autoshare/modules/create_archive

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#!/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 "$(dirname "$0")/../includes/functions.sh"
set -euo pipefail
cleanup() {
local archive_name="$1"
rm -f "${archive_name}"*
log "INFO" "Cleaning up ${archive_name##*/} remains before exit"
}
check_input() {
local input_file="$1"
local password="$2"
local size="$3"
[[ -e "$input_file" ]] || { log "ERROR" "Input file '${input_file}' does not exist"; exit 2; }
[[ -n "${password}" ]] || { log "ERROR" "No password given"; exit 2; }
[[ "$size" =~ ^([1-9][0-9]*)?$ ]] || { log "ERROR" "Invalid size '$size', must be empty or a positive number"; exit 2; }
}
calc_smart_volumes() {
# Calculates a "smart" volume size so that each volume (including the final part)
# will be approximately the same size
local input_file="$1"
local size="$2"
local total_size num_volumes smart_size
total_size=$(du -s -BM "${input_file}" | grep -oP '^\d+') || return 1
# If total file size is smaller than volume size, don't pack it into volumes
(( total_size < size )) && return 1
num_volumes=$(( (total_size + size - 1) / size ))
smart_size=$(( (total_size + num_volumes - 1) / num_volumes ))
log "INFO" "Calculated smart volume size '$smart_size'"
echo "$smart_size"
}
get_volumes() {
local input_file="$1"
local size="${2:-}"
local volumes=""
local smart_size
if [[ -n "$size" ]]; then
log "INFO" "Volumes size is set to ${size}MB"
smart_size="$(calc_smart_volumes "$input_file" "$size" || echo -n)"
volumes="-v${smart_size}m"
fi
[[ -n "$volumes" ]] && log "INFO" "Volumes set to '$volumes'" || log "INFO" "Volumes argument unset"
echo "$volumes"
}
generate_name() {
# Generates a random archive name of 20 alphanumeric characters
local archive_dir="$1"
local archive_name
archive_name="$archive_dir/$(tr -dc '[:alnum:]' < /dev/urandom | head -c 20).7z"
log "INFO" "Generated archive name '$archive_name'"
echo "$archive_name"
}
create_archive() {
local input_file="$1"
local password="$2"
local volumes="$3"
local archive_name="$4"
7z a -mhe=on "-p${password}" "$volumes" "$archive_name" "${input_file}"
}
main() {
local input_file="${1:-}"
local password="${2:-}"
local size="${3:-}"
local volumes archive_name archive_dir
check_dependencies "7z"
check_input "$input_file" "$password" "$size"
archive_dir="$(dirname "$0")/../archives"
mkdir -p "$archive_dir"
archive_name="$(generate_name "$archive_dir")"
volumes="$(get_volumes "$input_file" "$size")"
log "INFO" "Packing '${input_file}' into archive '$archive_name' with password '${password}'"
trap 'cleanup "$archive_name"' ERR INT
create_archive \
"$input_file" \
"$password" \
"$volumes" \
"$archive_name"
log "NOTICE" "Archive created"
}
main "$@"