aboutsummaryrefslogtreecommitdiff
path: root/drivers/s390/char/ctrlchar.c
blob: 0ea6f36a25277862234b3045f35fa6d70689baa6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
/*
 *  drivers/s390/char/ctrlchar.c
 *  Unified handling of special chars.
 *
 *    Copyright (C) 2001 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Fritz Elfert <felfert@millenux.com> <elfert@de.ibm.com>
 *
 */

#include <linux/stddef.h>
#include <asm/errno.h>
#include <linux/sysrq.h>
#include <linux/ctype.h>

#include "ctrlchar.h"

#ifdef CONFIG_MAGIC_SYSRQ
static int ctrlchar_sysrq_key;

static void
ctrlchar_handle_sysrq(void *tty)
{
	handle_sysrq(ctrlchar_sysrq_key, NULL, (struct tty_struct *) tty);
}

static DECLARE_WORK(ctrlchar_work, ctrlchar_handle_sysrq, 0);
#endif


/**
 * Check for special chars at start of input.
 *
 * @param buf Console input buffer.
 * @param len Length of valid data in buffer.
 * @param tty The tty struct for this console.
 * @return CTRLCHAR_NONE, if nothing matched,
 *         CTRLCHAR_SYSRQ, if sysrq was encountered
 *         otherwise char to be inserted logically or'ed
 *         with CTRLCHAR_CTRL
 */
unsigned int
ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
{
	if ((len < 2) || (len > 3))
		return CTRLCHAR_NONE;

	/* hat is 0xb1 in codepage 037 (US etc.) and thus */
	/* converted to 0x5e in ascii ('^') */
	if ((buf[0] != '^') && (buf[0] != '\252'))
		return CTRLCHAR_NONE;

#ifdef CONFIG_MAGIC_SYSRQ
	/* racy */
	if (len == 3 && buf[1] == '-') {
		ctrlchar_sysrq_key = buf[2];
		ctrlchar_work.data = tty;
		schedule_work(&ctrlchar_work);
		return CTRLCHAR_SYSRQ;
	}
#endif

	if (len != 2)
		return CTRLCHAR_NONE;

	switch (tolower(buf[1])) {
	case 'c':
		return INTR_CHAR(tty) | CTRLCHAR_CTRL;
	case 'd':
		return EOF_CHAR(tty)  | CTRLCHAR_CTRL;
	case 'z':
		return SUSP_CHAR(tty) | CTRLCHAR_CTRL;
	}
	return CTRLCHAR_NONE;
}