From 8faa27a736710018ad6325609b2a9f48dc4e01d6 Mon Sep 17 00:00:00 2001
From: parkrrrr <parkrrrr@f51c46e8-681c-474f-0cfe-069cfd0219fb>
Date: Wed, 8 Dec 2004 14:53:21 +0000
Subject: [PATCH] Fixed two segfaults involving stack filter: empty lists
 didn't push right, and we didn't udpate the waypt_count on stack operations.

---
 gpsbabel/defs.h        |  1 +
 gpsbabel/queue.h       | 13 +++++++++----
 gpsbabel/stackfilter.c |  9 +++++++++
 gpsbabel/waypt.c       |  6 ++++++
 4 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/gpsbabel/defs.h b/gpsbabel/defs.h
index 5f008e1ec..e0ac7e40c 100644
--- a/gpsbabel/defs.h
+++ b/gpsbabel/defs.h
@@ -266,6 +266,7 @@ void waypt_compute_bounds(bounds *);
 void waypt_flush(queue *);
 void waypt_flush_all(void);
 unsigned int waypt_count(void);
+void set_waypt_count(unsigned int nc);
 void free_gpx_extras (xml_tag * tag);
 void xcsv_setup_internal_style(const char *style_buf);
 void xcsv_read_internal_style(const char *style_buf);
diff --git a/gpsbabel/queue.h b/gpsbabel/queue.h
index 2cbb72748..e042e235e 100644
--- a/gpsbabel/queue.h
+++ b/gpsbabel/queue.h
@@ -33,10 +33,15 @@ queue * dequeue(queue *element);
 #define QUEUE_LAST(head) (head)->prev
 #define QUEUE_EMPTY (head)->next == head
 #define QUEUE_MOVE(newhead,oldhead) \
-	(newhead)->next = (oldhead)->next; \
-	(newhead)->prev = (oldhead)->prev; \
-	(newhead)->next->prev = (newhead); \
-	(newhead)->prev->next = (newhead); \
+        if ( (oldhead)->next == (oldhead) ) {\
+		(newhead)->next = (newhead)->prev = (newhead); \
+	} \
+	else { \
+		(newhead)->next = (oldhead)->next; \
+		(newhead)->prev = (oldhead)->prev; \
+		(newhead)->next->prev = (newhead); \
+		(newhead)->prev->next = (newhead); \
+	} \
 	(oldhead)->next = (oldhead)->prev = (oldhead)
 
 #define ENQUEUE_TAIL(listhead, element) \
diff --git a/gpsbabel/stackfilter.c b/gpsbabel/stackfilter.c
index adb3a9144..c8c5021fb 100644
--- a/gpsbabel/stackfilter.c
+++ b/gpsbabel/stackfilter.c
@@ -62,6 +62,7 @@ arglist_t stackfilt_args[] = {
 
 struct stack_elt {
 	queue waypts;
+	unsigned int waypt_ct;
 	struct stack_elt *next;
 } *stack = NULL;
 
@@ -74,10 +75,13 @@ stackfilt_process(void)
 	queue *tmp = NULL;
 	queue tmp_queue;
 	waypoint *wpt_tmp;
+	unsigned int tmp_count;
 	
 	if ( opt_push ) {
 		tmp_elt = (struct stack_elt *)xmalloc(sizeof(struct stack_elt));
 		QUEUE_MOVE(&(tmp_elt->waypts), &waypt_head);
+		tmp_elt->waypt_ct = waypt_count();
+		set_waypt_count(0);
 		tmp_elt->next = stack;
 		stack = tmp_elt;
 		if ( opt_copy ) {
@@ -102,6 +106,7 @@ stackfilt_process(void)
 		else {
 			waypt_flush( &waypt_head );
 			QUEUE_MOVE(&(waypt_head), &(stack->waypts) );
+			set_waypt_count(stack->waypt_ct);
 		}
 		stack = tmp_elt->next;
 		xfree( tmp_elt );
@@ -118,6 +123,10 @@ stackfilt_process(void)
 		QUEUE_MOVE(&tmp_queue, &(tmp_elt->waypts) );
 		QUEUE_MOVE(&(tmp_elt->waypts), &waypt_head );
 		QUEUE_MOVE(&waypt_head, &tmp_queue );
+		
+		tmp_count = waypt_count();
+		set_waypt_count( tmp_elt->waypt_ct );
+		tmp_elt->waypt_ct = tmp_count;
 	}
 }
 
diff --git a/gpsbabel/waypt.c b/gpsbabel/waypt.c
index fde54f87b..ae15046f4 100644
--- a/gpsbabel/waypt.c
+++ b/gpsbabel/waypt.c
@@ -135,6 +135,12 @@ waypt_count(void)
 	return waypt_ct;
 }
 
+void
+set_waypt_count(unsigned int nc)
+{
+	waypt_ct = nc;
+}
+
 void
 waypt_disp(const waypoint *wpt)
 {
-- 
2.30.2