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