random number generator seeding update for macOS

using file descriptor's free approach instead.

Change-Id: I9baa3d471b4ed6f624985a5b6325648ef7875596
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1710665Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62933}

AUTHORS

@@ -74,6 +74,7 @@ Colin Ihrig <cjihrig@gmail.com>
 Daniel Andersson <kodandersson@gmail.com>
 Daniel Bevenius <daniel.bevenius@gmail.com>
 Daniel James <dnljms@gmail.com>
+David Carlier <devnexen@gmail.com>
 Deepak Mohan <hop2deep@gmail.com>
 Deon Dior <diaoyuanjie@gmail.com>
 Dominic Farolini <domfarolino@gmail.com>

src/base/utils/random-number-generator.cc

@@ -51,6 +51,13 @@ RandomNumberGenerator::RandomNumberGenerator() {
   result = rand_s(&second_half);
   DCHECK_EQ(0, result);
   SetSeed((static_cast<int64_t>(first_half) << 32) + second_half);
+#elif V8_OS_MACOSX
+  // Despite its prefix suggests it is not RC4 algorithm anymore.
+  // It always succeeds while having decent performance and
+  // no file descriptor involved.
+  int64_t seed;
+  arc4random_buf(&seed, sizeof(seed));
+  SetSeed(seed);
 #else
   // Gather entropy from /dev/urandom if available.
   FILE* fp = fopen("/dev/urandom", "rb");