Bufferize the output for DDB printouts.

In order to CATER this, DDB buffered output can be choosen at compile
time through the option DDB_BUFR_SIZE=nbytes where nbytes choose the size
of the buffer (suggested size is 128 bytes), which should be manually
specified in any interested config file.

Sponsored by:	Nokia

sys/conf/options

@@ -48,6 +48,7 @@ TWA_FLASH_FIRMWARE	opt_twa.h
 
 # Debugging options.
 DDB
+DDB_BUFR_SIZE	opt_ddb.h
 DDB_CAPTURE_DEFAULTBUFSIZE	opt_ddb.h
 DDB_CAPTURE_MAXBUFSIZE	opt_ddb.h
 DDB_CTF		opt_ddb.h

sys/ddb/db_output.c

@@ -47,6 +47,13 @@ __FBSDID("$FreeBSD$");
 #include <ddb/ddb.h>
 #include <ddb/db_output.h>
 
+struct dbputchar_arg {
+	size_t	da_nbufr;
+	size_t	da_remain;
+	char	*da_pbufr;
+	char	*da_pnext;
+};
+
 /*
  *	Character output - tracks position in line.
  *	To do this correctly, we should know how wide
@@ -73,6 +80,8 @@ static int	ddb_use_printf = 0;
 SYSCTL_INT(_debug, OID_AUTO, ddb_use_printf, CTLFLAG_RW, &ddb_use_printf, 0,
     "use printf for all ddb output");
 
+static void	db_putc(int c);
+static void	db_puts(const char *str);
 static void	db_putchar(int c, void *arg);
 static void	db_pager(void);
 
@@ -107,9 +116,34 @@ db_force_whitespace()
  * Output character.  Buffer whitespace.
  */
 static void
-db_putchar(c, arg)
-	int	c;		/* character to output */
-	void *	arg;
+db_putchar(int c, void *arg)
+{
+	struct dbputchar_arg *dap = arg;
+
+	if (dap->da_pbufr == NULL) {
+
+		 /* No bufferized output is provided. */
+		db_putc(c);
+	} else {
+
+		*dap->da_pnext++ = c;
+		dap->da_remain--;
+
+		/* Leave always the buffer 0 terminated. */
+		*dap->da_pnext = '\0';
+
+		/* Check if the buffer needs to be flushed. */
+		if (dap->da_remain < 2 || c == '\n') {
+			db_puts(dap->da_pbufr);
+			dap->da_pnext = dap->da_pbufr;
+			dap->da_remain = dap->da_nbufr;
+			*dap->da_pnext = '\0';
+		}
+	}
+}
+
+static void
+db_putc(int c)
 {
 
 	/*
@@ -180,6 +214,15 @@ db_putchar(c, arg)
 	/* other characters are assumed non-printing */
 }
 
+static void
+db_puts(const char *str)
+{
+	int i;
+
+	for (i = 0; str[i] != '\0'; i++)
+		db_putc(str[i]);
+}
+
 /*
  * Turn on the pager.
  */
@@ -272,30 +315,43 @@ db_print_position()
  * Printing
  */
 void
-#if __STDC__
 db_printf(const char *fmt, ...)
-#else
-db_printf(fmt)
-	const char *fmt;
-#endif
 {
+#ifdef DDB_BUFR_SIZE
+	char bufr[DDB_BUFR_SIZE];
+#endif
+	struct dbputchar_arg dca;
 	va_list	listp;
 
+#ifdef DDB_BUFR_SIZE
+	dca.da_pbufr = bufr;
+	dca.da_pnext = dca.da_pbufr;
+	dca.da_nbufr = sizeof(bufr);
+	dca.da_remain = sizeof(bufr);
+	*dca.da_pnext = '\0';
+#else
+	dca.da_pbufr = NULL;
+#endif
+
 	va_start(listp, fmt);
-	kvprintf (fmt, db_putchar, NULL, db_radix, listp);
+	kvprintf (fmt, db_putchar, &dca, db_radix, listp);
 	va_end(listp);
+
+#ifdef DDB_BUFR_SIZE
+	if (*dca.da_pbufr != '\0')
+		db_puts(dca.da_pbufr);
+#endif
 }
 
 int db_indent;
 
 void
-#if __STDC__
 db_iprintf(const char *fmt,...)
-#else
-db_iprintf(fmt)
-	const char *fmt;
-#endif
 {
+#ifdef DDB_BUFR_SIZE
+	char bufr[DDB_BUFR_SIZE];
+#endif
+	struct dbputchar_arg dca;
 	register int i;
 	va_list listp;
 
@@ -303,9 +359,25 @@ db_iprintf(fmt)
 		db_printf("\t");
 	while (--i >= 0)
 		db_printf(" ");
+
+#ifdef DDB_BUFR_SIZE
+	dca.da_pbufr = bufr;
+	dca.da_pnext = dca.da_pbufr;
+	dca.da_nbufr = sizeof(bufr);
+	dca.da_remain = sizeof(bufr);
+	*dca.da_pnext = '\0';
+#else
+	dca.da_pbufr = NULL;
+#endif
+
 	va_start(listp, fmt);
-	kvprintf (fmt, db_putchar, NULL, db_radix, listp);
+	kvprintf (fmt, db_putchar, &dca, db_radix, listp);
 	va_end(listp);
+
+#ifdef DDB_BUFR_SIZE
+	if (*dca.da_pbufr != '\0')
+		db_puts(dca.da_pbufr);
+#endif
 }
 
 /*