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- /****************************************************************************
- * fs/vfs/fs_lseek.c
- *
- * Copyright (C) 2008, 2017 Gregory Nutt. All rights reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- * used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <sys/types.h>
- #include <unistd.h>
- #include <sched.h>
- #include <errno.h>
- #include <assert.h>
- #include "inode/inode.h"
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: file_seek
- *
- * Description:
- * This is the internal implementation of lseek. See the comments in
- * lseek() for further information.
- *
- * Input Parameters:
- * file File structure instance
- * offset Defines the offset to position to
- * whence Defines how to use offset
- *
- * Returned Value:
- * The resulting offset on success. A negated errno value is returned on
- * any failure (see lseek comments).
- *
- ****************************************************************************/
- off_t file_seek(FAR struct file *filep, off_t offset, int whence)
- {
- FAR struct inode *inode;
- int ret;
- DEBUGASSERT(filep);
- inode = filep->f_inode;
- /* Invoke the file seek method if available */
- if (inode && inode->u.i_ops && inode->u.i_ops->seek)
- {
- ret = (int)inode->u.i_ops->seek(filep, offset, whence);
- if (ret < 0)
- {
- return ret;
- }
- }
- else
- {
- /* No... Just set the common file position value */
- switch (whence)
- {
- case SEEK_CUR:
- offset += filep->f_pos;
- /* FALLTHROUGH */
- case SEEK_SET:
- if (offset >= 0)
- {
- filep->f_pos = offset; /* Might be beyond the end-of-file */
- break;
- }
- else
- {
- return -EINVAL;
- }
- break;
- case SEEK_END:
- return -ENOSYS;
- default:
- return -EINVAL;
- }
- }
- return filep->f_pos;
- }
- /****************************************************************************
- * Name: lseek
- *
- * Description:
- * The lseek() function repositions the offset of the open file associated
- * with the file descriptor fd to the argument 'offset' according to the
- * directive 'whence' as follows:
- *
- * SEEK_SET
- * The offset is set to offset bytes.
- * SEEK_CUR
- * The offset is set to its current location plus offset bytes.
- * SEEK_END
- * The offset is set to the size of the file plus offset bytes.
- *
- * The lseek() function allows the file offset to be set beyond the end of the
- * file (but this does not change the size of the file). If data is later written
- * at this point, subsequent reads of the data in the gap (a "hole") return null
- * bytes ('\0') until data is actually written into the gap.
- *
- * Input Parameters:
- * fd File descriptor of device
- * offset Defines the offset to position to
- * whence Defines how to use offset
- *
- * Returned Value:
- * The resulting offset on success. -1 on failure withi errno set properly:
- *
- * EBADF fd is not an open file descriptor.
- * EINVAL whence is not one of SEEK_SET, SEEK_CUR, SEEK_END; or the
- * resulting file offset would be negative, or beyond the end of a
- * seekable device.
- * EOVERFLOW The resulting file offset cannot be represented in an off_t.
- * ESPIPE fd is associated with a pipe, socket, or FIFO.
- *
- ****************************************************************************/
- off_t lseek(int fd, off_t offset, int whence)
- {
- FAR struct file *filep;
- off_t newpos;
- int errcode;
- int ret;
- /* Get the file structure corresponding to the file descriptor. */
- ret = fs_getfilep(fd, &filep);
- if (ret < 0)
- {
- errcode = -ret;
- goto errout;
- }
- DEBUGASSERT(filep != NULL);
- /* Then let file_seek do the real work */
- newpos = file_seek(filep, offset, whence);
- if (newpos < 0)
- {
- errcode = (int)-newpos;
- goto errout;
- }
- return newpos;
- errout:
- set_errno(errcode);
- return (off_t)ERROR;
- }
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