Add a simple scripting facility to DDB(4), allowing the user to

define a set of named scripts.  Each script consists of a list of DDB
commands separated by ";"s that will be executed verbatim.  No higher
level language constructs, such as branching, are provided for:
scripts are executed by sequentially injecting commands into the DDB
input buffer.

Four new commands are present in DDB: "run" to run a specific script,
"script" to define or print a script, "scripts" to list currently
defined scripts, and "unscript" to delete a script, modeled on shell
alias commands.  Scripts may also be manipulated using sysctls in the
debug.ddb.scripting MIB space, although users will prefer to use the
soon-to-be-added ddb(8) tool for usability reasons.

Scripts with certain names are automatically executed on various DDB
events, such as entering the debugger via a panic, a witness error,
watchdog, breakpoint, sysctl, serial break, etc, allowing customized
handling.

MFC after:	3 months

1 files changed, 30 insertions, 1 deletions

diff --git a/sys/ddb/db_lex.c b/sys/ddb/db_lex.c
index a04103b00deb..1c8151e5371c 100644
--- a/sys/ddb/db_lex.c
+++ b/sys/ddb/db_lex.c
@@ -35,11 +35,12 @@
 __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
+#include <sys/libkern.h>
 
 #include <ddb/ddb.h>
 #include <ddb/db_lex.h>
 
-static char	db_line[120];
+static char	db_line[DB_MAXLINE];
 static char *	db_lp, *db_endlp;
 
 static int	db_lex(void);
@@ -60,6 +61,32 @@ db_read_line()
 	return (i);
 }
 
+/*
+ * Simulate a line of input into DDB.
+ */
+void
+db_inject_line(const char *command)
+{
+
+	strlcpy(db_line, command, sizeof(db_line));
+	db_lp = db_line;
+	db_endlp = db_lp + strlen(command);
+}
+
+/*
+ * In rare cases, we may want to pull the remainder of the line input
+ * verbatim, rather than lexing it.  For example, when assigning literal
+ * values associated with scripts.  In that case, return a static pointer to
+ * the current location in the input buffer.  The caller must be aware that
+ * the contents are not stable if other lex/input calls are made.
+ */
+char *
+db_get_line(void)
+{
+
+	return (db_lp);
+}
+
 static void
 db_flush_line()
 {
@@ -264,6 +291,8 @@ db_lex()
 		return (tDOLLAR);
 	    case '!':
 		return (tEXCL);
+	    case ';':
+		return (tSEMI);
 	    case '<':
 		c = db_read_char();
 		if (c == '<')