console-tools/showkey.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * shows keys pressed. inspired by kbd package
   4  *
   5  * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
   6  *
   7  * Licensed under GPLv2, see file LICENSE in this source tree.
   8  */
   9
  10 #include "libbb.h"
  11 #include <linux/kd.h>
  12
  13 // set raw tty mode
  14 // also used by microcom
  15 // libbb candidates?
  16 static void xget1(struct termios *t, struct termios *oldt)
  17 {
  18         tcgetattr(STDIN_FILENO, oldt);
  19         *t = *oldt;
  20         cfmakeraw(t);
  21 }
  22
  23 static void xset1(struct termios *tio)
  24 {
  25         int ret = tcsetattr(STDIN_FILENO, TCSAFLUSH, tio);
  26         if (ret) {
  27                 bb_perror_msg("can't tcsetattr for stdin");
  28         }
  29 }
  30
  31 /*
  32  * GLOBALS
  33  */
  34 struct globals {
  35         int kbmode;
  36         struct termios tio, tio0;
  37 };
  38 #define G (*ptr_to_globals)
  39 #define kbmode  (G.kbmode)
  40 #define tio     (G.tio)
  41 #define tio0    (G.tio0)
  42 #define INIT_G() do { \
  43         SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
  44 } while (0)
  45
  46
  47 static void signal_handler(int signo)
  48 {
  49         // restore keyboard and console settings
  50         xset1(&tio0);
  51         xioctl(STDIN_FILENO, KDSKBMODE, (void *)(ptrdiff_t)kbmode);
  52         // alarmed? -> exit 0
  53         exit(SIGALRM == signo);
  54 }
  55
  56 int showkey_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  57 int showkey_main(int argc UNUSED_PARAM, char **argv)
  58 {
  59         enum {
  60                 OPT_a = (1<<0), // display the decimal/octal/hex values of the keys
  61                 OPT_k = (1<<1), // display only the interpreted keycodes (default)
  62                 OPT_s = (1<<2), // display only the raw scan-codes
  63         };
  64
  65         // FIXME: aks are all mutually exclusive
  66         getopt32(argv, "aks");
  67
  68         INIT_G();
  69
  70         // get keyboard settings
  71         xioctl(STDIN_FILENO, KDGKBMODE, &kbmode);
  72         printf("kb mode was %s\n\nPress any keys. Program terminates %s\n\n",
  73                 kbmode == K_RAW ? "RAW" :
  74                         (kbmode == K_XLATE ? "XLATE" :
  75                                 (kbmode == K_MEDIUMRAW ? "MEDIUMRAW" :
  76                                         (kbmode == K_UNICODE ? "UNICODE" : "?UNKNOWN?")))
  77                 , (option_mask32 & OPT_a) ? "when CTRL+D pressed" : "10s after last keypress"
  78         );
  79         // prepare for raw mode
  80         xget1(&tio, &tio0);
  81         // put stdin in raw mode
  82         xset1(&tio);
  83
  84         if (option_mask32 & OPT_a) {
  85                 unsigned char c;
  86                 // just read stdin char by char
  87                 while (1 == safe_read(STDIN_FILENO, &c, 1)) {
  88                         printf("%3u 0%03o 0x%02x\r\n", c, c, c);
  89                         if (04 /*CTRL-D*/ == c)
  90                                 break;
  91                 }
  92         } else {
  93                 // we should exit on any signal
  94                 bb_signals(BB_FATAL_SIGS, signal_handler);
  95                 // set raw keyboard mode
  96                 xioctl(STDIN_FILENO, KDSKBMODE, (void *)(ptrdiff_t)((option_mask32 & OPT_k) ? K_MEDIUMRAW : K_RAW));
  97
  98                 // read and show scancodes
  99                 while (1) {
 100                         char buf[18];
 101                         int i, n;
 102                         // setup 10s watchdog
 103                         alarm(10);
 104                         // read scancodes
 105                         n = read(STDIN_FILENO, buf, sizeof(buf));
 106                         i = 0;
 107                         while (i < n) {
 108                                 char c = buf[i];
 109                                 // show raw scancodes ordered? ->
 110                                 if (option_mask32 & OPT_s) {
 111                                         printf("0x%02x ", buf[i++]);
 112                                 // show interpreted scancodes (default) ? ->
 113                                 } else {
 114                                         int kc;
 115                                         if (i+2 < n
 116                                          && (c & 0x7f) == 0
 117                                          && (buf[i+1] & 0x80) != 0
 118                                          && (buf[i+2] & 0x80) != 0
 119                                         ) {
 120                                                 kc = ((buf[i+1] & 0x7f) << 7) | (buf[i+2] & 0x7f);
 121                                                 i += 3;
 122                                         } else {
 123                                                 kc = (c & 0x7f);
 124                                                 i++;
 125                                         }
 126                                         printf("keycode %3u %s", kc, (c & 0x80) ? "release" : "press");
 127                                 }
 128                         }
 129                         puts("\r");
 130                 }
 131         }
 132
 133         // cleanup
 134         signal_handler(SIGALRM);
 135
 136         // should never be here!
 137         return EXIT_SUCCESS;
 138 }