2008-02-01 23:19:20 +01:00
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/****************************************************************************
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2014-09-28 19:46:11 +02:00
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* fs/vfs/fs_lseek.c
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2008-02-01 23:19:20 +01:00
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*
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2021-02-03 14:47:23 +01:00
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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2008-02-01 23:19:20 +01:00
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*
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2021-02-03 14:47:23 +01:00
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* http://www.apache.org/licenses/LICENSE-2.0
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2008-02-01 23:19:20 +01:00
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*
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2021-02-03 14:47:23 +01:00
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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2008-02-01 23:19:20 +01:00
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <sched.h>
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#include <errno.h>
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2013-09-28 22:47:49 +02:00
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#include <assert.h>
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2008-02-01 23:19:20 +01:00
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2014-09-29 15:14:38 +02:00
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#include "inode/inode.h"
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2008-02-01 23:19:20 +01:00
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/****************************************************************************
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2014-10-06 18:53:25 +02:00
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* Public Functions
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2008-02-01 23:19:20 +01:00
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****************************************************************************/
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2013-09-28 22:47:49 +02:00
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/****************************************************************************
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* Name: file_seek
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*
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* Description:
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* This is the internal implementation of lseek. See the comments in
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* lseek() for further information.
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*
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2018-03-13 16:52:27 +01:00
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* Input Parameters:
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2013-09-28 22:47:49 +02:00
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* file File structure instance
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* offset Defines the offset to position to
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* whence Defines how to use offset
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*
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2018-02-01 17:00:02 +01:00
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* Returned Value:
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2017-09-28 21:53:56 +02:00
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* The resulting offset on success. A negated errno value is returned on
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* any failure (see lseek comments).
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2013-09-28 22:47:49 +02:00
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*
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****************************************************************************/
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off_t file_seek(FAR struct file *filep, off_t offset, int whence)
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{
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FAR struct inode *inode;
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2021-11-05 06:52:40 +01:00
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off_t ret;
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2013-09-28 22:47:49 +02:00
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2013-09-28 23:37:16 +02:00
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DEBUGASSERT(filep);
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2013-09-28 22:47:49 +02:00
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inode = filep->f_inode;
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/* Invoke the file seek method if available */
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if (inode && inode->u.i_ops && inode->u.i_ops->seek)
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{
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2021-11-05 06:52:40 +01:00
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ret = inode->u.i_ops->seek(filep, offset, whence);
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2013-09-28 22:47:49 +02:00
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if (ret < 0)
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{
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2017-09-28 21:53:56 +02:00
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return ret;
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2013-09-28 22:47:49 +02:00
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}
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}
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else
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{
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/* No... Just set the common file position value */
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switch (whence)
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{
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case SEEK_CUR:
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offset += filep->f_pos;
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2018-02-17 21:48:18 +01:00
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2017-06-28 16:06:06 +02:00
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/* FALLTHROUGH */
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2018-02-17 21:48:18 +01:00
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2013-09-28 22:47:49 +02:00
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case SEEK_SET:
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if (offset >= 0)
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{
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filep->f_pos = offset; /* Might be beyond the end-of-file */
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break;
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}
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else
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{
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2017-09-28 21:53:56 +02:00
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return -EINVAL;
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2013-09-28 22:47:49 +02:00
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}
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break;
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case SEEK_END:
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2017-09-28 21:53:56 +02:00
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return -ENOSYS;
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2013-09-28 22:47:49 +02:00
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default:
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2017-09-28 21:53:56 +02:00
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return -EINVAL;
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2013-09-28 22:47:49 +02:00
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}
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}
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return filep->f_pos;
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}
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2020-05-02 19:25:16 +02:00
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/****************************************************************************
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* Name: nx_seek
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*
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* Description:
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* nx_seek() function repositions the offset of the open file associated
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* with the file descriptor fd to the argument 'offset' according to the
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* directive 'whence'. nx_seek() is an internal OS function. It is
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* functionally equivalent to lseek() except that:
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*
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* - It does not modify the errno variable, and
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* - It is not a cancellation point.
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*
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****************************************************************************/
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off_t nx_seek(int fd, off_t offset, int whence)
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{
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FAR struct file *filep;
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2021-11-05 06:52:40 +01:00
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off_t ret;
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2020-05-02 19:25:16 +02:00
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/* Get the file structure corresponding to the file descriptor. */
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ret = fs_getfilep(fd, &filep);
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if (ret < 0)
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{
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return ret;
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}
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DEBUGASSERT(filep != NULL);
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/* Then let file_seek do the real work */
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return file_seek(filep, offset, whence);
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}
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2008-02-01 23:19:20 +01:00
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/****************************************************************************
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* Name: lseek
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*
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* Description:
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* The lseek() function repositions the offset of the open file associated
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2013-09-29 00:50:07 +02:00
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* with the file descriptor fd to the argument 'offset' according to the
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2008-02-01 23:19:20 +01:00
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* directive 'whence' as follows:
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*
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* SEEK_SET
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* The offset is set to offset bytes.
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* SEEK_CUR
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* The offset is set to its current location plus offset bytes.
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* SEEK_END
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* The offset is set to the size of the file plus offset bytes.
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*
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2020-05-02 19:25:16 +02:00
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* The lseek() function allows the file offset to be set beyond the end of
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* the file (but this does not change the size of the file). If data is
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* later written at this point, subsequent reads of the data in the gap (a
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* "hole") return null bytes ('\0') until data is actually written into the
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* gap.
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2008-02-01 23:19:20 +01:00
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*
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2018-03-13 16:52:27 +01:00
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* Input Parameters:
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2008-02-01 23:19:20 +01:00
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* fd File descriptor of device
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* offset Defines the offset to position to
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* whence Defines how to use offset
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*
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2018-02-01 17:00:02 +01:00
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* Returned Value:
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2020-05-02 19:25:16 +02:00
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* The resulting offset on success. -1 on failure withi errno set properly:
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2008-02-01 23:19:20 +01:00
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*
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2013-09-29 00:50:07 +02:00
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* EBADF fd is not an open file descriptor.
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2008-02-01 23:19:20 +01:00
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* EINVAL whence is not one of SEEK_SET, SEEK_CUR, SEEK_END; or the
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2020-05-02 19:25:16 +02:00
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* resulting file offset would be negative, or beyond the end of
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* a seekable device.
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2008-02-01 23:19:20 +01:00
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* EOVERFLOW The resulting file offset cannot be represented in an off_t.
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2013-09-29 00:50:07 +02:00
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* ESPIPE fd is associated with a pipe, socket, or FIFO.
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2008-02-01 23:19:20 +01:00
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*
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****************************************************************************/
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off_t lseek(int fd, off_t offset, int whence)
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{
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2017-09-28 21:53:56 +02:00
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off_t newpos;
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2008-02-01 23:19:20 +01:00
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2020-05-02 19:25:16 +02:00
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/* Let nx_seek do the real work */
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2008-02-01 23:19:20 +01:00
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2020-05-02 19:25:16 +02:00
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newpos = nx_seek(fd, offset, whence);
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2017-10-11 16:39:19 +02:00
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if (newpos < 0)
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{
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2020-05-02 19:25:16 +02:00
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set_errno(-newpos);
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return ERROR;
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2017-10-11 16:39:19 +02:00
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}
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2017-09-28 21:53:56 +02:00
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2019-10-27 18:48:14 +01:00
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return newpos;
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2008-02-01 23:19:20 +01:00
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}
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