1 files changed, 91 insertions, 0 deletions
diff --git a/crawl-ref/source/rng.cc b/crawl-ref/source/rng.cc
new file mode 100644
index 0000000000..409f0975c9
--- /dev/null
+++ b/crawl-ref/source/rng.cc
@@ -0,0 +1,91 @@
+/*
+ * File:      rng.cc
+ * Summary:   Random number generator wrapping.
+ */
+
+#include "AppHdr.h"
+
+#include "rng.h"
+
+#include "mt19937ar.h"
+
+#ifdef USE_MORE_SECURE_SEED
+
+// for times()
+#include <sys/times.h>
+
+// for getpid()
+#include <sys/types.h>
+#include <unistd.h>
+
+#endif
+
+#ifdef MORE_HARDENED_PRNG
+#include "sha256.h"
+#endif
+
+void seed_rng(unsigned long* seed_key, size_t num_keys)
+{
+    // MT19937 -- see mt19937ar.cc for details/licence
+    init_by_array(seed_key, num_keys);
+}
+
+void seed_rng(long seed)
+{
+    // MT19937 -- see mt19937ar.cc for details/licence
+    init_genrand(seed);
+}
+
+void seed_rng()
+{
+    unsigned long seed = time( NULL );
+#ifdef USE_MORE_SECURE_SEED
+
+    /* (at least) 256-bit wide seed */
+    unsigned long seed_key[8];
+
+    struct tms  buf;
+    seed += times( &buf ) + getpid();
+    seed_key[0] = seed;
+
+    /* Try opening from various system provided (hopefully) CSPRNGs */
+    FILE* seed_f = fopen("/dev/urandom", "rb");
+    if (!seed_f)
+        seed_f = fopen("/dev/random", "rb");
+    if (!seed_f)
+        seed_f = fopen("/dev/srandom", "rb");
+    if (!seed_f)
+        seed_f = fopen("/dev/arandom", "rb");
+    if (seed_f)
+    {
+        fread(&seed_key[1], sizeof(unsigned long), 7, seed_f);
+        fclose(seed_f);
+    }
+
+    seed_rng(seed_key, 8);
+
+#else
+    seed_rng(seed);
+#endif
+}
+
+// MT19937 -- see mt19937ar.cc for details
+unsigned long random_int( void )
+{
+#ifndef MORE_HARDENED_PRNG
+    return (genrand_int32());
+#else
+    return (sha256_genrand());
+#endif
+}
+
+void push_rng_state()
+{
+    push_mt_state();
+}
+
+void pop_rng_state()
+{
+    pop_mt_state();
+}
+