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/***
*isatty.c - check if file handle refers to a device
*
* Copyright (c) 1989-1992, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines _isatty() - check if file handle refers to a device
*
*Revision History:
* 06-08-89 PHG Module created
* 03-12-90 GJF Made calling type _CALLTYPE1, added #include
* <cruntime.h> and fixed the copyright. Also, cleaned
* up the formatting a bit.
* 08-14-90 SBM Compiles cleanly with -W3, minor optimization
* 09-28-90 GJF New-style function declarator.
* 12-04-90 GJF Appended Win32 version onto the source with #ifdef-s.
* It's not worth it to try to merge the versions more
* closely.
* 12-06-90 SRW Changed to use _osfile and _osfhnd instead of _osfinfo
* 01-16-91 GJF ANSI naming.
* 02-13-92 GJF Replaced _nfile by _nhandle for Win32.
*
*******************************************************************************/
#include <cruntime.h>
#include <msdos.h>
#include <internal.h>
#include <io.h>
/***
*int _isatty(handle) - check if handle is a device
*
*Purpose:
* Checks if the given handle is associated with a character device
* (terminal, console, printer, serial port)
*
*Entry:
* int handle - handle of file to be tested
*
*Exit:
* returns non-0 if handle refers to character device,
* returns 0 otherwise
*
*Exceptions:
*
*******************************************************************************/
int _CALLTYPE1 _isatty (
int fh
)
{
/* see if file handle is valid, otherwise return FALSE */
#ifdef _WIN32_
if ( (unsigned)fh >= (unsigned)_nhandle )
#else
if ((unsigned)fh >= (unsigned)_nfile)
#endif
return 0;
/* check file handle database to see if device bit set */
return (int)(_osfile[fh] & FDEV);
}
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