truncate.c revision 7257d1b4d25bfac0c802847390e98a464fd787ac
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* Copyright (c) 1988 AT&T */
/* All Rights Reserved */
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* ftruncate() and truncate() set a file to a specified
* length using fcntl(F_FREESP) system call. If the file
* was previously longer than length, the bytes past the
* length will no longer be accessible. If it was shorter,
* bytes not written will be zero filled.
*/
#include <sys/feature_tests.h>
#if !defined(_LP64) && _FILE_OFFSET_BITS == 64
#pragma weak _ftruncate64 = ftruncate64
#pragma weak _truncate64 = truncate64
#define ftruncate ftruncate64
#define truncate truncate64
#endif /* !_LP64 && _FILE_OFFSET_BITS == 64 */
#include "lint.h"
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <pthread.h>
#include <sys/types.h>
int
ftruncate(int fildes, off_t len)
{
struct flock lck;
lck.l_whence = 0; /* offset l_start from beginning of file */
lck.l_start = len;
lck.l_type = F_WRLCK; /* setting a write lock */
lck.l_len = (off_t)0; /* until the end of the file address space */
if (fcntl(fildes, F_FREESP, &lck) == -1) {
return (-1);
}
return (0);
}
int
truncate(const char *path, off_t len)
{
int rval = 0;
int cancel_state;
int fd;
/*
* truncate() is not a cancellation point,
* even though it calls open() and close().
*/
(void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cancel_state);
if ((fd = open(path, O_WRONLY)) == -1 || ftruncate(fd, len) == -1)
rval = -1;
if (fd >= 0)
(void) close(fd);
(void) pthread_setcancelstate(cancel_state, NULL);
return (rval);
}