1/*-
2 * Copyright (c) 2007 Dag-Erling Co�dan Sm�rgrav
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer
10 * in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <sys/cdefs.h>
29__FBSDID("$FreeBSD: head/lib/libutil/flopen.c 169449 2007-05-10 14:56:07Z des $");
30
31#include <sys/stat.h>
32
33#include <errno.h>
34#include <fcntl.h>
35#include <stdarg.h>
36
37int
38flopen(const char *path, int flags, ...)
39{
40 int fd, operation, serrno;
41 struct stat sb, fsb;
42 mode_t mode;
43
44#ifdef O_EXLOCK
45 flags &= ~O_EXLOCK;
46#endif
47
48 mode = 0;
49 if (flags & O_CREAT) {
50 va_list ap;
51
52 va_start(ap, flags);
53 mode = va_arg(ap, int); /* mode_t promoted to int */
54 va_end(ap);
55 }
56
57 operation = LOCK_EX;
58 if (flags & O_NONBLOCK)
59 operation |= LOCK_NB;
60
61 for (;;) {
62 if ((fd = open(path, flags, mode)) == -1)
63 /* non-existent or no access */
64 return (-1);
65 if (flock(fd, operation) == -1) {
66 /* unsupported or interrupted */
67 serrno = errno;
68 close(fd);
69 errno = serrno;
70 return (-1);
71 }
72 if (stat(path, &sb) == -1) {
73 /* disappeared from under our feet */
74 close(fd);
75 continue;
76 }
77 if (fstat(fd, &fsb) == -1) {
78 /* can't happen [tm] */
79 serrno = errno;
80 close(fd);
81 errno = serrno;
82 return (-1);
83 }
84 if (sb.st_dev != fsb.st_dev ||
85 sb.st_ino != fsb.st_ino) {
86 /* changed under our feet */
87 close(fd);
88 continue;
89 }
90 return (fd);
91 }
92}