FIX: put a note to list_relocate, add test

There was a fatal thinko, llist_relocate NUST NOT be called on a empty
list, the pointers will just point to invaildated memory. This cant be
handled by the llist code. The programmer is responsible to take proper
actions.

src/lib/llist.h

@@ -299,6 +299,9 @@ LLIST_FUNC (LList llist_unlink (LList self),
 /**
  * Fix a node which got relocated in memory.
  * It is supported to realloc/move list nodes in memory but one must call 'list_relocate' after doing so.
+ * IMPORTANT: it is not possible to relocate nodes which are empty this way, nor can this be determined
+ * after the relocation, so either llist_init them afterwards or insert a bogus node before moving the node
+ * and relocating it and remove it afterwards.
  * @param self node which got relocated
  * @return self
  */
@@ -306,6 +309,7 @@ LLIST_FUNC (LList llist_relocate (LList self),
             return self->next->prev = self->prev->next = self;
 );
 
+
 /**
  * Insert a node after another.
  * @param self node after which we want to insert

tests/15list.tests

@@ -44,9 +44,11 @@ out: .
 out: .
 END
 
+TEST "llist_relocate" relocate <<END
+END
+
 
 # not yet tested functions, write tests when needed
-PLANNED "llist_relocate"
 PLANNED "llist_insertlist_next"
 PLANNED "llist_insertlist_prev"
 PLANNED "llist_insertafter_range"

tests/library/test-llist.c

@@ -185,4 +185,23 @@ TEST ("whiles")
 }
 
 
+TEST ("relocate")
+{
+  llist source;
+  llist_init (&source);
+
+  llist something;
+  llist_init (&something);
+
+  llist_insert_head (&source, &something);
+
+  llist target = {NULL,NULL};
+
+  target = source;
+
+  llist_relocate (&target);
+  ENSURE (llist_is_head (&target, &something));
+}
+
+
 TESTS_END