Author: gibbs
Date: Tue Jun 14 21:37:25 2011
New Revision: 223099
URL: http://svn.freebsd.org/changeset/base/223099
Log:
sys/kern/subr_kdb.c:
Modify the "alternate break sequence" detecting state
machine so that only a contiguous invocation of the
break sequence is accepted. The old implementation
did not reset the state machine when detecting an
unexpected character.
While here, use an enum for the states of the machine
instead of magic numbers.bmitted by:
Sponsored by: Spectra Logic Corporation
Modified:
head/sys/kern/subr_kdb.c
Modified: head/sys/kern/subr_kdb.c
==============================================================================
--- head/sys/kern/subr_kdb.c Tue Jun 14 20:30:49 2011 (r223098)
+++ head/sys/kern/subr_kdb.c Tue Jun 14 21:37:25 2011 (r223099)
@@ -244,29 +244,44 @@ kdb_reboot(void)
#define KEY_CRTLP 16 /* ^P */
#define KEY_CRTLR 18 /* ^R */
+/* States of th KDB "alternate break sequence" detecting state machine. */
+enum {
+ KDB_ALT_BREAK_SEEN_NONE,
+ KDB_ALT_BREAK_SEEN_CR,
+ KDB_ALT_BREAK_SEEN_CR_TILDE,
+};
+
int
kdb_alt_break(int key, int *state)
{
int brk;
+ /* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */
+ if (key == KEY_CR) {
+ *state = KDB_ALT_BREAK_SEEN_CR;
+ return (0);
+ }
+
brk = 0;
switch (*state) {
- case 0:
- if (key == KEY_CR)
- *state = 1;
- break;
- case 1:
+ case KDB_ALT_BREAK_SEEN_CR:
+ *state = KDB_ALT_BREAK_SEEN_NONE;
if (key == KEY_TILDE)
- *state = 2;
+ *state = KDB_ALT_BREAK_SEEN_CR_TILDE;
break;
- case 2:
+ case KDB_ALT_BREAK_SEEN_CR_TILDE:
+ *state = KDB_ALT_BREAK_SEEN_NONE;
if (key == KEY_CRTLB)
brk = KDB_REQ_DEBUGGER;
else if (key == KEY_CRTLP)
brk = KDB_REQ_PANIC;
else if (key == KEY_CRTLR)
brk = KDB_REQ_REBOOT;
- *state = 0;
+ break;
+ case KDB_ALT_BREAK_SEEN_NONE:
+ default:
+ *state = KDB_ALT_BREAK_SEEN_NONE;
+ break;
}
return (brk);
}
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