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Diffstat (limited to 'nuttx/lib/stdio/lib_rdflush.c')
-rw-r--r-- | nuttx/lib/stdio/lib_rdflush.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/nuttx/lib/stdio/lib_rdflush.c b/nuttx/lib/stdio/lib_rdflush.c new file mode 100644 index 000000000..948dcce5d --- /dev/null +++ b/nuttx/lib/stdio/lib_rdflush.c @@ -0,0 +1,144 @@ +/**************************************************************************** + * 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 */ + |