1/* 2 * Copyright (C) 2013 Google Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions are 6 * met: 7 * 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above 11 * copyright notice, this list of conditions and the following disclaimer 12 * in the documentation and/or other materials provided with the 13 * distribution. 14 * * Neither the name of Google Inc. nor the names of its 15 * contributors may be used to endorse or promote products derived from 16 * this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31#include "config.h" 32#include "wtf/ArrayBufferBuilder.h" 33 34#include "wtf/Assertions.h" 35#include <limits> 36 37namespace WTF { 38 39static const int defaultBufferCapacity = 32768; 40 41ArrayBufferBuilder::ArrayBufferBuilder() 42 : m_bytesUsed(0) 43 , m_variableCapacity(true) 44{ 45 m_buffer = ArrayBuffer::create(defaultBufferCapacity, 1); 46} 47 48bool ArrayBufferBuilder::expandCapacity(unsigned sizeToIncrease) 49{ 50 unsigned currentBufferSize = m_buffer->byteLength(); 51 52 // If the size of the buffer exceeds max of unsigned, it can't be grown any 53 // more. 54 if (sizeToIncrease > std::numeric_limits<unsigned>::max() - m_bytesUsed) 55 return false; 56 57 unsigned newBufferSize = m_bytesUsed + sizeToIncrease; 58 59 // Grow exponentially if possible. 60 unsigned exponentialGrowthNewBufferSize = std::numeric_limits<unsigned>::max(); 61 if (currentBufferSize <= std::numeric_limits<unsigned>::max() / 2) 62 exponentialGrowthNewBufferSize = currentBufferSize * 2; 63 if (exponentialGrowthNewBufferSize > newBufferSize) 64 newBufferSize = exponentialGrowthNewBufferSize; 65 66 // Copy existing data in current buffer to new buffer. 67 RefPtr<ArrayBuffer> newBuffer = ArrayBuffer::create(newBufferSize, 1); 68 if (!newBuffer) 69 return false; 70 71 memcpy(newBuffer->data(), m_buffer->data(), m_bytesUsed); 72 m_buffer = newBuffer; 73 return true; 74} 75 76unsigned ArrayBufferBuilder::append(const char* data, unsigned length) 77{ 78 ASSERT(length > 0); 79 80 unsigned currentBufferSize = m_buffer->byteLength(); 81 82 ASSERT(m_bytesUsed <= currentBufferSize); 83 84 unsigned remainingBufferSpace = currentBufferSize - m_bytesUsed; 85 86 unsigned bytesToSave = length; 87 88 if (length > remainingBufferSpace) { 89 if (m_variableCapacity) { 90 if (!expandCapacity(length)) 91 return 0; 92 } else { 93 bytesToSave = remainingBufferSpace; 94 } 95 } 96 97 memcpy(static_cast<char*>(m_buffer->data()) + m_bytesUsed, data, bytesToSave); 98 m_bytesUsed += bytesToSave; 99 100 return bytesToSave; 101} 102 103PassRefPtr<ArrayBuffer> ArrayBufferBuilder::toArrayBuffer() 104{ 105 // Fully used. Return m_buffer as-is. 106 if (m_buffer->byteLength() == m_bytesUsed) 107 return m_buffer; 108 109 return m_buffer->slice(0, m_bytesUsed); 110} 111 112String ArrayBufferBuilder::toString() 113{ 114 return String(static_cast<const char*>(m_buffer->data()), m_bytesUsed); 115} 116 117void ArrayBufferBuilder::shrinkToFit() 118{ 119 ASSERT(m_bytesUsed <= m_buffer->byteLength()); 120 121 if (m_buffer->byteLength() > m_bytesUsed) 122 m_buffer = m_buffer->slice(0, m_bytesUsed); 123} 124 125} // namespace WTF 126