From: Chris Hanson <org/chris-hanson/cph>
Date: Mon, 9 Aug 1999 19:08:50 +0000 (+0000)
Subject: If /dev/random is available, use it to seed the PRNG.
X-Git-Tag: 20090517-FFI~4488
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=3520a2229262955d9755d1459e03fc031e053262;p=mit-scheme.git

If /dev/random is available, use it to seed the PRNG.
---

diff --git a/v7/src/runtime/random.scm b/v7/src/runtime/random.scm
index 0cd61df3a..2a19e7317 100644
--- a/v7/src/runtime/random.scm
+++ b/v7/src/runtime/random.scm
@@ -1,6 +1,6 @@
 #| -*-Scheme-*-
 
-$Id: random.scm,v 14.18 1999/01/02 06:11:34 cph Exp $
+$Id: random.scm,v 14.19 1999/08/09 19:08:50 cph Exp $
 
 Copyright (c) 1993-1999 Massachusetts Institute of Technology
 
@@ -91,7 +91,20 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   (let ((state (if (default-object? state) #f state)))
     (if (or (eq? #t state) (int:integer? state))
 	(initial-random-state
-	 (congruential-rng (+ (real-time-clock) 123456789)))
+	 (congruential-rng
+	  ;; Use good random source if available
+	  (if (file-exists? "/dev/urandom")
+	      (call-with-input-file "/dev/urandom"
+		(lambda (port)
+		  (let* ((b1 (char->integer (read-char port)))
+			 (b2 (char->integer (read-char port)))
+			 (b3 (char->integer (read-char port)))
+			 (b4 (char->integer (read-char port))))
+		    (+ (* b1 #x1000000)
+		       (* b2 #x10000)
+		       (* b3 #x100)
+		       b4))))
+	      (+ (real-time-clock) 123456789))))
 	(copy-random-state
 	 (guarantee-random-state state 'MAKE-RANDOM-STATE)))))