Fix a crash in System_RNG on macOS 10.15

See #2268

1 files changed, 5 insertions, 1 deletions

diff --git a/src/lib/rng/system_rng/system_rng.cpp b/src/lib/rng/system_rng/system_rng.cpp
index af508fd90..3f884115a 100644
--- a/src/lib/rng/system_rng/system_rng.cpp
+++ b/src/lib/rng/system_rng/system_rng.cpp
@@ -119,7 +119,11 @@ class System_RNG_Impl final : public RandomNumberGenerator
 
       void randomize(uint8_t buf[], size_t len) override
          {
-         ::arc4random_buf(buf, len);
+         // macOS 10.15 arc4random crashes if called with len == 0
+         if(len > 0)
+            {
+            ::arc4random_buf(buf, len);
+            }
          }
 
       bool accepts_input() const override { return false; }