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

   1/*
   2 *  drivers/s390/char/ctrlchar.c
   3 *  Unified handling of special chars.
   4 *
   5 *    Copyright (C) 2001 IBM Deutschland Entwicklung GmbH, IBM Corporation
   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 int ctrlchar_sysrq_key;
  19static struct tty_struct *sysrq_tty;
  20
  21static void
  22ctrlchar_handle_sysrq(struct work_struct *work)
  23{
  24        handle_sysrq(ctrlchar_sysrq_key, sysrq_tty);
  25}
  26
  27static DECLARE_WORK(ctrlchar_work, ctrlchar_handle_sysrq);
  28#endif
  29
  30
  31/**
  32 * Check for special chars at start of input.
  33 *
  34 * @param buf Console input buffer.
  35 * @param len Length of valid data in buffer.
  36 * @param tty The tty struct for this console.
  37 * @return CTRLCHAR_NONE, if nothing matched,
  38 *         CTRLCHAR_SYSRQ, if sysrq was encountered
  39 *         otherwise char to be inserted logically or'ed
  40 *         with CTRLCHAR_CTRL
  41 */
  42unsigned int
  43ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
  44{
  45        if ((len < 2) || (len > 3))
  46                return CTRLCHAR_NONE;
  47
  48        /* hat is 0xb1 in codepage 037 (US etc.) and thus */
  49        /* converted to 0x5e in ascii ('^') */
  50        if ((buf[0] != '^') && (buf[0] != '\252'))
  51                return CTRLCHAR_NONE;
  52
  53#ifdef CONFIG_MAGIC_SYSRQ
  54        /* racy */
  55        if (len == 3 && buf[1] == '-') {
  56                ctrlchar_sysrq_key = buf[2];
  57                sysrq_tty = tty;
  58                schedule_work(&ctrlchar_work);
  59                return CTRLCHAR_SYSRQ;
  60        }
  61#endif
  62
  63        if (len != 2)
  64                return CTRLCHAR_NONE;
  65
  66        switch (tolower(buf[1])) {
  67        case 'c':
  68                return INTR_CHAR(tty) | CTRLCHAR_CTRL;
  69        case 'd':
  70                return EOF_CHAR(tty)  | CTRLCHAR_CTRL;
  71        case 'z':
  72                return SUSP_CHAR(tty) | CTRLCHAR_CTRL;
  73        }
  74        return CTRLCHAR_NONE;
  75}
  76