eof.c

C语言库函数的原型,有用的拿去

/***
*eof.c - test a handle for end of file
*
*       Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
*       defines _eof() - determine if a file is at eof
*
*******************************************************************************/

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

/***
*int _eof(filedes) - test a file for eof
*
*Purpose:
*       see if the file length is the same as the present position. if so, return
*       1. if not, return 0. if an error occurs, return -1
*
*Entry:
*       int filedes - handle of file to test
*
*Exit:
*       returns 1 if at eof
*       returns 0 if not at eof
*       returns -1 and sets errno if fails
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _eof (
        int filedes
        )
{
        __int64 here;
        __int64 end;
        int retval;

        _CHECK_FH_CLEAR_OSSERR_RETURN( filedes, EBADF, -1 );
        _VALIDATE_CLEAR_OSSERR_RETURN((filedes >= 0 && (unsigned)filedes < (unsigned)_nhandle), EBADF, -1);
        _VALIDATE_CLEAR_OSSERR_RETURN((_osfile(filedes) & FOPEN), EBADF, -1);

        /* Lock the file */
        _lock_fh(filedes);
        __try {
            if ( _osfile(filedes) & FOPEN ) {
                                /* See if the current position equals the end of the file. */

                                if ( ((here = _lseeki64_nolock(filedes, 0i64, SEEK_CUR)) == -1i64) ||
                                         ((end = _lseeki64_nolock(filedes, 0i64, SEEK_END)) == -1i64) )
                                                retval = -1;
                                else if ( here == end )
                                                retval = 1;
                                else {
                                                _lseeki64_nolock(filedes, here, SEEK_SET);
                                                retval = 0;
                                }
            }
            else {
                    errno = EBADF;
                    _doserrno = 0;
                    retval = -1;
                    _ASSERTE(("Invalid file descriptor. File possibly closed by a different thread",0));
            }
        }
        __finally {
                /* Unlock the file */
                _unlock_fh(filedes);
        }

        /* Done */
        return(retval);
}