From b2b4054f97f0190cfd65efb3923b876f7f821da7 Mon Sep 17 00:00:00 2001
From: Ryan Dahl <ry@tinyclouds.org>
Date: Tue, 19 Jun 2018 17:45:58 +0200
Subject: [PATCH] Fix snapshot source code wrapping.

---
 deno2/js/mock_runtime.js  | 38 +++++++++++++++++++-----------------
 deno2/snapshot_creator.cc | 41 ++++++++++++++++++++++++---------------
 2 files changed, 45 insertions(+), 34 deletions(-)

diff --git a/deno2/js/mock_runtime.js b/deno2/js/mock_runtime.js
index 0671fba648..1e7a6afe20 100644
--- a/deno2/js/mock_runtime.js
+++ b/deno2/js/mock_runtime.js
@@ -1,55 +1,57 @@
 // A simple runtime that doesn't involve typescript or protobufs to test
 // libdeno. Invoked by mock_runtime_test.cc
 
+const global = this;
+
 function assert(cond) {
   if (!cond) throw Error("mock_runtime.js assert failed");
 }
 
-function typedArrayToArrayBuffer(ta) {
+global.typedArrayToArrayBuffer = (ta) => {
   return ta.buffer.slice(ta.byteOffset, ta.byteOffset + ta.byteLength);
-}
+};
 
-function CanCallFunction() {
+global.CanCallFunction = () => {
   deno.print("Hello world from foo");
   return "foo";
-}
+};
 
 // This object is created to test snapshotting.
 // See DeserializeInternalFieldsCallback and SerializeInternalFieldsCallback.
 const snapshotted = new Uint8Array([1, 3, 3, 7]);
 
-function TypedArraySnapshots() {
+global.TypedArraySnapshots = () => {
   assert(snapshotted[0] === 1);
   assert(snapshotted[1] === 3);
   assert(snapshotted[2] === 3);
   assert(snapshotted[3] === 7);
-}
+};
 
-function PubSuccess() {
+global.PubSuccess = () => {
   deno.sub((channel, msg) => {
     assert(channel === "PubSuccess");
     deno.print("PubSuccess: ok");
   });
-}
+};
 
-function PubByteLength() {
+global.PubByteLength = () => {
   deno.sub((channel, msg) => {
     assert(channel === "PubByteLength");
     assert(msg instanceof ArrayBuffer);
     assert(msg.byteLength === 3);
   });
-}
+};
 
-function SubReturnEmpty() {
+global.SubReturnEmpty = () => {
   const ui8 = new Uint8Array("abc".split("").map(c => c.charCodeAt(0)));
   const ab = typedArrayToArrayBuffer(ui8);
   let r = deno.pub("SubReturnEmpty", ab);
   assert(r == null);
   r = deno.pub("SubReturnEmpty", ab);
   assert(r == null);
-}
+};
 
-function SubReturnBar() {
+global.SubReturnBar = () => {
   const ui8 = new Uint8Array("abc".split("").map(c => c.charCodeAt(0)));
   const ab = typedArrayToArrayBuffer(ui8);
   const r = deno.pub("SubReturnBar", ab);
@@ -58,18 +60,18 @@ function SubReturnBar() {
   const rui8 = new Uint8Array(r);
   const rstr = String.fromCharCode(...rui8);
   assert(rstr === "bar");
-}
+};
 
-function DoubleSubFails() {
+global.DoubleSubFails = () => {
   // deno.sub is an internal function and should only be called once from the
   // runtime.
   deno.sub((channel, msg) => assert(false));
   deno.sub((channel, msg) => assert(false));
-}
+};
 
 // The following join has caused SnapshotBug to segfault when using kKeep.
 [].join("");
 
-function SnapshotBug() {
+global.SnapshotBug = () => {
   assert("1,2,3" === String([1, 2, 3]));
-}
+};
diff --git a/deno2/snapshot_creator.cc b/deno2/snapshot_creator.cc
index db9e52e50d..b822abd6e9 100644
--- a/deno2/snapshot_creator.cc
+++ b/deno2/snapshot_creator.cc
@@ -42,6 +42,30 @@ v8::StartupData MakeSnapshot(const char* js_filename, const char* js_source) {
   return snapshot_blob;
 }
 
+// Wrap the js_source in an IIFE to work around a bug in the V8 snapshot
+// serializer. Without it, CreateBlob() triggers the following assert:
+//   Debug check failed : outer_scope_info()->IsScopeInfo() || is_toplevel().
+//   ==== C stack trace ====
+//   v8::internal::SharedFunctionInfo::FlushCompiled
+//   v8::SnapshotCreator::CreateBlob
+//   deno::MakeSnapshot
+// Avoid misaligning the source map, and ensure that the sourceMappingUrl
+// comment remains at the last line.
+// Try removing this when this bug is fixed:
+// https://bugs.chromium.org/p/v8/issues/detail?id=7857
+std::string WrapSourceCode(const std::string& js_source) {
+  auto smu_offset = js_source.rfind("//# sourceMappingURL=");
+  std::string tail =
+      smu_offset == std::string::npos ? "" : js_source.substr(smu_offset);
+  auto wrapped_js_source =
+      "(function() {" + js_source.substr(0, smu_offset) + "\n})();\n" + tail;
+  // Double check that the source mapping url comment is at the last line.
+  auto last_line = wrapped_js_source.substr(wrapped_js_source.rfind('\n'));
+  CHECK(smu_offset == std::string::npos ||
+        last_line.find("sourceMappingURL") != std::string::npos);
+  return wrapped_js_source;
+}
+
 }  // namespace deno
 
 int main(int argc, char** argv) {
@@ -57,22 +81,7 @@ int main(int argc, char** argv) {
   std::string js_source;
   CHECK(deno::ReadFileToString(js_fn, &js_source));
 
-  // Wrap the js_source in an IIFE to work around a bug in the V8 snapshot
-  // serializer. Without it, CreateBlob() triggers the following assert:
-  //   Debug check failed : outer_scope_info()->IsScopeInfo() || is_toplevel().
-  //   ==== C stack trace ====
-  //   v8::internal::SharedFunctionInfo::FlushCompiled
-  //   v8::SnapshotCreator::CreateBlob
-  //   deno::MakeSnapshot
-  // Avoid misaligning the source map, and ensure that the sourceMappingUrl
-  // comment remains at the last line.
-  auto smu_offset = js_source.rfind("//#");
-  CHECK(smu_offset != std::string::npos);
-  auto wrapped_js_source = "(function() {" + js_source.substr(0, smu_offset) +
-                           "\n})();\n" + js_source.substr(smu_offset);
-  // Double check that the source mapping url comment is at the last line.
-  auto last_line = wrapped_js_source.substr(wrapped_js_source.rfind('\n'));
-  CHECK(last_line.find("sourceMappingURL") != std::string::npos);
+  auto wrapped_js_source = deno::WrapSourceCode(js_source);
 
   deno_init();
   auto snapshot_blob = deno::MakeSnapshot(js_fn, wrapped_js_source.c_str());