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/****************************************************************************
* lib/stdio/lib_fseek.c
*
* Copyright (C) 2007, 2008, 2011 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.
*
****************************************************************************/
/****************************************************************************
* Compilation Switches
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include "lib_internal.h"
/****************************************************************************
* Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Global Constant Data
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Constant Data
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: fseek
*
* Description:
* The fseek() function sets the file position indicator for the stream
* pointed to by stream. The new position, measured in bytes, is obtained
* by adding offset bytes to the position specified by whence. If whence is
* set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to the
* start of the file, the current position indicator, or end-of-file,
* respectively. A successful call to the fseek() function clears the
* end-of-file indicator for the stream and undoes any effects of the ungetc(3)
* function on the same stream.
*
* Returned Value:
* Zero on succes; -1 on failure with errno set appropriately.
*
****************************************************************************/
int fseek(FAR FILE *stream, long int offset, int whence)
{
#if CONFIG_STDIO_BUFFER_SIZE > 0
/* Flush any valid read/write data in the buffer (also verifies stream) */
if (lib_rdflush(stream) < 0 || lib_wrflush(stream) < 0)
{
return ERROR;
}
#else
/* Verify that we were provided with a stream */
if (!stream)
{
set_errno(EBADF);
return ERROR;
}
#endif
/* On success or failure, discard any characters saved by ungetc() */
#if CONFIG_NUNGET_CHARS > 0
stream->fs_nungotten = 0;
#endif
/* Perform the fseek on the underlying file descriptor */
return lseek(stream->fs_filedes, offset, whence) == (off_t)-1 ? ERROR : OK;
}
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