lib: get rid of extraneous output with vty_prepend

the vty_*prepend* family can be used to reduce the amount of output
produced by "show running-config" and "write ...". it buffers output in
struct vty->prepend (1024 bytes) and outputs it when vty_out is called.
if vty_out isn't called, it can be removed with vty_unprepend later.

applied on zebra and ospfd to get rid of empty interface blocks.

2 files changed, 32 insertions, 0 deletions

diff --git a/lib/vty.c b/lib/vty.c
index 9c58b50d..fa3f7718 100644
--- a/lib/vty.c
+++ b/lib/vty.c
@@ -90,6 +90,25 @@ static u_char restricted_mode = 0;
 char integrate_default[] = SYSCONFDIR INTEGRATE_DEFAULT_CONFIG;
 
 
+void
+vty_prepend (struct vty *vty, const char *format, ...)
+{
+  va_list args;
+
+  va_start (args, format);
+  vsnprintf (vty->prepend + vty->prepend_pos,
+	     sizeof(vty->prepend) - vty->prepend_pos,
+	     format, args);
+  vty->prepend_pos = strlen (vty->prepend);
+  va_end (args);
+}
+
+void
+vty_unprepend (struct vty *vty)
+{
+  vty->prepend_pos = 0;
+}
+
 /* VTY standard output function. */
 int
 vty_out (struct vty *vty, const char *format, ...)
@@ -100,6 +119,12 @@ vty_out (struct vty *vty, const char *format, ...)
   char buf[1024];
   char *p = NULL;
 
+  if (vty->prepend_pos)
+    {
+      vty->prepend_pos = 0;
+      vty_out (vty, "%s", vty->prepend);
+    }
+
   if (vty_shell (vty))
     {
       va_start (args, format);
diff --git a/lib/vty.h b/lib/vty.h
index 7df04b5f..d8f47d86 100644
--- a/lib/vty.h
+++ b/lib/vty.h
@@ -118,6 +118,10 @@ struct vty
   /* Timeout seconds and thread. */
   unsigned long v_timeout;
   struct thread *t_timeout;
+
+  /* Auto-prepending; any vty_out will print this buffer, then clear it: */
+  int prepend_pos;
+  char prepend[1024];
 };
 
 /* Integrated configuration file. */
@@ -207,6 +211,9 @@ extern void vty_terminate (void);
 extern void vty_reset (void);
 extern struct vty *vty_new (void);
 extern int vty_out (struct vty *, const char *, ...) PRINTF_ATTRIBUTE(2, 3);
+extern void vty_prepend (struct vty *, const char *, ...) PRINTF_ATTRIBUTE(2, 3);
+extern void vty_unprepend (struct vty *);
+#define vty_prepending(v) ((v)->prepend_pos)
 extern void vty_read_config (char *, char *);
 extern void vty_time_print (struct vty *, int);
 extern void vty_serv_sock (const char *, unsigned short, const char *);