sh: Make getopts memory-safe if with changing arguments.

POSIX does not permit to continuing a getopts loop with different
arguments. For parsing the positional parameters, we handle this case by
resetting the getopts state when the positional parameters are changed in
any way (and the getopts state is local to a function). However, in the
syntax getopts <optstring> <var> <arg...>, changes could lead to invalid
memory access.

In the syntax getopts <optstring> <var> <arg...>, store a copy of the
arguments and continue to use them until getopts is reset.

bin/sh/eval.c

@@ -1039,6 +1039,7 @@ evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 		shellparam.reset = 1;
 		shellparam.nparam = argc - 1;
 		shellparam.p = argv + 1;
+		shellparam.optp = NULL;
 		shellparam.optnext = NULL;
 		INTOFF;
 		savelocalvars = localvars;

bin/sh/options.c

@@ -325,6 +325,7 @@ setparam(char **argv)
 	shellparam.malloc = 1;
 	shellparam.nparam = nparam;
 	shellparam.p = newparam;
+	shellparam.optp = NULL;
 	shellparam.reset = 1;
 	shellparam.optnext = NULL;
 }
@@ -344,6 +345,11 @@ freeparam(struct shparam *param)
 			ckfree(*ap);
 		ckfree(param->p);
 	}
+	if (param->optp) {
+		for (ap = param->optp ; *ap ; ap++)
+			ckfree(*ap);
+		ckfree(param->optp);
+	}
 }
 
 
@@ -417,20 +423,33 @@ getoptsreset(const char *value)
 int
 getoptscmd(int argc, char **argv)
 {
-	char **optbase = NULL;
+	char **optbase = NULL, **ap;
+	int i;
 
 	if (argc < 3)
 		error("usage: getopts optstring var [arg]");
-	else if (argc == 3)
-		optbase = shellparam.p;
-	else
-		optbase = &argv[3];
 
 	if (shellparam.reset == 1) {
+		INTOFF;
+		if (shellparam.optp) {
+			for (ap = shellparam.optp ; *ap ; ap++)
+				ckfree(*ap);
+			ckfree(shellparam.optp);
+			shellparam.optp = NULL;
+		}
+		if (argc > 3) {
+			shellparam.optp = ckmalloc((argc - 2) * sizeof *ap);
+			memset(shellparam.optp, '\0', (argc - 2) * sizeof *ap);
+			for (i = 0; i < argc - 3; i++)
+				shellparam.optp[i] = savestr(argv[i + 3]);
+		}
+		INTON;
+		optbase = argc == 3 ? shellparam.p : shellparam.optp;
 		shellparam.optnext = optbase;
 		shellparam.optptr = NULL;
 		shellparam.reset = 0;
-	}
+	} else
+		optbase = shellparam.optp ? shellparam.optp : shellparam.p;
 
 	return getopts(argv[1], argv[2], optbase, &shellparam.optnext,
 		       &shellparam.optptr);

bin/sh/options.h

@@ -38,6 +38,7 @@ struct shparam {
 	unsigned char malloc;	/* if parameter list dynamically allocated */
 	unsigned char reset;	/* if getopts has been reset */
 	char **p;		/* parameter list */
+	char **optp;		/* parameter list for getopts */
 	char **optnext;		/* next parameter to be processed by getopts */
 	char *optptr;		/* used by getopts */
 };

bin/sh/tests/builtins/getopts9.0

@@ -0,0 +1,9 @@
+# $FreeBSD$
+
+args='-ab'
+getopts ab opt $args
+echo $?:$opt:$OPTARG
+for dummy in dummy1 dummy2; do
+	getopts ab opt $args
+	echo $?:$opt:$OPTARG
+done

bin/sh/tests/builtins/getopts9.0.stdout

@@ -0,0 +1,3 @@
+0:a:
+0:b:
+1:?: