* libs/libc/unistd/lib_truncate.c
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <assert.h>
#ifndef CONFIG_DISABLE_MOUNTPOINT
* Public Functions
****************************************************************************/
* Name: truncate
*
* Description:
* The truncate() function causes the regular file named by path to have
* a size of length bytes.
*
* If the file previously was larger than length, the extra data is
* discarded. If it was previously shorter than length, it is unspecified
* whether the file is changed or its size increased. If the file is
* extended, the extended area appears as if it were zero-filled.
* With truncate(), the file must be open for writing; for truncate(),
* the process must have write permission for the file.
*
* truncate() does not modify the file offset for any open file
* descriptions associated with the file.
*
* Input Parameters:
* path - The path to the regular file to be truncated.
* length - The new length of the regular file.
*
* Returned Value:
* Upon successful completion, truncate() return 0s. Otherwise a -1 is
* returned, and errno is set to indicate the error.
* EINTR
* - A signal was caught during execution.
* EINVAL
* - The length argument was less than 0.
* EFBIG or EINVAL
* - The length argument was greater than the maximum file size.
* EIO
* - An I/O error occurred while reading from or writing to a file
* system.
* EACCES
* - A component of the path prefix denies search permission, or write
* permission is denied on the file.
* EISDIR
* - The named file is a directory.
* ELOOP
* - Too many symbolic links were encountered in resolving path.
* ENAMETOOLONG
* - The length of the specified pathname exceeds PATH_MAX bytes, or
* the length of a component of the pathname exceeds NAME_MAX bytes.
* ENOENT
* - A component of path does not name an existing file or path is an
* empty string.
* ENOTDIR
* - A component of the path prefix of path is not a directory.
* EROFS
* - he named file resides on a read-only file system.
* ENAMETOOLONG
* - Pathname resolution of a symbolic link produced an intermediate
* result whose length exceeds PATH_MAX.
*
****************************************************************************/
int truncate(FAR const char *path, off_t length)
{
int fd;
int ret;
DEBUGASSERT(path != NULL && length >= 0);
fd = open(path, O_WRONLY);
if (fd < 0)
{
return ERROR;
}
ret = ftruncate(fd, length);
close(fd);
return ret;
}
#endif