incubator-nuttx/libs/libc/stdio/lib_fseeko.c

103 lines
3.4 KiB
C

/****************************************************************************
* libs/libc/stdio/lib_fseeko.c
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include "libc.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: fseeko
*
* Description:
* The fseeko() function sets the file position indicator for the stream
* pointed to by stream. The new position, measured in bytes, is obtained
* by adding offset bytes to the position specified by whence. If whence is
* set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to the
* start of the file, the current position indicator, or end-of-file,
* respectively. A successful call to the fseeko() function clears the
* end-of-file indicator for the stream and undoes any effects of the
* ungetc(3) function on the same stream.
*
* Returned Value:
* Zero on success; -1 on failure with errno set appropriately.
*
****************************************************************************/
int fseeko(FAR FILE *stream, off_t offset, int whence)
{
#ifdef CONFIG_DEBUG_FEATURES
/* Verify that we were provided with a stream */
if (!stream)
{
set_errno(EBADF);
return ERROR;
}
#endif
#ifndef CONFIG_STDIO_DISABLE_BUFFERING
/* Flush any valid read/write data in the buffer (also verifies stream) */
flockfile(stream);
if (lib_rdflush_unlocked(stream) < 0 || lib_wrflush_unlocked(stream) < 0)
{
funlockfile(stream);
return ERROR;
}
funlockfile(stream);
#endif
/* On success or failure, discard any characters saved by ungetc() */
#if CONFIG_NUNGET_CHARS > 0
stream->fs_nungotten = 0;
#endif
/* Perform the fseeko on the underlying file descriptor */
if (stream->fs_iofunc.seek != NULL)
{
return stream->fs_iofunc.seek(stream->fs_cookie, &offset,
whence) == (off_t)-1 ? ERROR : OK;
}
else
{
return lseek((int)(intptr_t)stream->fs_cookie, offset,
whence) == (off_t)-1 ? ERROR : OK;
}
}