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