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1 // Copyright 2014 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "mojo/edk/embedder/platform_channel_utils_posix.h" | |
6 | |
7 #include <sys/socket.h> | |
8 #include <sys/uio.h> | |
9 #include <unistd.h> | |
10 | |
11 #include "base/logging.h" | |
12 #include "base/posix/eintr_wrapper.h" | |
13 #include "build/build_config.h" | |
14 | |
15 namespace mojo { | |
16 namespace embedder { | |
17 | |
18 // On Linux, |SIGPIPE| is suppressed by passing |MSG_NOSIGNAL| to | |
19 // |send()|/|sendmsg()|. (There is no way of suppressing |SIGPIPE| on | |
20 // |write()|/|writev().) On Mac, |SIGPIPE| is suppressed by setting the | |
21 // |SO_NOSIGPIPE| option on the socket. | |
22 // | |
23 // Performance notes: | |
24 // - On Linux, we have to use |send()|/|sendmsg()| rather than | |
25 // |write()|/|writev()| in order to suppress |SIGPIPE|. This is okay, since | |
26 // |send()| is (slightly) faster than |write()| (!), while |sendmsg()| is | |
27 // quite comparable to |writev()|. | |
28 // - On Mac, we may use |write()|/|writev()|. Here, |write()| is considerably | |
29 // faster than |send()|, whereas |sendmsg()| is quite comparable to | |
30 // |writev()|. | |
31 // - On both platforms, an appropriate |sendmsg()|/|writev()| is considerably | |
32 // faster than two |send()|s/|write()|s. | |
33 // - Relative numbers (minimum real times from 10 runs) for one |write()| of | |
34 // 1032 bytes, one |send()| of 1032 bytes, one |writev()| of 32+1000 bytes, | |
35 // one |sendmsg()| of 32+1000 bytes, two |write()|s of 32 and 1000 bytes, two | |
36 // |send()|s of 32 and 1000 bytes: | |
37 // - Linux: 0.81 s, 0.77 s, 0.87 s, 0.89 s, 1.31 s, 1.22 s | |
38 // - Mac: 2.21 s, 2.91 s, 2.98 s, 3.08 s, 3.59 s, 4.74 s | |
39 | |
40 // Flags to use with calling |send()| or |sendmsg()| (see above). | |
41 #if defined(OS_MACOSX) | |
42 const int kSendFlags = 0; | |
43 #else | |
44 const int kSendFlags = MSG_NOSIGNAL; | |
45 #endif | |
46 | |
47 ssize_t PlatformChannelWrite(PlatformHandle h, | |
48 const void* bytes, | |
49 size_t num_bytes) { | |
50 DCHECK(h.is_valid()); | |
51 DCHECK(bytes); | |
52 DCHECK_GT(num_bytes, 0u); | |
53 | |
54 #if defined(OS_MACOSX) | |
55 return HANDLE_EINTR(write(h.fd, bytes, num_bytes)); | |
56 #else | |
57 return send(h.fd, bytes, num_bytes, kSendFlags); | |
58 #endif | |
59 } | |
60 | |
61 ssize_t PlatformChannelWritev(PlatformHandle h, | |
62 struct iovec* iov, | |
63 size_t num_iov) { | |
64 DCHECK(h.is_valid()); | |
65 DCHECK(iov); | |
66 DCHECK_GT(num_iov, 0u); | |
67 | |
68 #if defined(OS_MACOSX) | |
69 return HANDLE_EINTR(writev(h.fd, iov, static_cast<int>(num_iov))); | |
70 #else | |
71 struct msghdr msg = {}; | |
72 msg.msg_iov = iov; | |
73 msg.msg_iovlen = num_iov; | |
74 return HANDLE_EINTR(sendmsg(h.fd, &msg, kSendFlags)); | |
75 #endif | |
76 } | |
77 | |
78 ssize_t PlatformChannelSendmsgWithHandles(PlatformHandle h, | |
79 struct iovec* iov, | |
80 size_t num_iov, | |
81 PlatformHandle* platform_handles, | |
82 size_t num_platform_handles) { | |
83 DCHECK(iov); | |
84 DCHECK_GT(num_iov, 0u); | |
85 DCHECK(platform_handles); | |
86 DCHECK_GT(num_platform_handles, 0u); | |
87 DCHECK_LE(num_platform_handles, kPlatformChannelMaxNumHandles); | |
88 | |
89 char cmsg_buf[CMSG_SPACE(kPlatformChannelMaxNumHandles * sizeof(int))]; | |
90 struct msghdr msg = {}; | |
91 msg.msg_iov = iov; | |
92 msg.msg_iovlen = num_iov; | |
93 msg.msg_control = cmsg_buf; | |
94 msg.msg_controllen = CMSG_LEN(num_platform_handles * sizeof(int)); | |
95 struct cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); | |
96 cmsg->cmsg_level = SOL_SOCKET; | |
97 cmsg->cmsg_type = SCM_RIGHTS; | |
98 cmsg->cmsg_len = CMSG_LEN(num_platform_handles * sizeof(int)); | |
99 for (size_t i = 0; i < num_platform_handles; i++) { | |
100 DCHECK(platform_handles[i].is_valid()); | |
101 reinterpret_cast<int*>(CMSG_DATA(cmsg))[i] = platform_handles[i].fd; | |
102 } | |
103 | |
104 return HANDLE_EINTR(sendmsg(h.fd, &msg, kSendFlags)); | |
105 } | |
106 | |
107 bool PlatformChannelSendHandles(PlatformHandle h, | |
108 PlatformHandle* handles, | |
109 size_t num_handles) { | |
110 DCHECK(handles); | |
111 DCHECK_GT(num_handles, 0u); | |
112 DCHECK_LE(num_handles, kPlatformChannelMaxNumHandles); | |
113 | |
114 // Note: |sendmsg()| fails on Mac if we don't write at least one character. | |
115 struct iovec iov = {const_cast<char*>(""), 1}; | |
116 char cmsg_buf[CMSG_SPACE(kPlatformChannelMaxNumHandles * sizeof(int))]; | |
117 struct msghdr msg = {}; | |
118 msg.msg_iov = &iov; | |
119 msg.msg_iovlen = 1; | |
120 msg.msg_control = cmsg_buf; | |
121 msg.msg_controllen = CMSG_LEN(num_handles * sizeof(int)); | |
122 struct cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); | |
123 cmsg->cmsg_level = SOL_SOCKET; | |
124 cmsg->cmsg_type = SCM_RIGHTS; | |
125 cmsg->cmsg_len = CMSG_LEN(num_handles * sizeof(int)); | |
126 for (size_t i = 0; i < num_handles; i++) { | |
127 DCHECK(handles[i].is_valid()); | |
128 reinterpret_cast<int*>(CMSG_DATA(cmsg))[i] = handles[i].fd; | |
129 } | |
130 | |
131 ssize_t result = HANDLE_EINTR(sendmsg(h.fd, &msg, kSendFlags)); | |
132 if (result < 1) { | |
133 DCHECK_EQ(result, -1); | |
134 return false; | |
135 } | |
136 | |
137 for (size_t i = 0; i < num_handles; i++) | |
138 handles[i].CloseIfNecessary(); | |
139 return true; | |
140 } | |
141 | |
142 ssize_t PlatformChannelRecvmsg(PlatformHandle h, | |
143 void* buf, | |
144 size_t num_bytes, | |
145 std::deque<PlatformHandle>* platform_handles) { | |
146 DCHECK(buf); | |
147 DCHECK_GT(num_bytes, 0u); | |
148 DCHECK(platform_handles); | |
149 | |
150 struct iovec iov = {buf, num_bytes}; | |
151 char cmsg_buf[CMSG_SPACE(kPlatformChannelMaxNumHandles * sizeof(int))]; | |
152 struct msghdr msg = {}; | |
153 msg.msg_iov = &iov; | |
154 msg.msg_iovlen = 1; | |
155 msg.msg_control = cmsg_buf; | |
156 msg.msg_controllen = sizeof(cmsg_buf); | |
157 | |
158 ssize_t result = HANDLE_EINTR(recvmsg(h.fd, &msg, MSG_DONTWAIT)); | |
159 if (result < 0) | |
160 return result; | |
161 | |
162 // Success; no control messages. | |
163 if (msg.msg_controllen == 0) | |
164 return result; | |
165 | |
166 DCHECK(!(msg.msg_flags & MSG_CTRUNC)); | |
167 | |
168 for (cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); cmsg; | |
169 cmsg = CMSG_NXTHDR(&msg, cmsg)) { | |
170 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) { | |
171 size_t payload_length = cmsg->cmsg_len - CMSG_LEN(0); | |
172 DCHECK_EQ(payload_length % sizeof(int), 0u); | |
173 size_t num_fds = payload_length / sizeof(int); | |
174 const int* fds = reinterpret_cast<int*>(CMSG_DATA(cmsg)); | |
175 for (size_t i = 0; i < num_fds; i++) { | |
176 platform_handles->push_back(PlatformHandle(fds[i])); | |
177 DCHECK(platform_handles->back().is_valid()); | |
178 } | |
179 } | |
180 } | |
181 | |
182 return result; | |
183 } | |
184 | |
185 } // namespace embedder | |
186 } // namespace mojo | |
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