Add UniformRandomInt RNG

Simple uniform RNG that depends on rand() as randomness source
Init random in hack.cpp

include/helpers.hpp

@@ -164,6 +164,7 @@ bool IsEntityVisiblePenetration(CachedEntity *entity, int hb);
 // void EndPrediction();
 
 float RandFloatRange(float min, float max);
+int UniformRandomInt(int min, int max);
 
 bool Developer(CachedEntity *ent);
 

src/hack.cpp

@@ -143,6 +143,22 @@ void critical_error_handler(int signum)
     ::raise(SIGABRT);
 }
 
+static void InitRandom()
+{
+    int rand_seed;
+    FILE *rnd = fopen("/dev/urandom", "rb");
+    if (!rnd || fread(&rand_seed, sizeof(rand_seed), 1, rnd) < 1)
+    {
+        logging::Info("Warning!!! Failed read from /dev/urandom (%s). Randomness is going to be weak", strerror(errno));
+        timespec t;
+        clock_gettime(CLOCK_MONOTONIC, &t);
+        rand_seed = t.tv_nsec ^ t.tv_sec & getpid();
+    }
+    srand(rand_seed);
+    if (rnd)
+        fclose(rnd);
+}
+
 void hack::Initialize()
 {
     ::signal(SIGSEGV, &critical_error_handler);
@@ -178,9 +194,8 @@ free(logname);*/
     }
 
 #endif /* TEXTMODE */
-
     logging::Info("Initializing...");
-    srand(time(0));
+    InitRandom();
     sharedobj::LoadAllSharedObjects();
     CreateInterfaces();
     CDumper dumper;

src/helpers.cpp

@@ -801,6 +801,30 @@ float RandFloatRange(float min, float max)
     return (min + 1) + (((float) rand()) / (float) RAND_MAX) * (max - (min + 1));
 }
 
+int UniformRandomInt(int min, int max)
+{
+    uint32_t bound, len, r, result = 0;
+    /* Protect from random stupidity */
+    if (min > max)
+        std::swap(min, max);
+
+    len = max - min + 1;
+    /* RAND_MAX is implementation dependent.
+     * It's guaranteed that this value is at least 32767.
+     * glibc's RAND_MAX is 2^31 - 1 exactly. Since source games hard
+     * depend on glibc, we will do so as well
+     */
+    while (len)
+    {
+        bound = (1U + RAND_MAX) % len;
+        while ((r = rand()) < bound);
+        result *= 1U + RAND_MAX;
+        result += r % len;
+        len -= len > RAND_MAX ? RAND_MAX : len;
+    }
+    return int(result) + min;
+}
+
 bool IsEntityVisible(CachedEntity *entity, int hb)
 {
     if (g_Settings.bInvalid)