forked from openrs2/openrs2
This is closer to the client's implementation, which ignores the gzip header/trailer entirely and just decompresses the inner DEFLATE stream. While Jagex always produce valid gzip files, some cache editors in the private server scene do not set the checksum/length correctly in the trailer. I'm planning to add an option to use the lax gzip implementation to support reading these caches. Signed-off-by: Graham <gpe@openrs2.org>bzip2
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package org.openrs2.compress.cli.gzip |
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import com.github.ajalt.clikt.core.CliktCommand |
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import com.github.ajalt.clikt.parameters.options.option |
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import com.github.ajalt.clikt.parameters.types.defaultStdin |
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import com.github.ajalt.clikt.parameters.types.defaultStdout |
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import com.github.ajalt.clikt.parameters.types.inputStream |
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import com.github.ajalt.clikt.parameters.types.outputStream |
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import org.openrs2.compress.gzip.Gzip |
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public class GunzipLaxCommand : CliktCommand(name = "gunzip-lax") { |
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private val input by option().inputStream().defaultStdin() |
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private val output by option().outputStream(truncateExisting = true).defaultStdout() |
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override fun run() { |
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Gzip.createLaxInputStream(input).use { input -> |
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output.use { output -> |
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input.copyTo(output) |
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} |
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} |
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} |
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} |
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package org.openrs2.compress.gzip |
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import java.io.DataInputStream |
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import java.io.IOException |
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import java.io.InputStream |
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import java.util.zip.Inflater |
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public class GzipLaxInputStream( |
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private val input: InputStream |
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) : InputStream() { |
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private val inflater = Inflater(true) |
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private val buffer = ByteArray(4096) |
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private var checkedTrailer = false |
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init { |
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val dataInput = DataInputStream(input) |
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if (dataInput.readUnsignedShort() != HEADER_MAGIC) { |
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throw IOException("Invalid GZIP header magic") |
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} else if (dataInput.readUnsignedByte() != METHOD_DEFLATE) { |
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throw IOException("Unsupported compression method") |
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} |
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val flags = dataInput.readUnsignedByte() |
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dataInput.skip(6) |
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if ((flags and FLAG_EXTRA) != 0) { |
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dataInput.skip(dataInput.readUnsignedShort().toLong()) |
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} |
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if ((flags and FLAG_NAME) != 0) { |
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while (dataInput.readUnsignedByte() != 0) { |
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// empty |
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} |
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} |
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if ((flags and FLAG_COMMENT) != 0) { |
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while (dataInput.readUnsignedByte() != 0) { |
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// empty |
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} |
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} |
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if ((flags and FLAG_HEADER_CRC) != 0) { |
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dataInput.skip(2) |
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} |
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} |
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override fun read(): Int { |
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val n = read(buffer, 0, 1) |
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return if (n < 0) { |
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-1 |
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} else { |
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buffer[0].toInt() and 0xFF |
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} |
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} |
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override fun read(b: ByteArray, off: Int, len: Int): Int { |
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while (true) { |
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val n = inflater.inflate(b, off, len) |
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if (n != 0) { |
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return n |
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} |
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when { |
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inflater.finished() -> { |
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checkTrailer() |
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return -1 |
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} |
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inflater.needsInput() -> fill() |
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inflater.needsDictionary() -> throw IOException("Dictionaries not supported") |
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} |
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} |
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} |
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override fun close() { |
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inflater.end() |
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input.close() |
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} |
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private fun fill() { |
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val n = input.read(buffer, 0, buffer.size) |
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if (n < 0) { |
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throw IOException("Compressed data truncated") |
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} |
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inflater.setInput(buffer, 0, n) |
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} |
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private fun checkTrailer() { |
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if (checkedTrailer) { |
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return |
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} |
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checkedTrailer = true |
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var len = TRAILER_LEN |
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len -= inflater.remaining |
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if (len < 0) { |
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throw IOException("Compressed data overflow") |
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} else if (input.skip(len) != len) { |
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throw IOException("GZIP trailer missing") |
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} |
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} |
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private companion object { |
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private const val HEADER_MAGIC = 0x1F8B |
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private const val METHOD_DEFLATE = 8 |
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private const val FLAG_HEADER_CRC = 0x2 |
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private const val FLAG_EXTRA = 0x4 |
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private const val FLAG_NAME = 0x8 |
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private const val FLAG_COMMENT = 0x10 |
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private const val TRAILER_LEN = 8L |
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} |
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} |
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