Merge pull request #11 from Col-E/feature/lazy

Lazy reading in LocalFileHeader/CentralDirectoryFileHeader

Author: Col-E

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>software.coley</groupId>
     <artifactId>lljzip</artifactId>
-    <version>1.4.0</version>
+    <version>1.5.0</version>
 
     <name>LL Java ZIP</name>
     <description>Lower level ZIP support for Java</description>
@@ -95,6 +95,11 @@
                     <target>1.8</target>
                 </configuration>
             </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>2.22.2</version>
+            </plugin>
         </plugins>
     </build>
 

src/main/java/software/coley/llzip/ZipIO.java

@@ -1,9 +1,12 @@
 package software.coley.llzip;
 
+import software.coley.llzip.format.model.CentralDirectoryFileHeader;
+import software.coley.llzip.format.model.EndOfCentralDirectory;
+import software.coley.llzip.format.model.ZipArchive;
 import software.coley.llzip.format.read.ForwardScanZipReaderStrategy;
 import software.coley.llzip.format.read.JvmZipReaderStrategy;
+import software.coley.llzip.format.read.NaiveLocalFileZipReaderStrategy;
 import software.coley.llzip.format.read.ZipReaderStrategy;
-import software.coley.llzip.format.model.ZipArchive;
 import software.coley.llzip.util.BufferData;
 import software.coley.llzip.util.ByteData;
 import software.coley.llzip.util.FileMapUtil;
@@ -15,6 +18,11 @@
 
 /**
  * IO wrappers for reading {@link ZipArchive} contents.
+ * <ul>
+ *     <li>For JAR files or anything intended to be read by the JVM use the JVM operations which use {@link JvmZipReaderStrategy}.</li>
+ *     <li>For regular ZIP files use {@link ForwardScanZipReaderStrategy}.</li>
+ *     <li>For ZIP files without {@link CentralDirectoryFileHeader} or {@link EndOfCentralDirectory} items, use {@link NaiveLocalFileZipReaderStrategy}</li>
+ * </ul>
  *
  * @author Matt Coley
  */
@@ -64,6 +72,51 @@ public static ZipArchive readStandard(Path data) throws IOException {
 		return read(data, new ForwardScanZipReaderStrategy());
 	}
 
+	/**
+	 * Creates an archive using the {@link NaiveLocalFileZipReaderStrategy}.
+	 *
+	 * @param data
+	 * 		Zip bytes.
+	 *
+	 * @return Archive from bytes.
+	 *
+	 * @throws IOException
+	 * 		When the archive bytes cannot be read from, usually indicating a malformed zip.
+	 */
+	public static ZipArchive readNaive(ByteData data) throws IOException {
+		return read(data, new NaiveLocalFileZipReaderStrategy());
+	}
+
+	/**
+	 * Creates an archive using the {@link NaiveLocalFileZipReaderStrategy}.
+	 *
+	 * @param data
+	 * 		Zip bytes.
+	 *
+	 * @return Archive from bytes.
+	 *
+	 * @throws IOException
+	 * 		When the archive bytes cannot be read from, usually indicating a malformed zip.
+	 */
+	public static ZipArchive readNaive(byte[] data) throws IOException {
+		return read(data, new NaiveLocalFileZipReaderStrategy());
+	}
+
+	/**
+	 * Creates an archive using the {@link NaiveLocalFileZipReaderStrategy}.
+	 *
+	 * @param data
+	 * 		Zip path.
+	 *
+	 * @return Archive from bytes.
+	 *
+	 * @throws IOException
+	 * 		When the archive bytes cannot be read from, usually indicating a malformed zip.
+	 */
+	public static ZipArchive readNaive(Path data) throws IOException {
+		return read(data, new NaiveLocalFileZipReaderStrategy());
+	}
+
 	/**
 	 * Creates an archive using the {@link JvmZipReaderStrategy} which handles some edge cases not usually
 	 * expected from zip files.
@@ -127,6 +180,7 @@ public static ZipArchive read(ByteData data, ZipReaderStrategy strategy) throws
 		if (data == null)
 			throw new IOException("Data is null!");
 		// The fixed size elements of a CDFH is 22 bytes (plus the variable size bits which can be 0)
+		// - Even if we only want to read local/central file entries, those are even larger at a minimum
 		if (data.length() < 22)
 			throw new IOException("Not enough bytes to read Central-Directory-File-Header, minimum=22");
 		// Create instance

src/main/java/software/coley/llzip/format/ZipPatterns.java

@@ -15,16 +15,32 @@ public interface ZipPatterns {
 	 * Any PK header match.
 	 */
 	int[] PK = {0x50, 0x4B};
+	/**
+	 * Any PK header match, as a {@code u2/word/short}
+	 */
+	int PK_WORD = 0x4B_50;
 	/**
 	 * Header for {@link LocalFileHeader}.
 	 */
 	int[] LOCAL_FILE_HEADER = {0x50, 0x4B, 0x03, 0x04};
+	/**
+	 * Header for {@link LocalFileHeader}, as a {@code s4/quad/int}
+	 */
+	int LOCAL_FILE_HEADER_QUAD = 0x04_03_4B_50;
 	/**
 	 * Header for {@link CentralDirectoryFileHeader}.
 	 */
 	int[] CENTRAL_DIRECTORY_FILE_HEADER = {0x50, 0x4B, 0x01, 0x02};
+	/**
+	 * Header for {@link CentralDirectoryFileHeader}, as a {@code s4/quad/int}
+	 */
+	int CENTRAL_DIRECTORY_FILE_HEADER_QUAD = 0x02_01_4B_50;
 	/**
 	 * Header for {@link EndOfCentralDirectory}.
 	 */
 	int[] END_OF_CENTRAL_DIRECTORY = {0x50, 0x4B, 0x05, 0x06};
+	/**
+	 * Header for {@link EndOfCentralDirectory}, as a {@code s4/quad/int}
+	 */
+	int END_OF_CENTRAL_DIRECTORY_QUAD = 0x06_05_4B_50;
 }

src/main/java/software/coley/llzip/format/compression/DeflateDecompressor.java

@@ -17,7 +17,7 @@
  */
 public class DeflateDecompressor implements Decompressor {
 	@Override
-	public ByteData decompress(LocalFileHeader header, ByteData bytes) throws IOException {
+	public ByteData decompress(LocalFileHeader header, ByteData data) throws IOException {
 		if (header.getCompressionMethod() != ZipCompressions.DEFLATED)
 			throw new IOException("LocalFileHeader contents not using 'Deflated'!");
 		Inflater inflater = new Inflater(true);
@@ -26,14 +26,14 @@ public ByteData decompress(LocalFileHeader header, ByteData bytes) throws IOExce
 			byte[] output = new byte[1024];
 			byte[] buffer = new byte[1024];
 			long position = 0L;
-			long length = bytes.length();
+			long length = data.length();
 			do {
 				if (inflater.needsInput()) {
 					int remaining = (int) Math.min(buffer.length, length);
 					if (remaining == 0) {
 						break;
 					}
-					bytes.get(position, buffer, 0, remaining);
+					data.get(position, buffer, 0, remaining);
 					length -= remaining;
 					position += remaining;
 					inflater.setInput(buffer, 0, remaining);