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 * $FreeBSD: head/lib/libutil/flopen.c 193591 2009-06-06 18:47:03Z des $ 28 */ 29 30 #include <sys/stat.h> 31 32 #include <errno.h> 33 #include <stdarg.h> 34 #include <unistd.h> 35 #include <fcntl.h> 36 #include <libutil.h> 37 38 int 39 flopen(const char *path, int flags, ...) 40 { 41 int fd, operation, serrno, trunc; 42 struct stat sb, fsb; 43 mode_t mode; 44 45 #ifdef O_EXLOCK 46 flags &= ~O_EXLOCK; 47 #endif 48 49 mode = 0; 50 if (flags & O_CREAT) { 51 va_list ap; 52 53 va_start(ap, flags); 54 mode = (mode_t)va_arg(ap, int); /* mode_t promoted to int */ 55 va_end(ap); 56 } 57 58 operation = LOCK_EX; 59 if (flags & O_NONBLOCK) 60 operation |= LOCK_NB; 61 62 trunc = (flags & O_TRUNC); 63 flags &= ~O_TRUNC; 64 65 for (;;) { 66 if ((fd = open(path, flags, mode)) == -1) 67 /* non-existent or no access */ 68 return (-1); 69 if (flock(fd, operation) == -1) { 70 /* unsupported or interrupted */ 71 serrno = errno; 72 (void)close(fd); 73 errno = serrno; 74 return (-1); 75 } 76 if (stat(path, &sb) == -1) { 77 /* disappeared from under our feet */ 78 (void)close(fd); 79 continue; 80 } 81 if (fstat(fd, &fsb) == -1) { 82 /* can't happen [tm] */ 83 serrno = errno; 84 (void)close(fd); 85 errno = serrno; 86 return (-1); 87 } 88 if (sb.st_dev != fsb.st_dev || 89 sb.st_ino != fsb.st_ino) { 90 /* changed under our feet */ 91 (void)close(fd); 92 continue; 93 } 94 if (trunc && ftruncate(fd, 0) != 0) { 95 /* can't happen [tm] */ 96 serrno = errno; 97 (void)close(fd); 98 errno = serrno; 99 return (-1); 100 } 101 return (fd); 102 } 103 } 104