modules/programs: sane-sandboxed: remove all forking from normPath

reduces time for librewolf benchmark from 90ms -> 65ms. there's still _some_ forking in this script, but it's constant now.

modules/programs/sane-sandboxed

@@ -74,12 +74,14 @@ bwrapFlags=()
 
 ## UTILITIES/BOILERPLATE
 
+# `normPath nameOfOutVar "$path"`
 # remove duplicate //, reduce '.' and '..' (naively).
 # expects a full path as input
 # chomps trailing slashes.
 # does not resolve symlinks, nor check for existence of any component of the path.
 normPath() {
-  _npUnparsed="$1"
+  _npOut="$1"
+  _npUnparsed="$2"
   _npComps=()
   while [ -n "$_npUnparsed" ]; do
     # chomp leading `/`
@@ -102,18 +104,18 @@ normPath() {
   done
 
   # join the components
-  _npOut=
-  for _npComp in "${_npComps[@]}"; do
-    _npOut="$_npOut/$_npComp"
-  done
-  if [ -z "$_npOut" ]; then
-    echo "/"
+  if [ ${#_npComps[@]} -eq 0 ]; then
+    declare -g "$_npOut"="/"
   else
-    echo "$_npOut"
+    _npJoined=
+    for _npComp in "${_npComps[@]}"; do
+      _npJoined="$_npJoined/$_npComp"
+    done
+    declare -g "$_npOut"="$_npJoined"
   fi
 }
 
-# normPath() {
+# normPathBashBuiltin() {
 #   # normPath implementation optimized by using bash builtins (`help realpath`):
 #   # -s: canonicalize `.` and `..` without resolving symlinks
 #   # -c: enforce that each component exist (intentionally omitted)
@@ -123,17 +125,18 @@ normPath() {
 
 # legacy coreutils normPath: definitive, but slow (requires a fork/exec subshell).
 # bash `normPath` aims to be equivalent to this one.
-# normPath() {
+# normPathCoreutils() {
 #   # `man realpath`:
 #   # --logical: resolve `..` before dereferencing symlinks
 #   # --no-symlinks: don't follow symlinks
 #   # --canonicalize-missing: don't error if path components don't exist
-#   normPathOut="$(realpath --logical --no-symlinks --canonicalize-missing "$1")"
+#   realpath --logical --no-symlinks --canonicalize-missing "$1"
 # }
 
+# `parent nameOfOutVar "$path"`
 # return the path to this file or directory's parent, even if the input doesn't exist.
 parent() {
-  normPath "$1/.."
+  normPath "$1" "$2/.."
   # normPath "$(dirname "$1")"
 }
 
@@ -203,7 +206,8 @@ tryPath() {
     false
   elif [ "$_how" = "parent" ]; then
     # the caller wants access to the entire directory containing this directory regardless of the file's existence.
-    tryPath "$(parent "$_path")" "existing"
+    parent _tryPathParent "$_path"
+    tryPath "$_tryPathParent" "existing"
   elif [ "$_how" = "existingFileOrParent" ]; then
     # the caller wants access to the file, or write access to the directory so it may create the file if it doesn't exist.
     tryPath "$_path" "existing" || tryPath "$_path" "parent"
@@ -620,7 +624,8 @@ canonicalizePaths() {
   # remove '//' and simplify '.', '..' paths, into canonical absolute logical paths.
   _normPaths=()
   for _path in "${paths[@]}"; do
-    _normPaths+=("$(normPath "$_path")")
+    normPath _canonPath "$_path"
+    _normPaths+=("$_canonPath")
   done
 
   # remove subpaths, but the result might include duplicates.