mirror of
https://github.com/tsolomko/SWCompression.git
synced 2026-06-23 14:56:41 +00:00
Timofey Solomko
99 lines
3.3 KiB
Swift
99 lines
3.3 KiB
Swift
// Copyright (c) 2017 Timofey Solomko
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// Licensed under MIT License
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//
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// See LICENSE for license information
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import Foundation
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struct ZipLocalHeader {
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let versionNeeded: UInt16
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let generalPurposeBitFlags: UInt16
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let compressionMethod: UInt16
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let lastModFileTime: UInt16
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let lastModFileDate: UInt16
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let crc32: UInt32
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private(set) var compSize: UInt64
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private(set) var uncompSize: UInt64
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private(set) var zip64FieldsArePresent: Bool = false
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let fileName: String
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private(set) var modificationTimestamp: UInt32?
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private(set) var accessTimestamp: UInt32?
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private(set) var creationTimestamp: UInt32?
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let headerSize: Int
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init(_ pointerData: DataWithPointer) throws {
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// Check signature.
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guard pointerData.uint32() == 0x04034b50
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else { throw ZipError.wrongSignature }
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self.versionNeeded = pointerData.uint16()
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self.generalPurposeBitFlags = pointerData.uint16()
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let useUtf8 = generalPurposeBitFlags & 0x800 != 0
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self.compressionMethod = pointerData.uint16()
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self.lastModFileTime = pointerData.uint16()
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self.lastModFileDate = pointerData.uint16()
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self.crc32 = pointerData.uint32()
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self.compSize = pointerData.uint64(count: 4)
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self.uncompSize = pointerData.uint64(count: 4)
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let fileNameLength = pointerData.uint16().toInt()
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let extraFieldLength = pointerData.uint16().toInt()
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self.headerSize = 30 + fileNameLength + extraFieldLength
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guard let fileName = ZipCommon.getStringField(pointerData, fileNameLength, useUtf8)
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else { throw ZipError.wrongTextField }
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self.fileName = fileName
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let extraFieldStart = pointerData.index
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while pointerData.index - extraFieldStart < extraFieldLength {
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// There are a lot of possible extra fields.
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let headerID = pointerData.uint16()
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let size = pointerData.uint16().toInt()
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switch headerID {
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case 0x0001: // Zip64
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// In local header both uncompressed size and compressed size fields are required.
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self.uncompSize = pointerData.uint64()
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self.compSize = pointerData.uint64()
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self.zip64FieldsArePresent = true
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case 0x5455: // Extended Timestamp
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let flags = pointerData.byte()
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guard flags & 0xF8 == 0 else { break }
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if flags & 0x01 != 0 {
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self.modificationTimestamp = pointerData.uint32()
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}
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if flags & 0x02 != 0 {
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self.accessTimestamp = pointerData.uint32()
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}
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if flags & 0x04 != 0 {
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self.creationTimestamp = pointerData.uint32()
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}
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default:
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pointerData.index += size
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}
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}
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// Let's check headers's values for consistency.
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guard self.versionNeeded & 0xFF <= 63
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else { throw ZipError.wrongVersion }
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guard self.generalPurposeBitFlags & 0x2000 == 0 &&
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self.generalPurposeBitFlags & 0x40 == 0 &&
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self.generalPurposeBitFlags & 0x01 == 0
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else { throw ZipError.encryptionNotSupported }
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guard self.generalPurposeBitFlags & 0x20 == 0
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else { throw ZipError.patchingNotSupported }
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}
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}
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