// 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 <linux/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;
                        }
                } else if (size < 4) {
                        /* empty or end-of-file */
                        goto exit_3;
                }

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

                if (!fill && chunksize == 0) {
                        /* empty or end-of-file */
                        goto exit_3;
                }

                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;
                }
        }

exit_3:
        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