/* pipeutils.c -- Utilities for using pipes as signals
   This file is part of Redshift.

   Redshift 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 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.  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"



/* Create non-blocking set of pipe fds. */
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);
}