144 lines
4.7 KiB
C
144 lines
4.7 KiB
C
/****************************************************************************
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* libs/libc/stdio/lib_freopen.c
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*
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* Copyright (C) 2015 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include <errno.h>
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#include "libc.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: freopen
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*
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* Description:
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* Reuses stream to either open the file specified by path or to change
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* its access mode.
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*
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* If a new path is specified, the function first attempts to close
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* any file already associated with stream (third parameter) and
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* disassociates it. Then, independently of whether that stream was
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* successfuly closed or not, freopen opens the file specified by path
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* and associates it with the stream just as fopen would do using the
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* specified mode.
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*
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* If path is a null pointer, the function attempts to change the mode
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* of the stream. Although a particular library implementation is allowed
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* to restrict the changes permitted, and under which circumstances.
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*
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* The error indicator and eof indicator are automatically cleared (as if
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* clearerr was called).
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*
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* Input Parameters:
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* path - If non-NULL, refers to the name of the file to be opened.
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* mode - String describing the new file access mode
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* stream - Pointer to the type FILE to be reopened.
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*
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* Returned Value:
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* If the file is successfully reopened, the function returns the pointer
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* passed as parameter stream, which can be used to identify the reopened
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* stream. Otherwise, a null pointer is returned and the errno variable
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* is also set to a system-specific error code on failure.
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*
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****************************************************************************/
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FAR FILE *freopen(FAR const char *path, FAR const char *mode,
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FAR FILE *stream)
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{
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int oflags;
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int ret;
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int fd;
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/* Was a file name provided? */
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if (path != NULL)
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{
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/* Yes, close the stream */
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if (stream)
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{
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(void)fclose(stream);
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}
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/* And attempt to reopen the file at the provided path */
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return fopen(path, mode);
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}
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/* Otherwise, we are just changing the mode of the current file. */
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if (stream)
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{
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/* Convert the mode string into standard file open mode flags. */
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oflags = lib_mode2oflags(mode);
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if (oflags < 0)
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{
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return NULL;
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}
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/* Get the underlying file descriptor from the stream */
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fd = fileno(stream);
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if (fd < 0)
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{
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return NULL;
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}
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/* Set the new file mode for the file descriptor */
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ret = fcntl(fd, F_SETFL, oflags);
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if (ret < 0)
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{
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return NULL;
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}
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clearerr(stream);
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return stream;
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}
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set_errno(EINVAL);
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return NULL;
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}
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