From 6c2ba8d2215b27eeeb16e8b41f9b8497f384f593 Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Thu, 15 Aug 2019 14:39:26 +0200
Subject: [PATCH] tools: make code cache and snapshot deterministic

Use a fixed random seed to ensure that the generated sources are
identical across runs.

The final node binary still reseeds itself on start-up so there should
be no security implications caused by predictable random numbers (e.g.,
`Math.random()`, ASLR, the hash seed, etc.)

Fixes: https://github.com/nodejs/node/issues/29108
---
 tools/code_cache/mkcodecache.cc   | 2 ++
 tools/snapshot/node_mksnapshot.cc | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/tools/code_cache/mkcodecache.cc b/tools/code_cache/mkcodecache.cc
index defa1462ce45ec..bc45d46a43b6cd 100644
--- a/tools/code_cache/mkcodecache.cc
+++ b/tools/code_cache/mkcodecache.cc
@@ -26,6 +26,8 @@ int wmain(int argc, wchar_t* argv[]) {
 int main(int argc, char* argv[]) {
 #endif  // _WIN32
 
+  v8::V8::SetFlagsFromString("--random_seed=42");
+
   if (argc < 2) {
     std::cerr << "Usage: " << argv[0] << " <path/to/output.cc>\n";
     return 1;
diff --git a/tools/snapshot/node_mksnapshot.cc b/tools/snapshot/node_mksnapshot.cc
index f52cccb705f53a..29f9e1cbcbb096 100644
--- a/tools/snapshot/node_mksnapshot.cc
+++ b/tools/snapshot/node_mksnapshot.cc
@@ -19,6 +19,8 @@ int wmain(int argc, wchar_t* argv[]) {
 int main(int argc, char* argv[]) {
 #endif  // _WIN32
 
+  v8::V8::SetFlagsFromString("--random_seed=42");
+
   if (argc < 2) {
     std::cerr << "Usage: " << argv[0] << " <path/to/output.cc>\n";
     return 1;