[babeltrace.git] / include / babeltrace / compat / send.h

#ifndef _BABELTRACE_COMPAT_SEND_H
#define _BABELTRACE_COMPAT_SEND_H

/*
 * babeltrace/compat/send.h
 *
 * Copyright (C) 2015  Michael Jeanson <mjeanson@efficios.com>
 *               2015  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/*
 * This wrapper is used on platforms that have no way of ignoring SIGPIPE
 * during a send().
 */

#ifndef MSG_NOSIGNAL
# ifdef SO_NOSIGPIPE
#   define MSG_NOSIGNAL SO_NOSIGPIPE
# endif
#endif

#if defined(MSG_NOSIGNAL)
static inline
ssize_t bt_send_nosigpipe(int fd, const void *buffer, size_t size)
{
	return send(fd, buffer, size, MSG_NOSIGNAL);
}
#else

#include <signal.h>

static inline
ssize_t bt_send_nosigpipe(int fd, const void *buffer, size_t size)
{
	ssize_t sent;
	int saved_err;
	sigset_t sigpipe_set, pending_set, old_set;
	int sigpipe_was_pending;

	/*
	 * Discard the SIGPIPE from send(), not disturbing any SIGPIPE
	 * that might be already pending. If a bogus SIGPIPE is sent to
	 * the entire process concurrently by a malicious user, it may
	 * be simply discarded.
	 */
	if (sigemptyset(&pending_set)) {
		return -1;
	}
	/*
	 * sigpending returns the mask of signals that are _both_
	 * blocked for the thread _and_ pending for either the thread or
	 * the entire process.
	 */
	if (sigpending(&pending_set)) {
		return -1;
	}
	sigpipe_was_pending = sigismember(&pending_set, SIGPIPE);
	/*
	 * If sigpipe was pending, it means it was already blocked, so
	 * no need to block it.
	 */
	if (!sigpipe_was_pending) {
		if (sigemptyset(&sigpipe_set)) {
			return -1;
		}
		if (sigaddset(&sigpipe_set, SIGPIPE)) {
			return -1;
		}
		if (pthread_sigmask(SIG_BLOCK, &sigpipe_set, &old_set)) {
			return -1;
		}
	}

	/* Send and save errno. */
	sent = send(fd, buffer, size, 0);
	saved_err = errno;

	if (sent == -1 && errno == EPIPE && !sigpipe_was_pending) {
		struct timespec timeout = { 0, 0 };
		int ret;

		do {
			ret = sigtimedwait(&sigpipe_set, NULL,
				&timeout);
		} while (ret == -1 && errno == EINTR);
	}
	if (!sigpipe_was_pending) {
		if (pthread_sigmask(SIG_SETMASK, &old_set, NULL)) {
			return -1;
		}
	}
	/* Restore send() errno */
	errno = saved_err;
end:
	return sent;
}
#endif

#endif /* _BABELTRACE_COMPAT_SEND_H */
Commit	Line	Data
	1	#ifndef _BABELTRACE_COMPAT_SEND_H
	2	#define _BABELTRACE_COMPAT_SEND_H
	3
	4	/*
	5	* babeltrace/compat/send.h
	6	*
	7	* Copyright (C) 2015 Michael Jeanson <mjeanson@efficios.com>
	8	* 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	9	*
	10	* Permission is hereby granted, free of charge, to any person obtaining a copy
	11	* of this software and associated documentation files (the "Software"), to deal
	12	* in the Software without restriction, including without limitation the rights
	13	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	14	* copies of the Software, and to permit persons to whom the Software is
	15	* furnished to do so, subject to the following conditions:
	16	*
	17	* The above copyright notice and this permission notice shall be included in
	18	* all copies or substantial portions of the Software.
	19	*
	20	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	21	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	22	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	23	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	24	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	25	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	26	* SOFTWARE.
	27	*/
	28
	29	/*
	30	* This wrapper is used on platforms that have no way of ignoring SIGPIPE
	31	* during a send().
	32	*/
	33
	34	#ifndef MSG_NOSIGNAL
	35	# ifdef SO_NOSIGPIPE
	36	# define MSG_NOSIGNAL SO_NOSIGPIPE
	37	# endif
	38	#endif
	39
	40	#if defined(MSG_NOSIGNAL)
	41	static inline
	42	ssize_t bt_send_nosigpipe(int fd, const void *buffer, size_t size)
	43	{
	44	return send(fd, buffer, size, MSG_NOSIGNAL);
	45	}
	46	#else
	47
	48	#include <signal.h>
	49
	50	static inline
	51	ssize_t bt_send_nosigpipe(int fd, const void *buffer, size_t size)
	52	{
	53	ssize_t sent;
	54	int saved_err;
	55	sigset_t sigpipe_set, pending_set, old_set;
	56	int sigpipe_was_pending;
	57
	58	/*
	59	* Discard the SIGPIPE from send(), not disturbing any SIGPIPE
	60	* that might be already pending. If a bogus SIGPIPE is sent to
	61	* the entire process concurrently by a malicious user, it may
	62	* be simply discarded.
	63	*/
	64	if (sigemptyset(&pending_set)) {
	65	return -1;
	66	}
	67	/*
	68	* sigpending returns the mask of signals that are _both_
	69	* blocked for the thread _and_ pending for either the thread or
	70	* the entire process.
	71	*/
	72	if (sigpending(&pending_set)) {
	73	return -1;
	74	}
	75	sigpipe_was_pending = sigismember(&pending_set, SIGPIPE);
	76	/*
	77	* If sigpipe was pending, it means it was already blocked, so
	78	* no need to block it.
	79	*/
	80	if (!sigpipe_was_pending) {
	81	if (sigemptyset(&sigpipe_set)) {
	82	return -1;
	83	}
	84	if (sigaddset(&sigpipe_set, SIGPIPE)) {
	85	return -1;
	86	}
	87	if (pthread_sigmask(SIG_BLOCK, &sigpipe_set, &old_set)) {
	88	return -1;
	89	}
	90	}
	91
	92	/* Send and save errno. */
	93	sent = send(fd, buffer, size, 0);
	94	saved_err = errno;
	95
	96	if (sent == -1 && errno == EPIPE && !sigpipe_was_pending) {
	97	struct timespec timeout = { 0, 0 };
	98	int ret;
	99
	100	do {
	101	ret = sigtimedwait(&sigpipe_set, NULL,
	102	&timeout);
	103	} while (ret == -1 && errno == EINTR);
	104	}
	105	if (!sigpipe_was_pending) {
	106	if (pthread_sigmask(SIG_SETMASK, &old_set, NULL)) {
	107	return -1;
	108	}
	109	}
	110	/* Restore send() errno */
	111	errno = saved_err;
	112	end:
	113	return sent;
	114	}
	115	#endif
	116
	117	#endif /* _BABELTRACE_COMPAT_SEND_H */