// // Data+Compression.swift // ZIPFoundation // // Copyright © 2017-2020 Thomas Zoechling, https://www.peakstep.com and the ZIP Foundation project authors. // Released under the MIT License. // // See https://github.com/weichsel/ZIPFoundation/blob/master/LICENSE for license information. // import Foundation /// An unsigned 32-Bit Integer representing a checksum. public typealias CRC32 = UInt32 /// A custom handler that consumes a `Data` object containing partial entry data. /// - Parameters: /// - data: A chunk of `Data` to consume. /// - Throws: Can throw to indicate errors during data consumption. public typealias Consumer = (_ data: Data) throws -> Void /// A custom handler that receives a position and a size that can be used to provide data from an arbitrary source. /// - Parameters: /// - position: The current read position. /// - size: The size of the chunk to provide. /// - Returns: A chunk of `Data`. /// - Throws: Can throw to indicate errors in the data source. public typealias Provider = (_ position: Int, _ size: Int) throws -> Data /// The lookup table used to calculate `CRC32` checksums. public let crcTable: [UInt32] = [ 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d] extension Data { enum CompressionError: Error { case invalidStream case corruptedData } /// Calculate the `CRC32` checksum of the receiver. /// /// - Parameter checksum: The starting seed. /// - Returns: The checksum calcualted from the bytes of the receiver and the starting seed. public func crc32(checksum: CRC32) -> CRC32 { // The typecast is necessary on 32-bit platforms because of // https://bugs.swift.org/browse/SR-1774 let mask = 0xffffffff as UInt32 let bufferSize = self.count/MemoryLayout.size var result = checksum ^ mask #if swift(>=5.0) crcTable.withUnsafeBufferPointer { crcTablePointer in self.withUnsafeBytes { bufferPointer in let bytePointer = bufferPointer.bindMemory(to: UInt8.self) for bufferIndex in 0..> 8) ^ crcTablePointer[index] } } } #else self.withUnsafeBytes { (bytes) in let bins = stride(from: 0, to: bufferSize, by: 256) for bin in bins { for binIndex in 0..<256 { let byteIndex = bin + binIndex guard byteIndex < bufferSize else { break } let byte = bytes[byteIndex] let index = Int((result ^ UInt32(byte)) & 0xff) result = (result >> 8) ^ crcTable[index] } } } #endif return result ^ mask } /// Compress the output of `provider` and pass it to `consumer`. /// - Parameters: /// - size: The uncompressed size of the data to be compressed. /// - bufferSize: The maximum size of the compression buffer. /// - provider: A closure that accepts a position and a chunk size. Returns a `Data` chunk. /// - consumer: A closure that processes the result of the compress operation. /// - Returns: The checksum of the processed content. public static func compress(size: Int, bufferSize: Int, provider: Provider, consumer: Consumer) throws -> CRC32 { #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS) return try self.process(operation: COMPRESSION_STREAM_ENCODE, size: size, bufferSize: bufferSize, provider: provider, consumer: consumer) #else return try self.encode(size: size, bufferSize: bufferSize, provider: provider, consumer: consumer) #endif } /// Decompress the output of `provider` and pass it to `consumer`. /// - Parameters: /// - size: The compressed size of the data to be decompressed. /// - bufferSize: The maximum size of the decompression buffer. /// - skipCRC32: Optional flag to skip calculation of the CRC32 checksum to improve performance. /// - provider: A closure that accepts a position and a chunk size. Returns a `Data` chunk. /// - consumer: A closure that processes the result of the decompress operation. /// - Returns: The checksum of the processed content. public static func decompress(size: Int, bufferSize: Int, skipCRC32: Bool, provider: Provider, consumer: Consumer) throws -> CRC32 { #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS) return try self.process(operation: COMPRESSION_STREAM_DECODE, size: size, bufferSize: bufferSize, skipCRC32: skipCRC32, provider: provider, consumer: consumer) #else return try self.decode(bufferSize: bufferSize, skipCRC32: skipCRC32, provider: provider, consumer: consumer) #endif } } // MARK: - Apple Platforms #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS) import Compression extension Data { static func process(operation: compression_stream_operation, size: Int, bufferSize: Int, skipCRC32: Bool = false, provider: Provider, consumer: Consumer) throws -> CRC32 { var crc32 = CRC32(0) let destPointer = UnsafeMutablePointer.allocate(capacity: bufferSize) defer { destPointer.deallocate() } let streamPointer = UnsafeMutablePointer.allocate(capacity: 1) defer { streamPointer.deallocate() } var stream = streamPointer.pointee var status = compression_stream_init(&stream, operation, COMPRESSION_ZLIB) guard status != COMPRESSION_STATUS_ERROR else { throw CompressionError.invalidStream } defer { compression_stream_destroy(&stream) } stream.src_size = 0 stream.dst_ptr = destPointer stream.dst_size = bufferSize var position = 0 var sourceData: Data? repeat { if stream.src_size == 0 { do { sourceData = try provider(position, Swift.min((size - position), bufferSize)) if let sourceData = sourceData { position += sourceData.count stream.src_size = sourceData.count } } catch { throw error } } if let sourceData = sourceData { sourceData.withUnsafeBytes { (rawBufferPointer) in if let baseAddress = rawBufferPointer.baseAddress { let pointer = baseAddress.assumingMemoryBound(to: UInt8.self) stream.src_ptr = pointer.advanced(by: sourceData.count - stream.src_size) let flags = sourceData.count < bufferSize ? Int32(COMPRESSION_STREAM_FINALIZE.rawValue) : 0 status = compression_stream_process(&stream, flags) } } if operation == COMPRESSION_STREAM_ENCODE && !skipCRC32 { crc32 = sourceData.crc32(checksum: crc32) } } switch status { case COMPRESSION_STATUS_OK, COMPRESSION_STATUS_END: let outputData = Data(bytesNoCopy: destPointer, count: bufferSize - stream.dst_size, deallocator: .none) try consumer(outputData) if operation == COMPRESSION_STREAM_DECODE && !skipCRC32 { crc32 = outputData.crc32(checksum: crc32) } stream.dst_ptr = destPointer stream.dst_size = bufferSize default: throw CompressionError.corruptedData } } while status == COMPRESSION_STATUS_OK return crc32 } } // MARK: - Linux #else import CZlib extension Data { static func encode(size: Int, bufferSize: Int, provider: Provider, consumer: Consumer) throws -> CRC32 { var stream = z_stream() let streamSize = Int32(MemoryLayout.size) var result = deflateInit2_(&stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED, -MAX_WBITS, 9, Z_DEFAULT_STRATEGY, ZLIB_VERSION, streamSize) defer { deflateEnd(&stream) } guard result == Z_OK else { throw CompressionError.invalidStream } var flush = Z_NO_FLUSH var position = 0 var zipCRC32 = CRC32(0) repeat { let readSize = Swift.min((size - position), bufferSize) var inputChunk = try provider(position, readSize) zipCRC32 = inputChunk.crc32(checksum: zipCRC32) stream.avail_in = UInt32(inputChunk.count) try inputChunk.withUnsafeMutableBytes { (rawBufferPointer) in if let baseAddress = rawBufferPointer.baseAddress { let pointer = baseAddress.assumingMemoryBound(to: UInt8.self) stream.next_in = pointer flush = position + bufferSize >= size ? Z_FINISH : Z_NO_FLUSH } else if rawBufferPointer.count > 0 { throw CompressionError.corruptedData } else { stream.next_in = nil flush = Z_FINISH } var outputChunk = Data(count: bufferSize) repeat { stream.avail_out = UInt32(bufferSize) try outputChunk.withUnsafeMutableBytes { (rawBufferPointer) in guard let baseAddress = rawBufferPointer.baseAddress, rawBufferPointer.count > 0 else { throw CompressionError.corruptedData } let pointer = baseAddress.assumingMemoryBound(to: UInt8.self) stream.next_out = pointer result = deflate(&stream, flush) } guard result >= Z_OK else { throw CompressionError.corruptedData } outputChunk.count = bufferSize - Int(stream.avail_out) try consumer(outputChunk) } while stream.avail_out == 0 } position += readSize } while flush != Z_FINISH return zipCRC32 } static func decode(bufferSize: Int, skipCRC32: Bool, provider: Provider, consumer: Consumer) throws -> CRC32 { var stream = z_stream() let streamSize = Int32(MemoryLayout.size) var result = inflateInit2_(&stream, -MAX_WBITS, ZLIB_VERSION, streamSize) defer { inflateEnd(&stream) } guard result == Z_OK else { throw CompressionError.invalidStream } var unzipCRC32 = CRC32(0) var position = 0 repeat { stream.avail_in = UInt32(bufferSize) var chunk = try provider(position, bufferSize) position += chunk.count try chunk.withUnsafeMutableBytes { (rawBufferPointer) in if let baseAddress = rawBufferPointer.baseAddress, rawBufferPointer.count > 0 { let pointer = baseAddress.assumingMemoryBound(to: UInt8.self) stream.next_in = pointer repeat { var outputData = Data(count: bufferSize) stream.avail_out = UInt32(bufferSize) try outputData.withUnsafeMutableBytes { (rawBufferPointer) in if let baseAddress = rawBufferPointer.baseAddress, rawBufferPointer.count > 0 { let pointer = baseAddress.assumingMemoryBound(to: UInt8.self) stream.next_out = pointer } else { throw CompressionError.corruptedData } result = inflate(&stream, Z_NO_FLUSH) guard result != Z_NEED_DICT && result != Z_DATA_ERROR && result != Z_MEM_ERROR else { throw CompressionError.corruptedData } } let remainingLength = UInt32(bufferSize) - stream.avail_out outputData.count = Int(remainingLength) try consumer(outputData) if !skipCRC32 { unzipCRC32 = outputData.crc32(checksum: unzipCRC32) } } while stream.avail_out == 0 } } } while result != Z_STREAM_END return unzipCRC32 } } #endif #if !swift(>=5.0) // Since Swift 5.0, `Data.withUnsafeBytes()` passes an `UnsafeRawBufferPointer` instead of an `UnsafePointer` // into `body`. // We provide a compatible method for targets that use Swift 4.x so that we can use the new version // across all language versions. internal extension Data { func withUnsafeBytes(_ body: (UnsafeRawBufferPointer) throws -> T) rethrows -> T { let count = self.count return try withUnsafeBytes { (pointer: UnsafePointer) throws -> T in try body(UnsafeRawBufferPointer(start: pointer, count: count)) } } #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS) #else mutating func withUnsafeMutableBytes(_ body: (UnsafeMutableRawBufferPointer) throws -> T) rethrows -> T { let count = self.count guard count > 0 else { return try body(UnsafeMutableRawBufferPointer(start: nil, count: count)) } return try withUnsafeMutableBytes { (pointer: UnsafeMutablePointer) throws -> T in try body(UnsafeMutableRawBufferPointer(start: pointer, count: count)) } } #endif } #endif