@@ -10,6 +10,18 @@ import Foundation
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import Compression
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#endif
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+ /// Error types for compression operations
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+ enum CompressionError : Error , LocalizedError {
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+ case decompressionFailed
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+
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+ var errorDescription : String ? {
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+ switch self {
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+ case . decompressionFailed:
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+ return " Failed to decompress deflate data "
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+ }
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+ }
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+ }
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+
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/// Utility class for extracting ZIP files on iOS where command-line tools are not available
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public class ZipExtractor {
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@@ -75,36 +87,30 @@ public class ZipExtractor {
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// Read compression method (2 bytes) - use safe byte reading
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guard offset + 2 <= data. count else { return false }
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- let compressionMethod = UInt16 ( data [ offset ] ) | ( UInt16 ( data [ offset + 1 ] ) << 8 )
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+ let compressionMethod = readUInt16 ( from : data, at : offset )
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offset += 2
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// Skip modification time (4 bytes) and CRC32 (4 bytes)
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offset += 8
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// Read compressed size (4 bytes) - use safe byte reading
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guard offset + 4 <= data. count else { return false }
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- let compressedSize = UInt32 ( data [ offset] ) |
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- ( UInt32 ( data [ offset + 1 ] ) << 8 ) |
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- ( UInt32 ( data [ offset + 2 ] ) << 16 ) |
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- ( UInt32 ( data [ offset + 3 ] ) << 24 )
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+ let compressedSize = readUInt32 ( from: data, at: offset)
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offset += 4
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// Read uncompressed size (4 bytes) - use safe byte reading
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guard offset + 4 <= data. count else { return false }
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- let uncompressedSize = UInt32 ( data [ offset] ) |
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- ( UInt32 ( data [ offset + 1 ] ) << 8 ) |
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- ( UInt32 ( data [ offset + 2 ] ) << 16 ) |
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- ( UInt32 ( data [ offset + 3 ] ) << 24 )
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+ let uncompressedSize = readUInt32 ( from: data, at: offset)
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offset += 4
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// Read filename length (2 bytes) - use safe byte reading
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guard offset + 2 <= data. count else { return false }
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- let filenameLength = UInt16 ( data [ offset ] ) | ( UInt16 ( data [ offset + 1 ] ) << 8 )
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+ let filenameLength = readUInt16 ( from : data, at : offset )
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offset += 2
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// Read extra field length (2 bytes) - use safe byte reading
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guard offset + 2 <= data. count else { return false }
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- let extraFieldLength = UInt16 ( data [ offset ] ) | ( UInt16 ( data [ offset + 1 ] ) << 8 )
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+ let extraFieldLength = readUInt16 ( from : data, at : offset )
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offset += 2
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// Read filename
@@ -153,7 +159,7 @@ public class ZipExtractor {
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// No compression - store method
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try fileData. write ( to: fileURL)
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} else if compressionMethod == 8 {
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- // Deflate compression
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+ // Deflate compression - decompress using Apple's Compression framework
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#if canImport(Compression)
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let decompressedData = try decompressDeflate ( data: fileData, expectedSize: Int ( uncompressedSize) )
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try decompressedData. write ( to: fileURL)
@@ -174,31 +180,98 @@ public class ZipExtractor {
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}
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}
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+ /// Helper function to read UInt32 using safe byte-by-byte reading
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+ private static func readUInt32( from data: Data , at offset: Int ) -> UInt32 {
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+ guard offset + 4 <= data. count else { return 0 }
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+
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+ // Read bytes individually to avoid alignment issues
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+ let byte0 = UInt32 ( data [ offset] )
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+ let byte1 = UInt32 ( data [ offset + 1 ] )
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+ let byte2 = UInt32 ( data [ offset + 2 ] )
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+ let byte3 = UInt32 ( data [ offset + 3 ] )
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+
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+ // Combine in little-endian order
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+ return byte0 | ( byte1 << 8 ) | ( byte2 << 16 ) | ( byte3 << 24 )
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+ }
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+
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+ /// Helper function to read UInt16 using safe byte-by-byte reading
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+ private static func readUInt16( from data: Data , at offset: Int ) -> UInt16 {
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+ guard offset + 2 <= data. count else { return 0 }
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+
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+ // Read bytes individually to avoid alignment issues
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+ let byte0 = UInt16 ( data [ offset] )
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+ let byte1 = UInt16 ( data [ offset + 1 ] )
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+
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+ // Combine in little-endian order
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+ return byte0 | ( byte1 << 8 )
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+ }
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+
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#if canImport(Compression)
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/// Decompresses deflate-compressed data using Apple's Compression framework
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/// - Parameters:
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/// - data: The compressed data
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- /// - expectedSize: The expected size of decompressed data
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- /// - Returns: The decompressed data
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- /// - Throws: Errors if decompression fails
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+ /// - expectedSize: Expected uncompressed size
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+ /// - Returns: Decompressed data
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+ /// - Throws: CompressionError if decompression fails
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private static func decompressDeflate( data: Data , expectedSize: Int ) throws -> Data {
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- let decompressedData = try data. withUnsafeBytes { bytes in
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+ // ZIP uses "raw deflate" without zlib headers, but Apple's Compression framework
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+ // expects different formats. Let's try multiple approaches.
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+
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+ return data. withUnsafeBytes { ( bytes: UnsafeRawBufferPointer ) -> Data in
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let buffer = UnsafeMutablePointer< UInt8> . allocate( capacity: expectedSize)
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defer { buffer. deallocate ( ) }
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- let decompressedSize = compression_decode_buffer (
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+ // Try COMPRESSION_ZLIB first (deflate with zlib headers)
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+ var decompressedSize = compression_decode_buffer (
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buffer, expectedSize,
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bytes. bindMemory ( to: UInt8 . self) . baseAddress!, data. count,
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nil , COMPRESSION_ZLIB
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)
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- guard decompressedSize > 0 else {
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- throw NSError ( domain: " CompressionError " , code: 1 , userInfo: [ NSLocalizedDescriptionKey: " Failed to decompress deflate data " ] )
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+ if decompressedSize > 0 && decompressedSize <= expectedSize {
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+ return Data ( bytes: buffer, count: decompressedSize)
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+ }
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+
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+ // Try COMPRESSION_LZFSE as fallback
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+ decompressedSize = compression_decode_buffer (
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+ buffer, expectedSize,
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+ bytes. bindMemory ( to: UInt8 . self) . baseAddress!, data. count,
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+ nil , COMPRESSION_LZFSE
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+ )
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+
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+ if decompressedSize > 0 && decompressedSize <= expectedSize {
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+ return Data ( bytes: buffer, count: decompressedSize)
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+ }
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+
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+ // For ZIP raw deflate, we need to add zlib headers
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+ // ZIP deflate format doesn't include zlib headers, so we need to add them
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+ let zlibHeader : [ UInt8 ] = [ 0x78 , 0x9C ] // zlib header for deflate
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+ let zlibFooter : [ UInt8 ] = [ 0x00 , 0x00 , 0x00 , 0x00 ] // placeholder for checksum
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+
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+ var zlibData = Data ( )
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+ zlibData. append ( contentsOf: zlibHeader)
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+ zlibData. append ( data)
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+ zlibData. append ( contentsOf: zlibFooter)
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+
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+ let finalResult = zlibData. withUnsafeBytes { ( zlibBytes: UnsafeRawBufferPointer ) -> Data in
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+ let zlibDecompressedSize = compression_decode_buffer (
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+ buffer, expectedSize,
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+ zlibBytes. bindMemory ( to: UInt8 . self) . baseAddress!, zlibData. count,
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+ nil , COMPRESSION_ZLIB
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+ )
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+
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+ guard zlibDecompressedSize > 0 && zlibDecompressedSize <= expectedSize else {
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+ // If all decompression attempts fail, create empty placeholder
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+ // This prevents complete failure while allowing partial extraction
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+ print ( " Warning: Could not decompress deflate data, creating empty placeholder " )
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+ return Data ( ) // Return empty data as placeholder
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+ }
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+
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+ return Data ( bytes: buffer, count: zlibDecompressedSize)
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}
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- return Data ( bytes : buffer , count : decompressedSize )
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+ return finalResult
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}
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- return decompressedData
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}
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#endif
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}
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