165 lines
4.6 KiB
C
165 lines
4.6 KiB
C
/****************************************************************************
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* libs/libc/stdio/lib_freopen.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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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* successfully 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, open the file directly if no stream is opened yet */
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if (stream == NULL)
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{
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return fopen(path, mode);
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}
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/* Otherwise, open the file */
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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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fd = open(path, oflags, 0666);
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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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/* Make sure that we have exclusive access to the stream */
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flockfile(stream);
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/* Flush the stream and invalidate the read buffer. */
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lib_fflush_unlocked(stream);
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#ifndef CONFIG_STDIO_DISABLE_BUFFERING
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lib_rdflush_unlocked(stream);
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#endif
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funlockfile(stream);
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/* Duplicate the new fd to the stream. */
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ret = dup2(fd, fileno(stream));
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close(fd);
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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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/* 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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