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("$FreeBSD$"); 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 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