[Mesa-dev] [PATCH 3/3] mesa: Fix string_to_uint_map->iterate to return same numbers from put()

[Carl Worth]

There is an internal implementation detail that the hash table
underlying the struct string_to_uint_map stores each value internally
as (value+1). The user needn't be very concerned with this (other than
knowing that a value of UINT_MAX cannot be stored) since put() adds 1
and get() subtracts 1.

However, the recently added iterate() method was written to directly
leak the internal, off-by-one values, which could be quite
confusing. Fix this with a little wrapper around the user's callback
function to perform the subtraction.

And now that we have a wrapper in place, we give a better signature to
the callback function being passed to iterate(), so that this callback
function can actually expect a char* and an unsigned argument, (rather
than a couple of void* ). So the iterate() method should be much more
convenient to use now.
---
 src/mesa/program/hash_table.h | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/src/mesa/program/hash_table.h b/src/mesa/program/hash_table.h
index ece43a1..c7089b2 100644
--- a/src/mesa/program/hash_table.h
+++ b/src/mesa/program/hash_table.h
@@ -198,6 +198,11 @@ string_to_uint_map_dtor(struct string_to_uint_map *);
 #ifdef __cplusplus
 }
 
+struct string_map_iterate_wrapper_closure {
+   void (*callback)(const char *key, unsigned value, void *closure);
+   void *closure;
+};
+
 /**
  * Map from a string (name) to an unsigned integer value
  *
@@ -231,9 +236,19 @@ public:
    /**
     * Runs a passed callback for the hash
     */
-   void iterate(void (*func)(const void *, void *, void *), void *closure)
+   void iterate(void (*func)(const char *, unsigned, void *), void *closure)
    {
-      hash_table_call_foreach(this->ht, func, closure);
+      struct string_map_iterate_wrapper_closure *wrapper;
+
+      wrapper = (struct string_map_iterate_wrapper_closure *)
+         malloc(sizeof(struct string_map_iterate_wrapper_closure));
+      if (wrapper == NULL)
+         return;
+
+      wrapper->callback = func;
+      wrapper->closure = closure;
+
+      hash_table_call_foreach(this->ht, subtract_one_wrapper, wrapper);
    }
 
    /**
@@ -289,6 +304,16 @@ private:
       free((char *)key);
    }
 
+   static void subtract_one_wrapper(const void *key, void *data, void *closure)
+   {
+      struct string_map_iterate_wrapper_closure *wrapper =
+         (struct string_map_iterate_wrapper_closure *) closure;
+      unsigned value = (intptr_t) data;
+
+      value -= 1;
+
+      wrapper->callback((const char *) key, value, wrapper->closure);
+   }
    struct hash_table *ht;
 };
 
-- 
2.1.1