LXR linux/drivers/s390/char/ctrlchar.c

   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
  18static struct sysrq_work ctrlchar_sysrq;
  19
  20static void
  21ctrlchar_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
  28void 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 */
  47unsigned int
  48ctrlchar_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