mirror of
https://github.com/tsolomko/SWCompression.git
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Timofey Solomko
48 lines
1.7 KiB
Swift
48 lines
1.7 KiB
Swift
// Copyright (c) 2021 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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import BitByteData
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/**
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The purpose of this struct is to accompany `ZipEntryInfo` instances while processing a `ZipContainer` and to store
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information which is necessary for reading entry's data later.
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*/
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struct ZipEntryInfoHelper {
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let entryInfo: ZipEntryInfo
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let hasDataDescriptor: Bool
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let zip64FieldsArePresent: Bool
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let nextCdEntryOffset: Int
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let dataOffset: Int
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let compSize: UInt64
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let uncompSize: UInt64
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init(_ byteReader: LittleEndianByteReader, _ currentDiskNumber: UInt32) throws {
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// Read Central Directory entry.
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let cdEntry = try ZipCentralDirectoryEntry(byteReader)
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// Move to the location of Local Header.
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byteReader.offset = cdEntry.localHeaderOffset.toInt()
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// Read Local Header.
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let localHeader = try ZipLocalHeader(byteReader)
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try localHeader.validate(with: cdEntry, currentDiskNumber)
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// If file has data descriptor, then some properties are only present in CD entry.
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self.hasDataDescriptor = localHeader.generalPurposeBitFlags & 0x08 != 0
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self.entryInfo = ZipEntryInfo(byteReader, cdEntry, localHeader, hasDataDescriptor)
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// Save some properties from CD entry and Local Header.
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self.zip64FieldsArePresent = localHeader.zip64FieldsArePresent
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self.nextCdEntryOffset = cdEntry.nextEntryOffset
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self.dataOffset = localHeader.dataOffset
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self.compSize = hasDataDescriptor ? cdEntry.compSize : localHeader.compSize
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self.uncompSize = hasDataDescriptor ? cdEntry.uncompSize : localHeader.uncompSize
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}
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}
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