fixed SliceInputStream

src/org/geometerplus/zlibrary/core/util/InputStreamWithOffset.java

@@ -41,12 +41,22 @@ public class InputStreamWithOffset extends InputStream {
 		if (shift > 0) {
 			myOffset += (int)shift;
 		}
-		while ((shift < n) && (read() != -1)) {
+		while (shift < n && read() != -1) {
 			++shift;
 		}
 		return shift;
 	}
 
+	// does not call virtual methods
+	protected final long baseSkip(long n) throws IOException {
+		long shift = myDecoratedStream.skip(n);
+		while (shift < n && myDecoratedStream.read() != -1) {
+			++shift;
+		}
+		myOffset += shift;
+		return shift;
+	}
+
 	@Override
 	public int read() throws IOException {
 		int result = myDecoratedStream.read();

src/org/geometerplus/zlibrary/core/util/SliceInputStream.java

@@ -25,36 +25,29 @@ import java.io.InputStream;
 public class SliceInputStream extends InputStreamWithOffset {
 	private final int myStart;
 	private final int myLength;
-	private boolean myCreated = false;
 
 	public SliceInputStream(InputStream base, int start, int length) throws IOException {
 		super(base);
-		super.skip(start);
+		baseSkip(start);
 		myStart = start;
 		myLength = length;
-		myCreated = true;
 	}
 
 	@Override
 	public int read() throws IOException {
-		if (myCreated) {
-			if (offset() >= myLength) {
-				return -1;
-			}
+		if (offset() >= myLength) {
+			return -1;
 		}
 		return super.read();
 	}
 
 	@Override
 	public int read(byte[] b, int off, int len) throws IOException {
-		if (myCreated) {
-			int maxbytes = myLength - offset();
-			if (maxbytes <= 0) {
-				return -1;
-			}
-			len = Math.min(len, maxbytes);
+		final int maxbytes = myLength - offset();
+		if (maxbytes <= 0) {
+			return -1;
 		}
-		return super.read(b, off, len);
+		return super.read(b, off, Math.min(len, maxbytes));
 	}
 
 	@Override