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1 /*
2  * Copyright (C) 2008 Apple 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
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24  */
25 
26 #include "config.h"
27 #include "StorageMap.h"
28 
29 #if ENABLE(DOM_STORAGE)
30 
31 namespace WebCore {
32 
create(unsigned quota)33 PassRefPtr<StorageMap> StorageMap::create(unsigned quota)
34 {
35     return adoptRef(new StorageMap(quota));
36 }
37 
StorageMap(unsigned quota)38 StorageMap::StorageMap(unsigned quota)
39     : m_iterator(m_map.end())
40     , m_iteratorIndex(UINT_MAX)
41     , m_quotaSize(quota)  // quota measured in bytes
42     , m_currentLength(0)
43 {
44 }
45 
copy()46 PassRefPtr<StorageMap> StorageMap::copy()
47 {
48     RefPtr<StorageMap> newMap = create(m_quotaSize);
49     newMap->m_map = m_map;
50     newMap->m_currentLength = m_currentLength;
51     return newMap.release();
52 }
53 
invalidateIterator()54 void StorageMap::invalidateIterator()
55 {
56     m_iterator = m_map.end();
57     m_iteratorIndex = UINT_MAX;
58 }
59 
setIteratorToIndex(unsigned index)60 void StorageMap::setIteratorToIndex(unsigned index)
61 {
62     // FIXME: Once we have bidirectional iterators for HashMap we can be more intelligent about this.
63     // The requested index will be closest to begin(), our current iterator, or end(), and we
64     // can take the shortest route.
65     // Until that mechanism is available, we'll always increment our iterator from begin() or current.
66 
67     if (m_iteratorIndex == index)
68         return;
69 
70     if (index < m_iteratorIndex) {
71         m_iteratorIndex = 0;
72         m_iterator = m_map.begin();
73         ASSERT(m_iterator != m_map.end());
74     }
75 
76     while (m_iteratorIndex < index) {
77         ++m_iteratorIndex;
78         ++m_iterator;
79         ASSERT(m_iterator != m_map.end());
80     }
81 }
82 
length() const83 unsigned StorageMap::length() const
84 {
85     return m_map.size();
86 }
87 
key(unsigned index)88 String StorageMap::key(unsigned index)
89 {
90     if (index >= length())
91         return String();
92 
93     setIteratorToIndex(index);
94     return m_iterator->first;
95 }
96 
getItem(const String & key) const97 String StorageMap::getItem(const String& key) const
98 {
99     return m_map.get(key);
100 }
101 
setItem(const String & key,const String & value,String & oldValue,bool & quotaException)102 PassRefPtr<StorageMap> StorageMap::setItem(const String& key, const String& value, String& oldValue, bool& quotaException)
103 {
104     ASSERT(!value.isNull());
105     quotaException = false;
106 
107     // Implement copy-on-write semantics here.  We're guaranteed that the only refs of StorageMaps belong to Storage objects
108     // so if more than one Storage object refs this map, copy it before mutating it.
109     if (refCount() > 1) {
110         RefPtr<StorageMap> newStorageMap = copy();
111         newStorageMap->setItem(key, value, oldValue, quotaException);
112         return newStorageMap.release();
113     }
114 
115     // Quota tracking.  This is done in a couple of steps to keep the overflow tracking simple.
116     unsigned newLength = m_currentLength;
117     bool overflow = newLength + value.length() < newLength;
118     newLength += value.length();
119 
120     oldValue = m_map.get(key);
121     overflow |= newLength - oldValue.length() > newLength;
122     newLength -= oldValue.length();
123 
124     unsigned adjustedKeyLength = oldValue.isNull() ? key.length() : 0;
125     overflow |= newLength + adjustedKeyLength < newLength;
126     newLength += adjustedKeyLength;
127 
128     ASSERT(!overflow);  // Overflow is bad...even if quotas are off.
129     bool overQuota = newLength > m_quotaSize / sizeof(UChar);
130     if (m_quotaSize != noQuota && (overflow || overQuota)) {
131         quotaException = true;
132         return 0;
133     }
134     m_currentLength = newLength;
135 
136     pair<HashMap<String, String>::iterator, bool> addResult = m_map.add(key, value);
137     if (!addResult.second)
138         addResult.first->second = value;
139 
140     invalidateIterator();
141 
142     return 0;
143 }
144 
removeItem(const String & key,String & oldValue)145 PassRefPtr<StorageMap> StorageMap::removeItem(const String& key, String& oldValue)
146 {
147     // Implement copy-on-write semantics here.  We're guaranteed that the only refs of StorageMaps belong to Storage objects
148     // so if more than one Storage object refs this map, copy it before mutating it.
149     if (refCount() > 1) {
150         RefPtr<StorageMap> newStorage = copy();
151         newStorage->removeItem(key, oldValue);
152         return newStorage.release();
153     }
154 
155     oldValue = m_map.take(key);
156     if (!oldValue.isNull()) {
157         invalidateIterator();
158         ASSERT(m_currentLength - key.length() <= m_currentLength);
159         m_currentLength -= key.length();
160     }
161     ASSERT(m_currentLength - oldValue.length() <= m_currentLength);
162     m_currentLength -= oldValue.length();
163 
164     return 0;
165 }
166 
contains(const String & key) const167 bool StorageMap::contains(const String& key) const
168 {
169     return m_map.contains(key);
170 }
171 
importItem(const String & key,const String & value)172 void StorageMap::importItem(const String& key, const String& value)
173 {
174     // Be sure to copy the keys/values as items imported on a background thread are destined
175     // to cross a thread boundary
176     pair<HashMap<String, String>::iterator, bool> result = m_map.add(key.threadsafeCopy(), value.threadsafeCopy());
177     ASSERT(result.second);  // True if the key didn't exist previously.
178 
179     ASSERT(m_currentLength + key.length() >= m_currentLength);
180     m_currentLength += key.length();
181     ASSERT(m_currentLength + value.length() >= m_currentLength);
182     m_currentLength += value.length();
183 }
184 
185 }
186 
187 #endif // ENABLE(DOM_STORAGE)
188