| /**************************************************************************** |
| * lib/lib_rdflush.c |
| * |
| * Copyright (C) 2008 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(FILE *stream) |
| { |
| if (!stream) |
| { |
| *get_errno_ptr() = 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 */ |
| |