1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 1997 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27/*	Copyright (c) 1988 AT&T	*/
28/*	  All Rights Reserved	*/
29
30/*
31 * University Copyright- Copyright (c) 1982, 1986, 1988
32 * The Regents of the University of California
33 * All Rights Reserved
34 *
35 * University Acknowledgment- Portions of this document are derived from
36 * software developed by the University of California, Berkeley, and its
37 * contributors.
38 */
39
40/*LINTLIBRARY*/
41
42#include	<unistd.h>
43#include	<sys/types.h>
44#include	"curses_inc.h"
45#ifdef SYSV
46#include	<fcntl.h>
47#endif /* SYSV */
48
49/*
50 * Set the file descriptor for typeahead checks to fd.  fd can be -1
51 * to disable the checking.
52 */
53
54int
55typeahead(int fd)
56{
57#ifdef	SYSV
58	/*
59	 * Doing fcntls before and after each typeahead check
60	 * read is a serious problem on the 3b2. Profiling
61	 * results indicated that a simple program(edit.c from
62	 * "The New Curses and Terminfo Package") was spending
63	 * 9.2% of the time in fcntl().
64	 */
65
66	int	savefd = cur_term->_check_fd;
67
68	/* Close the previous duped file descriptor. */
69	if (savefd >= 0)
70		(void) close(savefd);
71
72	/*
73	 * Duplicate the file descriptor so we have one to play with.
74	 * We cannot use dup(2), unfortunately, so we do typeahead checking
75	 * on terminals only. Besides, if typeahead is done when input is
76	 * coming from a file, nothing would EVER get drawn on the screen!
77	 */
78
79	/* MODIFIED: DRS 3/26/89 */
80
81	/*
82	 * a couple of notes by DRS:  first, a new file descriptor is
83	 * required, since O_NDELAY must be set.  calling fcntl() or dup()
84	 * would provide a new file descriptor, but NOT a new file pointer
85	 * for the open file (by file pointer, i mean a unix kernal file
86	 * ptr).  if a new underlying unix file ptr. is not allocated,
87	 * setting O_NDELAY will cause all normal terminal i/o to return
88	 * prematurely without blocking.
89	 *
90	 * second, the call to ttyname is NOT necessary, /dev/tty can be
91	 * used instead.  calling ttyname is quite expensive -- especially
92	 * for large /dev directories.
93	 *
94	 * note also that the code for the '#else' clause will not work
95	 * since the new file descriptor MUST have O_NDELAY set for the
96	 * rest of libcurses code to function properly.
97	 *
98	 * 4/24/89:  modified to set the close on exec() flag of the newly
99	 * 		opened file descriptor
100	 */
101
102	/*
103	 *	cur_term->_check_fd = (tty = ttyname(fd)) ?
104	 *	    open(tty, O_RDONLY | O_NDELAY) : -1;
105	 */
106	if (isatty(fd)) {
107		if ((cur_term->_check_fd = open("/dev/tty", O_RDONLY |
108		    O_NDELAY)) >= 0)
109			(void) fcntl(cur_term->_check_fd, F_SETFD, 1);
110	} else
111		cur_term->_check_fd = -1;
112
113#else	/* SYSV */
114	int savefd = cur_term->_check_fd;
115	/* Only do typeahead checking if the input is a tty. */
116	if (isatty(fd))
117		cur_term->_check_fd = fd;
118	else
119		cur_term->_check_fd = -1;
120#endif	/* SYSV */
121	return (savefd);
122}
123