usr/src/lib/libcurses/screen/chkinput.c

   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 #pragma ident   "%Z%%M% %I%     %E% SMI"
  41
  42 /*LINTLIBRARY*/
  43
  44 /*
  45  * chkinput()
  46  *
  47  * Routine to check to see if any input is waiting.
  48  * It returns a 1 if there is input waiting, and a zero if
  49  * no input is waiting.
  50  *
  51  * This function replaces system calls to ioctl() with the FIONREAD
  52  * parameter. It enables curses to stop a screen refresh whenever
  53  * a character is input.
  54  * Standard BTL UNIX 4.0 or 5.0 does not handle FIONREAD.
  55  * Changes have been made to 'wrefresh.c' to
  56  * call this routine as "_inputpending = chkinput()".
  57  * (delay.c and getch.c also use FIONREAD for nodelay, select and fast peek,
  58  * but these routines have not been changed).
  59  *
  60  * Philip N. Crusius - July 20, 1983
  61  * Modified to handle various systems March 9, 1984 by Mark Horton.
  62  */
  63
  64 #include        <unistd.h>
  65 #include        <sys/types.h>
  66 #include        "curses_inc.h"
  67
  68 #ifdef  FIONREAD
  69 #define HAVE_CHK
  70
  71 int
  72 _chkinput(void)
  73 {
  74         int     i;
  75
  76         ioctl(SP->check_fd, FIONREAD, &i);
  77         return (i > 0);
  78 }
  79 #endif  /* FIONREAD */
  80
  81 #ifdef  SELECT
  82 #ifndef HAVE_CHK
  83 #define HAVE_CHK
  84
  85 int
  86 _chkinput(void)
  87 {
  88         int ifds, ofds, efds, n;
  89         struct timeval tv;
  90
  91         ifds = 1 << SP->check_fd;
  92         ofds = efds = 0;
  93         tv.tv_sec = tv.t_usec = 0;
  94         n = select(20, &ifds, &ofds, &efds, &tv);
  95         return (n > 0);
  96 }
  97 #endif  /* HAVE_CHK */
  98 #endif  /* SELECT */
  99
 100 #ifndef HAVE_CHK
 101 #ifdef  SYSV
 102
 103 int
 104 _chkinput(void)
 105 {
 106         unsigned        char    c;      /* character input */
 107
 108         /*
 109          * Only check typeahead if the user is using our input
 110          * routines. This is because the read below will put
 111          * stuff into the inputQ that will never be read and the
 112          * screen will never get updated from now on.
 113          * This code should GO AWAY when a poll() or FIONREAD can
 114          * be done on the file descriptor as then the check
 115          * will be non-destructive.
 116          */
 117
 118         if (!cur_term->fl_typeahdok ||
 119             (cur_term->_chars_on_queue == INP_QSIZE) ||
 120             (cur_term->_check_fd < 0)) {
 121                 goto bad;
 122         }
 123
 124         /* If input is waiting in curses queue, return (TRUE). */
 125
 126         if ((int)cur_term->_chars_on_queue > 0) {
 127 #ifdef  DEBUG
 128                 if (outf) {
 129                         (void) fprintf(outf, "Found a character on the input "
 130                             "queue\n");
 131                         _print_queue();
 132                 }
 133 #endif  /* DEBUG */
 134                 goto good;
 135         }
 136
 137         if (read(cur_term->_check_fd, (char *)&c, 1) > 0) {
 138 #ifdef  DEBUG
 139                 if (outf) {
 140                         (void) fprintf(outf, "Reading ahead\n");
 141                 }
 142 #endif  /* DEBUG */
 143                 /*
 144                  * A character was waiting.  Put it at the end
 145                  * of the curses queue and return 1 to show that
 146                  * input is waiting.
 147                  */
 148 #ifdef  DEBUG
 149                 if (outf)
 150                         _print_queue();
 151 #endif  /* DEBUG */
 152                 cur_term->_input_queue[cur_term->_chars_on_queue++] = c;
 153 good:
 154                 return (TRUE);
 155         } else {
 156                 /* No input was waiting so return 0. */
 157 #ifdef  DEBUG
 158                 if (outf)
 159                         (void) fprintf(outf, "No input waiting\n");
 160 #endif  /* DEBUG */
 161 bad:
 162                 return (FALSE);
 163         }
 164 }
 165 #else   /* SYSV */
 166 int
 167 _chkinput()
 168 {
 169         return (FALSE);
 170 }
 171 #endif  /* SYSV */
 172 #endif  /* HAVE_CHK */
 173
 174 #ifdef  DEBUG
 175 void
 176 _print_queue()  /* FOR DEBUG ONLY */
 177 {
 178         int             i, j = cur_term->_chars_on_queue;
 179         chtype          *inputQ = cur_term->_input_queue;
 180
 181         if (outf)
 182                 for (i = 0; i < j; i++)
 183                         (void) fprintf(outf, "inputQ[%d] = %c\n", i, inputQ[i]);
 184 }
 185 #endif  /* DEBUG */