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 GPLv2, see file LICENSE in this source tree.
   9  */
  10 #include "libbb.h"
  11
  12 int64_t FAST_FUNC read_key(int fd, char *buffer, int timeout)
  13 {
  14         struct pollfd pfd;
  15         const char *seq;
  16         int n;
  17
  18         /* Known escape sequences for cursor and function keys.
  19          * See "Xterm Control Sequences"
  20          * http://invisible-island.net/xterm/ctlseqs/ctlseqs.html
  21          */
  22         static const char esccmds[] ALIGN1 = {
  23                 'O','A'        |0x80,KEYCODE_UP      ,
  24                 'O','B'        |0x80,KEYCODE_DOWN    ,
  25                 'O','C'        |0x80,KEYCODE_RIGHT   ,
  26                 'O','D'        |0x80,KEYCODE_LEFT    ,
  27                 'O','H'        |0x80,KEYCODE_HOME    ,
  28                 'O','F'        |0x80,KEYCODE_END     ,
  29 #if 0
  30                 'O','P'        |0x80,KEYCODE_FUN1    ,
  31                 /* [ESC] ESC O [2] P - [Alt-][Shift-]F1 */
  32                 /* ESC [ O 1 ; 2 P - Shift-F1 */
  33                 /* ESC [ O 1 ; 3 P - Alt-F1 */
  34                 /* ESC [ O 1 ; 4 P - Alt-Shift-F1 */
  35                 /* ESC [ O 1 ; 5 P - Ctrl-F1 */
  36                 /* ESC [ O 1 ; 6 P - Ctrl-Shift-F1 */
  37                 'O','Q'        |0x80,KEYCODE_FUN2    ,
  38                 'O','R'        |0x80,KEYCODE_FUN3    ,
  39                 'O','S'        |0x80,KEYCODE_FUN4    ,
  40 #endif
  41                 '[','A'        |0x80,KEYCODE_UP      ,
  42                 '[','B'        |0x80,KEYCODE_DOWN    ,
  43                 '[','C'        |0x80,KEYCODE_RIGHT   ,
  44                 '[','D'        |0x80,KEYCODE_LEFT    ,
  45                 /* ESC [ 1 ; 2 x, where x = A/B/C/D: Shift-<arrow> */
  46                 /* ESC [ 1 ; 3 x, where x = A/B/C/D: Alt-<arrow> - implemented below */
  47                 /* ESC [ 1 ; 4 x, where x = A/B/C/D: Alt-Shift-<arrow> */
  48                 /* ESC [ 1 ; 5 x, where x = A/B/C/D: Ctrl-<arrow> - implemented below */
  49                 /* ESC [ 1 ; 6 x, where x = A/B/C/D: Ctrl-Shift-<arrow> */
  50                 /* ESC [ 1 ; 7 x, where x = A/B/C/D: Ctrl-Alt-<arrow> */
  51                 /* ESC [ 1 ; 8 x, where x = A/B/C/D: Ctrl-Alt-Shift-<arrow> */
  52                 '[','H'        |0x80,KEYCODE_HOME    , /* xterm */
  53                 '[','F'        |0x80,KEYCODE_END     , /* xterm */
  54                 /* [ESC] ESC [ [2] H - [Alt-][Shift-]Home (End similarly?) */
  55                 /* '[','Z'        |0x80,KEYCODE_SHIFT_TAB, */
  56                 '[','1','~'    |0x80,KEYCODE_HOME    , /* vt100? linux vt? or what? */
  57                 '[','2','~'    |0x80,KEYCODE_INSERT  ,
  58                 /* ESC [ 2 ; 3 ~ - Alt-Insert */
  59                 '[','3','~'    |0x80,KEYCODE_DELETE  ,
  60                 /* [ESC] ESC [ 3 [;2] ~ - [Alt-][Shift-]Delete */
  61                 /* ESC [ 3 ; 3 ~ - Alt-Delete */
  62                 /* ESC [ 3 ; 5 ~ - Ctrl-Delete */
  63                 '[','4','~'    |0x80,KEYCODE_END     , /* vt100? linux vt? or what? */
  64                 '[','5','~'    |0x80,KEYCODE_PAGEUP  ,
  65                 /* ESC [ 5 ; 3 ~ - Alt-PgUp */
  66                 /* ESC [ 5 ; 5 ~ - Ctrl-PgUp */
  67                 /* ESC [ 5 ; 7 ~ - Ctrl-Alt-PgUp */
  68                 '[','6','~'    |0x80,KEYCODE_PAGEDOWN,
  69                 '[','7','~'    |0x80,KEYCODE_HOME    , /* vt100? linux vt? or what? */
  70                 '[','8','~'    |0x80,KEYCODE_END     , /* vt100? linux vt? or what? */
  71 #if 0
  72                 '[','1','1','~'|0x80,KEYCODE_FUN1    , /* old xterm, deprecated by ESC O P */
  73                 '[','1','2','~'|0x80,KEYCODE_FUN2    , /* old xterm... */
  74                 '[','1','3','~'|0x80,KEYCODE_FUN3    , /* old xterm... */
  75                 '[','1','4','~'|0x80,KEYCODE_FUN4    , /* old xterm... */
  76                 '[','1','5','~'|0x80,KEYCODE_FUN5    ,
  77                 /* [ESC] ESC [ 1 5 [;2] ~ - [Alt-][Shift-]F5 */
  78                 '[','1','7','~'|0x80,KEYCODE_FUN6    ,
  79                 '[','1','8','~'|0x80,KEYCODE_FUN7    ,
  80                 '[','1','9','~'|0x80,KEYCODE_FUN8    ,
  81                 '[','2','0','~'|0x80,KEYCODE_FUN9    ,
  82                 '[','2','1','~'|0x80,KEYCODE_FUN10   ,
  83                 '[','2','3','~'|0x80,KEYCODE_FUN11   ,
  84                 '[','2','4','~'|0x80,KEYCODE_FUN12   ,
  85                 /* ESC [ 2 4 ; 2 ~ - Shift-F12 */
  86                 /* ESC [ 2 4 ; 3 ~ - Alt-F12 */
  87                 /* ESC [ 2 4 ; 4 ~ - Alt-Shift-F12 */
  88                 /* ESC [ 2 4 ; 5 ~ - Ctrl-F12 */
  89                 /* ESC [ 2 4 ; 6 ~ - Ctrl-Shift-F12 */
  90 #endif
  91                 /* '[','1',';','5','A' |0x80,KEYCODE_CTRL_UP   , - unused */
  92                 /* '[','1',';','5','B' |0x80,KEYCODE_CTRL_DOWN , - unused */
  93                 '[','1',';','5','C' |0x80,KEYCODE_CTRL_RIGHT,
  94                 '[','1',';','5','D' |0x80,KEYCODE_CTRL_LEFT ,
  95                 /* '[','1',';','3','A' |0x80,KEYCODE_ALT_UP    , - unused */
  96                 /* '[','1',';','3','B' |0x80,KEYCODE_ALT_DOWN  , - unused */
  97                 '[','1',';','3','C' |0x80,KEYCODE_ALT_RIGHT,
  98                 '[','1',';','3','D' |0x80,KEYCODE_ALT_LEFT ,
  99                 /* '[','3',';','3','~' |0x80,KEYCODE_ALT_DELETE, - unused */
 100                 0
 101         };
 102
 103         pfd.fd = fd;
 104         pfd.events = POLLIN;
 105
 106         buffer++; /* saved chars counter is in buffer[-1] now */
 107
 108  start_over:
 109         errno = 0;
 110         n = (unsigned char)buffer[-1];
 111         if (n == 0) {
 112                 /* If no data, wait for input.
 113                  * If requested, wait TIMEOUT ms. TIMEOUT = -1 is useful
 114                  * if fd can be in non-blocking mode.
 115                  */
 116                 if (timeout >= -1) {
 117                         if (safe_poll(&pfd, 1, timeout) == 0) {
 118                                 /* Timed out */
 119                                 errno = EAGAIN;
 120                                 return -1;
 121                         }
 122                 }
 123                 /* It is tempting to read more than one byte here,
 124                  * but it breaks pasting. Example: at shell prompt,
 125                  * user presses "c","a","t" and then pastes "\nline\n".
 126                  * When we were reading 3 bytes here, we were eating
 127                  * "li" too, and cat was getting wrong input.
 128                  */
 129                 n = safe_read(fd, buffer, 1);
 130                 if (n <= 0)
 131                         return -1;
 132         }
 133
 134         {
 135                 unsigned char c = buffer[0];
 136                 n--;
 137                 if (n)
 138                         memmove(buffer, buffer + 1, n);
 139                 /* Only ESC starts ESC sequences */
 140                 if (c != 27) {
 141                         buffer[-1] = n;
 142                         return c;
 143                 }
 144         }
 145
 146         /* Loop through known ESC sequences */
 147         seq = esccmds;
 148         while (*seq != '\0') {
 149                 /* n - position in sequence we did not read yet */
 150                 int i = 0; /* position in sequence to compare */
 151
 152                 /* Loop through chars in this sequence */
 153                 while (1) {
 154                         /* So far escape sequence matched up to [i-1] */
 155                         if (n <= i) {
 156                                 /* Need more chars, read another one if it wouldn't block.
 157                                  * Note that escape sequences come in as a unit,
 158                                  * so if we block for long it's not really an escape sequence.
 159                                  * Timeout is needed to reconnect escape sequences
 160                                  * split up by transmission over a serial console. */
 161                                 if (safe_poll(&pfd, 1, 50) == 0) {
 162                                         /* No more data!
 163                                          * Array is sorted from shortest to longest,
 164                                          * we can't match anything later in array -
 165                                          * anything later is longer than this seq.
 166                                          * Break out of both loops. */
 167                                         goto got_all;
 168                                 }
 169                                 errno = 0;
 170                                 if (safe_read(fd, buffer + n, 1) <= 0) {
 171                                         /* If EAGAIN, then fd is O_NONBLOCK and poll lied:
 172                                          * in fact, there is no data. */
 173                                         if (errno != EAGAIN) {
 174                                                 /* otherwise: it's EOF/error */
 175                                                 buffer[-1] = 0;
 176                                                 return -1;
 177                                         }
 178                                         goto got_all;
 179                                 }
 180                                 n++;
 181                         }
 182                         if (buffer[i] != (seq[i] & 0x7f)) {
 183                                 /* This seq doesn't match, go to next */
 184                                 seq += i;
 185                                 /* Forward to last char */
 186                                 while (!(*seq & 0x80))
 187                                         seq++;
 188                                 /* Skip it and the keycode which follows */
 189                                 seq += 2;
 190                                 break;
 191                         }
 192                         if (seq[i] & 0x80) {
 193                                 /* Entire seq matched */
 194                                 n = 0;
 195                                 /* n -= i; memmove(...);
 196                                  * would be more correct,
 197                                  * but we never read ahead that much,
 198                                  * and n == i here. */
 199                                 buffer[-1] = 0;
 200                                 return (signed char)seq[i+1];
 201                         }
 202                         i++;
 203                 }
 204         }
 205         /* We did not find matching sequence.
 206          * We possibly read and stored more input in buffer[] by now.
 207          * n = bytes read. Try to read more until we time out.
 208          */
 209         while (n < KEYCODE_BUFFER_SIZE-1) { /* 1 for count byte at buffer[-1] */
 210                 if (safe_poll(&pfd, 1, 50) == 0) {
 211                         /* No more data! */
 212                         break;
 213                 }
 214                 errno = 0;
 215                 if (safe_read(fd, buffer + n, 1) <= 0) {
 216                         /* If EAGAIN, then fd is O_NONBLOCK and poll lied:
 217                          * in fact, there is no data. */
 218                         if (errno != EAGAIN) {
 219                                 /* otherwise: it's EOF/error */
 220                                 buffer[-1] = 0;
 221                                 return -1;
 222                         }
 223                         break;
 224                 }
 225                 n++;
 226                 /* Try to decipher "ESC [ NNN ; NNN R" sequence */
 227                 if ((ENABLE_FEATURE_EDITING_ASK_TERMINAL
 228                     || ENABLE_FEATURE_VI_ASK_TERMINAL
 229                     || ENABLE_FEATURE_LESS_ASK_TERMINAL
 230                     )
 231                  && n >= 5
 232                  && buffer[0] == '['
 233                  && buffer[n-1] == 'R'
 234                  && isdigit(buffer[1])
 235                 ) {
 236                         char *end;
 237                         unsigned long row, col;
 238
 239                         row = strtoul(buffer + 1, &end, 10);
 240                         if (*end != ';' || !isdigit(end[1]))
 241                                 continue;
 242                         col = strtoul(end + 1, &end, 10);
 243                         if (*end != 'R')
 244                                 continue;
 245                         if (row < 1 || col < 1 || (row | col) > 0x7fff)
 246                                 continue;
 247
 248                         buffer[-1] = 0;
 249                         /* Pack into "1 <row15bits> <col16bits>" 32-bit sequence */
 250                         col |= (((-1 << 15) | row) << 16);
 251                         /* Return it in high-order word */
 252                         return ((int64_t) col << 32) | (uint32_t)KEYCODE_CURSOR_POS;
 253                 }
 254         }
 255  got_all:
 256
 257         if (n <= 1) {
 258                 /* Alt-x is usually returned as ESC x.
 259                  * Report ESC, x is remembered for the next call.
 260                  */
 261                 buffer[-1] = n;
 262                 return 27;
 263         }
 264
 265         /* We were doing "buffer[-1] = n; return c;" here, but this results
 266          * in unknown key sequences being interpreted as ESC + garbage.
 267          * This was not useful. Pretend there was no key pressed,
 268          * go and wait for a new keypress:
 269          */
 270         buffer[-1] = 0;
 271         goto start_over;
 272 }
 273
 274 void FAST_FUNC read_key_ungets(char *buffer, const char *str, unsigned len)
 275 {
 276         unsigned cur_len = (unsigned char)buffer[0];
 277         if (len > KEYCODE_BUFFER_SIZE-1 - cur_len)
 278                 len = KEYCODE_BUFFER_SIZE-1 - cur_len;
 279         memcpy(buffer + 1 + cur_len, str, len);
 280         buffer[0] += len;
 281 }