2005-04-07 Paul Jakma <paul.jakma@sun.com>

	* (global): Fix up list loops to match changes in lib/linklist,
	  and some basic auditing of usage.
	* configure.ac: define QUAGGA_NO_DEPRECATED_INTERFACES
	* HACKING: Add notes about deprecating interfaces and commands.
	* lib/linklist.h: Add usage comments.
	  Rename getdata macro to listgetdata.
	  Rename nextnode to listnextnode and fix its odd behaviour to be
	  less dangerous.
	  Make listgetdata macro assert node is not null, NULL list entries
          should be bug condition.
          ALL_LIST_ELEMENTS, new macro, forward-referencing macro for use
          with for loop, Suggested by Jim Carlson of Sun.
          Add ALL_LIST_ELEMENTS_RO for cases which obviously do not need the
          "safety" of previous macro.
	  LISTNODE_ADD and DELETE macros renamed to ATTACH, DETACH, to
	  distinguish from the similarly named functions, and reflect their
	  effect better.
	  Add a QUAGGA_NO_DEPRECATED_INTERFACES define guarded section
	  with the old defines which were modified above,
	  for backwards compatibility - guarded to prevent Quagga using it..
	* lib/linklist.c: fix up for linklist.h changes.
	* ospf6d/ospf6_abr.c: (ospf6_abr_examin_brouter) change to a single
	  scan of the area list, rather than scanning all areas first for
	  INTER_ROUTER and then again for INTER_NETWORK. According to
	  16.2, the scan should be area specific anyway, and further
	  ospf6d does not seem to implement 16.3 anyway.

1 files changed, 53 insertions, 11 deletions

diff --git a/lib/linklist.h b/lib/linklist.h
index b766420f..80b21f64 100644
--- a/lib/linklist.h
+++ b/lib/linklist.h
@@ -22,10 +22,15 @@
 #ifndef _ZEBRA_LINKLIST_H
 #define _ZEBRA_LINKLIST_H
 
+/* listnodes must always contain data to be valid. Adding an empty node
+ * to a list is invalid
+ */
 struct listnode 
 {
   struct listnode *next;
   struct listnode *prev;
+  
+  /* private member, use getdata() to retrieve, do not access directly */
   void *data;
 };
 
@@ -33,25 +38,31 @@ struct list
 {
   struct listnode *head;
   struct listnode *tail;
+
   /* invariant: count is the number of listnodes in the list */
   unsigned int count;
+
   /*
    * Returns -1 if val1 < val2, 0 if equal?, 1 if val1 > val2.
    * Used as definition of sorted for listnode_add_sort
    */
   int (*cmp) (void *val1, void *val2);
+
+  /* callback to free user-owned data when listnode is deleted. supplying
+   * this callback is very much encouraged!
+   */
   void (*del) (void *val);
 };
 
-#define nextnode(X) ((X) = (X)->next)
+#define listnextnode(X) ((X)->next)
 #define listhead(X) ((X)->head)
 #define listtail(X) ((X)->tail)
 #define listcount(X) ((X)->count)
 #define list_isempty(X) ((X)->head == NULL && (X)->tail == NULL)
-#define getdata(X) ((X)->data)
+#define listgetdata(X) (assert((X)->data != NULL), (X)->data)
 
 /* Prototypes. */
-struct list *list_new();
+struct list *list_new(); /* encouraged: set list.del callback on new lists */
 void list_free (struct list *);
 
 void listnode_add (struct list *, void *);
@@ -72,13 +83,33 @@ void list_add_node_prev (struct list *, struct listnode *, void *);
 void list_add_node_next (struct list *, struct listnode *, void *);
 void list_add_list (struct list *, struct list *);
 
-/* List iteration macro. */
-#define LIST_LOOP(L,V,N) \
-  for ((N) = (L)->head; (N); (N) = (N)->next) \
-    if (((V) = (N)->data) != NULL)
+/* List iteration macro. 
+ * Usage: for (ALL_LIST_ELEMENTS (...) { ... }
+ * It is safe to delete the listnode using this macro.
+ */
+#define ALL_LIST_ELEMENTS(list,node,nextnode,data) \
+  (node) = listhead(list); \
+  (node) != NULL && \
+    ((data) = listgetdata(node),(nextnode) = listnextnode(node), 1); \
+  (node) = (nextnode)
+
+/* read-only list iteration macro.
+ * Usage: as per ALL_LIST_ELEMENTS, but not safe to delete the listnode Only
+ * use this macro when it is *immediately obvious* the listnode is not
+ * deleted in the body of the loop. Does not have forward-reference overhead
+ * of previous macro.
+ */
+#define ALL_LIST_ELEMENTS_RO(list,node,data) \
+  (node) = listhead(list); \
+  (node) != NULL && ((data) = listgetdata(node), 1); \
+  (node) = listnextnode(node)
 
-/* List node add macro.  */
-#define LISTNODE_ADD(L,N) \
+/* these *do not* cleanup list nodes and referenced data, as the functions
+ * do - these macros simply {de,at}tach a listnode from/to a list.
+ */
+ 
+/* List node attach macro.  */
+#define LISTNODE_ATTACH(L,N) \
   do { \
     (N)->prev = (L)->tail; \
     if ((L)->head == NULL) \
@@ -89,8 +120,8 @@ void list_add_list (struct list *, struct list *);
     (L)->count++; \
   } while (0)
 
-/* List node delete macro.  */
-#define LISTNODE_DELETE(L,N) \
+/* List node detach macro.  */
+#define LISTNODE_DETACH(L,N) \
   do { \
     if ((N)->prev) \
       (N)->prev->next = (N)->next; \
@@ -103,4 +134,15 @@ void list_add_list (struct list *, struct list *);
     (L)->count--; \
   } while (0)
 
+/* Deprecated: 20050406 */
+#if !defined(QUAGGA_NO_DEPRECATED_INTERFACES)
+#warning "Using deprecated libzebra interfaces"
+#define LISTNODE_ADD(L,N) LISTNODE_ATTACH(L,N)
+#define LISTNODE_DELETE(L,N) LISTNODE_DETACH(L,N)
+#define nextnode(X) ((X) = (X)->next)
+#define getdata(X) listgetdata(X)
+#define LIST_LOOP(L,V,N) \
+  for (ALL_LIST_ELEMENTS_RO (L,N,V))
+#endif /* QUAGGA_NO_DEPRECATED_INTERFACES */
+
 #endif /* _ZEBRA_LINKLIST_H */