import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

xpcom/io/nsStorageStream.cpp

@@ -0,0 +1,648 @@
+/* -*- 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/. */
+
+/*
+ * The storage stream provides an internal buffer that can be filled by a
+ * client using a single output stream.  One or more independent input streams
+ * can be created to read the data out non-destructively.  The implementation
+ * uses a segmented buffer internally to avoid realloc'ing of large buffers,
+ * with the attendant performance loss and heap fragmentation.
+ */
+
+#include "nsAlgorithm.h"
+#include "nsStorageStream.h"
+#include "nsSegmentedBuffer.h"
+#include "nsStreamUtils.h"
+#include "nsCOMPtr.h"
+#include "nsICloneableInputStream.h"
+#include "nsIInputStream.h"
+#include "nsIIPCSerializableInputStream.h"
+#include "nsISeekableStream.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/ipc/InputStreamUtils.h"
+
+using mozilla::ipc::InputStreamParams;
+using mozilla::ipc::StringInputStreamParams;
+using mozilla::Maybe;
+using mozilla::Some;
+
+//
+// Log module for StorageStream logging...
+//
+// To enable logging (see prlog.h for full details):
+//
+//    set MOZ_LOG=StorageStreamLog:5
+//    set MOZ_LOG_FILE=storage.log
+//
+// This enables LogLevel::Debug level information and places all output in
+// the file storage.log.
+//
+static LazyLogModule sStorageStreamLog("nsStorageStream");
+#ifdef LOG
+#undef LOG
+#endif
+#define LOG(args) MOZ_LOG(sStorageStreamLog, mozilla::LogLevel::Debug, args)
+
+nsStorageStream::nsStorageStream()
+  : mSegmentedBuffer(0), mSegmentSize(0), mWriteInProgress(false),
+    mLastSegmentNum(-1), mWriteCursor(0), mSegmentEnd(0), mLogicalLength(0)
+{
+  LOG(("Creating nsStorageStream [%p].\n", this));
+}
+
+nsStorageStream::~nsStorageStream()
+{
+  delete mSegmentedBuffer;
+}
+
+NS_IMPL_ISUPPORTS(nsStorageStream,
+                  nsIStorageStream,
+                  nsIOutputStream)
+
+NS_IMETHODIMP
+nsStorageStream::Init(uint32_t aSegmentSize, uint32_t aMaxSize)
+{
+  mSegmentedBuffer = new nsSegmentedBuffer();
+  mSegmentSize = aSegmentSize;
+  mSegmentSizeLog2 = mozilla::FloorLog2(aSegmentSize);
+
+  // Segment size must be a power of two
+  if (mSegmentSize != ((uint32_t)1 << mSegmentSizeLog2)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  return mSegmentedBuffer->Init(aSegmentSize, aMaxSize);
+}
+
+NS_IMETHODIMP
+nsStorageStream::GetOutputStream(int32_t aStartingOffset,
+                                 nsIOutputStream** aOutputStream)
+{
+  if (NS_WARN_IF(!aOutputStream)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  if (mWriteInProgress) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsresult rv = Seek(aStartingOffset);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // Enlarge the last segment in the buffer so that it is the same size as
+  // all the other segments in the buffer.  (It may have been realloc'ed
+  // smaller in the Close() method.)
+  if (mLastSegmentNum >= 0)
+    if (mSegmentedBuffer->ReallocLastSegment(mSegmentSize)) {
+      // Need to re-Seek, since realloc changed segment base pointer
+      rv = Seek(aStartingOffset);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+    }
+
+  NS_ADDREF(this);
+  *aOutputStream = static_cast<nsIOutputStream*>(this);
+  mWriteInProgress = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageStream::Close()
+{
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  mWriteInProgress = false;
+
+  int32_t segmentOffset = SegOffset(mLogicalLength);
+
+  // Shrink the final segment in the segmented buffer to the minimum size
+  // needed to contain the data, so as to conserve memory.
+  if (segmentOffset) {
+    mSegmentedBuffer->ReallocLastSegment(segmentOffset);
+  }
+
+  mWriteCursor = 0;
+  mSegmentEnd = 0;
+
+  LOG(("nsStorageStream [%p] Close mWriteCursor=%x mSegmentEnd=%x\n",
+       this, mWriteCursor, mSegmentEnd));
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageStream::Flush()
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageStream::Write(const char* aBuffer, uint32_t aCount,
+                       uint32_t* aNumWritten)
+{
+  if (NS_WARN_IF(!aNumWritten) || NS_WARN_IF(!aBuffer)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  const char* readCursor;
+  uint32_t count, availableInSegment, remaining;
+  nsresult rv = NS_OK;
+
+  LOG(("nsStorageStream [%p] Write mWriteCursor=%x mSegmentEnd=%x aCount=%d\n",
+       this, mWriteCursor, mSegmentEnd, aCount));
+
+  remaining = aCount;
+  readCursor = aBuffer;
+  // If no segments have been created yet, create one even if we don't have
+  // to write any data; this enables creating an input stream which reads from
+  // the very end of the data for any amount of data in the stream (i.e.
+  // this stream contains N bytes of data and newInputStream(N) is called),
+  // even for N=0 (with the caveat that we require .write("", 0) be called to
+  // initialize internal buffers).
+  bool firstTime = mSegmentedBuffer->GetSegmentCount() == 0;
+  while (remaining || MOZ_UNLIKELY(firstTime)) {
+    firstTime = false;
+    availableInSegment = mSegmentEnd - mWriteCursor;
+    if (!availableInSegment) {
+      mWriteCursor = mSegmentedBuffer->AppendNewSegment();
+      if (!mWriteCursor) {
+        mSegmentEnd = 0;
+        rv = NS_ERROR_OUT_OF_MEMORY;
+        goto out;
+      }
+      mLastSegmentNum++;
+      mSegmentEnd = mWriteCursor + mSegmentSize;
+      availableInSegment = mSegmentEnd - mWriteCursor;
+      LOG(("nsStorageStream [%p] Write (new seg) mWriteCursor=%x mSegmentEnd=%x\n",
+           this, mWriteCursor, mSegmentEnd));
+    }
+
+    count = XPCOM_MIN(availableInSegment, remaining);
+    memcpy(mWriteCursor, readCursor, count);
+    remaining -= count;
+    readCursor += count;
+    mWriteCursor += count;
+    LOG(("nsStorageStream [%p] Writing mWriteCursor=%x mSegmentEnd=%x count=%d\n",
+         this, mWriteCursor, mSegmentEnd, count));
+  }
+
+out:
+  *aNumWritten = aCount - remaining;
+  mLogicalLength += *aNumWritten;
+
+  LOG(("nsStorageStream [%p] Wrote mWriteCursor=%x mSegmentEnd=%x numWritten=%d\n",
+       this, mWriteCursor, mSegmentEnd, *aNumWritten));
+  return rv;
+}
+
+NS_IMETHODIMP
+nsStorageStream::WriteFrom(nsIInputStream* aInStr, uint32_t aCount,
+                           uint32_t* aResult)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsStorageStream::WriteSegments(nsReadSegmentFun aReader, void* aClosure,
+                               uint32_t aCount, uint32_t* aResult)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsStorageStream::IsNonBlocking(bool* aNonBlocking)
+{
+  *aNonBlocking = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageStream::GetLength(uint32_t* aLength)
+{
+  *aLength = mLogicalLength;
+  return NS_OK;
+}
+
+// Truncate the buffer by deleting the end segments
+NS_IMETHODIMP
+nsStorageStream::SetLength(uint32_t aLength)
+{
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  if (mWriteInProgress) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  if (aLength > mLogicalLength) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  int32_t newLastSegmentNum = SegNum(aLength);
+  int32_t segmentOffset = SegOffset(aLength);
+  if (segmentOffset == 0) {
+    newLastSegmentNum--;
+  }
+
+  while (newLastSegmentNum < mLastSegmentNum) {
+    mSegmentedBuffer->DeleteLastSegment();
+    mLastSegmentNum--;
+  }
+
+  mLogicalLength = aLength;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageStream::GetWriteInProgress(bool* aWriteInProgress)
+{
+  *aWriteInProgress = mWriteInProgress;
+  return NS_OK;
+}
+
+nsresult
+nsStorageStream::Seek(int32_t aPosition)
+{
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  // An argument of -1 means "seek to end of stream"
+  if (aPosition == -1) {
+    aPosition = mLogicalLength;
+  }
+
+  // Seeking beyond the buffer end is illegal
+  if ((uint32_t)aPosition > mLogicalLength) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // Seeking backwards in the write stream results in truncation
+  SetLength(aPosition);
+
+  // Special handling for seek to start-of-buffer
+  if (aPosition == 0) {
+    mWriteCursor = 0;
+    mSegmentEnd = 0;
+    LOG(("nsStorageStream [%p] Seek mWriteCursor=%x mSegmentEnd=%x\n",
+         this, mWriteCursor, mSegmentEnd));
+    return NS_OK;
+  }
+
+  // Segment may have changed, so reset pointers
+  mWriteCursor = mSegmentedBuffer->GetSegment(mLastSegmentNum);
+  NS_ASSERTION(mWriteCursor, "null mWriteCursor");
+  mSegmentEnd = mWriteCursor + mSegmentSize;
+
+  // Adjust write cursor for current segment offset.  This test is necessary
+  // because SegNum may reference the next-to-be-allocated segment, in which
+  // case we need to be pointing at the end of the last segment.
+  int32_t segmentOffset = SegOffset(aPosition);
+  if (segmentOffset == 0 && (SegNum(aPosition) > (uint32_t) mLastSegmentNum)) {
+    mWriteCursor = mSegmentEnd;
+  } else {
+    mWriteCursor += segmentOffset;
+  }
+
+  LOG(("nsStorageStream [%p] Seek mWriteCursor=%x mSegmentEnd=%x\n",
+       this, mWriteCursor, mSegmentEnd));
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+// There can be many nsStorageInputStreams for a single nsStorageStream
+class nsStorageInputStream final
+  : public nsIInputStream
+  , public nsISeekableStream
+  , public nsIIPCSerializableInputStream
+  , public nsICloneableInputStream
+{
+public:
+  nsStorageInputStream(nsStorageStream* aStorageStream, uint32_t aSegmentSize)
+    : mStorageStream(aStorageStream), mReadCursor(0),
+      mSegmentEnd(0), mSegmentNum(0),
+      mSegmentSize(aSegmentSize), mLogicalCursor(0),
+      mStatus(NS_OK)
+  {
+  }
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSISEEKABLESTREAM
+  NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
+  NS_DECL_NSICLONEABLEINPUTSTREAM
+
+private:
+  ~nsStorageInputStream()
+  {
+  }
+
+protected:
+  nsresult Seek(uint32_t aPosition);
+
+  friend class nsStorageStream;
+
+private:
+  RefPtr<nsStorageStream> mStorageStream;
+  uint32_t         mReadCursor;    // Next memory location to read byte, or 0
+  uint32_t         mSegmentEnd;    // One byte past end of current buffer segment
+  uint32_t         mSegmentNum;    // Segment number containing read cursor
+  uint32_t         mSegmentSize;   // All segments, except the last, are of this size
+  uint32_t         mLogicalCursor; // Logical offset into stream
+  nsresult         mStatus;
+
+  uint32_t SegNum(uint32_t aPosition)
+  {
+    return aPosition >> mStorageStream->mSegmentSizeLog2;
+  }
+  uint32_t SegOffset(uint32_t aPosition)
+  {
+    return aPosition & (mSegmentSize - 1);
+  }
+};
+
+NS_IMPL_ISUPPORTS(nsStorageInputStream,
+                  nsIInputStream,
+                  nsISeekableStream,
+                  nsIIPCSerializableInputStream,
+                  nsICloneableInputStream)
+
+NS_IMETHODIMP
+nsStorageStream::NewInputStream(int32_t aStartingOffset,
+                                nsIInputStream** aInputStream)
+{
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  RefPtr<nsStorageInputStream> inputStream =
+    new nsStorageInputStream(this, mSegmentSize);
+
+  nsresult rv = inputStream->Seek(aStartingOffset);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  inputStream.forget(aInputStream);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Close()
+{
+  mStatus = NS_BASE_STREAM_CLOSED;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Available(uint64_t* aAvailable)
+{
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  *aAvailable = mStorageStream->mLogicalLength - mLogicalCursor;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Read(char* aBuffer, uint32_t aCount, uint32_t* aNumRead)
+{
+  return ReadSegments(NS_CopySegmentToBuffer, aBuffer, aCount, aNumRead);
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                                   uint32_t aCount, uint32_t* aNumRead)
+{
+  *aNumRead = 0;
+  if (mStatus == NS_BASE_STREAM_CLOSED) {
+    return NS_OK;
+  }
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  uint32_t count, availableInSegment, remainingCapacity, bytesConsumed;
+  nsresult rv;
+
+  remainingCapacity = aCount;
+  while (remainingCapacity) {
+    availableInSegment = mSegmentEnd - mReadCursor;
+    if (!availableInSegment) {
+      uint32_t available = mStorageStream->mLogicalLength - mLogicalCursor;
+      if (!available) {
+        goto out;
+      }
+
+      // We have data in the stream, but if mSegmentEnd is zero, then we
+      // were likely constructed prior to any data being written into
+      // the stream.  Therefore, if mSegmentEnd is non-zero, we should
+      // move into the next segment; otherwise, we should stay in this
+      // segment so our input state can be updated and we can properly
+      // perform the initial read.
+      if (mSegmentEnd > 0) {
+        mSegmentNum++;
+      }
+      mReadCursor = 0;
+      mSegmentEnd = XPCOM_MIN(mSegmentSize, available);
+      availableInSegment = mSegmentEnd;
+    }
+    const char* cur = mStorageStream->mSegmentedBuffer->GetSegment(mSegmentNum);
+
+    count = XPCOM_MIN(availableInSegment, remainingCapacity);
+    rv = aWriter(this, aClosure, cur + mReadCursor, aCount - remainingCapacity,
+                 count, &bytesConsumed);
+    if (NS_FAILED(rv) || (bytesConsumed == 0)) {
+      break;
+    }
+    remainingCapacity -= bytesConsumed;
+    mReadCursor += bytesConsumed;
+    mLogicalCursor += bytesConsumed;
+  }
+
+out:
+  *aNumRead = aCount - remainingCapacity;
+
+  bool isWriteInProgress = false;
+  if (NS_FAILED(mStorageStream->GetWriteInProgress(&isWriteInProgress))) {
+    isWriteInProgress = false;
+  }
+
+  if (*aNumRead == 0 && isWriteInProgress) {
+    return NS_BASE_STREAM_WOULD_BLOCK;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::IsNonBlocking(bool* aNonBlocking)
+{
+  // TODO: This class should implement nsIAsyncInputStream so that callers
+  // have some way of dealing with NS_BASE_STREAM_WOULD_BLOCK errors.
+
+  *aNonBlocking = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Seek(int32_t aWhence, int64_t aOffset)
+{
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  int64_t pos = aOffset;
+
+  switch (aWhence) {
+    case NS_SEEK_SET:
+      break;
+    case NS_SEEK_CUR:
+      pos += mLogicalCursor;
+      break;
+    case NS_SEEK_END:
+      pos += mStorageStream->mLogicalLength;
+      break;
+    default:
+      NS_NOTREACHED("unexpected whence value");
+      return NS_ERROR_UNEXPECTED;
+  }
+  if (pos == int64_t(mLogicalCursor)) {
+    return NS_OK;
+  }
+
+  return Seek(pos);
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Tell(int64_t* aResult)
+{
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  *aResult = mLogicalCursor;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::SetEOF()
+{
+  NS_NOTREACHED("nsStorageInputStream::SetEOF");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+nsresult
+nsStorageInputStream::Seek(uint32_t aPosition)
+{
+  uint32_t length = mStorageStream->mLogicalLength;
+  if (aPosition > length) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (length == 0) {
+    return NS_OK;
+  }
+
+  mSegmentNum = SegNum(aPosition);
+  mReadCursor = SegOffset(aPosition);
+  uint32_t available = length - aPosition;
+  mSegmentEnd = mReadCursor + XPCOM_MIN(mSegmentSize - mReadCursor, available);
+  mLogicalCursor = aPosition;
+  return NS_OK;
+}
+
+void
+nsStorageInputStream::Serialize(InputStreamParams& aParams, FileDescriptorArray&)
+{
+  nsCString combined;
+  int64_t offset;
+  mozilla::DebugOnly<nsresult> rv = Tell(&offset);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+  uint64_t remaining;
+  rv = Available(&remaining);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+  combined.SetCapacity(remaining);
+  uint32_t numRead = 0;
+
+  rv = Read(combined.BeginWriting(), remaining, &numRead);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  MOZ_ASSERT(numRead == remaining);
+  combined.SetLength(numRead);
+
+  rv = Seek(NS_SEEK_SET, offset);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+  StringInputStreamParams params;
+  params.data() = combined;
+  aParams = params;
+}
+
+Maybe<uint64_t>
+nsStorageInputStream::ExpectedSerializedLength()
+{
+  uint64_t remaining = 0;
+  DebugOnly<nsresult> rv = Available(&remaining);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  return Some(remaining);
+}
+
+bool
+nsStorageInputStream::Deserialize(const InputStreamParams& aParams,
+                                  const FileDescriptorArray&)
+{
+  NS_NOTREACHED("We should never attempt to deserialize a storage input stream.");
+  return false;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::GetCloneable(bool* aCloneableOut)
+{
+  *aCloneableOut = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Clone(nsIInputStream** aCloneOut)
+{
+  return mStorageStream->NewInputStream(mLogicalCursor, aCloneOut);
+}
+
+nsresult
+NS_NewStorageStream(uint32_t aSegmentSize, uint32_t aMaxSize,
+                    nsIStorageStream** aResult)
+{
+  RefPtr<nsStorageStream> storageStream = new nsStorageStream();
+  nsresult rv = storageStream->Init(aSegmentSize, aMaxSize);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  storageStream.forget(aResult);
+  return NS_OK;
+}
+
+// Undefine LOG, so that other .cpp files (or their includes) won't complain
+// about it already being defined, when we build in unified mode.
+#undef LOG