sh: Correctly handle positional parameters beyond INT_MAX on 64-bit systems.

Currently, there can be no more than INT_MAX positional parameters. Make
sure to treat all higher ones as unset to avoid incorrect results and
crashes.

On 64-bit systems, our atoi() takes the low 32 bits of the strtol() and
sign-extends them.

On 32-bit systems, the call to atoi() returned INT_MAX for too high values
and there is not enough address space for so many positional parameters, so
there was no issue.

bin/sh/expand.c

@@ -846,9 +846,11 @@ varisset(const char *name, int nulok)
 		}
 	} else if (is_digit(*name)) {
 		char *ap;
-		int num = atoi(name);
+		long num;
 
-		if (num > shellparam.nparam)
+		errno = 0;
+		num = strtol(name, NULL, 10);
+		if (errno != 0 || num > shellparam.nparam)
 			return 0;
 
 		if (num == 0)

bin/sh/tests/parameters/Makefile

@@ -15,6 +15,7 @@ FILES+=		positional1.0
 FILES+=		positional2.0
 FILES+=		positional3.0
 FILES+=		positional4.0
+FILES+=		positional5.0
 FILES+=		pwd1.0
 FILES+=		pwd2.0
 

bin/sh/tests/parameters/positional5.0

@@ -0,0 +1,14 @@
+# $FreeBSD$
+
+i=1
+r=0
+while [ $i -lt $((0x100000000)) ]; do
+	t=
+	eval t=\${$i-x}
+	case $t in
+	x) ;;
+	*) echo "Problem with \${$i}" >&2; r=1 ;;
+	esac
+	i=$((i + 0x10000000))
+done
+exit $r