From: Eric S. Raymond <esr@thyrsus.com>
Date: Thu, 25 May 2017 03:36:25 +0000 (-0400)
Subject: Once again, take srand()/random() out of the initialization chain.
X-Git-Tag: seed~53
X-Git-Url: https://jxself.org/git/?a=commitdiff_plain;h=6ba9a7de7fe7c829a2215f254bfbbbd2a5686584;p=open-adventure.git

Once again, take srand()/random() out of the initialization chain.

They have exactly the wrong kind of randomness for this job - not
returning consistent sequences across different platforms or C library
versions, and because pseodorandom not really better than sampling
the clock.
---

diff --git a/main.c b/main.c
index 6cfc411..ba7df1a 100644
--- a/main.c
+++ b/main.c
@@ -99,7 +99,7 @@ int main(int argc, char *argv[]) {
 	lcgstate.a = 1093;
 	lcgstate.c = 221587;
 	lcgstate.m = 1048576;
-	set_seed_from_time();
+	set_seed((long)time(NULL));
 
 /*  Read the database if we have not yet done so */
 
diff --git a/misc.c b/misc.c
index 7057bad..b6ca80e 100644
--- a/misc.c
+++ b/misc.c
@@ -724,7 +724,8 @@ L2:	ATDWRF=I;
 
 
 
-/*  Utility routines (SETBIT, TSTBIT, set_seed_from_time, get_next_lcg_value, randrange, RNDVOC, BUG) */
+/*  Utility routines (SETBIT, TSTBIT, set_seed, get_next_lcg_value,
+ *  randrange, RNDVOC, BUG) */
 
 #undef SETBIT
 long fSETBIT(long BIT) {
@@ -759,11 +760,9 @@ long TSTBIT;
 
 #define TSTBIT(MASK,BIT) fTSTBIT(MASK,BIT)
 
-void set_seed_from_time(void)
+void set_seed(long seedval)
 {
-  /* Use the current system time to get seed the ISO rand() function, from which we get a seed for the LCG. */
-  srand(time(NULL));
-  lcgstate.x = (unsigned long) rand() % lcgstate.m;
+  lcgstate.x = (unsigned long) seedval % lcgstate.m;
 }
 
 unsigned long get_next_lcg_value(void)
diff --git a/misc.h b/misc.h
index 095efba..f4567e3 100644
--- a/misc.h
+++ b/misc.h
@@ -73,6 +73,6 @@ extern long fIABS(long);
 #define IABS(N) fIABS(N)
 extern long fMOD(long,long);
 #define MOD(N,M) fMOD(N,M)
-extern void set_seed_from_time(void);
+extern void set_seed(long);
 extern unsigned long get_next_lcg_value(void);
 extern long randrange(long);