diff options
| -rw-r--r-- | libbb/read_key.c | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/libbb/read_key.c b/libbb/read_key.c new file mode 100644 index 000000000..598bd94f5 --- /dev/null +++ b/libbb/read_key.c @@ -0,0 +1,146 @@ +/* vi: set sw=4 ts=4: */ +/* + * Utility routines. + * + * Copyright (C) 2008 Denys Vlasenko + * + * Licensed under GPL version 2, see file LICENSE in this tarball for details. + */ +#include "libbb.h" + +int FAST_FUNC read_key(int fd, smalluint *nbuffered, char *buffer) +{ + struct pollfd pfd; + const char *seq; + int n; + int c; + + /* Known escape sequences for cursor and function keys */ + static const char esccmds[] ALIGN1 = { + 'O','A' |0x80,KEYCODE_UP , + 'O','B' |0x80,KEYCODE_DOWN , + 'O','C' |0x80,KEYCODE_RIGHT , + 'O','D' |0x80,KEYCODE_LEFT , + 'O','H' |0x80,KEYCODE_HOME , + 'O','F' |0x80,KEYCODE_END , +#if 0 + 'O','P' |0x80,KEYCODE_FUN1 , + 'O','Q' |0x80,KEYCODE_FUN2 , + 'O','R' |0x80,KEYCODE_FUN3 , + 'O','S' |0x80,KEYCODE_FUN4 , +#endif + '[','A' |0x80,KEYCODE_UP , + '[','B' |0x80,KEYCODE_DOWN , + '[','C' |0x80,KEYCODE_RIGHT , + '[','D' |0x80,KEYCODE_LEFT , + '[','H' |0x80,KEYCODE_HOME , + '[','F' |0x80,KEYCODE_END , + '[','1','~' |0x80,KEYCODE_HOME , + '[','2','~' |0x80,KEYCODE_INSERT , + '[','3','~' |0x80,KEYCODE_DELETE , + '[','4','~' |0x80,KEYCODE_END , + '[','5','~' |0x80,KEYCODE_PAGEUP , + '[','6','~' |0x80,KEYCODE_PAGEDOWN, +#if 0 + '[','1','1','~'|0x80,KEYCODE_FUN1 , + '[','1','2','~'|0x80,KEYCODE_FUN2 , + '[','1','3','~'|0x80,KEYCODE_FUN3 , + '[','1','4','~'|0x80,KEYCODE_FUN4 , + '[','1','5','~'|0x80,KEYCODE_FUN5 , + '[','1','7','~'|0x80,KEYCODE_FUN6 , + '[','1','8','~'|0x80,KEYCODE_FUN7 , + '[','1','9','~'|0x80,KEYCODE_FUN8 , + '[','2','0','~'|0x80,KEYCODE_FUN9 , + '[','2','1','~'|0x80,KEYCODE_FUN10 , + '[','2','3','~'|0x80,KEYCODE_FUN11 , + '[','2','4','~'|0x80,KEYCODE_FUN12 , +#endif + 0 + }; + + n = *nbuffered; + if (n == 0) { + /* If no data, block waiting for input. If we read more + * than the minimal ESC sequence size, the "n=0" below + * would instead have to figure out how much to keep, + * resulting in larger code. */ + n = safe_read(fd, buffer, 3); + if (n <= 0) + return -1; + } + + /* Grab character to return from buffer */ + c = (unsigned char)buffer[0]; + n--; + if (n) + memmove(buffer, buffer + 1, n); + + /* Only ESC starts ESC sequences */ + if (c != 27) + goto ret; + + /* Loop through known ESC sequences */ + pfd.fd = fd; + pfd.events = POLLIN; + seq = esccmds; + while (*seq != '\0') { + /* n - position in sequence we did not read yet */ + int i = 0; /* position in sequence to compare */ + + /* Loop through chars in this sequence */ + while (1) { + /* So far escape sequence matched up to [i-1] */ + if (n <= i) { + /* Need more chars, read another one if it wouldn't block. + * Note that escape sequences come in as a unit, + * so if we block for long it's not really an escape sequence. + * Timeout is needed to reconnect escape sequences + * split up by transmission over a serial console. */ + if (safe_poll(&pfd, 1, 50) == 0) { + /* No more data! + * Array is sorted from shortest to longest, + * we can't match anything later in array, + * break out of both loops. */ + goto ret; + } + errno = 0; + if (safe_read(fd, buffer + n, 1) <= 0) { + /* If EAGAIN, then fd is O_NONBLOCK and poll lied: + * in fact, there is no data. */ + if (errno != EAGAIN) + c = -1; /* otherwise it's EOF/error */ + goto ret; + } + n++; + } + if (buffer[i] != (seq[i] & 0x7f)) { + /* This seq doesn't match, go to next */ + seq += i; + /* Forward to last char */ + while (!(*seq & 0x80)) + seq++; + /* Skip it and the keycode which follows */ + seq += 2; + break; + } + if (seq[i] & 0x80) { + /* Entire seq matched */ + c = (signed char)seq[i+1]; + n = 0; + /* n -= i; memmove(...); + * would be more correct, + * but we never read ahead that much, + * and n == i here. */ + goto ret; + } + i++; + } + } + /* We did not find matching sequence, it was a bare ESC. + * We possibly read and stored more input in buffer[] + * by now. */ + + ret: + *nbuffered = n; + return c; +} |