- Change the ddb paging "support" to use a variable (db_lines_per_page) to

  control the number of lines per page rather than a constant.  The variable
  can be examined and changed in ddb as '$lines'.  Setting the variable to
  0 will effectively turn off paging.
- Change db_putchar() to force out pending whitespace before outputting
  newlines and carriage returns so that one can rub out content on the
  current line via '\r     \r' type strings.
- Change the simple pager to rub out the --More-- prompt explicitly when
  the routine exits.
- Add some aliases to the simple pager to make it more compatible with
  more(1): 'e' and 'j' do a single line.  'd' does half a page, and
  'f' does a full page.

MFC after:	1 month
Inspired by:	kris

5 files changed, 28 insertions, 12 deletions

diff --git a/sys/ddb/db_output.c b/sys/ddb/db_output.c
index ff2734c..27e57a5 100644
--- a/sys/ddb/db_output.c
+++ b/sys/ddb/db_output.c
@@ -65,8 +65,9 @@ db_expr_t	db_tab_stop_width = 8;		/* how wide are tab stops? */
 #define	NEXT_TAB(i) \
 	((((i) + db_tab_stop_width) / db_tab_stop_width) * db_tab_stop_width)
 db_expr_t	db_max_width = 79;		/* output line width */
+db_expr_t	db_lines_per_page = 20;		/* lines per page */
 static int	db_newlines;			/* # lines this page */
-static int	db_maxlines = -1;		/* max lines per page */
+static int	db_maxlines = -1;		/* max lines/page when paging */
 static db_page_calloutfcn_t *db_page_callout = NULL;
 static void	*db_page_callout_arg = NULL;
 static int	ddb_use_printf = 0;
@@ -143,6 +144,7 @@ db_putchar(c, arg)
 	}
 	else if (c == '\n') {
 	    /* Newline */
+	    db_force_whitespace();
 	    cnputc(c);
 	    db_output_position = 0;
 	    db_last_non_space = 0;
@@ -157,6 +159,7 @@ db_putchar(c, arg)
 	}
 	else if (c == '\r') {
 	    /* Return */
+	    db_force_whitespace();
 	    cnputc(c);
 	    db_output_position = 0;
 	    db_last_non_space = 0;
@@ -197,21 +200,33 @@ db_setup_paging(db_page_calloutfcn_t *callout, void *arg, int maxlines)
 void
 db_simple_pager(void *arg)
 {
-	int c;
+	int c, done;
 
 	db_printf("--More--\r");
-	for (;;) {
+	done = 0;
+	while (!done) {
 		c = cngetc();
 		switch (c) {
+		case 'e':
+		case 'j':
 		case '\n':
 			/* Just one more line. */
 			db_setup_paging(db_simple_pager, arg, 1);
-			return;
+			done++;
+			break;
+		case 'd':
+			/* Half a page. */
+			db_setup_paging(db_simple_pager, arg,
+			    db_lines_per_page / 2);
+			done++;
+			break;
+		case 'f':
 		case ' ':
 			/* Another page. */
 			db_setup_paging(db_simple_pager, arg,
-			    DB_LINES_PER_PAGE);
-			return;
+			    db_lines_per_page);
+			done++;
+			break;
 		case 'q':
 		case 'Q':
 		case 'x':
@@ -219,8 +234,8 @@ db_simple_pager(void *arg)
 			/* Quit */
 			if (arg != NULL) {
 				*(int *)arg = 1;
-				db_printf("\n");
-				return;
+				done++;
+				break;
 			}
 #if 0
 			/* FALLTHROUGH */
@@ -229,6 +244,7 @@ db_simple_pager(void *arg)
 #endif
 		}
 	}
+	db_printf("        \r");
 }
 
 /*
diff --git a/sys/ddb/db_ps.c b/sys/ddb/db_ps.c
index 5820059..b03382d 100644
--- a/sys/ddb/db_ps.c
+++ b/sys/ddb/db_ps.c
@@ -65,7 +65,7 @@ db_ps(dummy1, dummy2, dummy3, dummy4)
 	else
 		p = &proc0;
 
-	db_setup_paging(db_simple_pager, &quit, DB_LINES_PER_PAGE);
+	db_setup_paging(db_simple_pager, &quit, db_lines_per_page);
 	db_printf("  pid   proc     uarea   uid  ppid  pgrp  flag   stat  wmesg    wchan  cmd\n");
 	while (--np >= 0 && !quit) {
 		if (p == NULL) {
diff --git a/sys/ddb/db_thread.c b/sys/ddb/db_thread.c
index b58f0b0..8994f96 100644
--- a/sys/ddb/db_thread.c
+++ b/sys/ddb/db_thread.c
@@ -88,7 +88,7 @@ db_show_threads(db_expr_t addr, boolean_t hasaddr, db_expr_t cnt, char *mod)
 	struct thread *thr;
 	int pager_quit;
 
-	db_setup_paging(db_simple_pager, &pager_quit, DB_LINES_PER_PAGE);
+	db_setup_paging(db_simple_pager, &pager_quit, db_lines_per_page);
 
 	pager_quit = 0;
 	thr = kdb_thr_first();
diff --git a/sys/ddb/db_variables.c b/sys/ddb/db_variables.c
index cf8e2e7..6322a33 100644
--- a/sys/ddb/db_variables.c
+++ b/sys/ddb/db_variables.c
@@ -45,6 +45,7 @@ static struct db_variable db_vars[] = {
 	{ "maxoff",	&db_maxoff, FCN_NULL },
 	{ "maxwidth",	&db_max_width, FCN_NULL },
 	{ "tabstops",	&db_tab_stop_width, FCN_NULL },
+	{ "lines",	&db_lines_per_page, FCN_NULL },
 };
 static struct db_variable *db_evars =
 	db_vars + sizeof(db_vars)/sizeof(db_vars[0]);
diff --git a/sys/ddb/ddb.h b/sys/ddb/ddb.h
index 97d332e..ba66705 100644
--- a/sys/ddb/ddb.h
+++ b/sys/ddb/ddb.h
@@ -39,8 +39,6 @@
 
 #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);
 
@@ -78,6 +76,7 @@ extern int db_store_count;
 extern db_expr_t db_radix;
 extern db_expr_t db_max_width;
 extern db_expr_t db_tab_stop_width;
+extern db_expr_t db_lines_per_page;
 
 struct thread;
 struct vm_map;