1 //
2 // detail/impl/eventfd_select_interrupter.ipp
3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6 // Copyright (c) 2008 Roelof Naude (roelof.naude at gmail dot com)
7 //
8 // Distributed under the Boost Software License, Version 1.0. (See accompanying
9 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
10 //
11
12 #ifndef BOOST_ASIO_DETAIL_IMPL_EVENTFD_SELECT_INTERRUPTER_IPP
13 #define BOOST_ASIO_DETAIL_IMPL_EVENTFD_SELECT_INTERRUPTER_IPP
14
15 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
16 # pragma once
17 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
18
19 #include <boost/asio/detail/config.hpp>
20
21 #if defined(BOOST_ASIO_HAS_EVENTFD)
22
23 #include <sys/stat.h>
24 #include <sys/types.h>
25 #include <fcntl.h>
26 #if __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
27 # include <asm/unistd.h>
28 #else // __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
29 # include <sys/eventfd.h>
30 #endif // __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
31 #include <boost/asio/detail/cstdint.hpp>
32 #include <boost/asio/detail/eventfd_select_interrupter.hpp>
33 #include <boost/asio/detail/throw_error.hpp>
34 #include <boost/asio/error.hpp>
35
36 #include <boost/asio/detail/push_options.hpp>
37
38 namespace boost {
39 namespace asio {
40 namespace detail {
41
42 eventfd_select_interrupter::eventfd_select_interrupter()
43 {
44 open_descriptors();
45 }
46
47 void eventfd_select_interrupter::open_descriptors()
48 {
49 #if __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
50 write_descriptor_ = read_descriptor_ = syscall(__NR_eventfd, 0);
51 if (read_descriptor_ != -1)
52 {
53 ::fcntl(read_descriptor_, F_SETFL, O_NONBLOCK);
54 ::fcntl(read_descriptor_, F_SETFD, FD_CLOEXEC);
55 }
56 #else // __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
57 # if defined(EFD_CLOEXEC) && defined(EFD_NONBLOCK)
58 write_descriptor_ = read_descriptor_ =
59 ::eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK);
60 # else // defined(EFD_CLOEXEC) && defined(EFD_NONBLOCK)
61 errno = EINVAL;
62 write_descriptor_ = read_descriptor_ = -1;
63 # endif // defined(EFD_CLOEXEC) && defined(EFD_NONBLOCK)
|
(1) Event cond_true: |
Condition "this->read_descriptor_ == -1", taking true branch. |
|
(2) Event cond_true: |
Condition "*__errno_location() == 22", taking true branch. |
64 if (read_descriptor_ == -1 && errno == EINVAL)
65 {
66 write_descriptor_ = read_descriptor_ = ::eventfd(0, 0);
|
(3) Event cond_false: |
Condition "this->read_descriptor_ != -1", taking false branch. |
67 if (read_descriptor_ != -1)
68 {
69 ::fcntl(read_descriptor_, F_SETFL, O_NONBLOCK);
70 ::fcntl(read_descriptor_, F_SETFD, FD_CLOEXEC);
|
(4) Event if_end: |
End of if statement. |
71 }
72 }
73 #endif // __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
74
|
(5) Event cond_true: |
Condition "this->read_descriptor_ == -1", taking true branch. |
75 if (read_descriptor_ == -1)
76 {
77 int pipe_fds[2];
|
(6) Event cond_true: |
Condition "pipe(pipe_fds) == 0", taking true branch. |
78 if (pipe(pipe_fds) == 0)
79 {
80 read_descriptor_ = pipe_fds[0];
81 ::fcntl(read_descriptor_, F_SETFL, O_NONBLOCK);
82 ::fcntl(read_descriptor_, F_SETFD, FD_CLOEXEC);
83 write_descriptor_ = pipe_fds[1];
|
(7) Event check_return: |
Calling "fcntl(this->write_descriptor_, 4, 2048)" without checking return value. This library function may fail and return an error code. |
84 ::fcntl(write_descriptor_, F_SETFL, O_NONBLOCK);
85 ::fcntl(write_descriptor_, F_SETFD, FD_CLOEXEC);
86 }
87 else
88 {
89 boost::system::error_code ec(errno,
90 boost::asio::error::get_system_category());
91 boost::asio::detail::throw_error(ec, "eventfd_select_interrupter");
92 }
93 }
94 }
95
96 eventfd_select_interrupter::~eventfd_select_interrupter()
97 {
98 close_descriptors();
99 }
100
101 void eventfd_select_interrupter::close_descriptors()
102 {
103 if (write_descriptor_ != -1 && write_descriptor_ != read_descriptor_)
104 ::close(write_descriptor_);
105 if (read_descriptor_ != -1)
106 ::close(read_descriptor_);
107 }
108
109 void eventfd_select_interrupter::recreate()
110 {
111 close_descriptors();
112
113 write_descriptor_ = -1;
114 read_descriptor_ = -1;
115
116 open_descriptors();
117 }
118
119 void eventfd_select_interrupter::interrupt()
120 {
121 uint64_t counter(1UL);
122 int result = ::write(write_descriptor_, &counter, sizeof(uint64_t));
123 (void)result;
124 }
125
126 bool eventfd_select_interrupter::reset()
127 {
128 if (write_descriptor_ == read_descriptor_)
129 {
130 for (;;)
131 {
132 // Only perform one read. The kernel maintains an atomic counter.
133 uint64_t counter(0);
134 errno = 0;
135 int bytes_read = ::read(read_descriptor_, &counter, sizeof(uint64_t));
136 if (bytes_read < 0 && errno == EINTR)
137 continue;
138 bool was_interrupted = (bytes_read > 0);
139 return was_interrupted;
140 }
141 }
142 else
143 {
144 for (;;)
145 {
146 // Clear all data from the pipe.
147 char data[1024];
148 int bytes_read = ::read(read_descriptor_, data, sizeof(data));
149 if (bytes_read < 0 && errno == EINTR)
150 continue;
151 bool was_interrupted = (bytes_read > 0);
152 while (bytes_read == sizeof(data))
153 bytes_read = ::read(read_descriptor_, data, sizeof(data));
154 return was_interrupted;
155 }
156 }
157 }
158
159 } // namespace detail
160 } // namespace asio
161 } // namespace boost
162
163 #include <boost/asio/detail/pop_options.hpp>
164
165 #endif // defined(BOOST_ASIO_HAS_EVENTFD)
166
167 #endif // BOOST_ASIO_DETAIL_IMPL_EVENTFD_SELECT_INTERRUPTER_IPP
168