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 } 73