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393 lines
11 KiB
C++
393 lines
11 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* The contents of this file are subject to the Netscape Public
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* License Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.mozilla.org/NPL/
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*
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* Software distributed under the License is distributed on an "AS
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
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* implied. See the License for the specific language governing
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* rights and limitations under the License.
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*
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* The Original Code is Mozilla Communicator client code, released
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* March 31, 1998.
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*
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* The Initial Developer of the Original Code is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998-1999 Netscape Communications Corporation. All
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* Rights Reserved.
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*
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* Contributor(s):
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* Pierre Phaneuf <pp@ludusdesign.com>
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*/
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/*
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* The storage stream provides an internal buffer that can be filled by a
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* client using a single output stream. One or more independent input streams
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* can be created to read the data out non-destructively. The implementation
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* uses a segmented buffer internally to avoid realloc'ing of large buffers,
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* with the attendant performance loss and heap fragmentation.
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*/
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#include "nsStorageStream.h"
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#include "nsSegmentedBuffer.h"
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#include "nsCOMPtr.h"
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#include "prbit.h"
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nsStorageStream::nsStorageStream()
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: mSegmentedBuffer(0), mSegmentSize(0), mWriteInProgress(PR_FALSE),
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mLastSegmentNum(-1), mWriteCursor(0), mSegmentEnd(0), mLogicalLength(0)
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{
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NS_INIT_REFCNT();
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}
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nsStorageStream::~nsStorageStream()
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{
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if (mSegmentedBuffer)
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delete mSegmentedBuffer;
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}
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NS_IMPL_ADDREF(nsStorageStream)
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NS_IMPL_RELEASE(nsStorageStream)
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// Multiple inheritance requires customized QI
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NS_IMETHODIMP
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nsStorageStream::QueryInterface(const nsIID& aIID, void** aInstancePtr)
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{
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if (aInstancePtr == nsnull)
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return NS_ERROR_NULL_POINTER;
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if (aIID.Equals(NS_GET_IID(nsIStorageStream)) ||
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aIID.Equals(NS_GET_IID(nsISupports))) {
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NS_ADDREF(this);
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*aInstancePtr = NS_STATIC_CAST(nsIStorageStream*, this);
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return NS_OK;
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} else if (aIID.Equals(NS_GET_IID(nsIOutputStream))) {
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NS_ADDREF(this);
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*aInstancePtr = NS_STATIC_CAST(nsIOutputStream*, this);
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return NS_OK;
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}
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return NS_NOINTERFACE;
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}
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NS_IMETHODIMP
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nsStorageStream::Init(PRUint32 segmentSize, PRUint32 maxSize,
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nsIAllocator *segmentAllocator)
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{
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mSegmentedBuffer = new nsSegmentedBuffer();
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if (!mSegmentedBuffer)
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return NS_ERROR_OUT_OF_MEMORY;
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mSegmentSize = segmentSize;
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mSegmentSizeLog2 = PR_FloorLog2(segmentSize);
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// Segment size must be a power of two
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if (mSegmentSize != ((PRUint32)1 << mSegmentSizeLog2))
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return NS_ERROR_INVALID_ARG;
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return mSegmentedBuffer->Init(segmentSize, maxSize, segmentAllocator);
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}
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NS_IMETHODIMP
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nsStorageStream::GetOutputStream(PRInt32 aStartingOffset,
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nsIOutputStream * *aOutputStream)
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{
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NS_ENSURE_ARG(aOutputStream);
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if (mWriteInProgress)
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return NS_ERROR_NOT_AVAILABLE;
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nsresult rv = Seek(aStartingOffset);
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if (NS_FAILED(rv)) return rv;
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// Enlarge the last segment in the buffer so that it is the same size as
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// all the other segments in the buffer. (It may have been realloc'ed
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// smaller in the Close() method.)
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if (mLastSegmentNum >= 0)
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mSegmentedBuffer->ReallocLastSegment(mSegmentSize);
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// Need to re-Seek, since realloc might have changed segment base pointer
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rv = Seek(aStartingOffset);
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if (NS_FAILED(rv)) return rv;
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NS_ADDREF(this);
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*aOutputStream = NS_STATIC_CAST(nsIOutputStream*, this);
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mWriteInProgress = PR_TRUE;
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return NS_OK;
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}
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NS_IMETHODIMP
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nsStorageStream::Close()
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{
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mWriteInProgress = PR_FALSE;
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PRInt32 segmentOffset = SegOffset(mLogicalLength);
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// Shrink the final segment in the segmented buffer to the minimum size
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// needed to contain the data, so as to conserve memory.
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if (segmentOffset)
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mSegmentedBuffer->ReallocLastSegment(segmentOffset);
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mWriteCursor = 0;
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mSegmentEnd = 0;
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return NS_OK;
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}
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NS_IMETHODIMP
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nsStorageStream::Flush()
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{
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return NS_OK;
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}
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NS_IMETHODIMP
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nsStorageStream::Write(const char *aBuffer, PRUint32 aCount, PRUint32 *aNumWritten)
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{
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const char* readCursor;
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PRUint32 count, availableInSegment, remaining;
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nsresult rv = NS_OK;
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NS_ENSURE_ARG_POINTER(aNumWritten);
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NS_ENSURE_ARG(aBuffer);
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remaining = aCount;
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readCursor = aBuffer;
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while (remaining) {
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availableInSegment = mSegmentEnd - mWriteCursor;
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if (!availableInSegment) {
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mWriteCursor = mSegmentedBuffer->AppendNewSegment();
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mLastSegmentNum++;
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if (!mWriteCursor) {
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rv = NS_ERROR_OUT_OF_MEMORY;
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goto out;
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}
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mSegmentEnd = mWriteCursor + mSegmentSize;
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availableInSegment = mSegmentEnd - mWriteCursor;
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}
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count = PR_MIN(availableInSegment, remaining);
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memcpy(mWriteCursor, readCursor, count);
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remaining -= count;
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readCursor += count;
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mWriteCursor += count;
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};
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out:
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*aNumWritten = aCount - remaining;
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mLogicalLength += *aNumWritten;
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return rv;
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}
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NS_IMETHODIMP
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nsStorageStream::GetLength(PRUint32 *aLength)
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{
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NS_ENSURE_ARG(aLength);
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*aLength = mLogicalLength;
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return NS_OK;
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}
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// Truncate the buffer by deleting the end segments
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NS_IMETHODIMP
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nsStorageStream::SetLength(PRUint32 aLength)
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{
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if (mWriteInProgress)
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return NS_ERROR_NOT_AVAILABLE;
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if (aLength > mLogicalLength)
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return NS_ERROR_INVALID_ARG;
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PRInt32 newLastSegmentNum = SegNum(aLength);
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PRInt32 segmentOffset = SegOffset(aLength);
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if (segmentOffset == 0)
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newLastSegmentNum--;
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while (newLastSegmentNum < mLastSegmentNum) {
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mSegmentedBuffer->DeleteLastSegment();
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mLastSegmentNum--;
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}
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mLogicalLength = aLength;
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return NS_OK;
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}
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NS_IMETHODIMP
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nsStorageStream::GetWriteInProgress(PRBool *aWriteInProgress)
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{
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NS_ENSURE_ARG(aWriteInProgress);
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*aWriteInProgress = mWriteInProgress;
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return NS_OK;
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}
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NS_METHOD
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nsStorageStream::Seek(PRInt32 aPosition)
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{
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// An argument of -1 means "seek to end of stream"
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if (aPosition == -1)
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aPosition = mLogicalLength;
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// Seeking beyond the buffer end is illegal
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if ((PRUint32)aPosition > mLogicalLength)
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return NS_ERROR_INVALID_ARG;
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// Seeking backwards in the write stream results in truncation
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SetLength(aPosition);
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// Special handling for seek to start-of-buffer
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if (aPosition == 0) {
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mWriteCursor = 0;
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mSegmentEnd = 0;
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return NS_OK;
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}
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// Segment may have changed, so reset pointers
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mWriteCursor = mSegmentedBuffer->GetSegment(mLastSegmentNum);
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mSegmentEnd = mWriteCursor + mSegmentSize;
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PRInt32 segmentOffset = SegOffset(aPosition);
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mWriteCursor += segmentOffset;
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return NS_OK;
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}
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// There can be many nsStorageInputStreams for a single nsStorageStream
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class nsStorageInputStream : public nsIInputStream
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{
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public:
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nsStorageInputStream(nsStorageStream *aStorageStream, PRUint32 aSegmentSize)
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: mStorageStream(aStorageStream), mReadCursor(0),
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mSegmentEnd(0), mSegmentNum(0),
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mSegmentSize(aSegmentSize), mLogicalCursor(0)
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{
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NS_ADDREF(mStorageStream);
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NS_INIT_REFCNT();
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}
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virtual ~nsStorageInputStream()
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{
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NS_IF_RELEASE(mStorageStream);
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}
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NS_DECL_ISUPPORTS
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NS_DECL_NSIBASESTREAM
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NS_DECL_NSIINPUTSTREAM
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protected:
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NS_METHOD Seek(PRUint32 aPosition);
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friend class nsStorageStream;
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private:
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nsStorageStream* mStorageStream;
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const char* mReadCursor; // Next memory location to read byte, or NULL
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const char* mSegmentEnd; // One byte past end of current buffer segment
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PRUint32 mSegmentNum; // Segment number containing read cursor
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PRUint32 mSegmentSize; // All segments, except the last, are of this size
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PRUint32 mLogicalCursor; // Logical offset into stream
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PRUint32 SegNum(PRUint32 aPosition) {return aPosition >> mStorageStream->mSegmentSizeLog2;}
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PRUint32 SegOffset(PRUint32 aPosition) {return aPosition & (mSegmentSize - 1);}
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};
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NS_IMPL_ISUPPORTS1(nsStorageInputStream, nsIInputStream)
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NS_IMETHODIMP
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nsStorageStream::NewInputStream(PRInt32 aStartingOffset, nsIInputStream* *aInputStream)
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{
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nsStorageInputStream *inputStream = new nsStorageInputStream(this, mSegmentSize);
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if (!inputStream)
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return NS_ERROR_OUT_OF_MEMORY;
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NS_ADDREF(inputStream);
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if (aStartingOffset) {
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nsresult rv = inputStream->Seek(aStartingOffset);
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if (NS_FAILED(rv)) {
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NS_RELEASE(inputStream);
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return rv;
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}
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}
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*aInputStream = inputStream;
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return NS_OK;
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}
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NS_IMETHODIMP
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nsStorageInputStream::Close()
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{
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return NS_OK;
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}
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NS_IMETHODIMP
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nsStorageInputStream::Available(PRUint32 *aAvailable)
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{
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*aAvailable = mStorageStream->mLogicalLength - mLogicalCursor;
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return NS_OK;
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}
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NS_IMETHODIMP
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nsStorageInputStream::Read(char* aBuffer, PRUint32 aCount, PRUint32 *aNumRead)
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{
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char* writeCursor;
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PRUint32 count, availableInSegment, remainingCapacity;
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remainingCapacity = aCount;
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writeCursor = aBuffer;
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while (remainingCapacity) {
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availableInSegment = mSegmentEnd - mReadCursor;
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if (!availableInSegment) {
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PRUint32 available = mStorageStream->mLogicalLength - mLogicalCursor;
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if (!available)
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goto out;
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mReadCursor = mStorageStream->mSegmentedBuffer->GetSegment(mSegmentNum++);
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mSegmentEnd = mReadCursor + PR_MIN(mSegmentSize, available);
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}
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count = PR_MIN(availableInSegment, remainingCapacity);
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memcpy(writeCursor, mReadCursor, count);
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remainingCapacity -= count;
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mReadCursor += count;
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writeCursor += count;
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mLogicalCursor += count;
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};
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out:
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*aNumRead = aCount - remainingCapacity;
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if (*aNumRead == 0)
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return NS_BASE_STREAM_WOULD_BLOCK;
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else
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return NS_OK;
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}
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NS_METHOD
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nsStorageInputStream::Seek(PRUint32 aPosition)
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{
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PRUint32 length = mStorageStream->mLogicalLength;
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if (aPosition >= length)
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return NS_ERROR_INVALID_ARG;
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mSegmentNum = SegNum(aPosition);
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PRUint32 segmentOffset = SegOffset(aPosition);
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mReadCursor = mStorageStream->mSegmentedBuffer->GetSegment(mSegmentNum) +
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segmentOffset;
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PRUint32 available = length - aPosition;
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mSegmentEnd = mReadCursor + PR_MIN(mSegmentSize - segmentOffset, available);
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mLogicalCursor = aPosition;
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return NS_OK;
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}
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NS_COM nsresult
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NS_NewStorageStream(PRUint32 segmentSize, PRUint32 maxSize, nsIStorageStream **result)
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{
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NS_ENSURE_ARG(result);
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nsStorageStream* storageStream = new nsStorageStream();
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if (!storageStream) return NS_ERROR_OUT_OF_MEMORY;
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storageStream->Init(segmentSize, maxSize);
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NS_ADDREF(storageStream);
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*result = storageStream;
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return NS_OK;
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}
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