Make "register_tap_listener()" return NULL on success and a "GString *"

referring to a GString containing an error message on failure, and don't
have it print anything on failure.

If it fails, have its Tethereal-tap callers print an error message
before exiting, and have its Ethereal callers pop up a dialog box with
the error (except in cases where the failure is guaranteed not to be the
user's fault, and where we exit, in which case we just print an error
message before we exit).  In all cases, the error message includes the
text of the GString.

Fix a scanf format string in the DCE RPC statistics Ethereal tap, so
that it properly skips the comma before the filter string.

Fix some Ethereal error messages not to say "tethereal".

svn path=/trunk/; revision=7542

1 files changed, 17 insertions, 11 deletions

diff --git a/tap.c b/tap.c
index 0a0b24b998..044956bb07 100644
--- a/tap.c
+++ b/tap.c
@@ -1,7 +1,7 @@
 /* tap.c
  * packet tap interface   2002 Ronnie Sahlberg
  *
- * $Id: tap.c,v 1.8 2002/11/28 20:28:28 guy Exp $
+ * $Id: tap.c,v 1.9 2003/04/23 08:20:02 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -335,29 +335,35 @@ find_tap_id(char *name)
 
 /* this function attaches the tap_listener to the named tap.
  * function returns :
- *  0: ok.
- * !0: error
-*/
-int
+ *     NULL: ok.
+ * non-NULL: error, return value points to GString containing error
+ *           message.
+ */
+GString *
 register_tap_listener(char *tapname, void *tapdata, char *fstring, tap_reset_cb reset, tap_packet_cb packet, tap_draw_cb draw)
 {
 	tap_listener_t *tl;
 	int tap_id;
+	GString *error_string;
 
 	tap_id=find_tap_id(tapname);
 	if(!tap_id){
-		fprintf(stderr, "tap not found\n");
-		exit(10);
+		error_string = g_string_new("");
+		g_string_sprintf(error_string, "Tap %s not found", tapname);
+		return error_string;
 	}
 
 	tl=g_malloc(sizeof(tap_listener_t));
 	tl->code=NULL;
 	tl->needs_redraw=1;
 	if(fstring){
-		if(!dfilter_compile(fstring ,&tl->code)){
+		if(!dfilter_compile(fstring, &tl->code)){
+			error_string = g_string_new("");
+			g_string_sprintf(error_string,
+			    "Filter \"%s\" is invalid - %s",
+			    fstring, dfilter_error_msg);
 			g_free(tl);
-			fprintf(stderr,"register_tap_listener(): %s\n", dfilter_error_msg);
-			return 1;
+			return error_string;
 		} else {
 			num_tap_filters++;
 		}
@@ -372,7 +378,7 @@ register_tap_listener(char *tapname, void *tapdata, char *fstring, tap_reset_cb
 
 	tap_listener_queue=tl;
 
-	return 0;
+	return NULL;
 }
 
 /* this function removes a tap listener