jehanne/sys/src/lib/c/9sys/dup.c

/*
 * This file is part of Jehanne.
 *
 * Copyright (C) 2017 Giacomo Tesio <giacomo@tesio.it>
 *
 * Jehanne 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, version 2 of the License.
 *
 * Jehanne 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 Jehanne.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <u.h>
#include <libc.h>

int
jehanne_dup(int oldfd, int newfd)
{
	FdPair in, out;
	long f;

	in.fd[0] = oldfd;
	in.fd[1] = newfd;

	f = create("#d/new", -1, in.aslong);
	if(f == -1)
		return -1;
	if(f >= 0){
		/* this should never happen */
		close(f);
		return -1;
	}
	out.aslong = ~f;
	return out.fd[1];
}