1 /* 2 * Copyright (C) 2010 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 #ifndef CachedMetadata_h 32 #define CachedMetadata_h 33 34 #include "wtf/Forward.h" 35 #include "wtf/RefCounted.h" 36 #include "wtf/Vector.h" 37 38 namespace blink { 39 40 // Metadata retrieved from the embedding application's cache. 41 // 42 // Serialized data is NOT portable across architectures. However, reading the 43 // data type ID will reject data generated with a different byte-order. 44 class CachedMetadata : public RefCounted<CachedMetadata> { 45 public: 46 static PassRefPtr<CachedMetadata> create(unsigned dataTypeID, const char* data, size_t size) 47 { 48 return adoptRef(new CachedMetadata(dataTypeID, data, size)); 49 } 50 51 static PassRefPtr<CachedMetadata> deserialize(const char* data, size_t size) 52 { 53 return adoptRef(new CachedMetadata(data, size)); 54 } 55 56 const Vector<char>& serialize() const 57 { 58 return m_serializedData; 59 } 60 61 ~CachedMetadata() { } 62 63 unsigned dataTypeID() const 64 { 65 return readUnsigned(dataTypeIDStart); 66 } 67 68 const char* data() const 69 { 70 if (m_serializedData.size() < dataStart) 71 return 0; 72 return m_serializedData.data() + dataStart; 73 } 74 75 size_t size() const 76 { 77 if (m_serializedData.size() < dataStart) 78 return 0; 79 return m_serializedData.size() - dataStart; 80 } 81 82 private: 83 // Reads an unsigned value at position. Returns 0 on error. 84 unsigned readUnsigned(size_t position) const 85 { 86 if (m_serializedData.size() < position + sizeof(unsigned)) 87 return 0; 88 return *reinterpret_cast_ptr<unsigned*>(const_cast<char*>(m_serializedData.data() + position)); 89 } 90 91 // Appends an unsigned value to the end of the serialized data. 92 void appendUnsigned(unsigned value) 93 { 94 m_serializedData.append(reinterpret_cast<const char*>(&value), sizeof(unsigned)); 95 } 96 97 CachedMetadata(const char* data, size_t size) 98 { 99 // Serialized metadata should have non-empty data. 100 ASSERT(size > dataStart); 101 102 m_serializedData.append(data, size); 103 } 104 105 CachedMetadata(unsigned dataTypeID, const char* data, size_t size) 106 { 107 // Don't allow an ID of 0, it is used internally to indicate errors. 108 ASSERT(dataTypeID); 109 ASSERT(data); 110 111 appendUnsigned(dataTypeID); 112 m_serializedData.append(data, size); 113 } 114 115 // Serialization offsets. Format: [DATA_TYPE_ID][DATA]. 116 static const size_t dataTypeIDStart = 0; 117 static const size_t dataStart = sizeof(unsigned); 118 119 // Since the serialization format supports random access, storing it in 120 // serialized form avoids need for a copy during serialization. 121 Vector<char> m_serializedData; 122 }; 123 124 } 125 126 #endif 127