Add a one-shot callout facility to db_printf() that executes the registered

callout when a specified number of lines have been output.  This can be
used to implement pagers for ddb commands that output a lot of text.  A
simple paging function is included that automatically rearms itself when
fired.

Reviewed by:	bde, julian

1 files changed, 8 insertions, 0 deletions

diff --git a/sys/ddb/ddb.h b/sys/ddb/ddb.h
index 7259e97b6637..1ef452cfd440 100644
--- a/sys/ddb/ddb.h
+++ b/sys/ddb/ddb.h
@@ -39,9 +39,13 @@
 
 #include <machine/db_machdep.h>		/* type definitions */
 
+#define	DB_LINES_PER_PAGE	20
+
 typedef void db_cmdfcn_t(db_expr_t addr, boolean_t have_addr, db_expr_t count,
 	    char *modif);
 
+typedef void db_page_calloutfcn_t(void *arg);
+
 #define DB_COMMAND(cmd_name, func_name) \
 	DB_SET(cmd_name, func_name, db_cmd_set, 0, NULL)
 #define DB_SHOW_COMMAND(cmd_name, func_name) \
@@ -100,6 +104,8 @@ void		db_read_bytes(vm_offset_t addr, size_t size, char *data);
 int		db_readline(char *lstart, int lsize);
 void		db_restart_at_pc(boolean_t watchpt);
 void		db_set_watchpoints(void);
+void		db_setup_paging(db_page_calloutfcn_t *callout, void *arg,
+				int maxlines);
 void		db_skip_to_eol(void);
 boolean_t	db_stop_at_pc(boolean_t *is_breakpoint);
 #define		db_strcpy	strcpy
@@ -139,6 +145,8 @@ db_cmdfcn_t	ipc_port_print;
 db_cmdfcn_t	vm_page_print;
 #endif
 
+db_page_calloutfcn_t db_simple_pager;
+
 /* Scare the user with backtrace of curthread to console. */
 void		db_print_backtrace(void);