rt-thread/components/libc/compilers/dlib/syscall_lseek.c

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/*
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* Copyright (c) 2006-2021, RT-Thread Development Team
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*
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* SPDX-License-Identifier: Apache-2.0
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*
* Change Logs:
* Date Author Notes
* 2015-01-28 Bernard first version
*/
#include <rtthread.h>
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#include <LowLevelIOInterface.h>
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#include <unistd.h>
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#include <compiler_private.h>
#define DBG_TAG "dlib.syscall.lseek"
#define DBG_LVL DBG_INFO
#include <rtdbg.h>
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/*
* The "__lseek" function makes the next file operation (__read or
* __write) act on a new location. The parameter "whence" specifies
* how the "offset" parameter should be interpreted according to the
* following table:
*
* 0 (=SEEK_SET) - Goto location "offset".
* 1 (=SEEK_CUR) - Go "offset" bytes from the current location.
* 2 (=SEEK_END) - Go to "offset" bytes from the end.
*
* This function should return the current file position, or -1 on
* failure.
*/
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#pragma module_name = "?__lseek"
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long __lseek(int handle, long offset, int whence)
{
if (handle == _LLIO_STDOUT ||
handle == _LLIO_STDERR ||
handle == _LLIO_STDIN)
return _LLIO_ERROR;
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#ifdef DFS_USING_POSIX
return lseek(handle, offset, whence);
#else
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LOG_W(_WARNING_WITHOUT_FS);
return _LLIO_ERROR;
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#endif /* DFS_USING_POSIX */
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}