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| 1 | +// Portions derived from "DataCompression" (Apache-2.0) |
| 2 | +// https://github.com/mw99/DataCompression/ |
| 3 | +// |
| 4 | +// Copyright 2016, Markus Wanke |
| 5 | +// |
| 6 | +// Modifications for OpenTelemetry-Swift: namespacing, limited algorithms and internal visibility. |
| 7 | + |
| 8 | +#if canImport(Compression) |
| 9 | +import Compression |
| 10 | +import Foundation |
| 11 | + |
| 12 | +fileprivate extension Data { |
| 13 | + func withUnsafeBytes<ResultType, ContentType>( |
| 14 | + _ body: (UnsafePointer<ContentType>) throws -> ResultType |
| 15 | + ) rethrows -> ResultType |
| 16 | + { |
| 17 | + return try self.withUnsafeBytes({ (rawBufferPointer: UnsafeRawBufferPointer) -> ResultType in |
| 18 | + return try body(rawBufferPointer.bindMemory(to: ContentType.self).baseAddress!) |
| 19 | + }) |
| 20 | + } |
| 21 | +} |
| 22 | + |
| 23 | +extension Data { |
| 24 | + /// Compresses the data using the zlib deflate algorithm. |
| 25 | + /// - returns: raw deflated data according to [RFC-1951](https://tools.ietf.org/html/rfc1951). |
| 26 | + /// - note: Fixed at compression level 5 (best trade off between speed and time) |
| 27 | + func deflate() -> Data? |
| 28 | + { |
| 29 | + return self.withUnsafeBytes { (sourcePtr: UnsafePointer<UInt8>) -> Data? in |
| 30 | + let config = (operation: COMPRESSION_STREAM_ENCODE, algorithm: COMPRESSION_ZLIB) |
| 31 | + return perform(config, source: sourcePtr, sourceSize: count) |
| 32 | + } |
| 33 | + } |
| 34 | + |
| 35 | + /// Compresses the data using the deflate algorithm and makes it comply to the gzip stream format. |
| 36 | + /// - returns: deflated data in gzip format [RFC-1952](https://tools.ietf.org/html/rfc1952) |
| 37 | + /// - note: Fixed at compression level 5 (best trade off between speed and time) |
| 38 | + func gzip() -> Data? |
| 39 | + { |
| 40 | + var header = Data([0x1f, 0x8b, 0x08, 0x00]) // magic, magic, deflate, noflags |
| 41 | + |
| 42 | + var unixtime = UInt32(Date().timeIntervalSince1970).littleEndian |
| 43 | + header.append(Data(bytes: &unixtime, count: MemoryLayout<UInt32>.size)) |
| 44 | + |
| 45 | + header.append(contentsOf: [0x00, 0x03]) // normal compression level, unix file type |
| 46 | + |
| 47 | + let deflated = self.withUnsafeBytes { (sourcePtr: UnsafePointer<UInt8>) -> Data? in |
| 48 | + let config = (operation: COMPRESSION_STREAM_ENCODE, algorithm: COMPRESSION_ZLIB) |
| 49 | + return perform(config, source: sourcePtr, sourceSize: count, preload: header) |
| 50 | + } |
| 51 | + |
| 52 | + guard var result = deflated else { return nil } |
| 53 | + |
| 54 | + // append checksum |
| 55 | + var crc32: UInt32 = self.crc32().checksum.littleEndian |
| 56 | + result.append(Data(bytes: &crc32, count: MemoryLayout<UInt32>.size)) |
| 57 | + |
| 58 | + // append size of original data |
| 59 | + var isize: UInt32 = UInt32(truncatingIfNeeded: count).littleEndian |
| 60 | + result.append(Data(bytes: &isize, count: MemoryLayout<UInt32>.size)) |
| 61 | + |
| 62 | + return result |
| 63 | + } |
| 64 | + |
| 65 | + /// Calculate the Crc32 checksum of the data. |
| 66 | + /// - returns: Crc32 checksum type. Can still be further advanced. |
| 67 | + func crc32() -> Crc32 |
| 68 | + { |
| 69 | + var res = Crc32() |
| 70 | + res.advance(withChunk: self) |
| 71 | + return res |
| 72 | + } |
| 73 | + |
| 74 | + fileprivate typealias DataCompressionConfig = ( |
| 75 | + operation: compression_stream_operation, |
| 76 | + algorithm: compression_algorithm |
| 77 | + ) |
| 78 | + |
| 79 | + fileprivate func perform( |
| 80 | + _ config: DataCompressionConfig, |
| 81 | + source: UnsafePointer<UInt8>, |
| 82 | + sourceSize: Int, |
| 83 | + preload: Data = Data()) -> Data? |
| 84 | + { |
| 85 | + guard config.operation == COMPRESSION_STREAM_ENCODE || sourceSize > 0 else { return nil } |
| 86 | + |
| 87 | + let streamBase = UnsafeMutablePointer<compression_stream>.allocate(capacity: 1) |
| 88 | + defer { streamBase.deallocate() } |
| 89 | + var stream = streamBase.pointee |
| 90 | + |
| 91 | + let status = compression_stream_init(&stream, config.operation, config.algorithm) |
| 92 | + guard status != COMPRESSION_STATUS_ERROR else { return nil } |
| 93 | + defer { compression_stream_destroy(&stream) } |
| 94 | + |
| 95 | + var result = preload |
| 96 | + var flags: Int32 = Int32(COMPRESSION_STREAM_FINALIZE.rawValue) |
| 97 | + let blockLimit = 64 * 1024 |
| 98 | + var bufferSize = Swift.max(sourceSize, 64) |
| 99 | + |
| 100 | + if sourceSize > blockLimit { |
| 101 | + bufferSize = blockLimit |
| 102 | + if config.algorithm == COMPRESSION_LZFSE && config.operation != COMPRESSION_STREAM_ENCODE { |
| 103 | + // This fixes a bug in Apples lzfse decompressor. it will sometimes fail randomly when the input gets |
| 104 | + // splitted into multiple chunks and the flag is not 0. Even though it should always work with FINALIZE... |
| 105 | + flags = 0 |
| 106 | + } |
| 107 | + } |
| 108 | + |
| 109 | + let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: bufferSize) |
| 110 | + defer { buffer.deallocate() } |
| 111 | + |
| 112 | + stream.dst_ptr = buffer |
| 113 | + stream.dst_size = bufferSize |
| 114 | + stream.src_ptr = source |
| 115 | + stream.src_size = sourceSize |
| 116 | + |
| 117 | + while true { |
| 118 | + switch compression_stream_process(&stream, flags) { |
| 119 | + case COMPRESSION_STATUS_OK: |
| 120 | + guard stream.dst_size == 0 else { return nil } |
| 121 | + result.append(buffer, count: stream.dst_ptr - buffer) |
| 122 | + stream.dst_ptr = buffer |
| 123 | + stream.dst_size = bufferSize |
| 124 | + |
| 125 | + if flags == 0 && stream.src_size == 0 { // part of the lzfse bugfix above |
| 126 | + flags = Int32(COMPRESSION_STREAM_FINALIZE.rawValue) |
| 127 | + } |
| 128 | + |
| 129 | + case COMPRESSION_STATUS_END: |
| 130 | + result.append(buffer, count: stream.dst_ptr - buffer) |
| 131 | + return result |
| 132 | + |
| 133 | + default: |
| 134 | + return nil |
| 135 | + } |
| 136 | + } |
| 137 | + } |
| 138 | +} |
| 139 | + |
| 140 | +/// Struct based type representing a Crc32 checksum. |
| 141 | +public struct Crc32: CustomStringConvertible { |
| 142 | + private static let zLibCrc32: ZLibCrc32FuncPtr? = loadCrc32fromZLib() |
| 143 | + |
| 144 | + public init() {} |
| 145 | + |
| 146 | + // C convention function pointer type matching the signature of `libz::crc32` |
| 147 | + private typealias ZLibCrc32FuncPtr = @convention(c) ( |
| 148 | + _ cks: UInt32, |
| 149 | + _ buf: UnsafePointer<UInt8>, |
| 150 | + _ len: UInt32 |
| 151 | + ) -> UInt32 |
| 152 | + |
| 153 | + /// Raw checksum. Updated after a every call to `advance(withChunk:)` |
| 154 | + public var checksum: UInt32 = 0 |
| 155 | + |
| 156 | + /// Advance the current checksum with a chunk of data. Designed t be called multiple times. |
| 157 | + /// - parameter chunk: data to advance the checksum |
| 158 | + public mutating func advance(withChunk chunk: Data) |
| 159 | + { |
| 160 | + if let fastCrc32 = Crc32.zLibCrc32 { |
| 161 | + checksum = chunk.withUnsafeBytes({ (ptr: UnsafePointer<UInt8>) -> UInt32 in |
| 162 | + return fastCrc32(checksum, ptr, UInt32(chunk.count)) |
| 163 | + }) |
| 164 | + } |
| 165 | + else { |
| 166 | + checksum = slowCrc32(start: checksum, data: chunk) |
| 167 | + } |
| 168 | + } |
| 169 | + |
| 170 | + /// Formatted checksum. |
| 171 | + public var description: String |
| 172 | + { |
| 173 | + return String(format: "%08x", checksum) |
| 174 | + } |
| 175 | + |
| 176 | + /// Load `crc32()` from '/usr/lib/libz.dylib' if libz is installed. |
| 177 | + /// - returns: A function pointer to crc32() of zlib or nil if zlib can't be found |
| 178 | + private static func loadCrc32fromZLib() -> ZLibCrc32FuncPtr? |
| 179 | + { |
| 180 | + guard let libz = dlopen("/usr/lib/libz.dylib", RTLD_NOW) else { return nil } |
| 181 | + guard let fptr = dlsym(libz, "crc32") else { return nil } |
| 182 | + return unsafeBitCast(fptr, to: ZLibCrc32FuncPtr.self) |
| 183 | + } |
| 184 | + |
| 185 | + /// Rudimentary fallback implementation of the crc32 checksum. This is only a backup used |
| 186 | + /// when zlib can't be found under '/usr/lib/libz.dylib'. |
| 187 | + /// - returns: crc32 checksum (4 byte) |
| 188 | + private func slowCrc32(start: UInt32, data: Data) -> UInt32 |
| 189 | + { |
| 190 | + return ~data.reduce(~start) { (crc: UInt32, next: UInt8) -> UInt32 in |
| 191 | + let tableOffset = (crc ^ UInt32(next)) & 0xff |
| 192 | + return lookUpTable[Int(tableOffset)] ^ crc >> 8 |
| 193 | + } |
| 194 | + } |
| 195 | + |
| 196 | + /// Lookup table for faster crc32 calculation. |
| 197 | + /// table source: http://web.mit.edu/freebsd/head/sys/libkern/crc32.c |
| 198 | + private let lookUpTable: [UInt32] = [ |
| 199 | + 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, |
| 200 | + 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, |
| 201 | + 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, |
| 202 | + 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5, |
| 203 | + 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, |
| 204 | + 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, |
| 205 | + 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f, |
| 206 | + 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, |
| 207 | + 0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, |
| 208 | + 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, |
| 209 | + 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, |
| 210 | + 0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, |
| 211 | + 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, |
| 212 | + 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, |
| 213 | + 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, |
| 214 | + 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, |
| 215 | + 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, |
| 216 | + 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, |
| 217 | + 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7, |
| 218 | + 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, |
| 219 | + 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, |
| 220 | + 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79, |
| 221 | + 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, |
| 222 | + 0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, |
| 223 | + 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, |
| 224 | + 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, |
| 225 | + 0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, |
| 226 | + 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, |
| 227 | + 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, |
| 228 | + 0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, |
| 229 | + 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf, |
| 230 | + 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d, |
| 231 | + ] |
| 232 | +} |
| 233 | + |
| 234 | +#endif |
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