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 struct sysrq_work ctrlchar_sysrq;
  18
  19 static void
  20 ctrlchar_handle_sysrq(struct work_struct *work)
  21 {
  22         struct sysrq_work *sysrq = container_of(work, struct sysrq_work, work);
  23
  24         handle_sysrq(sysrq->key);
  25 }
  26
  27 void schedule_sysrq_work(struct sysrq_work *sw)
  28 {
  29         INIT_WORK(&sw->work, ctrlchar_handle_sysrq);
  30         schedule_work(&sw->work);
  31 }
  32 #endif
  33
  34
  35 /**
  36  * Check for special chars at start of input.
  37  *
  38  * @param buf Console input buffer.
  39  * @param len Length of valid data in buffer.
  40  * @param tty The tty struct for this console.
  41  * @return CTRLCHAR_NONE, if nothing matched,
  42  *         CTRLCHAR_SYSRQ, if sysrq was encountered
  43  *         otherwise char to be inserted logically or'ed
  44  *         with CTRLCHAR_CTRL
  45  */
  46 unsigned int
  47 ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
  48 {
  49         if ((len < 2) || (len > 3))
  50                 return CTRLCHAR_NONE;
  51
  52         /* hat is 0xb1 in codepage 037 (US etc.) and thus */
  53         /* converted to 0x5e in ascii ('^') */
  54         if ((buf[0] != '^') && (buf[0] != '\252'))
  55                 return CTRLCHAR_NONE;
  56
  57 #ifdef CONFIG_MAGIC_SYSRQ
  58         /* racy */
  59         if (len == 3 && buf[1] == '-') {
  60                 ctrlchar_sysrq.key = buf[2];
  61                 schedule_sysrq_work(&ctrlchar_sysrq);
  62                 return CTRLCHAR_SYSRQ;
  63         }
  64 #endif
  65
  66         if (len != 2)
  67                 return CTRLCHAR_NONE;
  68
  69         switch (tolower(buf[1])) {
  70         case 'c':
  71                 return INTR_CHAR(tty) | CTRLCHAR_CTRL;
  72         case 'd':
  73                 return EOF_CHAR(tty)  | CTRLCHAR_CTRL;
  74         case 'z':
  75                 return SUSP_CHAR(tty) | CTRLCHAR_CTRL;
  76         }
  77         return CTRLCHAR_NONE;
  78 }