include/boost/corosio/native/detail/kqueue/kqueue_traits.hpp

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kqueue_traits.hpp

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1			//
2			// Copyright (c) 2026 Michael Vandeberg
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_KQUEUE_KQUEUE_TRAITS_HPP
11			#define BOOST_COROSIO_NATIVE_DETAIL_KQUEUE_KQUEUE_TRAITS_HPP
12
13			#include <boost/corosio/detail/platform.hpp>
14
15			#if BOOST_COROSIO_HAS_KQUEUE
16
17			#include <boost/corosio/native/detail/make_err.hpp>
18			#include <boost/corosio/native/detail/reactor/reactor_descriptor_state.hpp>
19
20			#include <system_error>
21			#include <tuple>
22
23			#include <errno.h>
24			#include <fcntl.h>
25			#include <netinet/in.h>
26			#include <sys/socket.h>
27			#include <sys/uio.h>
28			#include <unistd.h>
29
30			/* kqueue backend traits.
31
32			Captures the platform-specific behavior of the BSD/macOS kqueue backend:
33			manual fcntl for O_NONBLOCK/FD_CLOEXEC, mandatory SO_NOSIGPIPE (macOS
34			lacks MSG_NOSIGNAL), writev() for writes, and accept()+fcntl for
35			accepted connections.
36			*/
37
38			namespace boost::corosio::detail {
39
40			class kqueue_scheduler;
41
42			struct kqueue_traits
43			{
44			using scheduler_type = kqueue_scheduler;
45			using desc_state_type = reactor_descriptor_state;
46
47			static constexpr bool needs_write_notification = false;
48
49			// No per-socket state or lifecycle hooks: the stream socket hook is a
50			// plain setsockopt passthrough, like epoll/select. SO_LINGER in particular
51			// is passed through unmodified. An abortive close (SO_LINGER{on,0}) thus
52			// sends a RST, which the peer's kqueue reports as EV_EOF carrying
53			// ECONNRESET in fflags -- so the peer surfaces connection_reset rather than
54			// a graceful eof, consistent with the other backends (#304). A positive
55			// linger timeout is likewise honored, so close() with unsent data blocks
56			// up to that timeout, as POSIX specifies.
57			struct stream_socket_hook
58			{
59		2657x	std::error_code on_set_option(
60			int fd, int level, int optname,
61			void const* data, std::size_t size) noexcept
62			{
63	3/4 ✓ Branch 0 taken 2657 times. ✗ Branch 1 not taken. ✓ Branch 2 taken 2 times. ✓ Branch 3 taken 2655 times.	2657x	if (::setsockopt(
64		2657x	fd, level, optname, data,
65		2657x	static_cast<socklen_t>(size)) != 0)
66	1/2 ✓ Branch 0 taken 2 times. ✗ Branch 1 not taken.	2x	return make_err(errno);
67		2655x	return {};
68		2657x	}
69		53978x	static void pre_shutdown(int) noexcept {}
70		17972x	static void pre_destroy(int) noexcept {}
71			};
72
73			struct write_policy
74			{
75		515x	static ssize_t write(int fd, iovec* iovecs, int count) noexcept
76			{
77			ssize_t n;
78		515x	do
79			{
80	1/2 ✓ Branch 0 taken 515 times. ✗ Branch 1 not taken.	515x	n = ::writev(fd, iovecs, count);
81		1030x	}
82	3/4 ✓ Branch 0 taken 3 times. ✓ Branch 1 taken 512 times. ✓ Branch 2 taken 3 times. ✗ Branch 3 not taken.	515x	while (n < 0 && errno == EINTR);
83		515x	return n;
84			}
85
86			// Single-buffer fast path. macOS lacks MSG_NOSIGNAL; SIGPIPE is
87			// suppressed by the mandatory SO_NOSIGPIPE set in accept_policy
88			// and set_fd_options, so plain write() is safe here.
89		489121x	static ssize_t write_one(
90			int fd, void const* data, std::size_t size) noexcept
91			{
92			ssize_t n;
93		489121x	do
94			{
95	1/2 ✓ Branch 0 taken 489121 times. ✗ Branch 1 not taken.	489121x	n = ::write(fd, data, size);
96		978242x	}
97	3/4 ✓ Branch 0 taken 511 times. ✓ Branch 1 taken 488610 times. ✓ Branch 2 taken 511 times. ✗ Branch 3 not taken.	489121x	while (n < 0 && errno == EINTR);
98		489121x	return n;
99			}
100			};
101
102			struct accept_policy
103			{
104		11726x	static int do_accept(
105			int fd, sockaddr_storage& peer, socklen_t& addrlen) noexcept
106			{
107			int new_fd;
108		11726x	do
109			{
110		11726x	addrlen = sizeof(peer);
111	1/2 ✓ Branch 0 taken 11726 times. ✗ Branch 1 not taken.	11726x	new_fd = ::accept(
112		11726x	fd, reinterpret_cast<sockaddr*>(&peer), &addrlen);
113		23452x	}
114	3/4 ✓ Branch 0 taken 5869 times. ✓ Branch 1 taken 5857 times. ✓ Branch 2 taken 5869 times. ✗ Branch 3 not taken.	11726x	while (new_fd < 0 && errno == EINTR);
115
116	2/2 ✓ Branch 0 taken 5869 times. ✓ Branch 1 taken 5857 times.	11726x	if (new_fd < 0)
117		5869x	return new_fd;
118
119	1/2 ✓ Branch 0 taken 5857 times. ✗ Branch 1 not taken.	5857x	int flags = ::fcntl(new_fd, F_GETFL, 0);
120	2/4 ✓ Branch 0 taken 5857 times. ✗ Branch 1 not taken. ✓ Branch 2 taken 5857 times. ✗ Branch 3 not taken.	11714x	if (flags == -1 \|\|
121	1/2 ✓ Branch 0 taken 5857 times. ✗ Branch 1 not taken.	5857x	::fcntl(new_fd, F_SETFL, flags \| O_NONBLOCK) == -1)
122			{
123		✗	int err = errno;
124		✗	::close(new_fd);
125		✗	errno = err;
126		✗	return -1;
127			}
128
129	2/4 ✓ Branch 0 taken 5857 times. ✗ Branch 1 not taken. ✗ Branch 2 not taken. ✓ Branch 3 taken 5857 times.	5857x	if (::fcntl(new_fd, F_SETFD, FD_CLOEXEC) == -1)
130			{
131		✗	int err = errno;
132		✗	::close(new_fd);
133		✗	errno = err;
134		✗	return -1;
135			}
136
137			#ifndef BOOST_COROSIO_MRDOCS
138			// SO_NOSIGPIPE is mandatory on kqueue platforms (macOS lacks
139			// MSG_NOSIGNAL). Skipped under MRDOCS so the docs build can
140			// parse this header on Linux, where SO_NOSIGPIPE is absent.
141		5857x	int one = 1;
142	3/4 ✓ Branch 0 taken 5857 times. ✗ Branch 1 not taken. ✓ Branch 2 taken 1 time. ✓ Branch 3 taken 5856 times.	5857x	if (::setsockopt(
143		5857x	new_fd, SOL_SOCKET, SO_NOSIGPIPE,
144		5857x	&one, sizeof(one)) == -1)
145			{
146	1/2 ✓ Branch 0 taken 1 time. ✗ Branch 1 not taken.	1x	int err = errno;
147	1/2 ✓ Branch 0 taken 1 time. ✗ Branch 1 not taken.	1x	::close(new_fd);
148	1/2 ✓ Branch 0 taken 1 time. ✗ Branch 1 not taken.	1x	errno = err;
149		1x	return -1;
150			}
151			#endif
152
153		5856x	return new_fd;
154		11726x	}
155			};
156
157			// Create a plain socket. Fd options are applied by configure_*().
158		7887x	static int create_socket(int family, int type, int protocol) noexcept
159			{
160	1/2 ✓ Branch 0 taken 7887 times. ✗ Branch 1 not taken.	7887x	return ::socket(family, type, protocol);
161			}
162
163			// Set O_NONBLOCK, FD_CLOEXEC, and SO_NOSIGPIPE on a new fd.
164			// Caller is responsible for closing fd on error.
165		7887x	static std::error_code set_fd_options(int fd) noexcept
166			{
167	1/2 ✓ Branch 0 taken 7887 times. ✗ Branch 1 not taken.	7887x	int flags = ::fcntl(fd, F_GETFL, 0);
168	1/2 ✗ Branch 0 not taken. ✓ Branch 1 taken 7887 times.	7887x	if (flags == -1)
169		✗	return make_err(errno);
170	2/4 ✓ Branch 0 taken 7887 times. ✗ Branch 1 not taken. ✗ Branch 2 not taken. ✓ Branch 3 taken 7887 times.	7887x	if (::fcntl(fd, F_SETFL, flags \| O_NONBLOCK) == -1)
171		✗	return make_err(errno);
172	2/4 ✓ Branch 0 taken 7887 times. ✗ Branch 1 not taken. ✗ Branch 2 not taken. ✓ Branch 3 taken 7887 times.	7887x	if (::fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
173		✗	return make_err(errno);
174
175			#ifndef BOOST_COROSIO_MRDOCS
176			// SO_NOSIGPIPE is mandatory on kqueue platforms (see accept_policy).
177		7887x	int one = 1;
178	2/4 ✓ Branch 0 taken 7887 times. ✗ Branch 1 not taken. ✗ Branch 2 not taken. ✓ Branch 3 taken 7887 times.	7887x	if (::setsockopt(fd, SOL_SOCKET, SO_NOSIGPIPE, &one, sizeof(one)) != 0)
179		✗	return make_err(errno);
180			#endif
181
182		7887x	return {};
183		7887x	}
184
185			// Apply protocol-specific options after socket creation.
186			// For IP sockets, sets IPV6_V6ONLY on AF_INET6 (best-effort).
187			static std::error_code
188		6010x	configure_ip_socket(int fd, int family) noexcept
189			{
190		6010x	auto ec = set_fd_options(fd);
191	1/2 ✗ Branch 0 not taken. ✓ Branch 1 taken 6010 times.	6010x	if (ec)
192		✗	return ec;
193
194	2/2 ✓ Branch 0 taken 5989 times. ✓ Branch 1 taken 21 times.	6010x	if (family == AF_INET6)
195			{
196		21x	int v6only = 1;
197	1/2 ✓ Branch 0 taken 21 times. ✗ Branch 1 not taken.	21x	std::ignore = ::setsockopt(
198		21x	fd, IPPROTO_IPV6, IPV6_V6ONLY,
199			&v6only, sizeof(v6only));
200		21x	}
201		6010x	return {};
202		6010x	}
203
204			// Apply protocol-specific options for acceptor sockets.
205			// For IP acceptors, sets IPV6_V6ONLY=0 (dual-stack, best-effort).
206			static std::error_code
207		1783x	configure_ip_acceptor(int fd, int family) noexcept
208			{
209		1783x	auto ec = set_fd_options(fd);
210	1/2 ✗ Branch 0 not taken. ✓ Branch 1 taken 1783 times.	1783x	if (ec)
211		✗	return ec;
212
213	2/2 ✓ Branch 0 taken 1772 times. ✓ Branch 1 taken 11 times.	1783x	if (family == AF_INET6)
214			{
215		11x	int val = 0;
216	1/2 ✓ Branch 0 taken 11 times. ✗ Branch 1 not taken.	11x	std::ignore = ::setsockopt(
217		11x	fd, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
218		11x	}
219		1783x	return {};
220		1783x	}
221
222			// Apply options for local (unix) sockets.
223			static std::error_code
224		94x	configure_local_socket(int fd) noexcept
225			{
226		94x	return set_fd_options(fd);
227			}
228
229			// Non-mutating validation for fds adopted via assign(). Used when
230			// the caller retains fd ownership responsibility.
231			static std::error_code
232		118x	validate_assigned_fd(int /fd/) noexcept
233			{
234		118x	return {};
235			}
236			};
237
238			} // namespace boost::corosio::detail
239
240			#endif // BOOST_COROSIO_HAS_KQUEUE
241
242			#endif // BOOST_COROSIO_NATIVE_DETAIL_KQUEUE_KQUEUE_TRAITS_HPP
243