xpcom/io/nsSegmentedBuffer.cpp@97036ab72558
xpcom/io/nsSegmentedBuffer.cpp
Tue, 06 Jan 2015 21:39:09 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Tue, 06 Jan 2015 21:39:09 +0100
- branch
- TOR_BUG_9701
- changeset 8
- 97036ab72558
- permissions
- -rw-r--r--
Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.
1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2 /* This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 #include "nsSegmentedBuffer.h"
7 #include "nsMemory.h"
9 nsresult
10 nsSegmentedBuffer::Init(uint32_t segmentSize, uint32_t maxSize)
11 {
12 if (mSegmentArrayCount != 0)
13 return NS_ERROR_FAILURE; // initialized more than once
14 mSegmentSize = segmentSize;
15 mMaxSize = maxSize;
16 #if 0 // testing...
17 mSegmentArrayCount = 2;
18 #else
19 mSegmentArrayCount = NS_SEGMENTARRAY_INITIAL_COUNT;
20 #endif
21 return NS_OK;
22 }
24 char*
25 nsSegmentedBuffer::AppendNewSegment()
26 {
27 if (GetSize() >= mMaxSize)
28 return nullptr;
30 if (mSegmentArray == nullptr) {
31 uint32_t bytes = mSegmentArrayCount * sizeof(char*);
32 mSegmentArray = (char**)nsMemory::Alloc(bytes);
33 if (mSegmentArray == nullptr)
34 return nullptr;
35 memset(mSegmentArray, 0, bytes);
36 }
38 if (IsFull()) {
39 uint32_t newArraySize = mSegmentArrayCount * 2;
40 uint32_t bytes = newArraySize * sizeof(char*);
41 char** newSegArray = (char**)nsMemory::Realloc(mSegmentArray, bytes);
42 if (newSegArray == nullptr)
43 return nullptr;
44 mSegmentArray = newSegArray;
45 // copy wrapped content to new extension
46 if (mFirstSegmentIndex > mLastSegmentIndex) {
47 // deal with wrap around case
48 memcpy(&mSegmentArray[mSegmentArrayCount],
49 mSegmentArray,
50 mLastSegmentIndex * sizeof(char*));
51 memset(mSegmentArray, 0, mLastSegmentIndex * sizeof(char*));
52 mLastSegmentIndex += mSegmentArrayCount;
53 memset(&mSegmentArray[mLastSegmentIndex], 0,
54 (newArraySize - mLastSegmentIndex) * sizeof(char*));
55 }
56 else {
57 memset(&mSegmentArray[mLastSegmentIndex], 0,
58 (newArraySize - mLastSegmentIndex) * sizeof(char*));
59 }
60 mSegmentArrayCount = newArraySize;
61 }
63 char* seg = (char*)moz_malloc(mSegmentSize);
64 if (seg == nullptr) {
65 return nullptr;
66 }
67 mSegmentArray[mLastSegmentIndex] = seg;
68 mLastSegmentIndex = ModSegArraySize(mLastSegmentIndex + 1);
69 return seg;
70 }
72 bool
73 nsSegmentedBuffer::DeleteFirstSegment()
74 {
75 NS_ASSERTION(mSegmentArray[mFirstSegmentIndex] != nullptr, "deleting bad segment");
76 moz_free(mSegmentArray[mFirstSegmentIndex]);
77 mSegmentArray[mFirstSegmentIndex] = nullptr;
78 int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
79 if (mFirstSegmentIndex == last) {
80 mLastSegmentIndex = last;
81 return true;
82 }
83 else {
84 mFirstSegmentIndex = ModSegArraySize(mFirstSegmentIndex + 1);
85 return false;
86 }
87 }
89 bool
90 nsSegmentedBuffer::DeleteLastSegment()
91 {
92 int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
93 NS_ASSERTION(mSegmentArray[last] != nullptr, "deleting bad segment");
94 moz_free(mSegmentArray[last]);
95 mSegmentArray[last] = nullptr;
96 mLastSegmentIndex = last;
97 return (bool)(mLastSegmentIndex == mFirstSegmentIndex);
98 }
100 bool
101 nsSegmentedBuffer::ReallocLastSegment(size_t newSize)
102 {
103 int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
104 NS_ASSERTION(mSegmentArray[last] != nullptr, "realloc'ing bad segment");
105 char *newSegment =
106 (char*)moz_realloc(mSegmentArray[last], newSize);
107 if (newSegment) {
108 mSegmentArray[last] = newSegment;
109 return true;
110 } else {
111 return false;
112 }
113 }
115 void
116 nsSegmentedBuffer::Empty()
117 {
118 if (mSegmentArray) {
119 for (uint32_t i = 0; i < mSegmentArrayCount; i++) {
120 if (mSegmentArray[i])
121 moz_free(mSegmentArray[i]);
122 }
123 nsMemory::Free(mSegmentArray);
124 mSegmentArray = nullptr;
125 }
126 mSegmentArrayCount = NS_SEGMENTARRAY_INITIAL_COUNT;
127 mFirstSegmentIndex = mLastSegmentIndex = 0;
128 }
130 #if 0
131 void
132 TestSegmentedBuffer()
133 {
134 nsSegmentedBuffer* buf = new nsSegmentedBuffer();
135 NS_ASSERTION(buf, "out of memory");
136 buf->Init(4, 16);
137 char* seg;
138 bool empty;
139 seg = buf->AppendNewSegment();
140 NS_ASSERTION(seg, "AppendNewSegment failed");
141 seg = buf->AppendNewSegment();
142 NS_ASSERTION(seg, "AppendNewSegment failed");
143 seg = buf->AppendNewSegment();
144 NS_ASSERTION(seg, "AppendNewSegment failed");
145 empty = buf->DeleteFirstSegment();
146 NS_ASSERTION(!empty, "DeleteFirstSegment failed");
147 empty = buf->DeleteFirstSegment();
148 NS_ASSERTION(!empty, "DeleteFirstSegment failed");
149 seg = buf->AppendNewSegment();
150 NS_ASSERTION(seg, "AppendNewSegment failed");
151 seg = buf->AppendNewSegment();
152 NS_ASSERTION(seg, "AppendNewSegment failed");
153 seg = buf->AppendNewSegment();
154 NS_ASSERTION(seg, "AppendNewSegment failed");
155 empty = buf->DeleteFirstSegment();
156 NS_ASSERTION(!empty, "DeleteFirstSegment failed");
157 empty = buf->DeleteFirstSegment();
158 NS_ASSERTION(!empty, "DeleteFirstSegment failed");
159 empty = buf->DeleteFirstSegment();
160 NS_ASSERTION(!empty, "DeleteFirstSegment failed");
161 empty = buf->DeleteFirstSegment();
162 NS_ASSERTION(empty, "DeleteFirstSegment failed");
163 delete buf;
164 }
165 #endif
167 ////////////////////////////////////////////////////////////////////////////////
