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
  17 static int ctrlchar_sysrq_key;
  18
  19 static void
  20 ctrlchar_handle_sysrq(struct work_struct *work)
  21 {
  22         handle_sysrq(ctrlchar_sysrq_key);
  23 }
  24
  25 static 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  */
  40 unsigned int
  41 ctrlchar_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 }