forked from Archive/PX4-Autopilot
145 lines
5.3 KiB
C
145 lines
5.3 KiB
C
/****************************************************************************
|
|
* lib/stdio/lib_rdflush.c
|
|
*
|
|
* Copyright (C) 2008, 2011 Gregory Nutt. All rights reserved.
|
|
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
|
|
*
|
|
* 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 <errno.h>
|
|
|
|
#include "lib_internal.h"
|
|
|
|
/****************************************************************************
|
|
* Definitions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Type Declarations
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Function Prototypes
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Global Constant Data
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Global Variables
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Constant Data
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Variables
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Global Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: lib_rdflush
|
|
*
|
|
* Description:
|
|
* Flush read data from the I/O buffer and adjust the file pointer to
|
|
* account for the unread data
|
|
*
|
|
****************************************************************************/
|
|
|
|
#if CONFIG_STDIO_BUFFER_SIZE > 0
|
|
int lib_rdflush(FAR FILE *stream)
|
|
{
|
|
if (!stream)
|
|
{
|
|
set_errno(EBADF);
|
|
return ERROR;
|
|
}
|
|
|
|
/* Get exclusive access to the stream */
|
|
|
|
lib_take_semaphore(stream);
|
|
|
|
/* If the buffer is currently being used for read access, then discard all
|
|
* of the read-ahead data. We do not support concurrent buffered read/write
|
|
* access.
|
|
*/
|
|
|
|
if (stream->fs_bufread != stream->fs_bufstart)
|
|
{
|
|
/* Now adjust the stream pointer to account for the read-ahead data that
|
|
* was not actually read by the user.
|
|
*/
|
|
|
|
#if CONFIG_NUNGET_CHARS > 0
|
|
off_t rdoffset = stream->fs_bufread - stream->fs_bufpos + stream->fs_nungotten;
|
|
#else
|
|
off_t rdoffset = stream->fs_bufread - stream->fs_bufpos;
|
|
#endif
|
|
/* Mark the buffer as empty (do this before calling fseek() because fseek()
|
|
* also calls this function).
|
|
*/
|
|
|
|
stream->fs_bufpos = stream->fs_bufread = stream->fs_bufstart;
|
|
#if CONFIG_NUNGET_CHARS > 0
|
|
stream->fs_nungotten = 0;
|
|
#endif
|
|
/* Then seek to the position corresponding to the last data read by the user */
|
|
|
|
if (fseek(stream, -rdoffset, SEEK_CUR) < 0)
|
|
{
|
|
lib_give_semaphore(stream);
|
|
return ERROR;
|
|
}
|
|
}
|
|
|
|
lib_give_semaphore(stream);
|
|
return OK;
|
|
}
|
|
#endif /* CONFIG_STDIO_BUFFER_SIZE */
|
|
|