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mustyantsevsujankota
mustyantsev
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sujankota
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feat(PLAT-3087): zip reader-writer (#23)
Implement reading zip (tdf) file from the end --------- Co-authored-by: sujankota <sreddy@virtru.com>
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‎sdk/pom.xml‎

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<version>5.0.0-alpha.14</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>junit</groupId>
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<artifactId>junit</artifactId>
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<version>4.13.1</version>
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<scope>test</scope>
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</dependency>
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</dependencies>
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</project>

‎sdk/src/main/java/io/opentdf/platform/sdk/ZipReader.java‎

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package io.opentdf.platform.sdk;
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import java.nio.ByteBuffer;
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import java.nio.ByteOrder;
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import java.nio.charset.StandardCharsets;
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public class ZipReader {
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private static final int END_OF_CENTRAL_DIRECTORY_SIGNATURE = 0x06054b50;
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private static final int ZIP64_END_OF_CENTRAL_DIRECTORY_SIGNATURE = 0x06064b50;
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private static final int ZIP64_END_OF_CENTRAL_DIRECTORY_LOCATOR_SIGNATURE = 0x07064b50;
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private static final int CENTRAL_DIRECTORY_LOCATOR_SIGNATURE = 0x02014b50;
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private static final int LOCAL_FILE_HEADER_SIGNATURE = 0x04034b50;
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private static final int ZIP64_MAGICVAL = 0xFFFFFFFF;
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private static final int ZIP64_EXTID= 0x0001;
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private int numEntries;
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private short fileNameLength;
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private short extraFieldLength;
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private long offsetToStartOfCentralDirectory;
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private long relativeOffsetEndOfZip64EndOfCentralDirectory;
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public void readEndOfCentralDirectory(ByteBuffer buffer) throws Exception {
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buffer.order(ByteOrder.LITTLE_ENDIAN);
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long fileSize = buffer.capacity();
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long pointer = fileSize - 22; // 22 is the minimum size of the EOCDR
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// Search for the EOCDR from the end of the file
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while (pointer >= 0) {
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buffer.position((int)pointer);
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int signature = buffer.getInt();
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if (signature == END_OF_CENTRAL_DIRECTORY_SIGNATURE) {
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System.out.println("Found End of Central Directory Record");
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break;
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}
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pointer--;
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}
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if (pointer < 0) {
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throw new Exception("Invalid tdf file");
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}
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// Read the EOCDR
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short diskNumber = buffer.getShort();
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short centralDirectoryDiskNumber = buffer.getShort();
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short numEntriesThisDisk = buffer.getShort();
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numEntries = buffer.getShort();
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int centralDirectorySize = buffer.getInt();
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offsetToStartOfCentralDirectory = buffer.getInt();
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short commentLength = buffer.getShort();
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// buffer's position at the start of the Central Directory
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boolean isZip64 = false;
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if (offsetToStartOfCentralDirectory != ZIP64_MAGICVAL) {
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//buffer.position((int)offsetToStartOfCentralDirectory);
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} else {
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isZip64 = true;
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long index = fileSize - (22+ 20); // 22 is the size of the EOCDR and 20 is the size of the Zip64 EOCDR
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buffer.position((int)index);
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readZip64EndOfCentralDirectoryLocator(buffer);
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index = fileSize - (22 + 20 + 56); // 56 is the size of the Zip64 EOCDR
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buffer.position((int)index);
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readZip64EndOfCentralDirectoryRecord(buffer);
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//buffer.position((int)offsetToStartOfCentralDirectory);
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}
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// buffer.position(centralDirectoryOffset);
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}
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private void readZip64EndOfCentralDirectoryLocator(ByteBuffer buffer) {
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int signature = buffer.getInt() ;
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if (signature != ZIP64_END_OF_CENTRAL_DIRECTORY_LOCATOR_SIGNATURE) {
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throw new RuntimeException("Invalid Zip64 End of Central Directory Record Signature");
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}
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int numberOfDiskWithZip64End = buffer.getInt();
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relativeOffsetEndOfZip64EndOfCentralDirectory = buffer.getLong();
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int totalNumberOfDisks = buffer.getInt();
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}
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private void readZip64EndOfCentralDirectoryRecord(ByteBuffer buffer) {
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int signature = buffer.getInt() ;
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if (signature != ZIP64_END_OF_CENTRAL_DIRECTORY_SIGNATURE) {
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throw new RuntimeException("Invalid Zip64 End of Central Directory Record ");
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}
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long sizeOfZip64EndOfCentralDirectoryRecord = buffer.getLong();
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short versionMadeBy = buffer.getShort();
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short versionNeededToExtract = buffer.getShort();
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int diskNumber = buffer.getInt();
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int diskWithCentralDirectory = buffer.getInt();
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long numEntriesOnThisDisk = buffer.getLong();
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numEntries = (int)buffer.getLong();
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long centralDirectorySize = buffer.getLong();
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offsetToStartOfCentralDirectory = buffer.getLong();
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}
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public int getNumEntries() {
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return numEntries;
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}
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public short getFileNameLength() {
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return fileNameLength;
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}
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public short getExtraFieldLength() {
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return extraFieldLength;
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}
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public long getCDOffset() {
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return offsetToStartOfCentralDirectory;
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}
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public long readCentralDirectoryFileHeader(ByteBuffer buffer) {
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System.out.println("Buffer position: " + buffer.position());
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int signature = buffer.getInt();
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if (signature != CENTRAL_DIRECTORY_LOCATOR_SIGNATURE) {
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throw new RuntimeException("Invalid Central Directory File Header Signature");
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}
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short versionMadeBy = buffer.getShort();
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short versionNeededToExtract = buffer.getShort();
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short generalPurposeBitFlag = buffer.getShort();
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short compressionMethod = buffer.getShort();
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short lastModFileTime = buffer.getShort();
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short lastModFileDate = buffer.getShort();
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int crc32 = buffer.getInt();
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int compressedSize = buffer.getInt();
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int uncompressedSize = buffer.getInt();
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fileNameLength = buffer.getShort();
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extraFieldLength = buffer.getShort();
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short fileCommentLength = buffer.getShort();
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short diskNumberStart = buffer.getShort();
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short internalFileAttributes = buffer.getShort();
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int externalFileAttributes = buffer.getInt();
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long relativeOffsetOfLocalHeader = buffer.getInt() ;
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byte[] fileName = new byte[fileNameLength];
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buffer.get(fileName);
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String fileNameString = new String(fileName, StandardCharsets.UTF_8);
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////
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if (compressedSize == ZIP64_MAGICVAL || uncompressedSize == ZIP64_MAGICVAL || relativeOffsetOfLocalHeader == ZIP64_MAGICVAL) {
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// Parse the extra field
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for (int i = 0; i < extraFieldLength; ) {
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int headerId = buffer.getShort();
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int dataSize = buffer.getShort();
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i += 4;
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if (headerId == ZIP64_EXTID) {
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if (compressedSize == ZIP64_MAGICVAL) {
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compressedSize = (int)buffer.getLong();
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i += 8;
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}
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if (uncompressedSize == ZIP64_MAGICVAL) {
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uncompressedSize = (int)buffer.getLong();
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i += 8;
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}
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if (relativeOffsetOfLocalHeader == ZIP64_MAGICVAL) {
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relativeOffsetOfLocalHeader = buffer.getLong();
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i += 8;
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}
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} else {
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// Skip other extra fields
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buffer.position(buffer.position() + dataSize);
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i += dataSize;
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}
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}
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}
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////
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byte[] extraField = new byte[extraFieldLength];
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buffer.get(extraField);
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byte[] fileComment = new byte[fileCommentLength];
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buffer.get(fileComment);
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String fileCommentString = new String(fileComment, StandardCharsets.UTF_8);
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return relativeOffsetOfLocalHeader;
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}
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public void readLocalFileHeader(ByteBuffer buffer) {
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int signature = buffer.getInt();
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if (signature != LOCAL_FILE_HEADER_SIGNATURE) {
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throw new RuntimeException("Invalid Local File Header Signature");
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}
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short versionNeededToExtract = buffer.getShort();
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short generalPurposeBitFlag = buffer.getShort();
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short compressionMethod = buffer.getShort();
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short lastModFileTime = buffer.getShort();
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short lastModFileDate = buffer.getShort();
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int crc32 = buffer.getInt();
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int compressedSize = buffer.getInt();
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int uncompressedSize = buffer.getInt();
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short fileNameLength = buffer.getShort();
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short extraFieldLength = buffer.getShort();
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byte[] fileName = new byte[fileNameLength];
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buffer.get(fileName);
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String fileNameString = new String(fileName, StandardCharsets.UTF_8);
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System.out.println("File name: " + fileNameString);
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byte[] extraField = new byte[extraFieldLength];
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buffer.get(extraField);
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/*byte[] fileData = new byte[compressedSize];
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buffer.get(fileData);
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if (compressionMethod == 0) {
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String fileContent = new String(fileData, StandardCharsets.UTF_8);
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System.out.println("File content: " + fileContent);
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} else {
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System.out.println("File is compressed, need to decompress it first");
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}*/
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}
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}

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