Now can download .pack.xz file for Forge library.

HMCLAPI/src/main/java/org/tukaani/xz/BlockOutputStream.java

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+/*
+ * BlockOutputStream
+ *
+ * Author: Lasse Collin <lasse.collin@tukaani.org>
+ *
+ * This file has been put into the public domain.
+ * You can do whatever you want with this file.
+ */
+
+package org.tukaani.xz;
+
+import java.io.OutputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import org.tukaani.xz.common.EncoderUtil;
+import org.tukaani.xz.check.Check;
+
+class BlockOutputStream extends FinishableOutputStream {
+    private final OutputStream out;
+    private final CountingOutputStream outCounted;
+    private FinishableOutputStream filterChain;
+    private final Check check;
+
+    private final int headerSize;
+    private final long compressedSizeLimit;
+    private long uncompressedSize = 0;
+
+    private final byte[] tempBuf = new byte[1];
+
+    public BlockOutputStream(OutputStream out, FilterEncoder[] filters,
+                             Check check) throws IOException {
+        this.out = out;
+        this.check = check;
+
+        // Initialize the filter chain.
+        outCounted = new CountingOutputStream(out);
+        filterChain = outCounted;
+        for (int i = filters.length - 1; i >= 0; --i)
+            filterChain = filters[i].getOutputStream(filterChain);
+
+        // Prepare to encode the Block Header field.
+        ByteArrayOutputStream bufStream = new ByteArrayOutputStream();
+
+        // Write a dummy Block Header Size field. The real value is written
+        // once everything else except CRC32 has been written.
+        bufStream.write(0x00);
+
+        // Write Block Flags. Storing Compressed Size or Uncompressed Size
+        // isn't supported for now.
+        bufStream.write(filters.length - 1);
+
+        // List of Filter Flags
+        for (int i = 0; i < filters.length; ++i) {
+            EncoderUtil.encodeVLI(bufStream, filters[i].getFilterID());
+            byte[] filterProps = filters[i].getFilterProps();
+            EncoderUtil.encodeVLI(bufStream, filterProps.length);
+            bufStream.write(filterProps);
+        }
+
+        // Header Padding
+        while ((bufStream.size() & 3) != 0)
+            bufStream.write(0x00);
+
+        byte[] buf = bufStream.toByteArray();
+
+        // Total size of the Block Header: Take the size of the CRC32 field
+        // into account.
+        headerSize = buf.length + 4;
+
+        // This is just a sanity check.
+        if (headerSize > EncoderUtil.BLOCK_HEADER_SIZE_MAX)
+            throw new UnsupportedOptionsException();
+
+        // Block Header Size
+        buf[0] = (byte)(buf.length / 4);
+
+        // Write the Block Header field to the output stream.
+        out.write(buf);
+        EncoderUtil.writeCRC32(out, buf);
+
+        // Calculate the maximum allowed size of the Compressed Data field.
+        // It is hard to exceed it so this is mostly to be pedantic.
+        compressedSizeLimit = (EncoderUtil.VLI_MAX & ~3)
+                              - headerSize - check.getSize();
+    }
+
+    public void write(int b) throws IOException {
+        tempBuf[0] = (byte)b;
+        write(tempBuf, 0, 1);
+    }
+
+    public void write(byte[] buf, int off, int len) throws IOException {
+        filterChain.write(buf, off, len);
+        check.update(buf, off, len);
+        uncompressedSize += len;
+        validate();
+    }
+
+    public void flush() throws IOException {
+        filterChain.flush();
+        validate();
+    }
+
+    public void finish() throws IOException {
+        // Finish the Compressed Data field.
+        filterChain.finish();
+        validate();
+
+        // Block Padding
+        for (long i = outCounted.getSize(); (i & 3) != 0; ++i)
+            out.write(0x00);
+
+        // Check
+        out.write(check.finish());
+    }
+
+    private void validate() throws IOException {
+        long compressedSize = outCounted.getSize();
+
+        // It is very hard to trigger this exception.
+        // This is just to be pedantic.
+        if (compressedSize < 0 || compressedSize > compressedSizeLimit
+                || uncompressedSize < 0)
+            throw new XZIOException("XZ Stream has grown too big");
+    }
+
+    public long getUnpaddedSize() {
+        return headerSize + outCounted.getSize() + check.getSize();
+    }
+
+    public long getUncompressedSize() {
+        return uncompressedSize;
+    }
+}