X-Git-Url: http://www.lcore.org/git/lcore.git/blobdiff_plain/68ac8381cae336dda0cd718dd6fa43b677f5ef8d..dbfefcf1c7180deedc221f927dd01e8cbf3d6d21:/blinklist.pas

diff --git a/blinklist.pas b/blinklist.pas
index 27232f4..5c3391d 100755
--- a/blinklist.pas
+++ b/blinklist.pas
@@ -54,11 +54,14 @@ var
   linklistdebug:integer;
 
 implementation
+
+uses sysutils;
 
 procedure linklistadd(var baseptr:tlinklist;newptr:tlinklist);
 var
   p:tlinklist;
 begin
+  if (newptr=baseptr) or assigned(newptr.prev) then raise exception.create('linklist double insertion detected');
   p := baseptr;
   baseptr := newptr;
   baseptr.prev := nil;
@@ -70,13 +73,16 @@ procedure linklistdel(var baseptr:tlinklist;item:tlinklist);
 begin
   if item = baseptr then baseptr := item.next;
   if item.prev <> nil then item.prev.next := item.next;
-  if item.next <> nil then item.next.prev := item.prev;
+  if item.next <> nil then item.next.prev := item.prev;
+  item.prev := nil;
+  item.next := nil;
 end;
 
 procedure linklist2add(var baseptr,newptr:tlinklist2);
 var
   p:tlinklist2;
 begin
+  if (newptr=baseptr) or assigned(newptr.prev2) then raise exception.create('linklist2 double insertion detected');
   p := baseptr;
   baseptr := newptr;
   baseptr.prev2 := nil;
@@ -88,7 +94,9 @@ procedure linklist2del(var baseptr:tlinklist2;item:tlinklist2);
 begin
   if item = baseptr then baseptr := item.next2;
   if item.prev2 <> nil then item.prev2.next2 := item.next2;
-  if item.next2 <> nil then item.next2.prev2 := item.prev2;
+  if item.next2 <> nil then item.next2.prev2 := item.prev2;
+  item.prev2 := nil;
+  item.next2 := nil;
 end;
 
 constructor tlinklist.create;