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