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