moved calls out of global space to main function, preparing for usage with strict mode

modules/archive.sh

@@ -1,12 +1,10 @@
 #!/bin/bash
 # This script packs a file or directory into a 7z archive with the given password.
 # It can (optionally) split the archives into volumes of a fixed size in megabytes.
+source colors.sh
+source functions.sh
 
-archive_dir="$(dirname "$0")/../archives"
-
-input_file="${1}"
-archive_pwd="${2}"
-size="$3"
+trap 'cleanup' EXIT
 
 cleanup() {
 	[[ -n "$archive" ]] && rm -f "$archive*"
@@ -72,10 +70,25 @@ create_archive() {
 	7z a -mhe=on "-p${archive_pwd}" "$volumes" "$archive" "${input_file}" >&2
 }
 
-trap cleanup 1 2 3 6
+main() {
+	archive_dir="$(dirname "$0")/../archives"
+	input_file="${1}"
+	archive_pwd="${2}"
+	size="$3"
 
-check_dependencies
-check_input
-set_volumes
-generate_name
-create_archive
+	check_dependencies
+	check_input
+	set_volumes
+	generate_name
+	create_archive
+}
+
+
+# Missing arguments must be caught here when using `set -e`, otherwise
+# the script will exit prematurely without logging the error.
+if (( $# == 3 )); then
+	main "$@"
+else
+	log_err "Missing arguments"
+	exit 2
+fi