bin: add bwrap script to run Nix unpriviledged

bin/bwrap.bash

@@ -0,0 +1,61 @@
+#!/usr/bin/env bash
+
+if [ -z ${NIXDIR+x} ]; then 
+    echo "NIXDIR is unset! It needs to be set in the code. Edit this shell file and read the instructions."
+    echo "Executing bash without Bubblewrap…"
+    exec bash
+fi
+
+if [ ! -e $NIXDIR ]; then
+    echo "NIXDIR doesn't point to a valid location! Falling back to Bash"
+    exec bash
+fi
+
+_bind() {
+    _bind_arg=$1
+    shift
+    for _path in "$@"; do
+        args+=("$_bind_arg" "$_path" "$_path")
+    done
+}
+
+bind() {
+    _bind --bind-try "$@"
+}
+
+robind() {
+    _bind --ro-bind-try "$@"
+}
+
+devbind() {
+    _bind --dev-bind-try "$@"
+}
+
+args=(
+    --bind $NIXDIR /nix
+    --chdir $HOME
+)
+
+bind \
+    $HOME
+
+devbind \
+    /dev \
+    /proc \
+    /tmp \
+    /run \
+    /u \
+    /p \
+    /bin \
+    /boot \
+    /etc \
+    /home \
+    /lib \
+    /lib32 \
+    /lib64 \
+    /libx32 \
+    /media \
+    /usr \
+    /var
+
+exec bwrap "${args[@]}" "$@"