You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
144 lines
5.3 KiB
144 lines
5.3 KiB
/**************************************************************************** |
|
* libc/stdio/lib_rdflush.c |
|
* |
|
* Copyright (C) 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 <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 */ |
|
|
|
|