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kernel/linux-imx6_3.14.28/drivers/s390/char/ctrlchar.c 1.57 KB
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  /*
   *  Unified handling of special chars.
   *
   *    Copyright IBM Corp. 2001
   *    Author(s): Fritz Elfert <felfert@millenux.com> <elfert@de.ibm.com>
   *
   */
  
  #include <linux/stddef.h>
  #include <asm/errno.h>
  #include <linux/sysrq.h>
  #include <linux/ctype.h>
  
  #include "ctrlchar.h"
  
  #ifdef CONFIG_MAGIC_SYSRQ
  static int ctrlchar_sysrq_key;
  
  static void
  ctrlchar_handle_sysrq(struct work_struct *work)
  {
  	handle_sysrq(ctrlchar_sysrq_key);
  }
  
  static DECLARE_WORK(ctrlchar_work, ctrlchar_handle_sysrq);
  #endif
  
  
  /**
   * Check for special chars at start of input.
   *
   * @param buf Console input buffer.
   * @param len Length of valid data in buffer.
   * @param tty The tty struct for this console.
   * @return CTRLCHAR_NONE, if nothing matched,
   *         CTRLCHAR_SYSRQ, if sysrq was encountered
   *         otherwise char to be inserted logically or'ed
   *         with CTRLCHAR_CTRL
   */
  unsigned int
  ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
  {
  	if ((len < 2) || (len > 3))
  		return CTRLCHAR_NONE;
  
  	/* hat is 0xb1 in codepage 037 (US etc.) and thus */
  	/* converted to 0x5e in ascii ('^') */
  	if ((buf[0] != '^') && (buf[0] != '\252'))
  		return CTRLCHAR_NONE;
  
  #ifdef CONFIG_MAGIC_SYSRQ
  	/* racy */
  	if (len == 3 && buf[1] == '-') {
  		ctrlchar_sysrq_key = buf[2];
  		schedule_work(&ctrlchar_work);
  		return CTRLCHAR_SYSRQ;
  	}
  #endif
  
  	if (len != 2)
  		return CTRLCHAR_NONE;
  
  	switch (tolower(buf[1])) {
  	case 'c':
  		return INTR_CHAR(tty) | CTRLCHAR_CTRL;
  	case 'd':
  		return EOF_CHAR(tty)  | CTRLCHAR_CTRL;
  	case 'z':
  		return SUSP_CHAR(tty) | CTRLCHAR_CTRL;
  	}
  	return CTRLCHAR_NONE;
  }