Merge pull request #15 from NeRdTheNed/master

Add copy zip writer strategy

Author: Col-E

.gitignore

@@ -1,2 +1,5 @@
 target/
-.idea/
+.idea/
+
+# macOS junk files
+.DS_Store

src/main/java/software/coley/llzip/format/model/JvmLocalFileHeader.java

@@ -44,7 +44,7 @@ public void read(ByteData data, long offset) {
 			// Valid data range found, map back to (localOffset, range)
 			fileData = readLongSlice(data,
 					new LazyLong(() -> dataOffsetStart - offset),
-					new LazyLong(() -> dataOffsetEnd - offset));
+					new LazyLong(() -> dataOffsetEnd - dataOffsetStart));
 			foundData = true;
 		} else {
 			// Keep data reference to attempt restoration with later when linking to the CEN.

src/main/java/software/coley/llzip/format/write/CopyZipWriterStrategy.java

@@ -0,0 +1,90 @@
+package software.coley.llzip.format.write;
+
+import software.coley.llzip.format.ZipPatterns;
+import software.coley.llzip.format.model.CentralDirectoryFileHeader;
+import software.coley.llzip.format.model.EndOfCentralDirectory;
+import software.coley.llzip.format.model.LocalFileHeader;
+import software.coley.llzip.format.model.ZipArchive;
+import software.coley.llzip.util.ByteDataUtil;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * Manually copies the input zip file.
+ * Data is written as-is, and no validation is performed.
+ *
+ * @author Ned Loynd
+ */
+public class CopyZipWriterStrategy implements ZipWriterStrategy {
+	private static void writeShortLE(OutputStream os, int value) throws IOException {
+		os.write(value & 0xFF);
+		os.write((value >> 8) & 0xFF);
+	}
+
+	private static void writeIntLE(OutputStream os, int value) throws IOException {
+		os.write(value & 0xFF);
+		os.write((value >> 8) & 0xFF);
+		os.write((value >> 16) & 0xFF);
+		os.write((value >> 24) & 0xFF);
+	}
+
+	@Override
+	public void write(ZipArchive archive, OutputStream os) throws IOException {
+		// Write local file headers.
+		for (final LocalFileHeader fileHeader : archive.getLocalFiles()) {
+			writeIntLE(os, ZipPatterns.LOCAL_FILE_HEADER_QUAD);
+			writeShortLE(os, fileHeader.getVersionNeededToExtract());
+			writeShortLE(os, fileHeader.getGeneralPurposeBitFlag());
+			writeShortLE(os, fileHeader.getCompressionMethod());
+			writeShortLE(os, fileHeader.getLastModFileTime());
+			writeShortLE(os, fileHeader.getLastModFileDate());
+			writeIntLE(os, fileHeader.getCrc32());
+			writeIntLE(os, (int) fileHeader.getCompressedSize());
+			writeIntLE(os, (int) fileHeader.getUncompressedSize());
+			writeShortLE(os, fileHeader.getFileNameLength());
+			writeShortLE(os, fileHeader.getExtraFieldLength());
+			os.write(ByteDataUtil.toByteArray(fileHeader.getFileName()));
+			os.write(ByteDataUtil.toByteArray(fileHeader.getExtraField()));
+			os.write(ByteDataUtil.toByteArray(fileHeader.getFileData()));
+		}
+
+		// Write central directory file headers.
+		for (final CentralDirectoryFileHeader directory : archive.getCentralDirectories()) {
+			writeIntLE(os, ZipPatterns.CENTRAL_DIRECTORY_FILE_HEADER_QUAD);
+			writeShortLE(os, directory.getVersionMadeBy());
+			writeShortLE(os, directory.getVersionNeededToExtract());
+			writeShortLE(os, directory.getGeneralPurposeBitFlag());
+			writeShortLE(os, directory.getCompressionMethod());
+			writeShortLE(os, directory.getLastModFileTime());
+			writeShortLE(os, directory.getLastModFileDate());
+			writeIntLE(os, directory.getCrc32());
+			writeIntLE(os, (int) directory.getCompressedSize());
+			writeIntLE(os, (int) directory.getUncompressedSize());
+			writeShortLE(os, directory.getFileNameLength());
+			writeShortLE(os, directory.getExtraFieldLength());
+			writeShortLE(os, directory.getFileCommentLength());
+			writeShortLE(os, directory.getDiskNumberStart());
+			writeShortLE(os, directory.getInternalFileAttributes());
+			writeIntLE(os, directory.getExternalFileAttributes());
+			writeIntLE(os, (int) directory.getRelativeOffsetOfLocalHeader());
+			os.write(ByteDataUtil.toByteArray(directory.getFileName()));
+			os.write(ByteDataUtil.toByteArray(directory.getExtraField()));
+			os.write(ByteDataUtil.toByteArray(directory.getFileComment()));
+		}
+
+		// Write end of central directory record.
+		final EndOfCentralDirectory end = archive.getEnd();
+		if (end != null) {
+			writeIntLE(os, ZipPatterns.END_OF_CENTRAL_DIRECTORY_QUAD);
+			writeShortLE(os, end.getDiskNumber());
+			writeShortLE(os, end.getCentralDirectoryStartDisk());
+			writeShortLE(os, end.getCentralDirectoryStartOffset());
+			writeShortLE(os, end.getNumEntries());
+			writeIntLE(os, (int) end.getCentralDirectorySize());
+			writeIntLE(os, (int) end.getCentralDirectoryOffset());
+			writeShortLE(os, end.getZipCommentLength());
+			os.write(ByteDataUtil.toByteArray(end.getZipComment()));
+		}
+	}
+}