windows-xp/Source/XPSP1/NT/base/crts/crtw32/lowio/flength.c

/***
*flength.c - find length of a file
*
*       Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       defines _filelength() - find the length of a file
*
*Revision History:
*       10-22-84  RN    initial version
*       10-27-87  JCR   Multi-thread support; also, cleaned up code to save
*                       an lseek() in some cases.
*       12-11-87  JCR   Added "_LOAD_DS" to declaration
*       05-25-88  PHG   Merged DLL and normal versions
*       03-12-90  GJF   Replaced _LOAD_DS with _CALLTYPE1, added #include
*                       <cruntime.h>, removed #include <register.h> and fixed
*                       the copyright. Also, cleaned up the formatting a bit.
*       07-23-90  SBM   Removed #include <assertm.h>
*       09-28-90  GJF   New-style function declarator.
*       12-04-90  GJF   Improved range check of file handle. Also, replaced
*                       numeric values with symbolic constants for seek
*                       methods.
*       01-16-91  GJF   ANSI naming.
*       02-13-92  GJF   Replaced _nfile by _nhandle for Win32.
*       04-06-93  SKS   Replace _CRTAPI* with __cdecl
*       01-04-95  GJF   _WIN32_ -> _WIN32
*       02-15-95  GJF   Appended Mac version of source file (somewhat cleaned
*                       up), with appropriate #ifdef-s.
*       06-27-95  GJF   Added check that the file handle is open.
*       07-08-96  GJF   Replaced defined(_WIN32) with !defined(_MAC), and
*                       defined(_M_M68K) || defined(_M_MPPC) with 
*                       defined(_MAC). Removed obsolete REG1 macro. Also, 
*                       detab-ed and cleaned up the format a bit.
*       12-19-97  GJF   Exception-safe locking.
*       05-17-99  PML   Remove all Macintosh support.
*
*******************************************************************************/

#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>

/***
*long _filelength(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 -1L if fails
*
*Exceptions:
*
*******************************************************************************/

long __cdecl _filelength (
        int filedes
        )
{
        long length;
        long here;

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

#ifdef  _MT
        _lock_fh(filedes);
        __try {
                if ( _osfile(filedes) & FOPEN ) {
#endif  /* _MT */

        /* Seek to end to get length of file. */
        if ( (here = _lseek_lk(filedes, 0L, SEEK_CUR)) == -1L )
                length = -1L;   /* return error */
        else {
                length = _lseek_lk(filedes, 0L, SEEK_END);
                if ( here != length )
                        _lseek_lk(filedes, here, SEEK_SET);
        }

#ifdef  _MT
                }
                else {
                        errno = EBADF;
                        _doserrno = 0L;
                        length = -1L;
                }
        }
        __finally {
                _unlock_fh(filedes);
        }
#endif  /* _MT */

        return(length);
}