Recover lost ARW files from an exFAT drive

recovery.swift

import Foundation

let minimumFileSize = 24_000_000
let separator = [UInt8](repeating: 0, count: 50)
let arwPrefix: [UInt8] = [0x49, 0x49, 0x2A, 0, 0x08, 0, 0, 0, 0x15, 0, 0xFE, 0, 0x04, 0, 0x01, 0, 0, 0, 0x01, 0, 0, 0, 0x03, 0x01, 0x03, 0, 0x01, 0, 0, 0, 0x06, 0]

let disc = try Data(contentsOf: URL(fileURLWithPath: "path-to-drive-image"))

var cursor = disc.startIndex

var fileNames = Set<String>()

while cursor + minimumFileSize < disc.endIndex {
	guard let separator = disc.firstRange(of: separator, in: (cursor + minimumFileSize)...) else {
		fatalError("no end of file found")
	}

	let timestamp = String(bytes: disc[(346..<365) + cursor], encoding: .ascii)!

	print(timestamp, cursor, separator.startIndex - cursor)

	let convertedTime = timestamp.replacingOccurrences(of: ":", with: "-")
	var counter = 1
	while fileNames.contains(convertedTime + " \(counter)") {
		counter += 1
	}
	let fileName = convertedTime + " \(counter)"
	fileNames.insert(fileName)

	try disc[cursor..<separator.startIndex].write(to: URL(fileURLWithPath: "~/Downloads/RecoveredPhotos/\(fileName).ARW"))

	cursor = disc.firstRange(of: arwPrefix, in: separator.endIndex...)?.startIndex ?? disc.endIndex
}

extension Range where Bound == Int {
	static func + (_ range: Self, _ offset: Int) -> Self {
		return (range.lowerBound + offset) ..< (range.upperBound + offset)
	}
}