// SPDX-License-Identifier: GPL-2.0-only

  /*
   * Wrapper for decompressing LZ4-compressed kernel, initramfs, and initrd
   *
   * Copyright (C) 2013, LG Electronics, Kyungsik Lee <kyungsik.lee@lge.com>

   */
  
  #ifdef STATIC
  #define PREBOOT
  #include "lz4/lz4_decompress.c"
  #else
  #include <linux/decompress/unlz4.h>
  #endif
  #include <linux/types.h>
  #include <linux/lz4.h>
  #include <linux/decompress/mm.h>
  #include <linux/compiler.h>
  
  #include <asm/unaligned.h>
  
  /*
   * 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 inline int INIT unlz4(u8 *input, long in_len,
  				long (*fill)(void *, unsigned long),
  				long (*flush)(void *, unsigned long),
  				u8 *output, long *posp,

  				void (*error) (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;

  	long size = in_len;

  #ifdef PREBOOT
  	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) {
  		size = fill(inp, 4);
  		if (size < 4) {
  			error("data corrupted");
  			goto exit_2;
  		}
  	}

  
  	chunksize = get_unaligned_le32(inp);
  	if (chunksize == ARCHIVE_MAGICNUMBER) {

  		if (!fill) {
  			inp += 4;
  			size -= 4;
  		}

  	} else {
  		error("invalid header");
  		goto exit_2;
  	}
  
  	if (posp)
  		*posp += 4;
  
  	for (;;) {

  		if (fill) {
  			size = fill(inp, 4);
  			if (size == 0)
  				break;
  			if (size < 4) {
  				error("data corrupted");
  				goto exit_2;
  			}
  		}

  
  		chunksize = get_unaligned_le32(inp);
  		if (chunksize == ARCHIVE_MAGICNUMBER) {

  			if (!fill) {
  				inp += 4;
  				size -= 4;
  			}

  			if (posp)
  				*posp += 4;
  			continue;
  		}

  
  		if (posp)
  			*posp += 4;

  		if (!fill) {
  			inp += 4;
  			size -= 4;
  		} else {

  			if (chunksize > LZ4_compressBound(uncomp_chunksize)) {

  				error("chunk length is longer than allocated");
  				goto exit_2;
  			}

  			size = fill(inp, chunksize);
  			if (size < chunksize) {
  				error("data corrupted");
  				goto exit_2;
  			}

  		}
  #ifdef PREBOOT
  		if (out_len >= uncomp_chunksize) {
  			dest_len = uncomp_chunksize;
  			out_len -= dest_len;
  		} else
  			dest_len = out_len;

  
  		ret = LZ4_decompress_fast(inp, outp, dest_len);
  		chunksize = ret;

  #else
  		dest_len = uncomp_chunksize;

  
  		ret = LZ4_decompress_safe(inp, outp, chunksize, dest_len);
  		dest_len = ret;

  #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;

  		if (!fill) {
  			size -= chunksize;

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

  		}

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

  STATIC int INIT __decompress(unsigned char *buf, long in_len,

  			      long (*fill)(void*, unsigned long),
  			      long (*flush)(void*, unsigned long),

  			      unsigned char *output, long out_len,

  			      long *posp,

  			      void (*error)(char *x)

  	)
  {
  	return unlz4(buf, in_len - 4, fill, flush, output, posp, error);
  }
  #endif