sane-sandboxed: be a little more careful with out vars

pkgs/additional/sane-sandboxed/sane-sandboxed

@@ -185,18 +185,21 @@ splitHead() {
 # does not resolve symlinks, nor check for existence of any component of the path.
 normPath() {
   local npOut="$1"
-  _npUnparsed="$2"
+  local npUnparsed="$2"
   local npComps=()
   while [ -n "$_npUnparsed" ]; do
     splitHead _npThisComp _npUnparsed "$_npUnparsed"
-    if [ "$_npThisComp" = "/.." ]; then
+    npUnparsed="$_npUnparsed"
+    local npThisComp="$_npThisComp"
+
+    if [ "$npThisComp" = "/.." ]; then
       # "go up" path component => delete the leaf dir (if any)
       if [ ${#npComps[@]} -ne 0 ]; then
         unset npComps[-1]
       fi
-    elif [ "$_npThisComp" != "/." ] && [ "$_npThisComp" != "/" ] && [ "$_npThisComp" != "" ]; then
+    elif [ "$npThisComp" != "/." ] && [ "$npThisComp" != "/" ] && [ "$npThisComp" != "" ]; then
       # normal, non-empty path component => append it
-      npComps+=("$_npThisComp")
+      npComps+=("$npThisComp")
     fi
   done
 
@@ -308,13 +311,15 @@ derefOnce() {
   local target=
 
   local walked=
-  _unwalked="$source"
-  while [ -n "$_unwalked" ]; do
+  local unwalked="$source"
+  while [ -n "$unwalked" ]; do
     splitHead _head _unwalked "$_unwalked"
+    unwalked="$_unwalked"
     walked="$walked$_head"
-    readlinkOnce linkTarget "$walked"
-    if [ -n "$linkTarget" ]; then
-      target="$linkTarget$_unwalked"
+
+    readlinkOnce _linkTarget "$walked"
+    if [ -n "$_linkTarget" ]; then
+      target="$_linkTarget$unwalked"
       break
     fi
   done
@@ -413,24 +418,25 @@ tryPath() {
 tryArgAsPath() {
   local arg="$1"
   local how="$2"
-  _path=
+  path=
   if [ "${arg:0:1}" = "/" ]; then
     # absolute path
-    _path="$_arg"
+    path="$arg"
   elif [ "${arg:0:8}" = "file:///" ]; then
     # URI to an absolute path which is presumably on this vfs
     # commonly found when xdg-open/mimeo passes a path on to an application
     # if URIs to relative paths exist, this implementation doesn't support them
     urldecode _path "${arg:7}"
-  elif [ "${_path:0:1}" = "-" ]; then
+    path="$_path"
+  elif [ "${path:0:1}" = "-" ]; then
     # 99% chance it's a CLI argument. if not, use `./-<...>`
     return
   else
     # assume relative path
-    _path="$PWD/$_arg"
+    _path="$PWD/$arg"
   fi
 
-  tryPath "$_path" "$how"
+  tryPath "$path" "$how"
 }