eof.c

C标准库源代码

/***
*eof.c - test a handle for end of file
*
*       Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       defines _eof() - determine if a file is at eof
*
*******************************************************************************/

#ifndef _MAC


#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
        )
{
        long here;
        long end;
        int retval;

        if ( ((unsigned)filedes >= (unsigned)_nhandle) ||
             !(_osfile(filedes) & FOPEN) )
        {
                errno = EBADF;
                _doserrno = 0;
                return(-1);
        }

        /* Lock the file */
        _lock_fh(filedes);

        /* See if the current position equals the end of the file. */

        if ( ((here = _lseek_lk(filedes, 0L, SEEK_CUR)) == -1L) ||
             ((end = _lseek_lk(filedes, 0L, SEEK_END)) == -1L) )
                retval = -1;
        else if ( here == end )
                retval = 1;
        else {
                _lseek_lk(filedes, here, SEEK_SET);
                retval = 0;
        }

        /* Unlock the file */
        _unlock_fh(filedes);

        /* Done */
        return(retval);
}


#else  /* _MAC */


#include <cruntime.h>
#include <io.h>
#include <errno.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <internal.h>
#include <memory.h>
#include <msdos.h>
#include <macos\files.h>
#include <macos\errors.h>

/***
*int _eof(fh) - 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 fh
        )
{
        long end;
        ParamBlockRec param;
        OSErr osErr;


        if ( (unsigned)fh >= (unsigned)_nfile || !(_osfile[fh] & FOPEN) )
        {
                errno = EBADF;
                _macerrno = 0;
                return -1;
        }

        if (_osfile[fh] & FDEV)
        {
                return 0;                 /*console is never at eof*/
        }

        /* See if the current position equals the end of the file. */

        memset(&param, 0, sizeof(ParamBlockRec));
        param.ioParam.ioRefNum = _osfhnd[fh];
        osErr = PBGetEOFSync(&param);
        if (osErr == noErr)
        {
                end = (long)param.ioParam.ioMisc;
                osErr = PBGetFPosSync(&param);
                if (osErr == noErr)
                {
                        if (end == param.ioParam.ioPosOffset)
                        {
                                return 1;
                        }
                        else
                        {
                                return 0;
                        }
                }
        }

        _dosmaperr(osErr);

        return -1;
}


#endif  /* _MAC */