, 0 deletions
diff --git a/xpcom/io/nsBinaryStream.cpp b/xpcom/io/nsBinaryStream.cpp
new file mode 100644
index 0000000000..555edf5345
--- /dev/null
+++ b/xpcom/io/nsBinaryStream.cpp
@@ -0,0 +1,1007 @@
+/* -*- 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/. */
+
+/**
+ * This file contains implementations of the nsIBinaryInputStream and
+ * nsIBinaryOutputStream interfaces.  Together, these interfaces allows reading
+ * and writing of primitive data types (integers, floating-point values,
+ * booleans, etc.) to a stream in a binary, untagged, fixed-endianness format.
+ * This might be used, for example, to implement network protocols or to
+ * produce architecture-neutral binary disk files, i.e. ones that can be read
+ * and written by both big-endian and little-endian platforms.  Output is
+ * written in big-endian order (high-order byte first), as this is traditional
+ * network order.
+ *
+ * @See nsIBinaryInputStream
+ * @See nsIBinaryOutputStream
+ */
+#include <algorithm>
+#include <string.h>
+
+#include "nsBinaryStream.h"
+
+#include "mozilla/EndianUtils.h"
+#include "mozilla/PodOperations.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/Span.h"
+#include "mozilla/UniquePtr.h"
+
+#include "nsCRT.h"
+#include "nsString.h"
+#include "nsISerializable.h"
+#include "nsIClassInfo.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIURI.h"       // for NS_IURI_IID
+#include "nsIX509Cert.h"  // for NS_IX509CERT_IID
+
+#include "js/ArrayBuffer.h"  // JS::{GetArrayBuffer{,ByteLength},IsArrayBufferObject}
+#include "js/GCAPI.h"        // JS::AutoCheckCannotGC
+#include "js/RootingAPI.h"  // JS::{Handle,Rooted}
+#include "js/Value.h"       // JS::Value
+
+using mozilla::AsBytes;
+using mozilla::MakeUnique;
+using mozilla::PodCopy;
+using mozilla::Span;
+using mozilla::UniquePtr;
+
+already_AddRefed<nsIObjectOutputStream> NS_NewObjectOutputStream(
+    nsIOutputStream* aOutputStream) {
+  MOZ_ASSERT(aOutputStream);
+  auto stream = mozilla::MakeRefPtr<nsBinaryOutputStream>();
+
+  MOZ_ALWAYS_SUCCEEDS(stream->SetOutputStream(aOutputStream));
+  return stream.forget();
+}
+
+already_AddRefed<nsIObjectInputStream> NS_NewObjectInputStream(
+    nsIInputStream* aInputStream) {
+  MOZ_ASSERT(aInputStream);
+  auto stream = mozilla::MakeRefPtr<nsBinaryInputStream>();
+
+  MOZ_ALWAYS_SUCCEEDS(stream->SetInputStream(aInputStream));
+  return stream.forget();
+}
+
+NS_IMPL_ISUPPORTS(nsBinaryOutputStream, nsIObjectOutputStream,
+                  nsIBinaryOutputStream, nsIOutputStream)
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Flush() {
+  if (NS_WARN_IF(!mOutputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mOutputStream->Flush();
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Close() {
+  if (NS_WARN_IF(!mOutputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mOutputStream->Close();
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::StreamStatus() {
+  if (NS_WARN_IF(!mOutputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mOutputStream->StreamStatus();
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Write(const char* aBuf, uint32_t aCount,
+                            uint32_t* aActualBytes) {
+  if (NS_WARN_IF(!mOutputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mOutputStream->Write(aBuf, aCount, aActualBytes);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteFrom(nsIInputStream* aInStr, uint32_t aCount,
+                                uint32_t* aResult) {
+  MOZ_ASSERT_UNREACHABLE("WriteFrom");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteSegments(nsReadSegmentFun aReader, void* aClosure,
+                                    uint32_t aCount, uint32_t* aResult) {
+  MOZ_ASSERT_UNREACHABLE("WriteSegments");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::IsNonBlocking(bool* aNonBlocking) {
+  if (NS_WARN_IF(!mOutputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mOutputStream->IsNonBlocking(aNonBlocking);
+}
+
+nsresult nsBinaryOutputStream::WriteFully(const char* aBuf, uint32_t aCount) {
+  if (NS_WARN_IF(!mOutputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  nsresult rv;
+  uint32_t bytesWritten;
+
+  rv = mOutputStream->Write(aBuf, aCount, &bytesWritten);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesWritten != aCount) {
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::SetOutputStream(nsIOutputStream* aOutputStream) {
+  if (NS_WARN_IF(!aOutputStream)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  mOutputStream = aOutputStream;
+  mBufferAccess = do_QueryInterface(aOutputStream);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteBoolean(bool aBoolean) { return Write8(aBoolean); }
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Write8(uint8_t aByte) {
+  return WriteFully((const char*)&aByte, sizeof(aByte));
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Write16(uint16_t aNum) {
+  aNum = mozilla::NativeEndian::swapToBigEndian(aNum);
+  return WriteFully((const char*)&aNum, sizeof(aNum));
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Write32(uint32_t aNum) {
+  aNum = mozilla::NativeEndian::swapToBigEndian(aNum);
+  return WriteFully((const char*)&aNum, sizeof(aNum));
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Write64(uint64_t aNum) {
+  nsresult rv;
+  uint32_t bytesWritten;
+
+  aNum = mozilla::NativeEndian::swapToBigEndian(aNum);
+  rv = Write(reinterpret_cast<char*>(&aNum), sizeof(aNum), &bytesWritten);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesWritten != sizeof(aNum)) {
+    return NS_ERROR_FAILURE;
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteFloat(float aFloat) {
+  static_assert(sizeof(float) == sizeof(uint32_t),
+                "False assumption about sizeof(float)");
+  return Write32(*reinterpret_cast<uint32_t*>(&aFloat));
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteDouble(double aDouble) {
+  static_assert(sizeof(double) == sizeof(uint64_t),
+                "False assumption about sizeof(double)");
+  return Write64(*reinterpret_cast<uint64_t*>(&aDouble));
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteStringZ(const char* aString) {
+  uint32_t length;
+  nsresult rv;
+
+  length = strlen(aString);
+  rv = Write32(length);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  return WriteFully(aString, length);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteWStringZ(const char16_t* aString) {
+  uint32_t length = NS_strlen(aString);
+  nsresult rv = Write32(length);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (length == 0) {
+    return NS_OK;
+  }
+
+#ifdef IS_BIG_ENDIAN
+  rv = WriteBytes(AsBytes(Span(aString, length)));
+#else
+  // XXX use WriteSegments here to avoid copy!
+  char16_t* copy;
+  char16_t temp[64];
+  if (length <= 64) {
+    copy = temp;
+  } else {
+    copy = static_cast<char16_t*>(malloc(length * sizeof(char16_t)));
+    if (!copy) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+  NS_ASSERTION((uintptr_t(aString) & 0x1) == 0, "aString not properly aligned");
+  mozilla::NativeEndian::copyAndSwapToBigEndian(copy, aString, length);
+  rv = WriteBytes(AsBytes(Span(copy, length)));
+  if (copy != temp) {
+    free(copy);
+  }
+#endif
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteUtf8Z(const char16_t* aString) {
+  return WriteStringZ(NS_ConvertUTF16toUTF8(aString).get());
+}
+
+nsresult nsBinaryOutputStream::WriteBytes(Span<const uint8_t> aBytes) {
+  nsresult rv;
+  uint32_t bytesWritten;
+
+  rv = Write(reinterpret_cast<const char*>(aBytes.Elements()), aBytes.Length(),
+             &bytesWritten);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesWritten != aBytes.Length()) {
+    return NS_ERROR_FAILURE;
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteBytesFromJS(const char* aString, uint32_t aLength) {
+  return WriteBytes(AsBytes(Span(aString, aLength)));
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteByteArray(const nsTArray<uint8_t>& aByteArray) {
+  return WriteBytes(aByteArray);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteObject(nsISupports* aObject, bool aIsStrongRef) {
+  return WriteCompoundObject(aObject, NS_GET_IID(nsISupports), aIsStrongRef);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteSingleRefObject(nsISupports* aObject) {
+  return WriteCompoundObject(aObject, NS_GET_IID(nsISupports), true);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteCompoundObject(nsISupports* aObject,
+                                          const nsIID& aIID,
+                                          bool aIsStrongRef) {
+  nsCOMPtr<nsIClassInfo> classInfo = do_QueryInterface(aObject);
+  nsCOMPtr<nsISerializable> serializable = do_QueryInterface(aObject);
+
+  // Can't deal with weak refs
+  if (NS_WARN_IF(!aIsStrongRef)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  if (NS_WARN_IF(!classInfo) || NS_WARN_IF(!serializable)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsCID cid;
+  nsresult rv = classInfo->GetClassIDNoAlloc(&cid);
+  if (NS_SUCCEEDED(rv)) {
+    rv = WriteID(cid);
+  } else {
+    nsCID* cidptr = nullptr;
+    rv = classInfo->GetClassID(&cidptr);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    rv = WriteID(*cidptr);
+
+    free(cidptr);
+  }
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = WriteID(aIID);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  return serializable->Write(this);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteID(const nsIID& aIID) {
+  nsresult rv = Write32(aIID.m0);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = Write16(aIID.m1);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = Write16(aIID.m2);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = WriteBytes(aIID.m3);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP_(char*)
+nsBinaryOutputStream::GetBuffer(uint32_t aLength, uint32_t aAlignMask) {
+  if (mBufferAccess) {
+    return mBufferAccess->GetBuffer(aLength, aAlignMask);
+  }
+  return nullptr;
+}
+
+NS_IMETHODIMP_(void)
+nsBinaryOutputStream::PutBuffer(char* aBuffer, uint32_t aLength) {
+  if (mBufferAccess) {
+    mBufferAccess->PutBuffer(aBuffer, aLength);
+  }
+}
+
+NS_IMPL_ISUPPORTS(nsBinaryInputStream, nsIObjectInputStream,
+                  nsIBinaryInputStream, nsIInputStream)
+
+NS_IMETHODIMP
+nsBinaryInputStream::Available(uint64_t* aResult) {
+  if (NS_WARN_IF(!mInputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mInputStream->Available(aResult);
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::StreamStatus() {
+  if (NS_WARN_IF(!mInputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mInputStream->StreamStatus();
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Read(char* aBuffer, uint32_t aCount, uint32_t* aNumRead) {
+  if (NS_WARN_IF(!mInputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // mInputStream might give us short reads, so deal with that.
+  uint32_t totalRead = 0;
+
+  uint32_t bytesRead;
+  do {
+    nsresult rv = mInputStream->Read(aBuffer, aCount, &bytesRead);
+    if (rv == NS_BASE_STREAM_WOULD_BLOCK && totalRead != 0) {
+      // We already read some data.  Return it.
+      break;
+    }
+
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    totalRead += bytesRead;
+    aBuffer += bytesRead;
+    aCount -= bytesRead;
+  } while (aCount != 0 && bytesRead != 0);
+
+  *aNumRead = totalRead;
+
+  return NS_OK;
+}
+
+// when forwarding ReadSegments to mInputStream, we need to make sure
+// 'this' is being passed to the writer each time. To do this, we need
+// a thunking function which keeps the real input stream around.
+
+// the closure wrapper
+struct MOZ_STACK_CLASS ReadSegmentsClosure {
+  nsCOMPtr<nsIInputStream> mRealInputStream;
+  void* mRealClosure;
+  nsWriteSegmentFun mRealWriter;
+  nsresult mRealResult;
+  uint32_t mBytesRead;  // to properly implement aToOffset
+};
+
+// the thunking function
+static nsresult ReadSegmentForwardingThunk(nsIInputStream* aStream,
+                                           void* aClosure,
+                                           const char* aFromSegment,
+                                           uint32_t aToOffset, uint32_t aCount,
+                                           uint32_t* aWriteCount) {
+  ReadSegmentsClosure* thunkClosure =
+      reinterpret_cast<ReadSegmentsClosure*>(aClosure);
+
+  NS_ASSERTION(NS_SUCCEEDED(thunkClosure->mRealResult),
+               "How did this get to be a failure status?");
+
+  thunkClosure->mRealResult = thunkClosure->mRealWriter(
+      thunkClosure->mRealInputStream, thunkClosure->mRealClosure, aFromSegment,
+      thunkClosure->mBytesRead + aToOffset, aCount, aWriteCount);
+
+  return thunkClosure->mRealResult;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                                  uint32_t aCount, uint32_t* aResult) {
+  if (NS_WARN_IF(!mInputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  ReadSegmentsClosure thunkClosure = {this, aClosure, aWriter, NS_OK, 0};
+
+  // mInputStream might give us short reads, so deal with that.
+  uint32_t bytesRead;
+  do {
+    nsresult rv = mInputStream->ReadSegments(ReadSegmentForwardingThunk,
+                                             &thunkClosure, aCount, &bytesRead);
+
+    if (rv == NS_BASE_STREAM_WOULD_BLOCK && thunkClosure.mBytesRead != 0) {
+      // We already read some data.  Return it.
+      break;
+    }
+
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    thunkClosure.mBytesRead += bytesRead;
+    aCount -= bytesRead;
+  } while (aCount != 0 && bytesRead != 0 &&
+           NS_SUCCEEDED(thunkClosure.mRealResult));
+
+  *aResult = thunkClosure.mBytesRead;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::IsNonBlocking(bool* aNonBlocking) {
+  if (NS_WARN_IF(!mInputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mInputStream->IsNonBlocking(aNonBlocking);
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Close() {
+  if (NS_WARN_IF(!mInputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mInputStream->Close();
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::SetInputStream(nsIInputStream* aInputStream) {
+  if (NS_WARN_IF(!aInputStream)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  mInputStream = aInputStream;
+  mBufferAccess = do_QueryInterface(aInputStream);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadBoolean(bool* aBoolean) {
+  uint8_t byteResult;
+  nsresult rv = Read8(&byteResult);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  *aBoolean = !!byteResult;
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Read8(uint8_t* aByte) {
+  nsresult rv;
+  uint32_t bytesRead;
+
+  rv = Read(reinterpret_cast<char*>(aByte), sizeof(*aByte), &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesRead != 1) {
+    return NS_ERROR_FAILURE;
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Read16(uint16_t* aNum) {
+  uint32_t bytesRead;
+  nsresult rv = Read(reinterpret_cast<char*>(aNum), sizeof(*aNum), &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesRead != sizeof(*aNum)) {
+    return NS_ERROR_FAILURE;
+  }
+  *aNum = mozilla::NativeEndian::swapFromBigEndian(*aNum);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Read32(uint32_t* aNum) {
+  uint32_t bytesRead;
+  nsresult rv = Read(reinterpret_cast<char*>(aNum), sizeof(*aNum), &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesRead != sizeof(*aNum)) {
+    return NS_ERROR_FAILURE;
+  }
+  *aNum = mozilla::NativeEndian::swapFromBigEndian(*aNum);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Read64(uint64_t* aNum) {
+  uint32_t bytesRead;
+  nsresult rv = Read(reinterpret_cast<char*>(aNum), sizeof(*aNum), &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesRead != sizeof(*aNum)) {
+    return NS_ERROR_FAILURE;
+  }
+  *aNum = mozilla::NativeEndian::swapFromBigEndian(*aNum);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadFloat(float* aFloat) {
+  static_assert(sizeof(float) == sizeof(uint32_t),
+                "False assumption about sizeof(float)");
+  return Read32(reinterpret_cast<uint32_t*>(aFloat));
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadDouble(double* aDouble) {
+  static_assert(sizeof(double) == sizeof(uint64_t),
+                "False assumption about sizeof(double)");
+  return Read64(reinterpret_cast<uint64_t*>(aDouble));
+}
+
+static nsresult WriteSegmentToCString(nsIInputStream* aStream, void* aClosure,
+                                      const char* aFromSegment,
+                                      uint32_t aToOffset, uint32_t aCount,
+                                      uint32_t* aWriteCount) {
+  nsACString* outString = static_cast<nsACString*>(aClosure);
+
+  outString->Append(aFromSegment, aCount);
+
+  *aWriteCount = aCount;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadCString(nsACString& aString) {
+  nsresult rv;
+  uint32_t length, bytesRead;
+
+  rv = Read32(&length);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  aString.Truncate();
+  rv = ReadSegments(WriteSegmentToCString, &aString, length, &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (bytesRead != length) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+// sometimes, WriteSegmentToString will be handed an odd-number of
+// bytes, which means we only have half of the last char16_t
+struct WriteStringClosure {
+  char16_t* mWriteCursor;
+  bool mHasCarryoverByte;
+  char mCarryoverByte;
+};
+
+// there are a few cases we have to account for here:
+// * even length buffer, no carryover - easy, just append
+// * odd length buffer, no carryover - the last byte needs to be saved
+//                                     for carryover
+// * odd length buffer, with carryover - first byte needs to be used
+//                              with the carryover byte, and
+//                              the rest of the even length
+//                              buffer is appended as normal
+// * even length buffer, with carryover - the first byte needs to be
+//                              used with the previous carryover byte.
+//                              this gives you an odd length buffer,
+//                              so you have to save the last byte for
+//                              the next carryover
+
+// same version of the above, but with correct casting and endian swapping
+static nsresult WriteSegmentToString(nsIInputStream* aStream, void* aClosure,
+                                     const char* aFromSegment,
+                                     uint32_t aToOffset, uint32_t aCount,
+                                     uint32_t* aWriteCount) {
+  MOZ_ASSERT(aCount > 0, "Why are we being told to write 0 bytes?");
+  static_assert(sizeof(char16_t) == 2, "We can't handle other sizes!");
+
+  WriteStringClosure* closure = static_cast<WriteStringClosure*>(aClosure);
+  char16_t* cursor = closure->mWriteCursor;
+
+  // we're always going to consume the whole buffer no matter what
+  // happens, so take care of that right now.. that allows us to
+  // tweak aCount later. Do NOT move this!
+  *aWriteCount = aCount;
+
+  // if the last Write had an odd-number of bytes read, then
+  if (closure->mHasCarryoverByte) {
+    // re-create the two-byte sequence we want to work with
+    char bytes[2] = {closure->mCarryoverByte, *aFromSegment};
+    *cursor = *(char16_t*)bytes;
+    // Now the little endianness dance
+    mozilla::NativeEndian::swapToBigEndianInPlace(cursor, 1);
+    ++cursor;
+
+    // now skip past the first byte of the buffer.. code from here
+    // can assume normal operations, but should not assume aCount
+    // is relative to the ORIGINAL buffer
+    ++aFromSegment;
+    --aCount;
+
+    closure->mHasCarryoverByte = false;
+  }
+
+  // this array is possibly unaligned... be careful how we access it!
+  const char16_t* unicodeSegment =
+      reinterpret_cast<const char16_t*>(aFromSegment);
+
+  // calculate number of full characters in segment (aCount could be odd!)
+  uint32_t segmentLength = aCount / sizeof(char16_t);
+
+  // copy all data into our aligned buffer.  byte swap if necessary.
+  // cursor may be unaligned, so we cannot use copyAndSwapToBigEndian directly
+  memcpy(cursor, unicodeSegment, segmentLength * sizeof(char16_t));
+  char16_t* end = cursor + segmentLength;
+  mozilla::NativeEndian::swapToBigEndianInPlace(cursor, segmentLength);
+  closure->mWriteCursor = end;
+
+  // remember this is the modifed aCount and aFromSegment,
+  // so that will take into account the fact that we might have
+  // skipped the first byte in the buffer
+  if (aCount % sizeof(char16_t) != 0) {
+    // we must have had a carryover byte, that we'll need the next
+    // time around
+    closure->mCarryoverByte = aFromSegment[aCount - 1];
+    closure->mHasCarryoverByte = true;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadString(nsAString& aString) {
+  nsresult rv;
+  uint32_t length, bytesRead;
+
+  rv = Read32(&length);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (length == 0) {
+    aString.Truncate();
+    return NS_OK;
+  }
+
+  // pre-allocate output buffer, and get direct access to buffer...
+  if (!aString.SetLength(length, mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  WriteStringClosure closure;
+  closure.mWriteCursor = aString.BeginWriting();
+  closure.mHasCarryoverByte = false;
+
+  rv = ReadSegments(WriteSegmentToString, &closure, length * sizeof(char16_t),
+                    &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  NS_ASSERTION(!closure.mHasCarryoverByte, "some strange stream corruption!");
+
+  if (bytesRead != length * sizeof(char16_t)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+nsresult nsBinaryInputStream::ReadBytesToBuffer(uint32_t aLength,
+                                                uint8_t* aBuffer) {
+  uint32_t bytesRead;
+  nsresult rv = Read(reinterpret_cast<char*>(aBuffer), aLength, &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesRead != aLength) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadBytes(uint32_t aLength, char** aResult) {
+  char* s = static_cast<char*>(malloc(aLength));
+  if (!s) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  nsresult rv = ReadBytesToBuffer(aLength, reinterpret_cast<uint8_t*>(s));
+  if (NS_FAILED(rv)) {
+    free(s);
+    return rv;
+  }
+
+  *aResult = s;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadByteArray(uint32_t aLength,
+                                   nsTArray<uint8_t>& aResult) {
+  if (!aResult.SetLength(aLength, mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  nsresult rv = ReadBytesToBuffer(aLength, aResult.Elements());
+  if (NS_FAILED(rv)) {
+    aResult.Clear();
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadArrayBuffer(uint64_t aLength,
+                                     JS::Handle<JS::Value> aBuffer,
+                                     JSContext* aCx, uint64_t* aReadLength) {
+  if (!aBuffer.isObject()) {
+    return NS_ERROR_FAILURE;
+  }
+  JS::Rooted<JSObject*> buffer(aCx, &aBuffer.toObject());
+  if (!JS::IsArrayBufferObject(buffer)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  size_t bufferLength = JS::GetArrayBufferByteLength(buffer);
+  if (bufferLength < aLength) {
+    return NS_ERROR_FAILURE;
+  }
+
+  uint32_t bufSize = std::min<uint64_t>(aLength, 4096);
+  UniquePtr<char[]> buf = MakeUnique<char[]>(bufSize);
+
+  uint64_t pos = 0;
+  *aReadLength = 0;
+  do {
+    // Read data into temporary buffer.
+    uint32_t bytesRead;
+    uint32_t amount = std::min<uint64_t>(aLength - pos, bufSize);
+    nsresult rv = Read(buf.get(), amount, &bytesRead);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+    MOZ_ASSERT(bytesRead <= amount);
+
+    if (bytesRead == 0) {
+      break;
+    }
+
+    // Copy data into actual buffer.
+
+    JS::AutoCheckCannotGC nogc;
+    bool isShared;
+    if (bufferLength != JS::GetArrayBufferByteLength(buffer)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    char* data = reinterpret_cast<char*>(
+        JS::GetArrayBufferData(buffer, &isShared, nogc));
+    MOZ_ASSERT(!isShared);  // Implied by JS::GetArrayBufferData()
+    if (!data) {
+      return NS_ERROR_FAILURE;
+    }
+
+    *aReadLength += bytesRead;
+    PodCopy(data + pos, buf.get(), bytesRead);
+
+    pos += bytesRead;
+  } while (pos < aLength);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadObject(bool aIsStrongRef, nsISupports** aObject) {
+  nsCID cid;
+  nsIID iid;
+  nsresult rv = ReadID(&cid);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = ReadID(&iid);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // HACK: Intercept old (pre-gecko6) nsIURI IID, and replace with
+  // the updated IID, so that we're QI'ing to an actual interface.
+  // (As soon as we drop support for upgrading from pre-gecko6, we can
+  // remove this chunk.)
+  static const nsIID oldURIiid = {
+      0x7a22cc0,
+      0xce5,
+      0x11d3,
+      {0x93, 0x31, 0x0, 0x10, 0x4b, 0xa0, 0xfd, 0x40}};
+
+  // hackaround for bug 670542
+  static const nsIID oldURIiid2 = {
+      0xd6d04c36,
+      0x0fa4,
+      0x4db3,
+      {0xbe, 0x05, 0x4a, 0x18, 0x39, 0x71, 0x03, 0xe2}};
+
+  // hackaround for bug 682031
+  static const nsIID oldURIiid3 = {
+      0x12120b20,
+      0x0929,
+      0x40e9,
+      {0x88, 0xcf, 0x6e, 0x08, 0x76, 0x6e, 0x8b, 0x23}};
+
+  // hackaround for bug 1195415
+  static const nsIID oldURIiid4 = {
+      0x395fe045,
+      0x7d18,
+      0x4adb,
+      {0xa3, 0xfd, 0xaf, 0x98, 0xc8, 0xa1, 0xaf, 0x11}};
+
+  if (iid.Equals(oldURIiid) || iid.Equals(oldURIiid2) ||
+      iid.Equals(oldURIiid3) || iid.Equals(oldURIiid4)) {
+    const nsIID newURIiid = NS_IURI_IID;
+    iid = newURIiid;
+  }
+
+  // Hack around bug 1508939
+  // The old CSP serialization can't be handled cleanly when
+  // it's embedded in an old style principal
+  static const nsIID oldCSPiid = {
+      0xb3c4c0ae,
+      0xbd5e,
+      0x4cad,
+      {0x87, 0xe0, 0x8d, 0x21, 0x0d, 0xbb, 0x3f, 0x9f}};
+  if (iid.Equals(oldCSPiid)) {
+    return NS_ERROR_FAILURE;
+  }
+  // END HACK
+
+  // HACK:  Service workers store resource security info on disk in the dom
+  //        Cache API.  When the uuid of the nsIX509Cert interface changes
+  //        these serialized objects cannot be loaded any more.  This hack
+  //        works around this issue.
+
+  // hackaround for bug 1247580 (FF45 to FF46 transition)
+  static const nsIID oldCertIID = {
+      0xf8ed8364,
+      0xced9,
+      0x4c6e,
+      {0x86, 0xba, 0x48, 0xaf, 0x53, 0xc3, 0x93, 0xe6}};
+
+  if (iid.Equals(oldCertIID)) {
+    const nsIID newCertIID = NS_IX509CERT_IID;
+    iid = newCertIID;
+  }
+  // END HACK
+
+  nsCOMPtr<nsISupports> object = do_CreateInstance(cid, &rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  nsCOMPtr<nsISerializable> serializable = do_QueryInterface(object);
+  if (NS_WARN_IF(!serializable)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  rv = serializable->Read(this);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  return object->QueryInterface(iid, reinterpret_cast<void**>(aObject));
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadID(nsID* aResult) {
+  nsresult rv = Read32(&aResult->m0);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = Read16(&aResult->m1);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = Read16(&aResult->m2);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  const uint32_t toRead = sizeof(aResult->m3);
+  uint32_t bytesRead = 0;
+  rv = Read(reinterpret_cast<char*>(&aResult->m3[0]), toRead, &bytesRead);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  if (bytesRead != toRead) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP_(char*)
+nsBinaryInputStream::GetBuffer(uint32_t aLength, uint32_t aAlignMask) {
+  if (mBufferAccess) {
+    return mBufferAccess->GetBuffer(aLength, aAlignMask);
+  }
+  return nullptr;
+}
+
+NS_IMETHODIMP_(void)
+nsBinaryInputStream::PutBuffer(char* aBuffer, uint32_t aLength) {
+  if (mBufferAccess) {
+    mBufferAccess->PutBuffer(aBuffer, aLength);
+  }
+}