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("$FreeBSD$"); 30 31 #include <sys/file.h> 32 #include <sys/stat.h> 33 34 #include <errno.h> 35 #include <fcntl.h> 36 #include <stdarg.h> 37 #include <unistd.h> 38 39 #include <libutil.h> 40 41 int 42 flopen(const char *path, int flags, ...) 43 { 44 int fd, operation, serrno, trunc; 45 struct stat sb, fsb; 46 mode_t mode; 47 48 #ifdef O_EXLOCK 49 flags &= ~O_EXLOCK; 50 #endif 51 52 mode = 0; 53 if (flags & O_CREAT) { 54 va_list ap; 55 56 va_start(ap, flags); 57 mode = va_arg(ap, int); /* mode_t promoted to int */ 58 va_end(ap); 59 } 60 61 operation = LOCK_EX; 62 if (flags & O_NONBLOCK) 63 operation |= LOCK_NB; 64 65 trunc = (flags & O_TRUNC); 66 flags &= ~O_TRUNC; 67 68 for (;;) { 69 if ((fd = open(path, flags, mode)) == -1) 70 /* non-existent or no access */ 71 return (-1); 72 if (flock(fd, operation) == -1) { 73 /* unsupported or interrupted */ 74 serrno = errno; 75 close(fd); 76 errno = serrno; 77 return (-1); 78 } 79 if (stat(path, &sb) == -1) { 80 /* disappeared from under our feet */ 81 close(fd); 82 continue; 83 } 84 if (fstat(fd, &fsb) == -1) { 85 /* can't happen [tm] */ 86 serrno = errno; 87 close(fd); 88 errno = serrno; 89 return (-1); 90 } 91 if (sb.st_dev != fsb.st_dev || 92 sb.st_ino != fsb.st_ino) { 93 /* changed under our feet */ 94 close(fd); 95 continue; 96 } 97 if (trunc && ftruncate(fd, 0) != 0) { 98 /* can't happen [tm] */ 99 serrno = errno; 100 close(fd); 101 errno = serrno; 102 return (-1); 103 } 104 return (fd); 105 } 106 } 107