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 * Check for special chars at start of input.
38 *
39 * @param buf Console input buffer.
40 * @param len Length of valid data in buffer.
41 * @param tty The tty struct for this console.
42 * @return CTRLCHAR_NONE, if nothing matched,
43 * CTRLCHAR_SYSRQ, if sysrq was encountered
44 * otherwise char to be inserted logically or'ed
45 * with CTRLCHAR_CTRL
46 */
47 unsigned int
ctrlchar_handle(const unsigned char * buf,int len,struct tty_struct * tty)48 ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
49 {
50 if ((len < 2) || (len > 3))
51 return CTRLCHAR_NONE;
52
53 /* hat is 0xb1 in codepage 037 (US etc.) and thus */
54 /* converted to 0x5e in ascii ('^') */
55 if ((buf[0] != '^') && (buf[0] != '\252'))
56 return CTRLCHAR_NONE;
57
58 #ifdef CONFIG_MAGIC_SYSRQ
59 /* racy */
60 if (len == 3 && buf[1] == '-') {
61 ctrlchar_sysrq.key = buf[2];
62 schedule_sysrq_work(&ctrlchar_sysrq);
63 return CTRLCHAR_SYSRQ;
64 }
65 #endif
66
67 if (len != 2)
68 return CTRLCHAR_NONE;
69
70 switch (tolower(buf[1])) {
71 case 'c':
72 return INTR_CHAR(tty) | CTRLCHAR_CTRL;
73 case 'd':
74 return EOF_CHAR(tty) | CTRLCHAR_CTRL;
75 case 'z':
76 return SUSP_CHAR(tty) | CTRLCHAR_CTRL;
77 }
78 return CTRLCHAR_NONE;
79 }
80