From 7ea95b7df3405229a6683a4884aabc8b42c878bd Mon Sep 17 00:00:00 2001
From: Martijn Dekker <martijn@inlv.org>
Date: Mon, 15 Nov 2021 19:07:19 +0100
Subject: [PATCH] tests: fix intermittent $RANDOM reseeding fails (re:
 af6a32d1)

When testing whether subshell $RANDOM reseeding worked, checking
for non-identical numbers is not sufficient. There is no check for
randomly occurring duplicate numbers, nor can there be, because
subshells cannot (or, in the case of virtual subshells, should not)
influence each other or the parent shell.

src/cmd/ksh93/tests/variables.sh:
- Try up to three times, tolerating identical numbers twice.
---
 src/cmd/ksh93/tests/variables.sh | 65 ++++++++++++++++++++------------
 1 file changed, 40 insertions(+), 25 deletions(-)

diff --git a/src/cmd/ksh93/tests/variables.sh b/src/cmd/ksh93/tests/variables.sh
index 45aa0895c..45a5defde 100755
--- a/src/cmd/ksh93/tests/variables.sh
+++ b/src/cmd/ksh93/tests/variables.sh
@@ -34,46 +34,60 @@ fi
 # When the $RANDOM variable is used in a forked subshell, it shouldn't
 # use the same pseudorandom seed as the main shell.
 # https://github.com/ksh93/ksh/issues/285
+# These tests sometimes fail as duplicate numbers can occur randomly, so try up to $N times.
+integer N=3 i rand1 rand2
 RANDOM=123
 function rand_print {
 	ulimit -t unlimited 2> /dev/null
 	print $RANDOM
 }
-integer rand1=$(rand_print)
-integer rand2=$(rand_print)
+for((i=0; i<N; i++))
+do	rand1=$(rand_print)
+	rand2=$(rand_print)
+	((rand1 != rand2)) && break
+done
 (( rand1 == rand2 )) && err_exit "Test 1: \$RANDOM seed in subshell doesn't change" \
 	"(both results are $rand1)"
 # Make sure we're actually using a different pseudorandom seed
-integer rand1=$(
-	ulimit -t unlimited 2> /dev/null
-	test $RANDOM
-	print $RANDOM
-)
-integer rand2=${ print $RANDOM ;}
+for((i=0; i<N; i++))
+do	rand1=$(
+		ulimit -t unlimited 2> /dev/null
+		test $RANDOM
+		print $RANDOM
+	)
+	rand2=${ print $RANDOM ;}
+	((rand1 != rand2)) && break
+done
 (( rand1 == rand2 )) && err_exit "Test 2: \$RANDOM seed in subshell doesn't change" \
 	"(both results are $rand1)"
 # $RANDOM should be reseeded when the final command is inside of a subshell
-rand1=$($SHELL -c 'RANDOM=1; (echo $RANDOM)')
-rand2=$($SHELL -c 'RANDOM=1; (echo $RANDOM)')
+for((i=0; i<N; i++))
+do	rand1=$("$SHELL" -c 'RANDOM=1; (echo $RANDOM)')
+	rand2=$("$SHELL" -c 'RANDOM=1; (echo $RANDOM)')
+	((rand1 != rand2)) && break
+done
 (( rand1 == rand2 )) && err_exit "Test 3: \$RANDOM seed in subshell doesn't change" \
 	"(both results are $rand1)"
 # $RANDOM should be reseeded for the ( simple_command & ) optimization
-( echo $RANDOM & ) >r1
-( echo $RANDOM & ) >r2
-integer giveup=0
-trap '((giveup++))' USR1
-(sleep 2; kill -s USR1 $$) &
-while	[[ ! -s r1 || ! -s r2 ]]
-do	((giveup)) && break
+for((i=0; i<N; i++))
+do	( echo $RANDOM & ) >|r1
+	( echo $RANDOM & ) >|r2
+	integer giveup=0
+	trap '((giveup++))' USR1
+	(sleep 2; kill -s USR1 $$) &
+	while	[[ ! -s r1 || ! -s r2 ]]
+	do	((giveup)) && break
+	done
+	if	((giveup))
+	then	err_exit "Test 4: ( echo $RANDOM & ) does not write output"
+	fi
+	kill $! 2>/dev/null
+	trap - USR1
+	unset giveup
+	[[ $(<r1) != "$(<r2)" ]] && break
 done
-if	((giveup))
-then	err_exit "Test 4: ( echo $RANDOM & ) does not write output"
-else	[[ $(<r1) == "$(<r2)" ]] && err_exit "Test 4: \$RANDOM seed in ( simple_command & ) doesn't change" \
-		"(both results are $(printf %q "$(<r1)"))"
-fi
-kill $! 2>/dev/null
-trap - USR1
-unset giveup
+[[ $(<r1) == "$(<r2)" ]] && err_exit "Test 4: \$RANDOM seed in ( simple_command & ) doesn't change" \
+	"(both results are $(printf %q "$(<r1)"))"
 # Virtual subshells should not influence the parent shell's RANDOM sequence
 RANDOM=456
 exp="$RANDOM $RANDOM $RANDOM $RANDOM $RANDOM"
@@ -85,6 +99,7 @@ do	: $( : $RANDOM $RANDOM $RANDOM )
 done
 [[ $got == "$exp" ]] || err_exit 'Using $RANDOM in subshell influences reproducible sequence in parent environment' \
 	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+unset N i rand1 rand2
 
 # SECONDS
 float secElapsed=0.0 secSleep=0.001