2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2007-2009 Dag-Erling Coïdan Smørgrav
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer
12 * in this position and unchanged.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
43 * Reliably open and lock a file.
45 * Please do not modify this code without first reading the revision history
46 * and discussing your changes with <des@freebsd.org>. Don't be fooled by the
47 * code's apparent simplicity; there would be no need for this function if it
48 * was easy to get right.
51 vflopenat(int dirfd, const char *path, int flags, va_list ap)
53 int fd, operation, serrno, trunc;
62 if (flags & O_CREAT) {
63 mode = (mode_t)va_arg(ap, int); /* mode_t promoted to int */
67 if (flags & O_NONBLOCK)
70 trunc = (flags & O_TRUNC);
74 if ((fd = openat(dirfd, path, flags, mode)) == -1)
75 /* non-existent or no access */
77 if (flock(fd, operation) == -1) {
78 /* unsupported or interrupted */
84 if (fstatat(dirfd, path, &sb, 0) == -1) {
85 /* disappeared from under our feet */
89 if (fstat(fd, &fsb) == -1) {
90 /* can't happen [tm] */
96 if (sb.st_dev != fsb.st_dev ||
97 sb.st_ino != fsb.st_ino) {
98 /* changed under our feet */
102 if (trunc && ftruncate(fd, 0) != 0) {
103 /* can't happen [tm] */
110 * The following change is provided as a specific example to
114 if (fcntl(fd, F_SETFD, FD_CLOEXEC) != 0) {
126 flopen(const char *path, int flags, ...)
132 ret = vflopenat(AT_FDCWD, path, flags, ap);
138 flopenat(int dirfd, const char *path, int flags, ...)
144 ret = vflopenat(dirfd, path, flags, ap);