src,crypto: remove uses of AllocatedBuffer from crypto_ec.cc

Refs: #39941
Signed-off-by: Darshan Sen <raisinten@gmail.com>

PR-URL: #42766
Reviewed-By: James M Snell <jasnell@gmail.com>

src/crypto/crypto_ec.cc

@@ -20,6 +20,8 @@
 namespace node {
 
 using v8::Array;
+using v8::ArrayBuffer;
+using v8::BackingStore;
 using v8::FunctionCallbackInfo;
 using v8::FunctionTemplate;
 using v8::Int32;
@@ -220,17 +222,23 @@ void ECDH::ComputeSecret(const FunctionCallbackInfo<Value>& args) {
     return;
   }
 
-  // NOTE: field_size is in bits
-  int field_size = EC_GROUP_get_degree(ecdh->group_);
-  size_t out_len = (field_size + 7) / 8;
-  AllocatedBuffer out = AllocatedBuffer::AllocateManaged(env, out_len);
+  std::unique_ptr<BackingStore> bs;
+  {
+    NoArrayBufferZeroFillScope no_zero_fill_scope(env->isolate_data());
+    // NOTE: field_size is in bits
+    int field_size = EC_GROUP_get_degree(ecdh->group_);
+    size_t out_len = (field_size + 7) / 8;
+    bs = ArrayBuffer::NewBackingStore(env->isolate(), out_len);
+  }
 
-  int r = ECDH_compute_key(
-      out.data(), out_len, pub.get(), ecdh->key_.get(), nullptr);
-  if (!r)
+  if (!ECDH_compute_key(
+          bs->Data(), bs->ByteLength(), pub.get(), ecdh->key_.get(), nullptr))
     return THROW_ERR_CRYPTO_OPERATION_FAILED(env, "Failed to compute ECDH key");
 
-  args.GetReturnValue().Set(out.ToBuffer().FromMaybe(Local<Value>()));
+  Local<ArrayBuffer> ab = ArrayBuffer::New(env->isolate(), std::move(bs));
+  Local<Value> buffer;
+  if (!Buffer::New(env, ab, 0, ab->ByteLength()).ToLocal(&buffer)) return;
+  args.GetReturnValue().Set(buffer);
 }
 
 void ECDH::GetPublicKey(const FunctionCallbackInfo<Value>& args) {
@@ -270,13 +278,19 @@ void ECDH::GetPrivateKey(const FunctionCallbackInfo<Value>& args) {
     return THROW_ERR_CRYPTO_OPERATION_FAILED(env,
         "Failed to get ECDH private key");
 
-  const int size = BN_num_bytes(b);
-  AllocatedBuffer out = AllocatedBuffer::AllocateManaged(env, size);
-  CHECK_EQ(size, BN_bn2binpad(b,
-                              reinterpret_cast<unsigned char*>(out.data()),
-                              size));
+  std::unique_ptr<BackingStore> bs;
+  {
+    NoArrayBufferZeroFillScope no_zero_fill_scope(env->isolate_data());
+    bs = ArrayBuffer::NewBackingStore(env->isolate(), BN_num_bytes(b));
+  }
+  CHECK_EQ(static_cast<int>(bs->ByteLength()),
+           BN_bn2binpad(
+               b, static_cast<unsigned char*>(bs->Data()), bs->ByteLength()));
 
-  args.GetReturnValue().Set(out.ToBuffer().FromMaybe(Local<Value>()));
+  Local<ArrayBuffer> ab = ArrayBuffer::New(env->isolate(), std::move(bs));
+  Local<Value> buffer;
+  if (!Buffer::New(env, ab, 0, ab->ByteLength()).ToLocal(&buffer)) return;
+  args.GetReturnValue().Set(buffer);
 }
 
 void ECDH::SetPrivateKey(const FunctionCallbackInfo<Value>& args) {