Interpret JavaScript string given in eval as UTF8

Author: kateinoigakukun

ext/witapi/witapi-core.c

@@ -2,6 +2,57 @@
 
 #include "ruby.h"
 
+// ========= Private Ruby API =========
+// from eval_intern.h
+VALUE rb_f_eval(int argc, const VALUE *argv, VALUE self);
+// from internal/vm.h
+PUREFUNC(VALUE rb_vm_top_self(void));
+// from vm_core.h
+typedef struct rb_control_frame_struct {
+  const VALUE *pc;  /* cfp[0] */
+  VALUE *sp;        /* cfp[1] */
+  const void *iseq; /* cfp[2] */
+  VALUE self;       /* cfp[3] / block[0] */
+  const VALUE *ep;  /* cfp[4] / block[1] */
+} rb_control_frame_t;
+
+typedef struct rb_execution_context_struct {
+  /* execution information */
+  VALUE *vm_stack;      /* must free, must mark */
+  size_t vm_stack_size; /* size in word (byte size / sizeof(VALUE)) */
+  rb_control_frame_t *cfp;
+} rb_execution_context_t;
+
+// from vm.c and vm_core.h
+RUBY_EXTERN struct rb_execution_context_struct *ruby_current_ec;
+#define GET_EC() (ruby_current_ec)
+rb_control_frame_t *
+rb_vm_get_ruby_level_next_cfp(const rb_execution_context_t *ec,
+                              const rb_control_frame_t *cfp);
+// ====== End of Private Ruby API =====
+
+VALUE
+ruby_eval_string_value_from_file(VALUE str, VALUE file) {
+  rb_execution_context_t *ec = GET_EC();
+  rb_control_frame_t *cfp =
+      ec ? rb_vm_get_ruby_level_next_cfp(ec, ec->cfp) : NULL;
+  VALUE self = cfp ? cfp->self : rb_vm_top_self();
+#define argc 4
+  const VALUE argv[argc] = {str, Qnil, file, INT2FIX(1)};
+  return rb_f_eval(argc, argv, self);
+#undef argc
+}
+
+static VALUE rb_eval_string_value_protect_thunk(VALUE str) {
+  return ruby_eval_string_value_from_file(str, rb_utf8_str_new("eval", 4));
+}
+
+// TODO(katei): This API should be moved to CRuby itself.
+VALUE
+rb_eval_string_value_protect(VALUE str, int *pstate) {
+  return rb_protect(rb_eval_string_value_protect_thunk, str, pstate);
+}
+
 #define TAG_NONE 0
 
 #include "bindgen/rb-abi-guest.h"
@@ -177,7 +228,8 @@ void rb_abi_guest_rb_eval_string_protect(
     rb_abi_guest_string_t *str, rb_abi_guest_tuple2_rb_abi_value_s32_t *ret0) {
   VALUE retval;
   RB_WASM_DEBUG_LOG("rb_eval_string_protect: str = %s\n", str->ptr);
-  RB_WASM_LIB_RT(retval = rb_eval_string_protect(str->ptr, &ret0->f1));
+  VALUE utf8_str = rb_utf8_str_new(str->ptr, str->len);
+  RB_WASM_LIB_RT(retval = rb_eval_string_value_protect(utf8_str, &ret0->f1));
   RB_WASM_DEBUG_LOG("rb_eval_string_protect: retval = %p, state = %d\n",
                     (void *)retval, ret0->f1);
 

packages/npm-packages/ruby-wasm-wasi/test/vm.test.ts

@@ -228,4 +228,10 @@ eval:11:in \`<main>'`);
     );
     expect(result.call("nil?").toString()).toBe("true");
   });
+
+  test("eval encoding", async () => {
+    const vm = await initRubyVM();
+    expect(vm.eval(`"hello".encoding.name`).toString()).toBe("UTF-8");
+    expect(vm.eval(`__ENCODING__.name`).toString()).toBe("UTF-8");
+  });
 });