`napi_check_object_type_tag` returns false if `upper` in `napi_type_tag` is `0`

[kjvalencik]

Version

All version supporting Node-API 8+

Platform

All

Subsystem

Node-API

What steps will reproduce the bug?

Create a type tag with an upper value of 0.

static const napi_type_tag MyTypeTag = {
  0xa5ed9ce2e4c00c38, 0x0
};

Tag an object with it:

napi_type_tag_object(env, obj, &MyTypeTag);

Check the type tag:

bool is_my_type;

napi_check_object_type_tag(env, obj, &MyTypeTag, &is_my_type);

How often does it reproduce? Is there a required condition?

100% of the time

What is the expected behavior?

napi_check_object_type_tag will set is_my_type to true.

What do you see instead?

is_my_type remains false.

Additional information

Type tags are stored in a BigInt. If upper is 0, then the leading zero gets truncated and the length is 1. However, the follow check expects the length to always be 2.

node/src/js_native_api_v8.cc

Line 2455 in 5fad0b9

if (size == 2 && sign == 0)

This could could be something like:

    napi_type_tag tag = { 0, 0 };
    
    /* ... */

    if (size <= 2 && sign == 0)
      *result = (tag.lower == type_tag->lower && tag.upper == type_tag->upper);

[daeyeon]

Create a type tag with an upper value of 0.

static const napi_type_tag MyTypeTag = {
  0x0, 0xa5ed9ce2e4c00c38
};

I guess you meant 0xa5ed9ce2e4c00c38, 0x0 since the first one is for a lower value.

node/src/js_native_api_types.h

Lines 160 to 163 in 5fad0b9

	typedef struct {
	uint64_t lower;
	uint64_t upper;
	} napi_type_tag;

[kjvalencik]

@daeyeon Good catch; that's correct. I was transcribing from Rust and my test code used named fields.