1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Unified handling of special chars.
4 *
5 * Copyright IBM Corp. 2001
6 * Author(s): Fritz Elfert <felfert@millenux.com> <elfert@de.ibm.com>
7 *
8 */
9
10 #include <linux/stddef.h>
11 #include <asm/errno.h>
12 #include <linux/sysrq.h>
13 #include <linux/ctype.h>
14
15 #include "ctrlchar.h"
16
17 #ifdef CONFIG_MAGIC_SYSRQ
18 static struct sysrq_work ctrlchar_sysrq;
19
20 static void
ctrlchar_handle_sysrq(struct work_struct * work)21 ctrlchar_handle_sysrq(struct work_struct *work)
22 {
23 struct sysrq_work *sysrq = container_of(work, struct sysrq_work, work);
24
25 handle_sysrq(sysrq->key);
26 }
27
schedule_sysrq_work(struct sysrq_work * sw)28 void schedule_sysrq_work(struct sysrq_work *sw)
29 {
30 INIT_WORK(&sw->work, ctrlchar_handle_sysrq);
31 schedule_work(&sw->work);
32 }
33 #endif
34
35
36 /**
37 * ctrlchar_handle - check for special chars at start of input
38 *
39 * @buf: console input buffer
40 * @len: length of valid data in buffer
41 * @tty: the tty struct for this console
42 *
43 * Return: CTRLCHAR_NONE, if nothing matched,
44 * CTRLCHAR_SYSRQ, if sysrq was encountered
45 * otherwise char to be inserted logically or'ed
46 * with CTRLCHAR_CTRL
47 */
48 unsigned int
ctrlchar_handle(const unsigned char * buf,int len,struct tty_struct * tty)49 ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
50 {
51 if ((len < 2) || (len > 3))
52 return CTRLCHAR_NONE;
53
54 /* hat is 0xb1 in codepage 037 (US etc.) and thus */
55 /* converted to 0x5e in ascii ('^') */
56 if ((buf[0] != '^') && (buf[0] != '\252'))
57 return CTRLCHAR_NONE;
58
59 #ifdef CONFIG_MAGIC_SYSRQ
60 /* racy */
61 if (len == 3 && buf[1] == '-') {
62 ctrlchar_sysrq.key = buf[2];
63 schedule_sysrq_work(&ctrlchar_sysrq);
64 return CTRLCHAR_SYSRQ;
65 }
66 #endif
67
68 if (len != 2)
69 return CTRLCHAR_NONE;
70
71 switch (tolower(buf[1])) {
72 case 'c':
73 return INTR_CHAR(tty) | CTRLCHAR_CTRL;
74 case 'd':
75 return EOF_CHAR(tty) | CTRLCHAR_CTRL;
76 case 'z':
77 return SUSP_CHAR(tty) | CTRLCHAR_CTRL;
78 }
79 return CTRLCHAR_NONE;
80 }
81