libcasper_impl.c revision 370004 
1/*-
2 * Copyright (c) 2013 The FreeBSD Foundation
3 * Copyright (c) 2015 Mariusz Zaborski <oshogbo@FreeBSD.org>
4 * All rights reserved.
5 *
6 * This software was developed by Pawel Jakub Dawidek under sponsorship from
7 * the FreeBSD Foundation.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 * $FreeBSD: stable/11/lib/libcasper/libcasper/libcasper_impl.c 370004 2021-06-16 20:30:46Z git2svn $
31 */
32
33#include <err.h>
34#include <errno.h>
35#include <fcntl.h>
36#include <paths.h>
37#include <stdlib.h>
38
39#include "libcasper_impl.h"
40
41bool
42fd_is_valid(int fd)
43{
44
45	return (fcntl(fd, F_GETFL) != -1 || errno != EBADF);
46}
47
48void
49fd_fix_environment(int *fdp)
50{
51	int nullfd, nfd;
52
53	if (*fdp > STDERR_FILENO)
54		return;
55
56	nullfd = open(_PATH_DEVNULL, O_RDWR);
57	if (nullfd == -1)
58		errx(1, "Unable to open %s", _PATH_DEVNULL);
59
60	while (*fdp <= STDERR_FILENO) {
61		nfd = dup(*fdp);
62		if (nfd == -1)
63			errx(1, "Unable to secure fd");
64		if (dup2(nullfd, *fdp) == -1)
65			errx(1, "Unable to secure fd");
66		*fdp = nfd;
67	}
68
69	close(nullfd);
70}
71
72