Check the class with `I` specifier of `mrb_get_args()`

Previously, the `I` specifier only checked if the object was `MRB_TT_ISTRUCT`.
So it was at risk of getting pointers to different C structs if multiple classes were to use the `MRB_TT_ISTRUCT` instance.

Change this behavior and change the C argument corresponding to the `I` specifier to `(void *, struct RClass)`.

This change is not compatible with the previous mruby.
Please note that if the user uses the previous specifications, `SIGSEGV` may occur or the machine stack may be destroyed.

resolve #5527

3 files changed, 9 insertions, 3 deletions

diff --git a/include/mruby.h b/include/mruby.h
index 77f862356..4d2b65254 100644
--- a/include/mruby.h
+++ b/include/mruby.h
@@ -901,7 +901,7 @@ MRB_API struct RClass* mrb_define_module_under_id(mrb_state *mrb, struct RClass
  * | `b`  | boolean        | {mrb_bool}        |                                                    |
  * | `n`  | {String}/{Symbol} | {mrb_sym}         |                                                    |
  * | `d`  | data           | void *, {mrb_data_type} const | 2nd argument will be used to check data type so it won't be modified; when `!` follows, the value may be `nil` |
- * | `I`  | inline struct  | void *          |                                                    |
+ * | `I`  | inline struct  | void *, struct RClass |                                                |
  * | `&`  | block          | {mrb_value}       | &! raises exception if no block given.             |
  * | `*`  | rest arguments | const {mrb_value} *, {mrb_int} | Receive the rest of arguments as an array; `*!` avoid copy of the stack.  |
  * | <code>\|</code> | optional     |                   | After this spec following specs would be optional. |
diff --git a/mrbgems/mruby-inline-struct/test/inline.c b/mrbgems/mruby-inline-struct/test/inline.c
index 6764b1af4..16d16fa4d 100644
--- a/mrbgems/mruby-inline-struct/test/inline.c
+++ b/mrbgems/mruby-inline-struct/test/inline.c
@@ -57,7 +57,8 @@ static mrb_value
 istruct_test_test_receive_direct(mrb_state *mrb, mrb_value self)
 {
   char *ptr;
-  mrb_get_args(mrb, "I", &ptr);
+  struct RClass *klass = mrb_class_get(mrb, "InlineStructTest");
+  mrb_get_args(mrb, "I", &ptr, klass);
   return mrb_bool_value(ptr[0] == 's');
 }
 
diff --git a/src/class.c b/src/class.c
index 6cf93414a..1b2beafe0 100644
--- a/src/class.c
+++ b/src/class.c
@@ -896,7 +896,7 @@ void mrb_hash_check_kdict(mrb_state *mrb, mrb_value self);
     b:      boolean        [mrb_bool]
     n:      String/Symbol  [mrb_sym]
     d:      data           [void*,mrb_data_type const] 2nd argument will be used to check data type so it won't be modified; when ! follows, the value may be nil
-    I:      inline struct  [void*]
+    I:      inline struct  [void*,struct RClass]
     &:      block          [mrb_value]            &! raises exception if no block given
     *:      rest argument  [const mrb_value*,mrb_int] The rest of the arguments as an array; *! avoid copy of the stack
     |:      optional                              Following arguments are optional
@@ -1141,11 +1141,16 @@ mrb_get_args(mrb_state *mrb, const char *format, ...)
     case 'I':
       {
         void* *p;
+        struct RClass *klass;
         mrb_value ss;
 
         p = va_arg(ap, void**);
+        klass = va_arg(ap, struct RClass*);
         if (i < argc) {
           ss = argv[i++];
+          if (!mrb_obj_is_kind_of(mrb, ss, klass)) {
+            mrb_raisef(mrb, E_TYPE_ERROR, "%v is not a %C", ss, klass);
+          }
           if (!mrb_istruct_p(ss))
           {
             mrb_raisef(mrb, E_TYPE_ERROR, "%v is not inline struct", ss);