From: Felix Fietkau <nbd@openwrt.org>
Date: Fri, 17 Apr 2015 01:54:51 +0200
Subject: [PATCH] ash: fix a regression in handling local variables

commit 109ee5d33694a03cda3424b4846584250832ba8e
"ash: make "locak VAR" unset VAR (bash does that)"

This commit introduced a regression where calling local on an already
local variable unsets it. This does not match bash behavior.

Update test case to check for this behavior

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---

--- a/shell/ash.c
+++ b/shell/ash.c
@@ -8961,6 +8961,21 @@ parse_command_args(char **argv, const ch
 }
 #endif
 
+static bool
+findlocal(struct var *vp)
+{
+	struct localvar *lvp = localvars;
+
+	while (lvp) {
+		if (lvp->vp == vp)
+			return true;
+
+		lvp = lvp->next;
+	}
+
+	return false;
+}
+
 /*
  * Make a variable a local variable.  When a variable is made local, it's
  * value and flags are saved in a localvar structure.  The saved values
@@ -9000,7 +9015,7 @@ mklocal(char *name)
 			vp->flags |= VSTRFIXED|VTEXTFIXED;
 			if (eq)
 				setvareq(name, 0);
-			else
+			else if (!findlocal(vp))
 				/* "local VAR" unsets VAR: */
 				setvar(name, NULL, 0);
 		}
--- a/shell/ash_test/ash-misc/local1.right
+++ b/shell/ash_test/ash-misc/local1.right
@@ -1,4 +1,5 @@
 A1:'A'
 A2:''
-A3:''
-A4:'A'
+A3:'B'
+A4:''
+A5:'A'
--- a/shell/ash_test/ash-misc/local1.tests
+++ b/shell/ash_test/ash-misc/local1.tests
@@ -3,9 +3,12 @@ f() {
 	local a
 	# the above line unsets $a
 	echo "A2:'$a'"
-	unset a
+	a=B
+	local a
 	echo "A3:'$a'"
+	unset a
+	echo "A4:'$a'"
 }
 echo "A1:'$a'"
 f
-echo "A4:'$a'"
+echo "A5:'$a'"