/*

 * Copyright (c) 2015, 2016 Oracle and/or its affiliates. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 *   - Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 *

 *   - Redistributions in binary form must reproduce the above copyright

 *     notice, this list of conditions and the following disclaimer in the

 *     documentation and/or other materials provided with the distribution.

 *

 *   - Neither the name of Oracle nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#ifndef LIBJIMAGE_IMAGEDECOMPRESSOR_HPP

#define LIBJIMAGE_IMAGEDECOMPRESSOR_HPP

#include <assert.h>

#include <string.h>

#include "imageFile.hpp"

#include "inttypes.hpp"

#include "jni.h"

/*

 * Compressed resources located in image have an header.

 * This header contains:

 * - _magic: A magic u4, required to retrieved the header in the compressed content

 * - _size: The size of the compressed resource.

 * - _uncompressed_size: The uncompressed size of the compressed resource.

 * - _decompressor_name_offset: The ImageDecompressor instance name StringsTable offset.

 * - _decompressor_config_offset: StringsTable offset of configuration that could be needed by

 *   the decompressor in order to decompress.

 * - _is_terminal: 1: the compressed content is terminal. Uncompressing it would

 *   create the actual resource. 0: the compressed content is not terminal. Uncompressing it

 *   will result in a compressed content to be decompressed (This occurs when a stack of compressors

 *   have been used to compress the resource.

 */

struct ResourceHeader {

    /* magic bytes that identifies a compressed resource header*/

    static const u4 resource_header_magic = 0xCAFEFAFA;

    u4 _magic; // Resource header

    u8 _size;    // Resource size

    u8 _uncompressed_size;  // Expected uncompressed size

    u4 _decompressor_name_offset;    // Strings table decompressor offset

    u4 _decompressor_config_offset; // Strings table config offset

    u1 _is_terminal; // Last decompressor 1, otherwise 0.

};

/*

 * Resources located in jimage file can be compressed. Compression occurs at

 * jimage file creation time. When compressed a resource is added an header that

 * contains the name of the compressor that compressed it.

 * Various compression strategies can be applied to compress a resource.

 * The same resource can even be compressed multiple time by a stack of compressors.

 * At runtime, a resource is decompressed in a loop until there is no more header

 * meaning that the resource is equivalent to the not compressed resource.

 * In each iteration, the name of the compressor located in the current header

 * is used to retrieve the associated instance of ImageDecompressor.

 * ImageDecompressor instances are retrieved from a static array in which

 * they are registered.

 */

class ImageDecompressor {

private:

    const char* _name;

    /*

     * Array of concrete decompressors. This array is used to retrieve the decompressor

     * that can handle resource decompression.

     */

    static ImageDecompressor** _decompressors;

    /**

     * Num of decompressors

     */

    static int _decompressors_num;

    /*

     * Identifier of a decompressor. This name is the identification key to retrieve

     * decompressor from a resource header.

     */

    inline const char* get_name() const { return _name; }

    static u8 getU8(u1* ptr, Endian *endian);

    static u4 getU4(u1* ptr, Endian *endian);

protected:

    ImageDecompressor(const char* name) : _name(name) {

    }

    virtual void decompress_resource(u1* data, u1* uncompressed,

        ResourceHeader* header, const ImageStrings* strings) = 0;

public:

    static void image_decompressor_init();

    static void image_decompressor_close();

    static ImageDecompressor* get_decompressor(const char * decompressor_name) ;

    static void decompress_resource(u1* compressed, u1* uncompressed,

        u8 uncompressed_size, const ImageStrings* strings, Endian* _endian);

};

/**

 * Zip decompressor.

 */

class ZipDecompressor : public ImageDecompressor {

public:

    ZipDecompressor(const char* sym) : ImageDecompressor(sym) { }

    void decompress_resource(u1* data, u1* uncompressed, ResourceHeader* header,

        const ImageStrings* strings);

    static jboolean decompress(void *in, u8 inSize, void *out, u8 outSize, char **pmsg);

};

/*

 * Shared Strings decompressor. This decompressor reconstruct the class

 * constant pool UTF_U entries by retrieving strings stored in jimage strings table.

 * In addition, if the UTF_8 entry is a descriptor, the descriptor has to be rebuilt,

 * all java type having been removed from the descriptor and added to the sting table.

 * eg: "(Ljava/lang/String;I)V" ==> "(L;I)V" and "java/lang", "String"

 * stored in string table. offsets to the 2 strings are compressed and stored in the

 * constantpool entry.

 */

class SharedStringDecompressor : public ImageDecompressor {

private:

    // the constant pool tag for UTF8 string located in strings table

    static const int externalized_string = 23;

    // the constant pool tag for UTF8 descriptors string located in strings table

    static const int externalized_string_descriptor = 25;

    // the constant pool tag for UTF8

    static const int constant_utf8 = 1;

    // the constant pool tag for long

    static const int constant_long = 5;

    // the constant pool tag for double

    static const int constant_double = 6;

    // array index is the constant pool tag. value is size.

    // eg: array[5]  = 8; means size of long is 8 bytes.

    static const u1 sizes[];

    // bit 5 and 6 are used to store the length of the compressed integer.

    // size can be 1 (01), 2 (10), 3 (11).

    // 0x60 ==> 0110000

    static const int compressed_index_size_mask = 0x60;

    /*

     * mask the length bits (5 and 6) and move to the right 5 bits.

     */

    inline static int get_compressed_length(char c) {

        return ((char) (c & compressed_index_size_mask) >> 5);

    }

    inline static bool is_compressed(signed char b1) { return b1 < 0; }

    static int decompress_int(unsigned char*& value);

public:

    SharedStringDecompressor(const char* sym) : ImageDecompressor(sym){}

    void decompress_resource(u1* data, u1* uncompressed, ResourceHeader* header,

    const ImageStrings* strings);

};

#endif // LIBJIMAGE_IMAGEDECOMPRESSOR_HPP