133 lines
3.7 KiB
C
133 lines
3.7 KiB
C
/****************************************************************************
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* libs/libc/stdio/lib_ftello.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 <sys/types.h>
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#include <stdio.h>
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#include <unistd.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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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: lib_getoffset
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*
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* Description:
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* It is insufficient to simply use the file offset; we must also account
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* for the data offset in the any buffered data. This function calculates
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* that offset.
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*
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* Returned Value:
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* The file position offset due to buffered data.
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*
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****************************************************************************/
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#ifndef CONFIG_STDIO_DISABLE_BUFFERING
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static off_t lib_getoffset(FAR FILE *stream)
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{
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off_t offset = 0;
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flockfile(stream);
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if (stream->fs_bufstart !=
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NULL && stream->fs_bufread !=
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stream->fs_bufstart)
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{
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#if CONFIG_NUNGET_CHARS > 0
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offset = stream->fs_bufread - stream->fs_bufpos +
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stream->fs_nungotten;
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#else
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offset = stream->fs_bufread - stream->fs_bufpos;
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#endif
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}
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else
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{
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offset = -(stream->fs_bufpos - stream->fs_bufstart);
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}
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funlockfile(stream);
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return offset;
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}
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#else
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# define lib_getoffset(stream) (0)
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#endif
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: ftello
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*
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* Description:
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* ftello() returns the current value of the file position indicator for
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* the stream pointed to by stream.
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*
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* Returned Value:
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* Zero on success; -1 on failure with errno set appropriately.
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*
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****************************************************************************/
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off_t ftello(FAR FILE *stream)
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{
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off_t position;
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off_t offset = 0;
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/* Verify that we were provided with a stream */
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if (!stream)
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{
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set_errno(EBADF);
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return ERROR;
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}
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/* Perform the lseek to the current position. This will not move the
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* file pointer, but will return its current setting
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*/
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if (stream->fs_iofunc.seek != NULL)
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{
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position = stream->fs_iofunc.seek(stream->fs_cookie, &offset,
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SEEK_CUR);
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}
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else
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{
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position = lseek((int)(intptr_t)stream->fs_cookie, 0, SEEK_CUR);
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}
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if (position != (off_t)-1)
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{
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return position - lib_getoffset(stream);
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}
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else
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{
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return ERROR;
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}
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}
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