Added smart volume size algorithm

modules/archive.sh

@@ -1,4 +1,6 @@
 #!/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.
 
 archive_dir="$(dirname "$0")/../archives"
 
@@ -6,6 +8,11 @@ input_file="${1}"
 archive_pwd="${2}"
 size="$3"
 
+cleanup() {
+	[[ -n "$archive" ]] && rm -f "$archive*"
+	echo "Cleaned up all $archive files" >&2
+}
+
 check_dependencies() {
 	if ! mkdir -p "$archive_dir"; then
 		echo "ERROR: Unable to create archive directory"
@@ -24,35 +31,49 @@ check_input() {
 		exit 2
 	fi
 
-	echo "Archiving file/directory '${input_file}'" >&2
+	if [[ -z "${archive_pwd}" ]]; then
+		echo "ERROR: No password given"
+		exit 2
+	fi
+
+	if ! [[ "$size" =~ ^([1-9][0-9]*)?$ ]]; then
+		echo "Invalid size $size, must be a positive number"
+		exit 2
+	fi
+
+	echo "Archiving file/directory '${input_file}' with password '${archive_pwd}'" >&2
+}
+
+calc_smart_volumes() {
+	total_size=$(du -s -BM "${input_file}" | grep -oP '^\d+') || return
+	num_volumes=$(echo "($total_size + $size - 1) / $size" | bc)
+	size=$(echo "($total_size + $num_volumes - 1) / $num_volumes" | bc)
+	echo "Calculated smart volume size '$size'" >&2
 }
 
 set_volumes() {
-	volumes=
+	[[ -z "$size" ]] && return
 
-	if [[ "$size" =~ ^[1-9][0-9]*$ ]]; then
-		volumes="-v${size}m"
-	elif [[ -n "$size" ]]; then
-		echo "Invalid size $size, must be a number"
-		exit 2
-	fi
+	calc_smart_volumes
+	volumes="-v${size}m"
 
 	echo "Volumes set to '$volumes'" >&2
 }
 
 generate_name() {
 	archive="$archive_dir/$(base64 /dev/urandom | tr -dc [:alnum:] | head -c 20).7z"
-
-	echo "Generated archive name $archive" >&2
+	echo "Generated archive name '$archive'" >&2
 }
 
 create_archive() {
-	echo "Packing ${input_file} into archive $archive with password ${archive_pwd}"
+	echo "Packing '${input_file}' into archive '$archive' with password '${archive_pwd}'"
 	[[ -n "$volumes" ]] && echo "and volumes of size $size MB"
 
 	7z a -mhe=on "-p${archive_pwd}" "$volumes" "$archive" "${input_file}" >&2
 }
 
+trap cleanup 1 2 3 6
+
 check_dependencies
 check_input
 set_volumes