110 lines
2.9 KiB
C
110 lines
2.9 KiB
C
/*-
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* Copyright (c) 2007 Dag-Erling Coïdan Smørgrav
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer
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* in this position and unchanged.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/file.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdarg.h>
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#include <unistd.h>
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#include <libutil.h>
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int
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flopen(const char *path, int flags, ...)
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{
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int fd, operation, serrno, trunc;
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struct stat sb, fsb;
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struct flock lock;
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mode_t mode;
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#ifdef O_EXLOCK
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flags &= ~O_EXLOCK;
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#endif
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mode = 0;
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if (flags & O_CREAT) {
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va_list ap;
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va_start(ap, flags);
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mode = va_arg(ap, int); /* mode_t promoted to int */
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va_end(ap);
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}
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lock.l_type = (flags & O_RDONLY) ? F_RDLCK : F_WRLCK;
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lock.l_start = 0;
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lock.l_whence = SEEK_SET;
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lock.l_len = 0;
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operation = (flags & O_NONBLOCK) ? F_SETLK : F_SETLKW;
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trunc = (flags & O_TRUNC);
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flags &= ~O_TRUNC;
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for (;;) {
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if ((fd = open(path, flags, mode)) == -1)
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/* non-existent or no access */
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return (-1);
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if (fcntl(fd, operation, &lock) == -1) {
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/* unsupported or interrupted */
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serrno = errno;
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close(fd);
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errno = serrno;
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return (-1);
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}
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if (stat(path, &sb) == -1) {
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/* disappeared from under our feet */
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close(fd);
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continue;
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}
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if (fstat(fd, &fsb) == -1) {
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/* can't happen [tm] */
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serrno = errno;
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close(fd);
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errno = serrno;
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return (-1);
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}
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if (sb.st_dev != fsb.st_dev ||
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sb.st_ino != fsb.st_ino) {
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/* changed under our feet */
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close(fd);
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continue;
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}
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if (trunc && ftruncate(fd, 0) != 0) {
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/* can't happen [tm] */
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serrno = errno;
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close(fd);
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errno = serrno;
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return (-1);
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}
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return (fd);
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}
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}
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