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