/*
 * Wrapper for decompressing LZ4-compressed kernel, initramfs, and initrd
 *
 * Copyright (C) 2013, LG Electronics, Kyungsik Lee <kyungsik.lee@lge.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include "decompress.h"
#include <xen/lz4.h>
#include "lz4/decompress.c"

/*
 * Note: Uncompressed chunk size is used in the compressor side
 * (userspace side for compression).
 * It is hardcoded because there is not proper way to extract it
 * from the binary stream which is generated by the preliminary
 * version of LZ4 tool so far.
 */
#define LZ4_DEFAULT_UNCOMPRESSED_CHUNK_SIZE (8 << 20)
#define ARCHIVE_MAGICNUMBER 0x184C2102

STATIC int INIT unlz4(unsigned char *input, unsigned int in_len,
		      int (*fill)(void *, unsigned int),
		      int (*flush)(void *, unsigned int),
		      unsigned char *output,
		      unsigned int *posp,
		      void (*error)(const char *x))
{
	int ret = -1;
	size_t chunksize = 0;
	size_t uncomp_chunksize = LZ4_DEFAULT_UNCOMPRESSED_CHUNK_SIZE;
	u8 *inp;
	u8 *inp_start;
	u8 *outp;
	int size = in_len -= 4;
#if defined(__XEN__) || defined(__MINIOS__)
	size_t out_len = get_unaligned_le32(input + in_len);
#endif
	size_t dest_len;


	if (output) {
		outp = output;
	} else if (!flush) {
		error("NULL output pointer and no flush function provided");
		goto exit_0;
	} else {
		outp = large_malloc(uncomp_chunksize);
		if (!outp) {
			error("Could not allocate output buffer");
			goto exit_0;
		}
	}

	if (input && fill) {
		error("Both input pointer and fill function provided,");
		goto exit_1;
	} else if (input) {
		inp = input;
	} else if (!fill) {
		error("NULL input pointer and missing fill function");
		goto exit_1;
	} else {
		inp = large_malloc(lz4_compressbound(uncomp_chunksize));
		if (!inp) {
			error("Could not allocate input buffer");
			goto exit_1;
		}
	}
	inp_start = inp;

	if (posp)
		*posp = 0;

	if (fill)
		fill(inp, 4);

	chunksize = get_unaligned_le32(inp);
	if (chunksize == ARCHIVE_MAGICNUMBER) {
		inp += 4;
		size -= 4;
	} else {
		error("invalid header");
		goto exit_2;
	}

	if (posp)
		*posp += 4;

	for (;;) {

		if (fill)
			fill(inp, 4);

		chunksize = get_unaligned_le32(inp);
		if (chunksize == ARCHIVE_MAGICNUMBER) {
			inp += 4;
			size -= 4;
			if (posp)
				*posp += 4;
			continue;
		}
		inp += 4;
		size -= 4;

		if (posp)
			*posp += 4;

		if (fill) {
			if (chunksize > lz4_compressbound(uncomp_chunksize)) {
				error("chunk length is longer than allocated");
				goto exit_2;
			}
			fill(inp, chunksize);
		}
#if defined(__XEN__) || defined(__MINIOS__)
		if (out_len >= uncomp_chunksize) {
			dest_len = uncomp_chunksize;
			out_len -= dest_len;
		} else
			dest_len = out_len;
		ret = lz4_decompress(inp, &chunksize, outp, dest_len);
#else
		dest_len = uncomp_chunksize;
		ret = lz4_decompress_unknownoutputsize(inp, chunksize, outp,
				&dest_len);
#endif
		if (ret < 0) {
			error("Decoding failed");
			goto exit_2;
		}

		ret = -1;
		if (flush && flush(outp, dest_len) != dest_len)
			goto exit_2;
		if (output)
			outp += dest_len;
		if (posp)
			*posp += chunksize;

		size -= chunksize;

		if (size == 0)
			break;
		else if (size < 0) {
			error("data corrupted");
			goto exit_2;
		}

		inp += chunksize;
		if (fill)
			inp = inp_start;
	}

	ret = 0;
exit_2:
	if (!input)
		large_free(inp_start);
exit_1:
	if (!output)
		large_free(outp);
exit_0:
	return ret;
}