fleni64.c

C标准库源代码

/***
*fleni64.c - find length of a file
*
*       Copyright (c) 1994-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       defines _filelengthi64() - find the length of a file
*
*******************************************************************************/

#include <cruntime.h>
#include <stdio.h>
#include <errno.h>
#include <io.h>
#include <internal.h>
#include <msdos.h>
#include <mtdll.h>
#include <stddef.h>
#include <stdlib.h>

/***
*__int64 _filelengthi64(filedes) - find length of a file
*
*Purpose:
*       Returns the length in bytes of the specified file.
*
*Entry:
*       int filedes - handle referring to file to find length of
*
*Exit:
*       returns length of file in bytes
*       returns -1i64 if fails
*
*Exceptions:
*
*******************************************************************************/

__int64 __cdecl _filelengthi64 (
        int filedes
        )
{
        __int64 length;
        __int64 here;

        if ( ((unsigned)filedes >= (unsigned)_nhandle) ||
             !(_osfile(filedes) & FOPEN) )
        {
            errno = EBADF;
            _doserrno = 0L;     /* not an OS error */
            return(-1L);
        }

        _lock_fh( filedes );

        /* Seek to end (and back) to get the file length. */

        if ( (here = _lseeki64_lk( filedes, 0i64, SEEK_CUR )) == -1i64 )
            length = -1i64;     /* return error */
        else {
            length = _lseeki64_lk( filedes, 0i64, SEEK_END );
            if ( here != length )
                _lseeki64_lk( filedes, here, SEEK_SET );
        }

        _unlock_fh( filedes );

        return( length );
}