s390/char/ctrlchar.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  *  Unified handling of special chars.
0004  *
0005  *    Copyright IBM Corp. 2001
0006  *    Author(s): Fritz Elfert <felfert@millenux.com> <elfert@de.ibm.com>
0007  *
0008  */
0009
0010 #include <linux/stddef.h>
0011 #include <asm/errno.h>
0012 #include <linux/sysrq.h>
0013 #include <linux/ctype.h>
0014
0015 #include "ctrlchar.h"
0016
0017 #ifdef CONFIG_MAGIC_SYSRQ
0018 static struct sysrq_work ctrlchar_sysrq;
0019
0020 static void
0021 ctrlchar_handle_sysrq(struct work_struct *work)
0022 {
0023     struct sysrq_work *sysrq = container_of(work, struct sysrq_work, work);
0024
0025     handle_sysrq(sysrq->key);
0026 }
0027
0028 void schedule_sysrq_work(struct sysrq_work *sw)
0029 {
0030     INIT_WORK(&sw->work, ctrlchar_handle_sysrq);
0031     schedule_work(&sw->work);
0032 }
0033 #endif
0034
0035
0036 /**
0037  * ctrlchar_handle - check for special chars at start of input
0038  *
0039  * @buf: console input buffer
0040  * @len: length of valid data in buffer
0041  * @tty: the tty struct for this console
0042  *
0043  * Return: CTRLCHAR_NONE, if nothing matched,
0044  *         CTRLCHAR_SYSRQ, if sysrq was encountered
0045  *         otherwise char to be inserted logically or'ed
0046  *         with CTRLCHAR_CTRL
0047  */
0048 unsigned int
0049 ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
0050 {
0051     if ((len < 2) || (len > 3))
0052         return CTRLCHAR_NONE;
0053
0054     /* hat is 0xb1 in codepage 037 (US etc.) and thus */
0055     /* converted to 0x5e in ascii ('^') */
0056     if ((buf[0] != '^') && (buf[0] != '\252'))
0057         return CTRLCHAR_NONE;
0058
0059 #ifdef CONFIG_MAGIC_SYSRQ
0060     /* racy */
0061     if (len == 3 && buf[1] == '-') {
0062         ctrlchar_sysrq.key = buf[2];
0063         schedule_sysrq_work(&ctrlchar_sysrq);
0064         return CTRLCHAR_SYSRQ;
0065     }
0066 #endif
0067
0068     if (len != 2)
0069         return CTRLCHAR_NONE;
0070
0071     switch (tolower(buf[1])) {
0072     case 'c':
0073         return INTR_CHAR(tty) | CTRLCHAR_CTRL;
0074     case 'd':
0075         return EOF_CHAR(tty)  | CTRLCHAR_CTRL;
0076     case 'z':
0077         return SUSP_CHAR(tty) | CTRLCHAR_CTRL;
0078     }
0079     return CTRLCHAR_NONE;
0080 }