include/boost/corosio/native/detail/select/select_op.hpp

56.5% Lines (26/46) 100.0% List of functions (12/12) 26.7% Branches (16/60)

[ ] prev/next file n p prev/next uncovered line

f(x) Functions (12)

Function Calls Lines Branches Blocks

Line	Branch	Hits	Source Code
1			//
2			// Copyright (c) 2026 Steve Gerbino
3			//
4			// Distributed under the Boost Software License, Version 1.0. (See accompanying
5			// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6			//
7			// Official repository: https://github.com/cppalliance/corosio
8			//
9
10			#ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_OP_HPP
11			#define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_OP_HPP
12
13			#include <boost/corosio/detail/platform.hpp>
14
15			#if BOOST_COROSIO_HAS_SELECT
16
17			#include <boost/corosio/native/detail/reactor/reactor_op.hpp>
18			#include <boost/corosio/native/detail/reactor/reactor_descriptor_state.hpp>
19
20			#include <errno.h>
21			#include <fcntl.h>
22			#include <sys/socket.h>
23			#include <unistd.h>
24
25			/*
26			File descriptors are registered with the select scheduler once (via
27			select_descriptor_state) and stay registered until closed.
28
29			select() is level-triggered but the descriptor_state pattern
30			(designed for edge-triggered) works correctly: is_enqueued_ CAS
31			prevents double-enqueue, add_ready_events is idempotent, and
32			EAGAIN ops stay parked until the next select() re-reports readiness.
33
34			cancel() captures shared_from_this() into op.impl_ptr to prevent
35			use-after-free when the socket is closed with pending ops.
36
37			Writes use sendmsg(MSG_NOSIGNAL) on Linux. On macOS/BSD where
38			MSG_NOSIGNAL may be absent, SO_NOSIGPIPE is set at socket creation
39			and accepted-socket setup instead.
40			*/
41
42			namespace boost::corosio::detail {
43
44			// Forward declarations
45			class select_tcp_socket;
46			class select_tcp_acceptor;
47			struct select_op;
48
49			// Forward declaration
50			class select_scheduler;
51
52			/// Per-descriptor state for persistent select registration.
53			struct select_descriptor_state final : reactor_descriptor_state
54			{};
55
56			/// select base operation — thin wrapper over reactor_op.
57			struct select_op : reactor_op<select_tcp_socket, select_tcp_acceptor>
58			{
59			void operator()() override;
60			};
61
62			/// select connect operation.
63			struct select_connect_op final : reactor_connect_op<select_op>
64			{
65			void operator()() override;
66			void cancel() noexcept override;
67			};
68
69			/// select scatter-read operation.
70			struct select_read_op final : reactor_read_op<select_op>
71			{
72			void cancel() noexcept override;
73			};
74
75			/** Provides sendmsg() with EINTR retry for select writes.
76
77			Uses MSG_NOSIGNAL where available (Linux). On platforms without
78			it (macOS/BSD), SO_NOSIGPIPE is set at socket creation time
79			and flags=0 is used here.
80			*/
81			struct select_write_policy
82			{
83		466290x	static ssize_t write(int fd, iovec* iovecs, int count) noexcept
84			{
85		466290x	msghdr msg{};
86		466290x	msg.msg_iov = iovecs;
87		466290x	msg.msg_iovlen = static_cast<std::size_t>(count);
88
89			#ifdef MSG_NOSIGNAL
90		466290x	constexpr int send_flags = MSG_NOSIGNAL;
91			#else
92			constexpr int send_flags = 0;
93			#endif
94
95			ssize_t n;
96		466290x	do
97			{
98	1/2 ✓ Branch 0 taken 466290 times. ✗ Branch 1 not taken.	466290x	n = ::sendmsg(fd, &msg, send_flags);
99		932580x	}
100	3/4 ✓ Branch 0 taken 1 time. ✓ Branch 1 taken 466289 times. ✓ Branch 2 taken 1 time. ✗ Branch 3 not taken.	466290x	while (n < 0 && errno == EINTR);
101		466290x	return n;
102			}
103			};
104
105			/// select gather-write operation.
106			struct select_write_op final : reactor_write_op<select_op, select_write_policy>
107			{
108			void cancel() noexcept override;
109			};
110
111			/** Provides accept() + fcntl(O_NONBLOCK\|FD_CLOEXEC) with FD_SETSIZE check.
112
113			Uses accept() instead of accept4() for broader POSIX compatibility.
114			*/
115			struct select_accept_policy
116			{
117		1786x	static int do_accept(int fd, sockaddr_storage& peer) noexcept
118			{
119		1786x	socklen_t addrlen = sizeof(peer);
120			int new_fd;
121		1786x	do
122			{
123	1/2 ✓ Branch 0 taken 1786 times. ✗ Branch 1 not taken.	1786x	new_fd = ::accept(fd, reinterpret_cast<sockaddr*>(&peer), &addrlen);
124		3572x	}
125	1/4 ✗ Branch 0 not taken. ✓ Branch 1 taken 1786 times. ✗ Branch 2 not taken. ✗ Branch 3 not taken.	1786x	while (new_fd < 0 && errno == EINTR);
126
127	1/2 ✗ Branch 0 not taken. ✓ Branch 1 taken 1786 times.	1786x	if (new_fd < 0)
128		✗	return new_fd;
129
130	1/2 ✗ Branch 0 not taken. ✓ Branch 1 taken 1786 times.	1786x	if (new_fd >= FD_SETSIZE)
131			{
132		✗	::close(new_fd);
133		✗	errno = EINVAL;
134		✗	return -1;
135			}
136
137	1/2 ✓ Branch 0 taken 1786 times. ✗ Branch 1 not taken.	1786x	int flags = ::fcntl(new_fd, F_GETFL, 0);
138	1/2 ✗ Branch 0 not taken. ✓ Branch 1 taken 1786 times.	1786x	if (flags == -1)
139			{
140		✗	int err = errno;
141		✗	::close(new_fd);
142		✗	errno = err;
143		✗	return -1;
144			}
145
146	2/4 ✓ Branch 0 taken 1786 times. ✗ Branch 1 not taken. ✗ Branch 2 not taken. ✓ Branch 3 taken 1786 times.	1786x	if (::fcntl(new_fd, F_SETFL, flags \| O_NONBLOCK) == -1)
147			{
148		✗	int err = errno;
149		✗	::close(new_fd);
150		✗	errno = err;
151		✗	return -1;
152			}
153
154	2/4 ✓ Branch 0 taken 1786 times. ✗ Branch 1 not taken. ✗ Branch 2 not taken. ✓ Branch 3 taken 1786 times.	1786x	if (::fcntl(new_fd, F_SETFD, FD_CLOEXEC) == -1)
155			{
156		✗	int err = errno;
157		✗	::close(new_fd);
158		✗	errno = err;
159		✗	return -1;
160			}
161
162			#ifdef SO_NOSIGPIPE
163		1786x	int one = 1;
164	2/4 ✓ Branch 0 taken 1786 times. ✗ Branch 1 not taken. ✗ Branch 2 not taken. ✓ Branch 3 taken 1786 times.	1786x	if (::setsockopt(new_fd, SOL_SOCKET, SO_NOSIGPIPE, &one, sizeof(one)) ==
165			-1)
166			{
167		✗	int err = errno;
168		✗	::close(new_fd);
169		✗	errno = err;
170		✗	return -1;
171			}
172			#endif
173
174		1786x	return new_fd;
175		1786x	}
176			};
177
178			/// select accept operation.
179			struct select_accept_op final
180			: reactor_accept_op<select_op, select_accept_policy>
181			{
182			void operator()() override;
183			void cancel() noexcept override;
184			};
185
186			} // namespace boost::corosio::detail
187
188			#endif // BOOST_COROSIO_HAS_SELECT
189
190			#endif // BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_OP_HPP
191