From 60744cc44549209ed819cfd86d804da47c635ca4 Mon Sep 17 00:00:00 2001
From: Ole Tange <ole@tange.dk>
Date: Tue, 17 Mar 2020 20:18:59 +0100
Subject: [PATCH] rand: --seed implemented.

---
 rand/rand | 60 +++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 45 insertions(+), 15 deletions(-)

diff --git a/rand/rand b/rand/rand
index 8705e07..869e8cc 100755
--- a/rand/rand
+++ b/rand/rand
@@ -10,7 +10,7 @@ rand - generate (pseudo-)random data
 
 =head1 SYNOPSIS
 
-B<rand> [-f FORMAT|--format FORMAT] [[I<from>] I<to>]
+B<rand> [-f FORMAT|--format FORMAT] [-s SEED|--seed SEED] [[I<from>] I<to>]
 
 
 =head1 DESCRIPTION
@@ -37,6 +37,13 @@ If I<from> is also given, numbers will be integers from I<from> to I<to>.
 
 Format number using I<FORMAT>. I<FORMAT> follows B<printf>s specification.
 
+
+=item B<--seed> I<SEED>
+
+=item B<-s> I<SEED>
+
+Use SEED for random number generator for reproducible numbers.
+
 =back
 
 
@@ -98,10 +105,16 @@ B<openssl>
 =cut
 
 randdata() {
-    # Generate random 8-bit data by AES encrypting /dev/zero with a
-    # random key    
-    key=$(openssl rand -hex 16)
-    iv=$(openssl rand -hex 16)
+    # Generate random 8-bit data by AES encrypting /dev/zero
+    if [ "$seed" == "" ] ; then
+	# use a random key
+	key=$(openssl rand -hex 16)
+	iv=$(openssl rand -hex 16)
+    else
+	# use seed from --seed
+	key=$(echo "$seed" | openssl sha256 -hex | cut -d' ' -f2)
+	iv=$(echo "$seed" | openssl sha512 -hex | cut -d' ' -f2)
+    fi
     < /dev/zero openssl enc -aes-128-ctr -K $key -iv $iv 2>/dev/null
 }
 export -f randdata
@@ -131,6 +144,7 @@ fmt='%s\n'
 while true; do
   case "$1" in
     -f | --fmt ) fmt="$2"; shift 2 ;;
+    -s | --seed ) seed="$2"; shift 2 ;;
     -D | --debug ) debug=true; shift ;;
     -h | --help ) help=1; shift 2 ;;
     -- ) shift; break ;;
@@ -139,16 +153,32 @@ while true; do
 done
 qfmt="$(parallel --shellquote --shellquote ::: "$fmt")"
 
-if [ "$1" == "" ] ; then
-    # Boost performance by running 1 per CPU core
-    eval parallel -u randdata ::: {1..$(parallel --number-of-threads)}
-else
-    # $1 set => numerical
-    if [ "$2" == "" ] ; then
-	# 0 .. $1
-	eval parallel -N0 --lb randints 0 $1 "$qfmt" ::: {1..$(parallel --number-of-threads)}
+if [ "$seed" == "" ] ; then
+    if [ "$1" == "" ] ; then
+	# Boost performance by running 1 per CPU core
+	eval parallel -u randdata ::: {1..$(parallel --number-of-threads)}
     else
-	# $1 .. $2
-	eval parallel -N0 --lb randints $1 $2 "$qfmt" ::: {1..$(parallel --number-of-threads)}
+	# $1 set => numerical
+	if [ "$2" == "" ] ; then
+	    # 0 .. $1
+	    eval parallel -N0 --lb randints 0 $1 "$qfmt" ::: {1..$(parallel --number-of-threads)}
+	else
+	    # $1 .. $2
+	    eval parallel -N0 --lb randints $1 $2 "$qfmt" ::: {1..$(parallel --number-of-threads)}
+	fi
+    fi
+else
+    if [ "$1" == "" ] ; then
+	# Run a single instance
+	randdata
+    else
+	# $1 set => numerical
+	if [ "$2" == "" ] ; then
+	    # 0 .. $1
+	    randints 0 $1 "$fmt"
+	else
+	    # $1 .. $2
+	    randints $1 $2 "$fmt"
+	fi
     fi
 fi