A (paranoid) script for extracting Backblaze's zip restore archives.

unpack_bacbklaze_restore_zip_archive.sh

#!/usr/bin/env bash
#
# Unpacking Backblaze archives
# ----------------------------
#
# A paranoid script for extracting a zip file into the current directory. It
# attempts to validate against common gotchas: it checks the list of extracted
# files against the list of archive contents, it valids the zipfile's contents
# checksums, and it uses "ditto" over "unzip" because it handles non-ASCII
# filenames properly.
#
# Usage: unpack_bacbklaze_restore_zip_archive.sh <zip archive>
set -euo pipefail

export LC_ALL=C
export LANG=en_US.UTF-8

unpack_with_ditto() {
	local zipfile="$1"
	echo "Unzipping ${zipfile}, logging to ${zipfile}.logs/ditto.txt"
	ditto -V -x -k --sequesterRsrc --rsrc "${1}" . &> "${1}.logs/ditto.txt"	
	echo "Computing ${zipfile}.logs/unzipped.txt"
	grep 'copying file' "${zipfile}.logs/ditto.txt" | sed 's/^copying file // ; s/ ....$//' | sort > "${zipfile}.logs/unzipped.txt"
}

unpack_with_unzip() {
	local zipfile="$1"
	echo "Unzipping ${zipfile}, logging to ${zipfile}.logs/unzip.txt"
	unzip -o "${zipfile}" &> "${1}.logs/unzip.txt"
	echo "Computing ${zipfile}.logs/unzipped.txt"
	grep inflating "${zipfile}.logs/unzip.txt" | sed 's/^  inflating: //' | awk '{$1=$1};1' | sort "${zipfile}.logs/unzipped.txt"
}

main() {
	local zipfile="$1"

	# Write files to a <name>.logs directory.
	mkdir -p "${zipfile}.logs"

	# Dump a list of file names from the zip archive. We can use this to 
	# compare against after unpacking to make sure we got everything.
	echo "Writing ${zipfile}.logs/file_list.txt"
	zipinfo -1 "${zipfile}" | sort > "${zipfile}.logs/file_list.txt"
	echo $(wc -l "${zipfile}.logs/file_list.txt" | awk '{print $1}') files in "${zipfile}"

	# Run unzip's "test" utility, which runs and in-memory extract and compares
	# the checksums.
	echo "Testing zipfile contents, logging to ${zipfile}.logs/ziptest.txt"
	unzip -t "${zipfile}" &> "${zipfile}.logs/ziptest.txt"

	# ================================================
	# Run the actual extraction.
	# If ditto fails, try "unpack_with_unzip"
	# ================================================
	unpack_with_ditto "${zipfile}"

	# Compare the list of extracted files with the list of archive contents
	# that we computed earlier. Any output here shows that something went
	# wrong, and the script will exit with a non-zero return code.
	echo "Diffing unzip file list with ditto extraction list"
	git diff --no-index "${zipfile}.logs/file_list.txt" "${zipfile}.logs/unzipped.txt" 2>&1 | tee "${zipfile}.logs/file_list_unzipped_diff.txt"
}
main $@