/* pipeutils.c -- Utilities for using pipes as signals
 * This file is part of redshift-ng.
 * 
 * redshift-ng is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * redshift-ng is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with redshift-ng.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * Copyright (c) 2017  Jon Lund Steffensen <jonlst@gmail.com>
 * Copyright (c) 2025  Mattias Andrée <m@maandree.se>
 */
#include "common.h"


int
pipeutils_create_nonblocking(int pipefds[2])
{
#ifdef WINDOWS
	(void) pipefds;
	return -1;
#else

	int i, flags;

# if defined(__linux__) && !defined(MISSING_PIPE2)
	if (!pipe2(pipefds, O_NONBLOCK)) {
		return 0;
	} else if (errno != ENOSYS) {
		weprintf("pipe2 <buffer> O_NONBLOCK:");
		return -1;
	}
# endif

	if (pipe(pipefds)) {
		weprintf("pipe:");
		return -1;
	}

	for (i = 0; i < 2; i++) {
		flags = fcntl(pipefds[0], F_GETFL);
		if (flags == -1) {
			weprintf("fcntl <pipe> F_GETFL:");
			goto fail;
		}
		if (fcntl(pipefds[0], F_SETFL, flags | O_NONBLOCK)) {
			weprintf("fcntl <pipe> F_SETFL +O_NONBLOCK:");
			goto fail;
		}
	}

	return 0;

fail:
	close(pipefds[0]);
	close(pipefds[1]);
	return -1;
#endif
}


/* Signal on write-end of pipe. */
void
pipeutils_signal(int write_fd)
{
	write(write_fd, "", 1);
}


/* Mark signal as handled on read-end of pipe. */
void
pipeutils_handle_signal(int read_fd)
{
	char data;
	read(read_fd, &data, 1);
}