From 0300dd8ba2222e34ac3655f1f6667f9f56ea00a7 Mon Sep 17 00:00:00 2001
From: Aaron O'Mullan <aaron.omullan@gmail.com>
Date: Fri, 3 Jul 2020 00:17:38 +0200
Subject: [PATCH] Fix crash on inspector setScriptSource calls when source is
 unchanged

Bug: chromium:1059746
Change-Id: I309c15a33a7185c9397b7893a9eefcb90981dc64
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2280085
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68713}
---
 AUTHORS                                          |  3 ++-
 src/inspector/v8-debugger-script.cc              |  4 +++-
 .../set-script-source-unchanged-expected.txt     |  1 +
 .../debugger/set-script-source-unchanged.js      | 16 ++++++++++++++++
 4 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 test/inspector/debugger/set-script-source-unchanged-expected.txt
 create mode 100644 test/inspector/debugger/set-script-source-unchanged.js

diff --git a/AUTHORS b/AUTHORS
index 7c43c60fc1..2a58b0e1c3 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -42,6 +42,7 @@ Cloudflare, Inc. <*@cloudflare.com>
 Julia Computing, Inc. <*@juliacomputing.com>
 
 Aaron Bieber <deftly@gmail.com>
+Aaron O'Mullan <aaron.omullan@gmail.com>
 Abdulla Kamar <abdulla.kamar@gmail.com>
 Adam Kallai <kadam@inf.u-szeged.hu>
 Akinori MUSHA <knu@FreeBSD.org>
@@ -216,4 +217,4 @@ Zhongping Wang <kewpie.w.zp@gmail.com>
 柳荣一 <admin@web-tinker.com>
 Yanbo Li <lybvinci@gmail.com>
 Gilang Mentari Hamidy <gilang@hamidy.net>
-Zeynep Cankara <zeynepcankara402@gmail.com>
\ No newline at end of file
+Zeynep Cankara <zeynepcankara402@gmail.com>
diff --git a/src/inspector/v8-debugger-script.cc b/src/inspector/v8-debugger-script.cc
index 6e54656d40..7a16f9f644 100644
--- a/src/inspector/v8-debugger-script.cc
+++ b/src/inspector/v8-debugger-script.cc
@@ -174,7 +174,9 @@ class ActualScript : public V8DebuggerScript {
       result->message = scope.Escape(result->message);
       return;
     }
-    if (preview) return;
+    // NOP if preview or unchanged source (diffs.empty() in PatchScript)
+    if (preview || result->script.IsEmpty()) return;
+
     m_hash = String16();
     Initialize(scope.Escape(result->script));
   }
diff --git a/test/inspector/debugger/set-script-source-unchanged-expected.txt b/test/inspector/debugger/set-script-source-unchanged-expected.txt
new file mode 100644
index 0000000000..13e3fbcf81
--- /dev/null
+++ b/test/inspector/debugger/set-script-source-unchanged-expected.txt
@@ -0,0 +1 @@
+Check that setScriptSource does not crash when source is unchanged
diff --git a/test/inspector/debugger/set-script-source-unchanged.js b/test/inspector/debugger/set-script-source-unchanged.js
new file mode 100644
index 0000000000..bef4d8aaa1
--- /dev/null
+++ b/test/inspector/debugger/set-script-source-unchanged.js
@@ -0,0 +1,16 @@
+// Copyright 2020 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+let {session, contextGroup, Protocol} =
+    InspectorTest.start('Check that setScriptSource does not crash when source is unchanged');
+
+let scriptSource = `function TestExpression() {}`;
+contextGroup.addScript(scriptSource);
+
+(async function test() {
+  Protocol.Debugger.enable();
+  const {params: {scriptId}} = await Protocol.Debugger.onceScriptParsed();
+  await Protocol.Debugger.setScriptSource({scriptId, scriptSource});
+  InspectorTest.completeTest();
+})();