From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Fedor Indutny <indutny@signal.org>
Date: Mon, 31 Mar 2025 11:21:29 -0700
Subject: fix: expose ReadFileSync override for modules

To avoid copying out `package.json` files out of the ASAR file we need
an API override to replace the native `ReadFileSync` in the `modules`
binding.

diff --git a/src/env_properties.h b/src/env_properties.h
index 39803ae466fc81a6b2ff6e12093cdf2082790a9f..29ce687a03ccc8e45881f70d34e009e028aa4074 100644
--- a/src/env_properties.h
+++ b/src/env_properties.h
@@ -490,6 +490,7 @@
   V(maybe_cache_generated_source_map, v8::Function)                            \
   V(messaging_deserialize_create_object, v8::Function)                         \
   V(message_port, v8::Object)                                                  \
+  V(modules_read_file_sync, v8::Function)                                      \
   V(builtin_module_require, v8::Function)                                      \
   V(performance_entry_callback, v8::Function)                                  \
   V(prepare_stack_trace_callback, v8::Function)                                \
diff --git a/src/node_modules.cc b/src/node_modules.cc
index 9eec93f52f0d0b2e45ae04ff357b4ced0770782f..eea4ba313d8dbcf7b88b79f5a3e9ba2eb39d7c3e 100644
--- a/src/node_modules.cc
+++ b/src/node_modules.cc
@@ -23,6 +23,7 @@ namespace modules {
 using v8::Array;
 using v8::Context;
 using v8::External;
+using v8::Function;
 using v8::FunctionCallbackInfo;
 using v8::HandleScope;
 using v8::Integer;
@@ -94,6 +95,7 @@ Local<Array> BindingData::PackageConfig::Serialize(Realm* realm) const {
 
 const BindingData::PackageConfig* BindingData::GetPackageJSON(
     Realm* realm, std::string_view path, ErrorContext* error_context) {
+  auto isolate = realm->isolate();
   auto binding_data = realm->GetBindingData<BindingData>();
 
   auto cache_entry = binding_data->package_configs_.find(path.data());
@@ -103,8 +105,36 @@ const BindingData::PackageConfig* BindingData::GetPackageJSON(
 
   PackageConfig package_config{};
   package_config.file_path = path;
+
+  Local<Function> modules_read_file_sync = realm->modules_read_file_sync();
+
+  int read_err;
   // No need to exclude BOM since simdjson will skip it.
-  if (ReadFileSync(&package_config.raw_json, path.data()) < 0) {
+  if (modules_read_file_sync.IsEmpty()) {
+    read_err = ReadFileSync(&package_config.raw_json, path.data());
+  } else {
+    Local<Value> args[] = {
+        v8::String::NewFromUtf8(isolate, path.data()).ToLocalChecked(),
+    };
+    Local<Value> result = modules_read_file_sync->Call(
+        realm->context(),
+        Undefined(isolate),
+        arraysize(args),
+        args).ToLocalChecked();
+
+    if (result->IsUndefined()) {
+      // Fallback
+      read_err = ReadFileSync(&package_config.raw_json, path.data());
+    } else if (result->IsFalse()) {
+      // Not found
+      read_err = -1;
+    } else {
+      BufferValue data(isolate, result);
+      package_config.raw_json = data.ToString();
+      read_err = 0;
+    }
+  }
+  if (read_err < 0) {
     return nullptr;
   }
   simdjson::ondemand::document document;
@@ -242,6 +272,12 @@ const BindingData::PackageConfig* BindingData::GetPackageJSON(
   return &cached.first->second;
 }
 
+void BindingData::OverrideReadFileSync(const FunctionCallbackInfo<Value>& args) {
+  Realm* realm = Realm::GetCurrent(args);
+  CHECK(args[0]->IsFunction());
+  realm->set_modules_read_file_sync(args[0].As<Function>());
+}
+
 void BindingData::ReadPackageJSON(const FunctionCallbackInfo<Value>& args) {
   CHECK_GE(args.Length(), 1);  // path, [is_esm, base, specifier]
   CHECK(args[0]->IsString());  // path
@@ -635,6 +671,8 @@ void SaveCompileCacheEntry(const FunctionCallbackInfo<Value>& args) {
 void BindingData::CreatePerIsolateProperties(IsolateData* isolate_data,
                                              Local<ObjectTemplate> target) {
   Isolate* isolate = isolate_data->isolate();
+  SetMethod(isolate, target, "overrideReadFileSync", OverrideReadFileSync);
+
   SetMethod(isolate, target, "readPackageJSON", ReadPackageJSON);
   SetMethod(isolate,
             target,
@@ -694,6 +732,8 @@ void BindingData::CreatePerContextProperties(Local<Object> target,
 
 void BindingData::RegisterExternalReferences(
     ExternalReferenceRegistry* registry) {
+  registry->Register(OverrideReadFileSync);
+
   registry->Register(ReadPackageJSON);
   registry->Register(GetNearestParentPackageJSONType);
   registry->Register(GetPackageScopeConfig<false>);
diff --git a/src/node_modules.h b/src/node_modules.h
index e4ba6b75bc86d14deada835903ba68a4cb0eccc5..ae77f9ec81b358bd356993617cd07671d382e8ca 100644
--- a/src/node_modules.h
+++ b/src/node_modules.h
@@ -54,6 +54,8 @@ class BindingData : public SnapshotableObject {
   SET_SELF_SIZE(BindingData)
   SET_MEMORY_INFO_NAME(BindingData)
 
+  static void OverrideReadFileSync(
+      const v8::FunctionCallbackInfo<v8::Value>& args);
   static void ReadPackageJSON(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void GetNearestParentPackageJSONType(
       const v8::FunctionCallbackInfo<v8::Value>& args);