FFI: Hold a weak reference to the CIF made by `procedure->pointer'.

* libguile/foreign.c (scm_procedure_to_pointer): Keep a weak reference
  to CIF so that it is not reclaimed before POINTER.  Before that it
  could be reclaimed and typically reused to store the CIF of another
  procedure with the same arity, leading to obscure wrong-type-arg
  errors.

diff --git a/libguile/foreign.c b/libguile/foreign.c
index 68e0efa..021c183 100644 (file)
--- a/libguile/foreign.c
+++ b/libguile/foreign.c
@@ -1127,7 +1127,7 @@ SCM_DEFINE (scm_procedure_to_pointer, "procedure->pointer", 3, 0, 0,
            "type should match @var{return-type} and @var{arg-types}.\n")
 #define FUNC_NAME s_scm_procedure_to_pointer
 {
-  SCM pointer;
+  SCM cif_pointer, pointer;
   ffi_cif *cif;
   ffi_status err;
   void *closure, *executable;
@@ -1144,8 +1144,16 @@ SCM_DEFINE (scm_procedure_to_pointer, "procedure->pointer", 3, 0, 0,
       SCM_MISC_ERROR ("`ffi_prep_closure_loc' failed", SCM_EOL);
     }
 
+  /* CIF points to GC-managed memory and it should remain as long as
+     POINTER (see below) is live.  Wrap it in a Scheme pointer to then
+     hold a weak reference on it.  */
+  cif_pointer = scm_from_pointer (cif, NULL);
+
   if (closure == executable)
-    pointer = scm_from_pointer (executable, ffi_closure_free);
+    {
+      pointer = scm_from_pointer (executable, ffi_closure_free);
+      register_weak_reference (pointer, cif_pointer);
+    }
   else
     {
       /* CLOSURE needs to be freed eventually.  However, since
@@ -1158,7 +1166,7 @@ SCM_DEFINE (scm_procedure_to_pointer, "procedure->pointer", 3, 0, 0,
       pointer = scm_from_pointer (executable, NULL);
       friend = scm_from_pointer (closure, ffi_closure_free);
 
-      register_weak_reference (pointer, friend);
+      register_weak_reference (pointer, scm_list_2 (cif_pointer, friend));
     }
 
   return pointer;