add error handling

sh.zio.backup

@@ -2,23 +2,36 @@
 
 wd="$(realpath "$(dirname "$(realpath -s "$0")")/.tmp")"
 git_url_prefix="https://git.zio.sh/zio/rootfs/raw/branch/main"
+helpers_dir="$wd/helpers"
+
+function die() {
+    echo -e "\033[1;31mError: $@\033[0m"
+    exit 255
+}
 
 function fetch() {
     url="$1"
     output="$2"
     curl -L -s -o "$output" "$url"
+    [[ $? != 0 ]] && die "Unable to download '$url'"
 }
 
+[[ ! -w "$(dirname "$(realpath -s "$0")")" ]] && die "No write permissions in current directory"
+
 mkdir -p "$wd"
-mkdir -p "$wd/helpers"
+mkdir -p "$helpers_dir"
 
 fetch "$git_url_prefix/usr/local/bin/sh.zio.backup" "$wd/backup.sh"
 fetch "$git_url_prefix/usr/local/libexec/zio/helpers/bash.sh" "$wd/helpers/bash.sh"
 
 chmod +x "$wd/backup.sh"
-chmod +x "$wd/helpers/bash.sh"
+chmod +x "$helpers_dir/bash.sh"
 
-export ZIO_HELPERS_DIR="$wd/helpers"
-. "$wd/backup.sh" $@
+if [[ -n "$SUDO_USER" ]]; then
+    chown -R "$SUDO_USER" "$wd"
+fi
+
+export ZIO_HELPERS_DIR="$helpers_dir"
+/usr/bin/env bash "$wd/backup.sh" $@
 
 rm -rf "$wd"