tdb2: typesafe traverse function

This make sure that the data being handed to the function in tdb_traverse
is the correct type.

ccan/tdb2/_info

@@ -85,6 +85,7 @@ int main(int argc, char *argv[])
 		printf("ccan/ilog\n");
 		printf("ccan/failtest\n");
 		printf("ccan/tally\n");
+		printf("ccan/typesafe_cb\n");
 		return 0;
 	}
 

ccan/tdb2/tdb2.h

@@ -40,6 +40,7 @@ extern "C" {
 #include <stdint.h>
 #endif
 #include <ccan/compiler/compiler.h>
+#include <ccan/typesafe_cb/typesafe_cb.h>
 
 union tdb_attribute;
 struct tdb_context;
@@ -249,9 +250,6 @@ enum TDB_ERROR tdb_transaction_commit(struct tdb_context *tdb);
  */
 enum TDB_ERROR tdb_transaction_prepare_commit(struct tdb_context *tdb);
 
-/* FIXME: Make typesafe */
-typedef int (*tdb_traverse_func)(struct tdb_context *, TDB_DATA, TDB_DATA, void *);
-
 /**
  * tdb_traverse - traverse a TDB
  * @tdb: the tdb context returned from tdb_open()
@@ -269,7 +267,14 @@ typedef int (*tdb_traverse_func)(struct tdb_context *, TDB_DATA, TDB_DATA, void
  * On success, returns the number of keys iterated.  On error returns
  * a negative enum TDB_ERROR value.
  */
-int64_t tdb_traverse(struct tdb_context *tdb, tdb_traverse_func fn, void *p);
+#define tdb_traverse(tdb, fn, p)					\
+	tdb_traverse_(tdb, typesafe_cb_preargs(int, (fn), (p),		\
+					       struct tdb_context *,	\
+					       TDB_DATA, TDB_DATA), (p))
+
+int64_t tdb_traverse_(struct tdb_context *tdb,
+		      int (*fn)(struct tdb_context *,
+				TDB_DATA, TDB_DATA, void *), void *p);
 
 /**
  * tdb_firstkey - get the "first" key in a TDB

ccan/tdb2/test/run-traverse.c

@@ -38,9 +38,9 @@ struct trav_data {
 	enum TDB_ERROR delete_error;
 };
 
-static int trav(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf, void *p)
+static int trav(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf,
+		struct trav_data *td)
 {
-	struct trav_data *td = p;
 	int val;
 
 	td->calls++;
@@ -75,9 +75,8 @@ struct trav_grow_data {
 };
 
 static int trav_grow(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf,
-		     void *p)
+		     struct trav_grow_data *tgd)	     
 {
-	struct trav_grow_data *tgd = p;
 	int val;
 	unsigned char buffer[128] = { 0 };
 

ccan/tdb2/traverse.c

@@ -18,7 +18,10 @@
 #include "private.h"
 #include <ccan/likely/likely.h>
 
-int64_t tdb_traverse(struct tdb_context *tdb, tdb_traverse_func fn, void *p)
+int64_t tdb_traverse_(struct tdb_context *tdb,
+		      int (*fn)(struct tdb_context *,
+				TDB_DATA, TDB_DATA, void *),
+		      void *p)
 {
 	enum TDB_ERROR ecode;
 	struct traverse_info tinfo;