chore(ext/ffi): migrate from op -> op2 for ffi (#20509)

Migrate to op2. Making a few decisions to get this across the line:

- Empty slices, no matter where the come from, are null pointers. The v8
bugs (https://bugs.chromium.org/p/v8/issues/detail?id=13489) and
(https://bugs.chromium.org/p/v8/issues/detail?id=13488) make passing
around zero-length slice pointers too dangerous as they might be
uninitialized or null data.
- Offsets and lengths are `#[number] isize` and `#[number] usize`
respectively -- 53 bits should be enough for anyone
- Pointers are bigints. This is a u64 in the fastcall world, and can
accept Integer/Int32/Number/BigInt v8 types in the slow world.

1 files changed, 19 insertions, 1 deletions

diff --git a/ext/ffi/00_ffi.js b/ext/ffi/00_ffi.js
index 67cb13ab6..fe7344e17 100644
--- a/ext/ffi/00_ffi.js
+++ b/ext/ffi/00_ffi.js
@@ -5,6 +5,7 @@ const ops = core.ops;
 const primordials = globalThis.__bootstrap.primordials;
 const {
   ArrayBufferIsView,
+  ArrayBufferPrototype,
   ArrayBufferPrototypeGetByteLength,
   ArrayPrototypeMap,
   ArrayPrototypeJoin,
@@ -221,7 +222,24 @@ class UnsafePointer {
     if (ObjectPrototypeIsPrototypeOf(UnsafeCallbackPrototype, value)) {
       return value.pointer;
     }
-    const pointer = ops.op_ffi_ptr_of(value);
+    let pointer;
+    if (ArrayBufferIsView(value)) {
+      if (value.length === 0) {
+        pointer = ops.op_ffi_ptr_of_exact(value);
+      } else {
+        pointer = ops.op_ffi_ptr_of(value);
+      }
+    } else if (ObjectPrototypeIsPrototypeOf(ArrayBufferPrototype, value)) {
+      if (value.length === 0) {
+        pointer = ops.op_ffi_ptr_of_exact(new Uint8Array(value));
+      } else {
+        pointer = ops.op_ffi_ptr_of(new Uint8Array(value));
+      }
+    } else {
+      throw new TypeError(
+        "Expected ArrayBuffer, ArrayBufferView or UnsafeCallbackPrototype",
+      );
+    }
     if (pointer) {
       POINTER_TO_BUFFER_WEAK_MAP.set(pointer, value);
     }