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| 1 | /* |
| 2 | * getkey.c - Single-key TTY input |
| 3 | * |
| 4 | * Written 2010 by Werner Almesberger |
| 5 | * Copyright 2010 Werner Almesberger |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License as published by |
| 9 | * the Free Software Foundation; either version 2 of the License, or |
| 10 | * (at your option) any later version. |
| 11 | */ |
| 12 | |
| 13 | |
| 14 | #include <stdlib.h> |
| 15 | #include <stdio.h> |
| 16 | #include <unistd.h> |
| 17 | #include <fcntl.h> |
| 18 | #include <termios.h> |
| 19 | #include <sys/types.h> |
| 20 | |
| 21 | #include "getkey.h" |
| 22 | |
| 23 | |
| 24 | #define TTY_NAME "/dev/tty" |
| 25 | |
| 26 | |
| 27 | static int tty = -1; |
| 28 | static struct termios old; |
| 29 | |
| 30 | |
| 31 | static void reset_tty(void) |
| 32 | { |
| 33 | if (tty >= 0) |
| 34 | if (tcsetattr(tty, TCSADRAIN, &old) < 0) |
| 35 | perror("tcsetattr"); |
| 36 | } |
| 37 | |
| 38 | |
| 39 | static void tty_open(void) |
| 40 | { |
| 41 | struct termios new; |
| 42 | |
| 43 | tty = open(TTY_NAME, O_RDONLY | O_NOCTTY); |
| 44 | if (tty < 0) { |
| 45 | perror(TTY_NAME); |
| 46 | exit(1); |
| 47 | } |
| 48 | |
| 49 | if (tcgetattr(tty, &old) < 0) { |
| 50 | perror("tcgetattr"); |
| 51 | exit(1); |
| 52 | } |
| 53 | atexit(reset_tty); |
| 54 | |
| 55 | new = old; |
| 56 | cfmakeraw(&new); |
| 57 | if (tcsetattr(tty, TCSANOW, &new) < 0) { |
| 58 | perror("tcsetattr"); |
| 59 | exit(1); |
| 60 | } |
| 61 | } |
| 62 | |
| 63 | |
| 64 | char getkey(void) |
| 65 | { |
| 66 | char buf; |
| 67 | ssize_t got; |
| 68 | |
| 69 | if (tty == -1) |
| 70 | tty_open(); |
| 71 | got = read(tty, &buf, 1); |
| 72 | if (got < 0) { |
| 73 | perror("read"); |
| 74 | reset_tty(); |
| 75 | exit(1); |
| 76 | } |
| 77 | return got ? buf : 0; |
| 78 | } |
| 79 |
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