1 /*-
2 * Copyright (c) 2007 Dag-Erling Coïdan Smørgrav
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: stable/10/lib/libutil/flopen.c 193591 2009-06-06 18:47:03Z des $");
30
31 #include <sys/file.h>
32 #include <sys/stat.h>
33
34 #include <errno.h>
35 #include <stdarg.h>
36 #include <unistd.h>
37
38 #include <libutil.h>
39
40 int
flopen(const char * path,int flags,...)41 flopen(const char *path, int flags, ...)
42 {
43 int fd, operation, serrno, trunc;
44 struct stat sb, fsb;
45 mode_t mode;
46
47 #ifdef O_EXLOCK
48 flags &= ~O_EXLOCK;
49 #endif
50
51 mode = 0;
52 if (flags & O_CREAT) {
53 va_list ap;
54
55 va_start(ap, flags);
56 mode = (mode_t)va_arg(ap, int); /* mode_t promoted to int */
57 va_end(ap);
58 }
59
60 operation = LOCK_EX;
61 if (flags & O_NONBLOCK)
62 operation |= LOCK_NB;
63
64 trunc = (flags & O_TRUNC);
65 flags &= ~O_TRUNC;
66
67 for (;;) {
68 if ((fd = open(path, flags, mode)) == -1)
69 /* non-existent or no access */
70 return (-1);
71 if (flock(fd, operation) == -1) {
72 /* unsupported or interrupted */
73 serrno = errno;
74 (void)close(fd);
75 errno = serrno;
76 return (-1);
77 }
78 if (stat(path, &sb) == -1) {
79 /* disappeared from under our feet */
80 (void)close(fd);
81 continue;
82 }
83 if (fstat(fd, &fsb) == -1) {
84 /* can't happen [tm] */
85 serrno = errno;
86 (void)close(fd);
87 errno = serrno;
88 return (-1);
89 }
90 if (sb.st_dev != fsb.st_dev ||
91 sb.st_ino != fsb.st_ino) {
92 /* changed under our feet */
93 (void)close(fd);
94 continue;
95 }
96 if (trunc && ftruncate(fd, 0) != 0) {
97 /* can't happen [tm] */
98 serrno = errno;
99 (void)close(fd);
100 errno = serrno;
101 return (-1);
102 }
103 return (fd);
104 }
105 }
106