103 lines
3.7 KiB
Swift
103 lines
3.7 KiB
Swift
//
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// TorrentFileManager.swift
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// BitTorrent
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//
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// Created by Ben Davis on 23/07/2017.
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// Copyright © 2017 Ben Davis. All rights reserved.
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//
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import Foundation
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enum TorrentFileManagerError: Error {
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case couldNotCreateFile
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}
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public class TorrentFileManager {
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let metaInfo: TorrentMetaInfo
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let rootDirectory: String
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fileprivate let fileHandle: MultiFileHandle
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convenience init(metaInfo: TorrentMetaInfo, rootDirectory: String) {
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let fileHandles = TorrentFileManager.createFileHandles(for: metaInfo, in: rootDirectory)
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self.init(metaInfo: metaInfo, rootDirectory: rootDirectory, fileHandles: fileHandles)
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}
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init(metaInfo: TorrentMetaInfo, rootDirectory: String, fileHandles: [FileHandleProtocol]) {
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self.metaInfo = metaInfo
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self.rootDirectory = rootDirectory
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self.fileHandle = MultiFileHandle(fileHandles: fileHandles)
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}
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private static func createFileHandles(for metaInfo: TorrentMetaInfo, in rootDirectory: String) -> [FileHandle] {
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var result: [FileHandle] = []
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for fileInfo in metaInfo.info.files {
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let fullPath = rootDirectory + "/" + fileInfo.path
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let fileHandle = FileHandle(forUpdatingAtPath: fullPath)!
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result.append(fileHandle)
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}
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return result
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}
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// MARK: set and get piece
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func setPiece(at index: Int, data: Data) {
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let byteIndex = index * metaInfo.info.pieceLength
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fileHandle.seek(toFileOffset: UInt64(byteIndex))
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fileHandle.write(data)
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}
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func getPiece(at index: Int) -> Data {
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let byteIndex = index * metaInfo.info.pieceLength
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let length = metaInfo.info.lengthOfPiece(at: index)
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fileHandle.seek(toFileOffset: UInt64(byteIndex))
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return fileHandle.readData(ofLength: length)
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}
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}
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// MARK: - Prepare directory
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extension TorrentFileManager {
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public static func prepareRootDirectory(_ rootDirectory: String,
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forTorrentMetaInfo metaInfo: TorrentMetaInfo) throws {
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try createDirectoryIfNeeded(directoryPath: rootDirectory)
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for file in metaInfo.info.files {
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let fullPath = rootDirectory + "/" + file.path
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try createSubDirectoryIfNeeded(at: fullPath)
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try createEmptyFileIfNeeded(at: fullPath, length: file.length)
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}
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}
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private static func createSubDirectoryIfNeeded(at path: String) throws {
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let directory = URL(fileURLWithPath: path, isDirectory: false).deletingLastPathComponent()
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try createDirectoryIfNeeded(directoryPath: directory.path)
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}
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private static func createDirectoryIfNeeded(directoryPath: String) throws {
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if (!FileManager.default.fileExists(atPath: directoryPath)) {
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try FileManager.default.createDirectory(atPath: directoryPath,
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withIntermediateDirectories: true,
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attributes: nil)
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}
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}
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private static func createEmptyFileIfNeeded(at path: String, length: Int) throws {
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guard !FileManager.default.fileExists(atPath: path) else {
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return
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}
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guard FileManager.default.createFile(atPath: path, contents: nil, attributes: nil) else {
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throw TorrentFileManagerError.couldNotCreateFile
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}
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let fileDescriptor: CInt = open(path, O_WRONLY, 0644) // open file for writing
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lseek(fileDescriptor, off_t(length), SEEK_SET) // seek to the last byte ...
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write(fileDescriptor, UnsafeRawPointer([0]), 1) // ... and write a 0 to it
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close(fileDescriptor) // Now we have a file of the correct size we close it
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}
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}
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