1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Unified handling of special chars.
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright IBM Corp. 2001
6*4882a593Smuzhiyun * Author(s): Fritz Elfert <felfert@millenux.com> <elfert@de.ibm.com>
7*4882a593Smuzhiyun *
8*4882a593Smuzhiyun */
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #include <linux/stddef.h>
11*4882a593Smuzhiyun #include <asm/errno.h>
12*4882a593Smuzhiyun #include <linux/sysrq.h>
13*4882a593Smuzhiyun #include <linux/ctype.h>
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun #include "ctrlchar.h"
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun #ifdef CONFIG_MAGIC_SYSRQ
18*4882a593Smuzhiyun static struct sysrq_work ctrlchar_sysrq;
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun static void
ctrlchar_handle_sysrq(struct work_struct * work)21*4882a593Smuzhiyun ctrlchar_handle_sysrq(struct work_struct *work)
22*4882a593Smuzhiyun {
23*4882a593Smuzhiyun struct sysrq_work *sysrq = container_of(work, struct sysrq_work, work);
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun handle_sysrq(sysrq->key);
26*4882a593Smuzhiyun }
27*4882a593Smuzhiyun
schedule_sysrq_work(struct sysrq_work * sw)28*4882a593Smuzhiyun void schedule_sysrq_work(struct sysrq_work *sw)
29*4882a593Smuzhiyun {
30*4882a593Smuzhiyun INIT_WORK(&sw->work, ctrlchar_handle_sysrq);
31*4882a593Smuzhiyun schedule_work(&sw->work);
32*4882a593Smuzhiyun }
33*4882a593Smuzhiyun #endif
34*4882a593Smuzhiyun
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun /**
37*4882a593Smuzhiyun * Check for special chars at start of input.
38*4882a593Smuzhiyun *
39*4882a593Smuzhiyun * @param buf Console input buffer.
40*4882a593Smuzhiyun * @param len Length of valid data in buffer.
41*4882a593Smuzhiyun * @param tty The tty struct for this console.
42*4882a593Smuzhiyun * @return CTRLCHAR_NONE, if nothing matched,
43*4882a593Smuzhiyun * CTRLCHAR_SYSRQ, if sysrq was encountered
44*4882a593Smuzhiyun * otherwise char to be inserted logically or'ed
45*4882a593Smuzhiyun * with CTRLCHAR_CTRL
46*4882a593Smuzhiyun */
47*4882a593Smuzhiyun unsigned int
ctrlchar_handle(const unsigned char * buf,int len,struct tty_struct * tty)48*4882a593Smuzhiyun ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
49*4882a593Smuzhiyun {
50*4882a593Smuzhiyun if ((len < 2) || (len > 3))
51*4882a593Smuzhiyun return CTRLCHAR_NONE;
52*4882a593Smuzhiyun
53*4882a593Smuzhiyun /* hat is 0xb1 in codepage 037 (US etc.) and thus */
54*4882a593Smuzhiyun /* converted to 0x5e in ascii ('^') */
55*4882a593Smuzhiyun if ((buf[0] != '^') && (buf[0] != '\252'))
56*4882a593Smuzhiyun return CTRLCHAR_NONE;
57*4882a593Smuzhiyun
58*4882a593Smuzhiyun #ifdef CONFIG_MAGIC_SYSRQ
59*4882a593Smuzhiyun /* racy */
60*4882a593Smuzhiyun if (len == 3 && buf[1] == '-') {
61*4882a593Smuzhiyun ctrlchar_sysrq.key = buf[2];
62*4882a593Smuzhiyun schedule_sysrq_work(&ctrlchar_sysrq);
63*4882a593Smuzhiyun return CTRLCHAR_SYSRQ;
64*4882a593Smuzhiyun }
65*4882a593Smuzhiyun #endif
66*4882a593Smuzhiyun
67*4882a593Smuzhiyun if (len != 2)
68*4882a593Smuzhiyun return CTRLCHAR_NONE;
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun switch (tolower(buf[1])) {
71*4882a593Smuzhiyun case 'c':
72*4882a593Smuzhiyun return INTR_CHAR(tty) | CTRLCHAR_CTRL;
73*4882a593Smuzhiyun case 'd':
74*4882a593Smuzhiyun return EOF_CHAR(tty) | CTRLCHAR_CTRL;
75*4882a593Smuzhiyun case 'z':
76*4882a593Smuzhiyun return SUSP_CHAR(tty) | CTRLCHAR_CTRL;
77*4882a593Smuzhiyun }
78*4882a593Smuzhiyun return CTRLCHAR_NONE;
79*4882a593Smuzhiyun }
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