From 2033e2af0461bc98d09af36dcb601f1d308f2c04 Mon Sep 17 00:00:00 2001
From: Robert Vollmert <rvollmert@gmx.net>
Date: Mon, 14 Dec 2009 20:05:31 +0100
Subject: Implement rng pushing and popping for sha256 hardened prng (Adeon)

the rng.cc used to call just push_mt_state which bypassed the
hashing process and didn't return the state as it was after
popping the state

Fixes bug #52.
---
 crawl-ref/source/rng.cc | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

(limited to 'crawl-ref/source/rng.cc')

diff --git a/crawl-ref/source/rng.cc b/crawl-ref/source/rng.cc
index 8c856e7229..4b7200093c 100644
--- a/crawl-ref/source/rng.cc
+++ b/crawl-ref/source/rng.cc
@@ -29,6 +29,12 @@ 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);
 
+    // Reset the sha256 generator to get predictable random numbers in case
+    // of a saved rng state.
+#ifdef MORE_HARDENED_PRNG
+    reset_sha256_state();
+#endif
+
     // for std::random_shuffle()
     srand(seed_key[0]);
 }
@@ -38,6 +44,12 @@ void seed_rng(long seed)
     // MT19937 -- see mt19937ar.cc for details/licence
     init_genrand(seed);
 
+    // Reset the sha256 generator to get predictable random numbers in case
+    // of a saved rng state.
+#ifdef MORE_HARDENED_PRNG
+    reset_sha256_state();
+#endif
+
     // for std::random_shuffle()
     srand(seed);
 }
@@ -87,11 +99,19 @@ unsigned long random_int( void )
 
 void push_rng_state()
 {
+#ifndef MORE_HARDENED_PRNG
     push_mt_state();
+#else
+    push_sha256_state();
+#endif
 }
 
 void pop_rng_state()
 {
+#ifndef MORE_HARDENED_PRNG
     pop_mt_state();
+#else
+    pop_sha256_state();
+#endif
 }
 
-- 
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