hush: get rid of charmap[]
[oweals/busybox.git] / 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 int FAST_FUNC read_key(int fd, smalluint *nbuffered, 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         n = 0;
70         if (nbuffered)
71                 n = *nbuffered;
72         if (n == 0) {
73                 /* If no data, block waiting for input. If we read more
74                  * than the minimal ESC sequence size, the "n=0" below
75                  * would instead have to figure out how much to keep,
76                  * resulting in larger code. */
77                 n = safe_read(fd, buffer, 3);
78                 if (n <= 0)
79                         return -1;
80         }
81
82         /* Grab character to return from buffer */
83         c = (unsigned char)buffer[0];
84         n--;
85         if (n)
86                 memmove(buffer, buffer + 1, n);
87
88         /* Only ESC starts ESC sequences */
89         if (c != 27)
90                 goto ret;
91
92         /* Loop through known ESC sequences */
93         pfd.fd = fd;
94         pfd.events = POLLIN;
95         seq = esccmds;
96         while (*seq != '\0') {
97                 /* n - position in sequence we did not read yet */
98                 int i = 0; /* position in sequence to compare */
99
100                 /* Loop through chars in this sequence */
101                 while (1) {
102                         /* So far escape sequence matched up to [i-1] */
103                         if (n <= i) {
104                                 /* Need more chars, read another one if it wouldn't block.
105                                  * Note that escape sequences come in as a unit,
106                                  * so if we block for long it's not really an escape sequence.
107                                  * Timeout is needed to reconnect escape sequences
108                                  * split up by transmission over a serial console. */
109                                 if (safe_poll(&pfd, 1, 50) == 0) {
110                                         /* No more data!
111                                          * Array is sorted from shortest to longest,
112                                          * we can't match anything later in array,
113                                          * break out of both loops. */
114                                         goto ret;
115                                 }
116                                 errno = 0;
117                                 if (safe_read(fd, buffer + n, 1) <= 0) {
118                                         /* If EAGAIN, then fd is O_NONBLOCK and poll lied:
119                                          * in fact, there is no data. */
120                                         if (errno != EAGAIN)
121                                                 c = -1; /* otherwise it's EOF/error */
122                                         goto ret;
123                                 }
124                                 n++;
125                         }
126                         if (buffer[i] != (seq[i] & 0x7f)) {
127                                 /* This seq doesn't match, go to next */
128                                 seq += i;
129                                 /* Forward to last char */
130                                 while (!(*seq & 0x80))
131                                         seq++;
132                                 /* Skip it and the keycode which follows */
133                                 seq += 2;
134                                 break;
135                         }
136                         if (seq[i] & 0x80) {
137                                 /* Entire seq matched */
138                                 c = (signed char)seq[i+1];
139                                 n = 0;
140                                 /* n -= i; memmove(...);
141                                  * would be more correct,
142                                  * but we never read ahead that much,
143                                  * and n == i here. */
144                                 goto ret;
145                         }
146                         i++;
147                 }
148         }
149         /* We did not find matching sequence, it was a bare ESC.
150          * We possibly read and stored more input in buffer[]
151          * by now. */
152
153  ret:
154         if (nbuffered)
155                 *nbuffered = n;
156         return c;
157 }