Merge pull request #9235 from ZehMatt/fix-util-rand

Improve util_rand

src/openrct2/Context.cpp

@@ -426,7 +426,6 @@ namespace OpenRCT2
             }
 
             gScenarioTicks = 0;
-            util_srand((uint32_t)time(nullptr));
             input_reset_place_obj_modifier();
             viewport_init_all();
 

src/openrct2/network/NetworkServerAdvertiser.cpp

@@ -30,6 +30,7 @@
 #    include <cstring>
 #    include <iterator>
 #    include <memory>
+#    include <random>
 #    include <string>
 
 enum MASTER_SERVER_STATUS
@@ -307,10 +308,14 @@ private:
         static constexpr char hexChars[] = {
             '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f',
         };
+
+        std::random_device rd;
+        std::uniform_int_distribution<int32_t> dist(0, static_cast<int32_t>(std::size(hexChars) - 1));
+
         char key[17];
         for (int32_t i = 0; i < 16; i++)
         {
-            int32_t hexCharIndex = util_rand() % std::size(hexChars);
+            int32_t hexCharIndex = dist(rd);
             key[i] = hexChars[hexCharIndex];
         }
         key[std::size(key) - 1] = 0;

src/openrct2/util/Util.cpp

@@ -21,6 +21,7 @@
 #include <cctype>
 #include <cmath>
 #include <ctime>
+#include <random>
 
 int32_t squaredmetres_to_squaredfeet(int32_t squaredMetres)
 {
@@ -526,15 +527,10 @@ bool str_is_null_or_empty(const char* str)
     return str == nullptr || str[0] == 0;
 }
 
-void util_srand(int32_t source)
-{
-    srand(source);
-}
-
-// Caveat: rand() might only return values up to 0x7FFF, which is the minimum specified in the C standard.
 uint32_t util_rand()
 {
-    return rand();
+    thread_local std::mt19937 _prng(std::random_device{}());
+    return _prng();
 }
 
 #define CHUNK (128 * 1024)

src/openrct2/util/Util.h

@@ -50,7 +50,6 @@ char* strcasestr(const char* haystack, const char* needle);
 bool utf8_is_bom(const char* str);
 bool str_is_null_or_empty(const char* str);
 
-void util_srand(int32_t source);
 uint32_t util_rand();
 
 uint8_t* util_zlib_deflate(const uint8_t* data, size_t data_in_size, size_t* data_out_size);

src/openrct2/world/MapGen.cpp

@@ -136,8 +136,6 @@ void mapgen_generate(mapgen_settings* settings)
     int32_t x, y, mapSize, floorTexture, wallTexture, waterLevel;
     TileElement* tileElement;
 
-    util_srand((int32_t)platform_get_ticks());
-
     mapSize = settings->mapSize;
     floorTexture = settings->floor;
     wallTexture = settings->wall;