Line data Source code
1 : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
2 : *
3 : * This Source Code Form is subject to the terms of the Mozilla Public
4 : * License, v. 2.0. If a copy of the MPL was not distributed with this
5 : * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 :
7 : #include "nsCacheMetaData.h"
8 : #include "nsICacheEntryDescriptor.h"
9 :
10 : const char *
11 0 : nsCacheMetaData::GetElement(const char * key)
12 : {
13 0 : const char * data = mBuffer;
14 0 : const char * limit = mBuffer + mMetaSize;
15 :
16 0 : while (data < limit) {
17 : // Point to the value part
18 0 : const char * value = data + strlen(data) + 1;
19 0 : MOZ_ASSERT(value < limit, "Cache Metadata corrupted");
20 0 : if (strcmp(data, key) == 0)
21 0 : return value;
22 :
23 : // Skip value part
24 0 : data = value + strlen(value) + 1;
25 : }
26 0 : MOZ_ASSERT(data == limit, "Metadata corrupted");
27 0 : return nullptr;
28 : }
29 :
30 :
31 : nsresult
32 0 : nsCacheMetaData::SetElement(const char * key,
33 : const char * value)
34 : {
35 0 : const uint32_t keySize = strlen(key) + 1;
36 0 : char * pos = (char *)GetElement(key);
37 :
38 0 : if (!value) {
39 : // No value means remove the key/value pair completely, if existing
40 0 : if (pos) {
41 0 : uint32_t oldValueSize = strlen(pos) + 1;
42 0 : uint32_t offset = pos - mBuffer;
43 0 : uint32_t remainder = mMetaSize - (offset + oldValueSize);
44 :
45 0 : memmove(pos - keySize, pos + oldValueSize, remainder);
46 0 : mMetaSize -= keySize + oldValueSize;
47 : }
48 0 : return NS_OK;
49 : }
50 :
51 0 : const uint32_t valueSize = strlen(value) + 1;
52 0 : uint32_t newSize = mMetaSize + valueSize;
53 0 : if (pos) {
54 0 : const uint32_t oldValueSize = strlen(pos) + 1;
55 0 : const uint32_t offset = pos - mBuffer;
56 0 : const uint32_t remainder = mMetaSize - (offset + oldValueSize);
57 :
58 : // Update the value in place
59 0 : newSize -= oldValueSize;
60 0 : nsresult rv = EnsureBuffer(newSize);
61 0 : NS_ENSURE_SUCCESS(rv, rv);
62 :
63 : // Move the remainder to the right place
64 0 : pos = mBuffer + offset;
65 0 : memmove(pos + valueSize, pos + oldValueSize, remainder);
66 : } else {
67 : // allocate new meta data element
68 0 : newSize += keySize;
69 0 : nsresult rv = EnsureBuffer(newSize);
70 0 : NS_ENSURE_SUCCESS(rv, rv);
71 :
72 : // Add after last element
73 0 : pos = mBuffer + mMetaSize;
74 0 : memcpy(pos, key, keySize);
75 0 : pos += keySize;
76 : }
77 :
78 : // Update value
79 0 : memcpy(pos, value, valueSize);
80 0 : mMetaSize = newSize;
81 :
82 0 : return NS_OK;
83 : }
84 :
85 : nsresult
86 0 : nsCacheMetaData::FlattenMetaData(char * buffer, uint32_t bufSize)
87 : {
88 0 : if (mMetaSize > bufSize) {
89 0 : NS_ERROR("buffer size too small for meta data.");
90 0 : return NS_ERROR_OUT_OF_MEMORY;
91 : }
92 :
93 0 : memcpy(buffer, mBuffer, mMetaSize);
94 0 : return NS_OK;
95 : }
96 :
97 : nsresult
98 0 : nsCacheMetaData::UnflattenMetaData(const char * data, uint32_t size)
99 : {
100 0 : if (data && size) {
101 : // Check if the metadata ends with a zero byte.
102 0 : if (data[size-1] != '\0') {
103 0 : NS_ERROR("Cache MetaData is not null terminated");
104 0 : return NS_ERROR_ILLEGAL_VALUE;
105 : }
106 : // Check that there are an even number of zero bytes
107 : // to match the pattern { key \0 value \0 }
108 0 : bool odd = false;
109 0 : for (uint32_t i = 0; i < size; i++) {
110 0 : if (data[i] == '\0')
111 0 : odd = !odd;
112 : }
113 0 : if (odd) {
114 0 : NS_ERROR("Cache MetaData is malformed");
115 0 : return NS_ERROR_ILLEGAL_VALUE;
116 : }
117 :
118 0 : nsresult rv = EnsureBuffer(size);
119 0 : NS_ENSURE_SUCCESS(rv, rv);
120 :
121 0 : memcpy(mBuffer, data, size);
122 0 : mMetaSize = size;
123 : }
124 0 : return NS_OK;
125 : }
126 :
127 : nsresult
128 0 : nsCacheMetaData::VisitElements(nsICacheMetaDataVisitor * visitor)
129 : {
130 0 : const char * data = mBuffer;
131 0 : const char * limit = mBuffer + mMetaSize;
132 :
133 0 : while (data < limit) {
134 0 : const char * key = data;
135 : // Skip key part
136 0 : data += strlen(data) + 1;
137 0 : MOZ_ASSERT(data < limit, "Metadata corrupted");
138 : bool keepGoing;
139 0 : nsresult rv = visitor->VisitMetaDataElement(key, data, &keepGoing);
140 0 : if (NS_FAILED(rv) || !keepGoing)
141 0 : return NS_OK;
142 :
143 : // Skip value part
144 0 : data += strlen(data) + 1;
145 : }
146 0 : MOZ_ASSERT(data == limit, "Metadata corrupted");
147 0 : return NS_OK;
148 : }
149 :
150 : nsresult
151 0 : nsCacheMetaData::EnsureBuffer(uint32_t bufSize)
152 : {
153 0 : if (mBufferSize < bufSize) {
154 0 : char * buf = (char *)realloc(mBuffer, bufSize);
155 0 : if (!buf) {
156 0 : return NS_ERROR_OUT_OF_MEMORY;
157 : }
158 0 : mBuffer = buf;
159 0 : mBufferSize = bufSize;
160 : }
161 0 : return NS_OK;
162 : }
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