libbb/read_key.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright (C) 2008 Rob Landley <rob@landley.net>
   6  * Copyright (C) 2008 Denys Vlasenko <vda.linux@googlemail.com>
   7  *
   8  * Licensed under GPL version 2, see file LICENSE in this tarball for details.
   9  */
  10 #include "libbb.h"
  11
  12 int64_t FAST_FUNC read_key(int fd, char *buffer)
  13 {
  14         struct pollfd pfd;
  15         const char *seq;
  16         int n;
  17         int c;
  18
  19         /* Known escape sequences for cursor and function keys */
  20         static const char esccmds[] ALIGN1 = {
  21                 'O','A'        |0x80,KEYCODE_UP      ,
  22                 'O','B'        |0x80,KEYCODE_DOWN    ,
  23                 'O','C'        |0x80,KEYCODE_RIGHT   ,
  24                 'O','D'        |0x80,KEYCODE_LEFT    ,
  25                 'O','H'        |0x80,KEYCODE_HOME    ,
  26                 'O','F'        |0x80,KEYCODE_END     ,
  27 #if 0
  28                 'O','P'        |0x80,KEYCODE_FUN1    ,
  29                 /* [ESC] ESC O [2] P - [Alt-][Shift-]F1 */
  30                 /* Ctrl- seems to not affect sequences */
  31                 'O','Q'        |0x80,KEYCODE_FUN2    ,
  32                 'O','R'        |0x80,KEYCODE_FUN3    ,
  33                 'O','S'        |0x80,KEYCODE_FUN4    ,
  34 #endif
  35                 '[','A'        |0x80,KEYCODE_UP      ,
  36                 '[','B'        |0x80,KEYCODE_DOWN    ,
  37                 '[','C'        |0x80,KEYCODE_RIGHT   ,
  38                 '[','D'        |0x80,KEYCODE_LEFT    ,
  39                 '[','H'        |0x80,KEYCODE_HOME    , /* xterm */
  40                 /* [ESC] ESC [ [2] H - [Alt-][Shift-]Home */
  41                 '[','F'        |0x80,KEYCODE_END     , /* xterm */
  42                 '[','1','~'    |0x80,KEYCODE_HOME    , /* vt100? linux vt? or what? */
  43                 '[','2','~'    |0x80,KEYCODE_INSERT  ,
  44                 '[','3','~'    |0x80,KEYCODE_DELETE  ,
  45                 /* [ESC] ESC [ 3 [;2] ~ - [Alt-][Shift-]Delete */
  46                 '[','4','~'    |0x80,KEYCODE_END     , /* vt100? linux vt? or what? */
  47                 '[','5','~'    |0x80,KEYCODE_PAGEUP  ,
  48                 '[','6','~'    |0x80,KEYCODE_PAGEDOWN,
  49                 '[','7','~'    |0x80,KEYCODE_HOME    , /* vt100? linux vt? or what? */
  50                 '[','8','~'    |0x80,KEYCODE_END     , /* vt100? linux vt? or what? */
  51 #if 0
  52                 '[','1','1','~'|0x80,KEYCODE_FUN1    ,
  53                 '[','1','2','~'|0x80,KEYCODE_FUN2    ,
  54                 '[','1','3','~'|0x80,KEYCODE_FUN3    ,
  55                 '[','1','4','~'|0x80,KEYCODE_FUN4    ,
  56                 '[','1','5','~'|0x80,KEYCODE_FUN5    ,
  57                 /* [ESC] ESC [ 1 5 [;2] ~ - [Alt-][Shift-]F5 */
  58                 '[','1','7','~'|0x80,KEYCODE_FUN6    ,
  59                 '[','1','8','~'|0x80,KEYCODE_FUN7    ,
  60                 '[','1','9','~'|0x80,KEYCODE_FUN8    ,
  61                 '[','2','0','~'|0x80,KEYCODE_FUN9    ,
  62                 '[','2','1','~'|0x80,KEYCODE_FUN10   ,
  63                 '[','2','3','~'|0x80,KEYCODE_FUN11   ,
  64                 '[','2','4','~'|0x80,KEYCODE_FUN12   ,
  65 #endif
  66                 0
  67         };
  68
  69         errno = 0;
  70         n = (unsigned char) *buffer++;
  71         if (n == 0) {
  72                 /* If no data, block waiting for input. If we read more
  73                  * than the minimal ESC sequence size, the "n=0" below
  74                  * would instead have to figure out how much to keep,
  75                  * resulting in larger code. */
  76                 n = safe_read(fd, buffer, 3);
  77                 if (n <= 0)
  78                         return -1;
  79         }
  80
  81         /* Grab character to return from buffer */
  82         c = (unsigned char)buffer[0];
  83         n--;
  84         if (n)
  85                 memmove(buffer, buffer + 1, n);
  86
  87         /* Only ESC starts ESC sequences */
  88         if (c != 27)
  89                 goto ret;
  90
  91         /* Loop through known ESC sequences */
  92         pfd.fd = fd;
  93         pfd.events = POLLIN;
  94         seq = esccmds;
  95         while (*seq != '\0') {
  96                 /* n - position in sequence we did not read yet */
  97                 int i = 0; /* position in sequence to compare */
  98
  99                 /* Loop through chars in this sequence */
 100                 while (1) {
 101                         /* So far escape sequence matched up to [i-1] */
 102                         if (n <= i) {
 103                                 /* Need more chars, read another one if it wouldn't block.
 104                                  * Note that escape sequences come in as a unit,
 105                                  * so if we block for long it's not really an escape sequence.
 106                                  * Timeout is needed to reconnect escape sequences
 107                                  * split up by transmission over a serial console. */
 108                                 if (safe_poll(&pfd, 1, 50) == 0) {
 109                                         /* No more data!
 110                                          * Array is sorted from shortest to longest,
 111                                          * we can't match anything later in array,
 112                                          * break out of both loops. */
 113                                         goto ret;
 114                                 }
 115                                 errno = 0;
 116                                 if (safe_read(fd, buffer + n, 1) <= 0) {
 117                                         /* If EAGAIN, then fd is O_NONBLOCK and poll lied:
 118                                          * in fact, there is no data. */
 119                                         if (errno != EAGAIN)
 120                                                 c = -1; /* otherwise it's EOF/error */
 121                                         goto ret;
 122                                 }
 123                                 n++;
 124                         }
 125                         if (buffer[i] != (seq[i] & 0x7f)) {
 126                                 /* This seq doesn't match, go to next */
 127                                 seq += i;
 128                                 /* Forward to last char */
 129                                 while (!(*seq & 0x80))
 130                                         seq++;
 131                                 /* Skip it and the keycode which follows */
 132                                 seq += 2;
 133                                 break;
 134                         }
 135                         if (seq[i] & 0x80) {
 136                                 /* Entire seq matched */
 137                                 c = (signed char)seq[i+1];
 138                                 n = 0;
 139                                 /* n -= i; memmove(...);
 140                                  * would be more correct,
 141                                  * but we never read ahead that much,
 142                                  * and n == i here. */
 143                                 goto ret;
 144                         }
 145                         i++;
 146                 }
 147         }
 148         /* We did not find matching sequence, it was a bare ESC.
 149          * We possibly read and stored more input in buffer[] by now. */
 150
 151         /* Try to decipher "ESC [ NNN ; NNN R" sequence */
 152         if (ENABLE_FEATURE_EDITING_ASK_TERMINAL
 153          && n != 0
 154          && buffer[0] == '['
 155         ) {
 156                 char *end;
 157                 unsigned long row, col;
 158
 159                 while (n < KEYCODE_BUFFER_SIZE-1) { /* 1 for cnt */
 160                         if (safe_poll(&pfd, 1, 50) == 0) {
 161                                 /* No more data! */
 162                                 break;
 163                         }
 164                         errno = 0;
 165                         if (safe_read(fd, buffer + n, 1) <= 0) {
 166                                 /* If EAGAIN, then fd is O_NONBLOCK and poll lied:
 167                                  * in fact, there is no data. */
 168                                 if (errno != EAGAIN)
 169                                         c = -1; /* otherwise it's EOF/error */
 170                                 goto ret;
 171                         }
 172                         if (buffer[n++] == 'R')
 173                                 goto got_R;
 174                 }
 175                 goto ret;
 176  got_R:
 177                 if (!isdigit(buffer[1]))
 178                         goto ret;
 179                 row = strtoul(buffer + 1, &end, 10);
 180                 if (*end != ';' || !isdigit(end[1]))
 181                         goto ret;
 182                 col = strtoul(end + 1, &end, 10);
 183                 if (*end != 'R')
 184                         goto ret;
 185                 if (row < 1 || col < 1 || (row | col) > 0x7fff)
 186                         goto ret;
 187
 188                 buffer[-1] = 0;
 189
 190                 /* Pack into "1 <row15bits> <col16bits>" 32-bit sequence */
 191                 c = (((-1 << 15) | row) << 16) | col;
 192                 /* Return it in high-order word */
 193                 return ((int64_t) c << 32) | (uint32_t)KEYCODE_CURSOR_POS;
 194         }
 195
 196  ret:
 197         buffer[-1] = n;
 198         return c;
 199 }