shithub: purgatorio

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string(2): add bound check on contains()

--- a/appl/lib/string.b

+++ b/appl/lib/string.b

@@ -498,14 +498,10 @@

 # Returns >0 if s∈in and <=0 if s∋in

 contains(in, s: string): int {

-	if(s == "") {

-		# Of course

+	if(in == "" || s == "") {

+		# Can't do anything

 		return 1;

 	}

-	if(len in < 1) {

-		# Can't have anything

-		return 0;

-	}

 	# For each rune 'in' the original string

 	for(r0 := 0; r0 < len in ; r0++) {

@@ -513,7 +509,7 @@

 		r1: int;

 		substring:

-		for(r1 = 0; r1 < len s; r1++) {

+		for(r1 = 0; r1 < len s && r0 + r1 < len in; r1++) {

 			if(in[r0 + r1] == s[r1]) {

 				# Match so far

 				continue substring;