1/*
2 * Copyright (C) 2010 Apple Inc. All rights reserved.
3 * Copyright (c) 2010 University of Szeged
4 * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
17 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
18 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
19 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
20 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
21 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
23 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
24 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
25 * THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#include "config.h"
29#if USE(UNIX_DOMAIN_SOCKETS)
30#include "SharedMemory.h"
31
32#include "Decoder.h"
33#include "Encoder.h"
34#include <errno.h>
35#include <fcntl.h>
36#include <stdlib.h>
37#include <sys/mman.h>
38#include <sys/stat.h>
39#include <sys/types.h>
40#include <unistd.h>
41#include <wtf/Assertions.h>
42#include <wtf/RandomNumber.h>
43#include <wtf/UniStdExtras.h>
44#include <wtf/text/CString.h>
45#include <wtf/text/WTFString.h>
46
47#if HAVE(LINUX_MEMFD_H)
48#include <linux/memfd.h>
49#include <sys/syscall.h>
50#endif
51
52namespace WebKit {
53
54SharedMemory::Handle::Handle()
55{
56}
57
58SharedMemory::Handle::~Handle()
59{
60}
61
62SharedMemory::Handle::Handle(Handle&&) = default;
63SharedMemory::Handle& SharedMemory::Handle::operator=(Handle&& other) = default;
64
65void SharedMemory::Handle::clear()
66{
67 m_attachment = IPC::Attachment();
68}
69
70bool SharedMemory::Handle::isNull() const
71{
72 return m_attachment.fileDescriptor() == -1;
73}
74
75void SharedMemory::Handle::encode(IPC::Encoder& encoder) const
76{
77 encoder << releaseAttachment();
78}
79
80bool SharedMemory::Handle::decode(IPC::Decoder& decoder, Handle& handle)
81{
82 ASSERT_ARG(handle, handle.isNull());
83
84 IPC::Attachment attachment;
85 if (!decoder.decode(attachment))
86 return false;
87
88 handle.adoptAttachment(WTFMove(attachment));
89 return true;
90}
91
92IPC::Attachment SharedMemory::Handle::releaseAttachment() const
93{
94 return WTFMove(m_attachment);
95}
96
97void SharedMemory::Handle::adoptAttachment(IPC::Attachment&& attachment)
98{
99 ASSERT(isNull());
100
101 m_attachment = WTFMove(attachment);
102}
103
104static inline int accessModeMMap(SharedMemory::Protection protection)
105{
106 switch (protection) {
107 case SharedMemory::Protection::ReadOnly:
108 return PROT_READ;
109 case SharedMemory::Protection::ReadWrite:
110 return PROT_READ | PROT_WRITE;
111 }
112
113 ASSERT_NOT_REACHED();
114 return PROT_READ | PROT_WRITE;
115}
116
117static int createSharedMemory()
118{
119 int fileDescriptor = -1;
120
121#if HAVE(LINUX_MEMFD_H)
122 static bool isMemFdAvailable = true;
123 if (isMemFdAvailable) {
124 do {
125 fileDescriptor = syscall(__NR_memfd_create, "WebKitSharedMemory", MFD_CLOEXEC);
126 } while (fileDescriptor == -1 && errno == EINTR);
127
128 if (fileDescriptor != -1)
129 return fileDescriptor;
130
131 if (errno != ENOSYS)
132 return fileDescriptor;
133
134 isMemFdAvailable = false;
135 }
136#endif
137
138 CString tempName;
139 for (int tries = 0; fileDescriptor == -1 && tries < 10; ++tries) {
140 String name = String("/WK2SharedMemory.") + String::number(static_cast<unsigned>(WTF::randomNumber() * (std::numeric_limits<unsigned>::max() + 1.0)));
141 tempName = name.utf8();
142
143 do {
144 fileDescriptor = shm_open(tempName.data(), O_CREAT | O_RDWR, S_IRUSR | S_IWUSR);
145 } while (fileDescriptor == -1 && errno == EINTR);
146 }
147
148 if (fileDescriptor != -1)
149 shm_unlink(tempName.data());
150
151 return fileDescriptor;
152}
153
154RefPtr<SharedMemory> SharedMemory::allocate(size_t size)
155{
156 int fileDescriptor = createSharedMemory();
157 if (fileDescriptor == -1) {
158 WTFLogAlways("Failed to create shared memory: %s", strerror(errno));
159 return nullptr;
160 }
161
162 while (ftruncate(fileDescriptor, size) == -1) {
163 if (errno != EINTR) {
164 closeWithRetry(fileDescriptor);
165 return nullptr;
166 }
167 }
168
169 void* data = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fileDescriptor, 0);
170 if (data == MAP_FAILED) {
171 closeWithRetry(fileDescriptor);
172 return nullptr;
173 }
174
175 RefPtr<SharedMemory> instance = adoptRef(new SharedMemory());
176 instance->m_data = data;
177 instance->m_fileDescriptor = fileDescriptor;
178 instance->m_size = size;
179 return instance;
180}
181
182RefPtr<SharedMemory> SharedMemory::map(const Handle& handle, Protection protection)
183{
184 ASSERT(!handle.isNull());
185
186 int fd = handle.m_attachment.releaseFileDescriptor();
187 void* data = mmap(0, handle.m_attachment.size(), accessModeMMap(protection), MAP_SHARED, fd, 0);
188 closeWithRetry(fd);
189 if (data == MAP_FAILED)
190 return nullptr;
191
192 RefPtr<SharedMemory> instance = wrapMap(data, handle.m_attachment.size(), -1);
193 instance->m_fileDescriptor = WTF::nullopt;
194 instance->m_isWrappingMap = false;
195 return instance;
196}
197
198RefPtr<SharedMemory> SharedMemory::wrapMap(void* data, size_t size, int fileDescriptor)
199{
200 RefPtr<SharedMemory> instance = adoptRef(new SharedMemory());
201 instance->m_data = data;
202 instance->m_size = size;
203 instance->m_fileDescriptor = fileDescriptor;
204 instance->m_isWrappingMap = true;
205 return instance;
206}
207
208SharedMemory::~SharedMemory()
209{
210 if (m_isWrappingMap)
211 return;
212
213 munmap(m_data, m_size);
214 if (m_fileDescriptor)
215 closeWithRetry(m_fileDescriptor.value());
216}
217
218bool SharedMemory::createHandle(Handle& handle, Protection)
219{
220 ASSERT_ARG(handle, handle.isNull());
221 ASSERT(m_fileDescriptor);
222
223 // FIXME: Handle the case where the passed Protection is ReadOnly.
224 // See https://bugs.webkit.org/show_bug.cgi?id=131542.
225
226 int duplicatedHandle = dupCloseOnExec(m_fileDescriptor.value());
227 if (duplicatedHandle == -1) {
228 ASSERT_NOT_REACHED();
229 return false;
230 }
231 handle.m_attachment = IPC::Attachment(duplicatedHandle, m_size);
232 return true;
233}
234
235unsigned SharedMemory::systemPageSize()
236{
237 static unsigned pageSize = 0;
238
239 if (!pageSize)
240 pageSize = getpagesize();
241
242 return pageSize;
243}
244
245} // namespace WebKit
246
247#endif
248
249