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

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