[gobject-introspection/ebassi/rebased-girffi-exec-fix: 3/8] girffi.h: add g_callable_info_get_closure_native_address() API

[Emmanuele Bassi <ebassi src gnome org>]

commit 2a4dede7c2fdc3e6a6a5b063449ab3a8c58c11c0
Author: Sergei Trofimovich <slyfox gentoo org>
Date:   Sat Jul 17 18:19:17 2021 +0100

    girffi.h: add g_callable_info_get_closure_native_address() API
    
    Commit 6bab939bf ("girffi.c: fix return value for g_callable_info_prepare_closure()")
    effectively changes semantics of return value from code pointer to data pinter (closure).
    
    `gjs` (and probably other software) relies on old (incorrect) semantics of
    g_callable_info_prepare_closure(): https://gitlab.gnome.org/GNOME/gjs/-/issues/428
    
    This change exposes the API that allows extracting directly
    callacble code pointer. `gjs` will have to adapt to the new API.
    
    Signed-off-by: Sergei Trofimovich <slyfox gentoo org>

 girepository/girffi.c | 17 +++++++++++++++++
 girepository/girffi.h |  5 +++++
 2 files changed, 22 insertions(+)
---
diff --git a/girepository/girffi.c b/girepository/girffi.c
index b3b92195..12770203 100644
--- a/girepository/girffi.c
+++ b/girepository/girffi.c
@@ -349,6 +349,7 @@ g_function_invoker_destroy (GIFunctionInvoker    *invoker)
 typedef struct {
   ffi_closure ffi_closure;
   gpointer writable_self;
+  gpointer native_address;
 } GIClosureWrapper;
 
 /**
@@ -386,6 +387,7 @@ g_callable_info_prepare_closure (GICallableInfo       *callable_info,
       return NULL;
     }
   closure->writable_self = closure;
+  closure->native_address = exec_ptr;
 
   atypes = g_callable_info_get_ffi_arg_types (callable_info, &n_args);
   status = ffi_prep_cif (cif, FFI_DEFAULT_ABI, n_args,
@@ -409,6 +411,21 @@ g_callable_info_prepare_closure (GICallableInfo       *callable_info,
   return &closure->ffi_closure;
 }
 
+/**
+ * g_callable_info_get_closure_native_address:
+ * @callable_info: a callable info from a typelib
+ * @closure: ffi closure
+ *
+ * Gets callable code from ffi_closure prepared by g_callable_info_prepare_closure()
+ */
+gpointer *
+g_callable_info_get_closure_native_address (GICallableInfo       *callable_info,
+                                            ffi_closure          *closure)
+{
+  GIClosureWrapper *wrapper = (GIClosureWrapper *)closure;
+  return wrapper->native_address;
+}
+
 /**
  * g_callable_info_free_closure:
  * @callable_info: a callable info from a typelib
diff --git a/girepository/girffi.h b/girepository/girffi.h
index d8a57369..c6cb5e91 100644
--- a/girepository/girffi.h
+++ b/girepository/girffi.h
@@ -95,6 +95,11 @@ ffi_closure * g_callable_info_prepare_closure     (GICallableInfo       *callabl
                                                    ffi_cif              *cif,
                                                    GIFFIClosureCallback  callback,
                                                    gpointer              user_data);
+
+GI_AVAILABLE_IN_1_70
+gpointer * g_callable_info_get_closure_native_address (GICallableInfo       *callable_info,
+                                                       ffi_closure          *closure);
+
 GI_AVAILABLE_IN_ALL
 void          g_callable_info_free_closure        (GICallableInfo       *callable_info,
                                                    ffi_closure          *closure);