Use getentropy in splitmix_init on unix-like platforms

cbits-unix/init.c

@@ -1,39 +1,13 @@
 #include <stdint.h>
-#include <stdio.h>
-#include <sys/time.h>
-#include <sys/types.h>
-#include <time.h>
 #include <unistd.h>
 
-uint64_t splitmix_init() {
-
-    /* if there is /dev/urandom, read from it */
-    FILE *urandom = fopen("/dev/urandom", "r");
-    if (urandom) {
-        uint64_t result = 0;
-        size_t r = fread(&result, sizeof(uint64_t), 1, urandom);
-        fclose(urandom);
-
-        if (r == 1) {
-            return result;
-        } else {
-            return 0xfeed1000;
-        }
-
-    } else {
-        /* time of day */
-        struct timeval tp = {0, 0};
-        gettimeofday(&tp, NULL);
+/* for macos */
+#ifdef __APPLE__
+#include <sys/random.h>
+#endif
 
-        /* cputime */
-        clock_t c = clock();
-
-        /* process id */
-        pid_t p = getpid();
-
-        return ((uint64_t) tp.tv_sec)
-            ^ ((uint64_t) tp.tv_usec)
-            ^ ((uint64_t) c << 16)
-            ^ ((uint64_t) p << 32);
-    }
+uint64_t splitmix_init() {
+	uint64_t result;
+	int r = getentropy(&result, sizeof(uint64_t));
+	return r == 0 ? result : 0xfeed1000;
 }