/*
    Copyright (c) 2005-2021 Intel Corporation

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/

/*-------------------------------------------------------------*/
/*--- Library top-level functions.                          ---*/
/*---                                             bzlib.cpp ---*/
/*-------------------------------------------------------------*/

/* ------------------------------------------------------------------
   The original source for this example:
   This file is part of bzip2/libbzip2, a program and library for
   lossless, block-sorting data compression.

   bzip2/libbzip2 version 1.0.6 of 6 September 2010
   Copyright (C) 1996-2010 Julian Seward <jseward@bzip.org>

   This program, "bzip2", the associated library "libbzip2", and all
   documentation, are copyright (C) 1996-2010 Julian R Seward.  All
   rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

   1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

   2. The origin of this software must not be misrepresented; you must 
   not claim that you wrote the original software.  If you use this 
   software in a product, an acknowledgment in the product 
   documentation would be appreciated but is not required.

   3. Altered source versions must be plainly marked as such, and must
   not be misrepresented as being the original software.

   4. The name of the author may not be used to endorse or promote 
   products derived from this software without specific prior written 
   permission.

   THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 PROFITS; OR BUSINESS
   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

   Julian Seward, jseward@bzip.org
   bzip2/libbzip2 version 1.0.6 of 6 September 2010
   ------------------------------------------------------------------ */

/* CHANGES
   0.9.0    -- original version.
   0.9.0a/b -- no changes in this file.
   0.9.0c   -- made zero-length BZ_FLUSH work correctly in bzCompress().
     fixed bzWrite/bzRead to ignore zero-length requests.
     fixed bzread to correctly handle read requests after EOF.
     wrong parameter order in call to bzDecompressInit in
     bzBuffToBuffDecompress.  Fixed.
*/

#include "bzlib_private.hpp"

/*---------------------------------------------------*/
/*--- Compression stuff                           ---*/
/*---------------------------------------------------*/

/*---------------------------------------------------*/
#ifndef BZ_NO_STDIO
void BZ2_bz__AssertH__fail(int errcode) {
    fprintf(stderr,
            "\n\nbzip2/libbzip2: internal error number %d.\n"
            "This is a bug in bzip2/libbzip2, %s.\n"
            "Please report it to me at: jseward@bzip.org.  If this happened\n"
            "when you were using some program which uses libbzip2 as a\n"
            "component, you should also report this bug to the author(s)\n"
            "of that program.  Please make an effort to report this bug;\n"
            "timely and accurate bug reports eventually lead to higher\n"
            "quality software.  Thanks.  Julian Seward, 10 December 2007.\n\n",
            errcode,
            BZ2_bzlibVersion());

    if (errcode == 1007) {
        fprintf(stderr,
                "\n*** A special note about internal error number 1007 ***\n"
                "\n"
                "Experience suggests that a common cause of i.e. 1007\n"
                "is unreliable memory or other hardware.  The 1007 assertion\n"
                "just happens to cross-check the results of huge numbers of\n"
                "memory reads/writes, and so acts (unintendedly) as a stress\n"
                "test of your memory system.\n"
                "\n"
                "I suggest the following: try compressing the file again,\n"
                "possibly monitoring progress in detail with the -vv flag.\n"
                "\n"
                "* If the error cannot be reproduced, and/or happens at different\n"
                "  points in compression, you may have a flaky memory system.\n"
                "  Try a memory-test program.  I have used Memtest86\n"
                "  (www.memtest86.com).  At the time of writing it is free (GPLd).\n"
                "  Memtest86 tests memory much more thorougly than your BIOSs\n"
                "  power-on test, and may find failures that the BIOS doesn't.\n"
                "\n"
                "* If the error can be repeatably reproduced, this is a bug in\n"
                "  bzip2, and I would very much like to hear about it.  Please\n"
                "  let me know, and, ideally, save a copy of the file causing the\n"
                "  problem -- without which I will be unable to investigate it.\n"
                "\n");
    }

    std::exit(-1);
}
#endif

/*---------------------------------------------------*/
static int bz_config_ok(void) {
    if (sizeof(int) != 4)
        return 0;
    if (sizeof(short) != 2)
        return 0;
    if (sizeof(char) != 1)
        return 0;
    return 1;
}

/*---------------------------------------------------*/
static void* default_bzalloc(void* opaque, Int32 items, Int32 size) {
    void* v = malloc(items * size);
    return v;
}

static void default_bzfree(void* opaque, void* addr) {
    if (addr != nullptr)
        free(addr);
}

/*---------------------------------------------------*/
static void prepare_new_block(EState* s) {
    Int32 i;
    s->nblock = 0;
    s->numZ = 0;
    s->state_out_pos = 0;
    BZ_INITIALISE_CRC(s->blockCRC);
    for (i = 0; i < 256; i++)
        s->inUse[i] = False;
    s->blockNo++;
}

/*---------------------------------------------------*/
static void init_RL(EState* s) {
    s->state_in_ch = 256;
    s->state_in_len = 0;
}

static Bool isempty_RL(EState* s) {
    if (s->state_in_ch < 256 && s->state_in_len > 0)
        return False;
    else
        return True;
}

/*---------------------------------------------------*/
int BZ_API(BZ2_bzCompressInit)(bz_stream* strm, int blockSize100k, int verbosity, int workFactor) {
    Int32 n;
    EState* s;

    if (!bz_config_ok())
        return BZ_CONFIG_ERROR;

    if (strm == nullptr || blockSize100k < 1 || blockSize100k > 9 || workFactor < 0 ||
        workFactor > 250)
        return BZ_PARAM_ERROR;

    if (workFactor == 0)
        workFactor = 30;
    if (strm->bzalloc == nullptr)
        strm->bzalloc = default_bzalloc;
    if (strm->bzfree == nullptr)
        strm->bzfree = default_bzfree;

    s = (EState*)BZALLOC(sizeof(EState));
    if (s == nullptr)
        return BZ_MEM_ERROR;
    s->strm = strm;

    s->arr1 = nullptr;
    s->arr2 = nullptr;
    s->ftab = nullptr;

    n = 100000 * blockSize100k;
    s->arr1 = (UInt32*)BZALLOC(n * sizeof(UInt32));
    s->arr2 = (UInt32*)BZALLOC((n + BZ_N_OVERSHOOT) * sizeof(UInt32));
    s->ftab = (UInt32*)BZALLOC(65537 * sizeof(UInt32));

    if (s->arr1 == nullptr || s->arr2 == nullptr || s->ftab == nullptr) {
        if (s->arr1 != nullptr)
            BZFREE(s->arr1);
        if (s->arr2 != nullptr)
            BZFREE(s->arr2);
        if (s->ftab != nullptr)
            BZFREE(s->ftab);
        if (s != nullptr)
            BZFREE(s);
        return BZ_MEM_ERROR;
    }

    s->blockNo = 0;
    s->state = BZ_S_INPUT;
    s->mode = BZ_M_RUNNING;
    s->combinedCRC = 0;
    s->blockSize100k = blockSize100k;
    s->nblockMAX = 100000 * blockSize100k - 19;
    s->verbosity = verbosity;
    s->workFactor = workFactor;

    s->block = (UChar*)s->arr2;
    s->mtfv = (UInt16*)s->arr1;
    s->zbits = nullptr;
    s->ptr = (UInt32*)s->arr1;

    strm->state = s;
    strm->total_in_lo32 = 0;
    strm->total_in_hi32 = 0;
    strm->total_out_lo32 = 0;
    strm->total_out_hi32 = 0;
    init_RL(s);
    prepare_new_block(s);
    return BZ_OK;
}

/*---------------------------------------------------*/
static void add_pair_to_block(EState* s) {
    Int32 i;
    UChar ch = (UChar)(s->state_in_ch);
    for (i = 0; i < s->state_in_len; i++) {
        BZ_UPDATE_CRC(s->blockCRC, ch);
    }
    s->inUse[s->state_in_ch] = True;
    switch (s->state_in_len) {
        case 1:
            s->block[s->nblock] = (UChar)ch;
            s->nblock++;
            break;
        case 2:
            s->block[s->nblock] = (UChar)ch;
            s->nblock++;
            s->block[s->nblock] = (UChar)ch;
            s->nblock++;
            break;
        case 3:
            s->block[s->nblock] = (UChar)ch;
            s->nblock++;
            s->block[s->nblock] = (UChar)ch;
            s->nblock++;
            s->block[s->nblock] = (UChar)ch;
            s->nblock++;
            break;
        default:
            s->inUse[s->state_in_len - 4] = True;
            s->block[s->nblock] = (UChar)ch;
            s->nblock++;
            s->block[s->nblock] = (UChar)ch;
            s->nblock++;
            s->block[s->nblock] = (UChar)ch;
            s->nblock++;
            s->block[s->nblock] = (UChar)ch;
            s->nblock++;
            s->block[s->nblock] = ((UChar)(s->state_in_len - 4));
            s->nblock++;
            break;
    }
}

/*---------------------------------------------------*/
static void flush_RL(EState* s) {
    if (s->state_in_ch < 256)
        add_pair_to_block(s);
    init_RL(s);
}

/*---------------------------------------------------*/
#define ADD_CHAR_TO_BLOCK(zs, zchh0)                                  \
    {                                                                 \
        UInt32 zchh = (UInt32)(zchh0);                                \
        /*-- fast track the common case --*/                          \
        if (zchh != zs->state_in_ch && zs->state_in_len == 1) {       \
            UChar ch = (UChar)(zs->state_in_ch);                      \
            BZ_UPDATE_CRC(zs->blockCRC, ch);                          \
            zs->inUse[zs->state_in_ch] = True;                        \
            zs->block[zs->nblock] = (UChar)ch;                        \
            zs->nblock++;                                             \
            zs->state_in_ch = zchh;                                   \
        }                                                             \
        else /*-- general, uncommon cases --*/                        \
            if (zchh != zs->state_in_ch || zs->state_in_len == 255) { \
            if (zs->state_in_ch < 256)                                \
                add_pair_to_block(zs);                                \
            zs->state_in_ch = zchh;                                   \
            zs->state_in_len = 1;                                     \
        }                                                             \
        else {                                                        \
            zs->state_in_len++;                                       \
        }                                                             \
    }

/*---------------------------------------------------*/
static Bool copy_input_until_stop(EState* s) {
    Bool progress_in = False;

    if (s->mode == BZ_M_RUNNING) {
        /*-- fast track the common case --*/
        while (True) {
            /*-- block full? --*/
            if (s->nblock >= s->nblockMAX)
                break;
            /*-- no input? --*/
            if (s->strm->avail_in == 0)
                break;
            progress_in = True;
            ADD_CHAR_TO_BLOCK(s, (UInt32)(*((UChar*)(s->strm->next_in))));
            s->strm->next_in++;
            s->strm->avail_in--;
            s->strm->total_in_lo32++;
            if (s->strm->total_in_lo32 == 0)
                s->strm->total_in_hi32++;
        }
    }
    else {
        /*-- general, uncommon case --*/
        while (True) {
            /*-- block full? --*/
            if (s->nblock >= s->nblockMAX)
                break;
            /*-- no input? --*/
            if (s->strm->avail_in == 0)
                break;
            /*-- flush/finish end? --*/
            if (s->avail_in_expect == 0)
                break;
            progress_in = True;
            ADD_CHAR_TO_BLOCK(s, (UInt32)(*((UChar*)(s->strm->next_in))));
            s->strm->next_in++;
            s->strm->avail_in--;
            s->strm->total_in_lo32++;
            if (s->strm->total_in_lo32 == 0)
                s->strm->total_in_hi32++;
            s->avail_in_expect--;
        }
    }
    return progress_in;
}

/*---------------------------------------------------*/
static Bool copy_output_until_stop(EState* s) {
    Bool progress_out = False;

    while (True) {
        /*-- no output space? --*/
        if (s->strm->avail_out == 0)
            break;

        /*-- block done? --*/
        if (s->state_out_pos >= s->numZ)
            break;

        progress_out = True;
        *(s->strm->next_out) = s->zbits[s->state_out_pos];
        s->state_out_pos++;
        s->strm->avail_out--;
        s->strm->next_out++;
        s->strm->total_out_lo32++;
        if (s->strm->total_out_lo32 == 0)
            s->strm->total_out_hi32++;
    }

    return progress_out;
}

/*---------------------------------------------------*/
static Bool handle_compress(bz_stream* strm) {
    Bool progress_in = False;
    Bool progress_out = False;
    EState* s = (EState*)strm->state;

    while (True) {
        if (s->state == BZ_S_OUTPUT) {
            progress_out |= copy_output_until_stop(s);
            if (s->state_out_pos < s->numZ)
                break;
            if (s->mode == BZ_M_FINISHING && s->avail_in_expect == 0 && isempty_RL(s))
                break;
            prepare_new_block(s);
            s->state = BZ_S_INPUT;
            if (s->mode == BZ_M_FLUSHING && s->avail_in_expect == 0 && isempty_RL(s))
                break;
        }

        if (s->state == BZ_S_INPUT) {
            progress_in |= copy_input_until_stop(s);
            if (s->mode != BZ_M_RUNNING && s->avail_in_expect == 0) {
                flush_RL(s);
                BZ2_compressBlock(s, (Bool)(s->mode == BZ_M_FINISHING));
                s->state = BZ_S_OUTPUT;
            }
            else if (s->nblock >= s->nblockMAX) {
                BZ2_compressBlock(s, False);
                s->state = BZ_S_OUTPUT;
            }
            else if (s->strm->avail_in == 0) {
                break;
            }
        }
    }

    return progress_in || progress_out;
}

/*---------------------------------------------------*/
int BZ_API(BZ2_bzCompress)(bz_stream* strm, int action) {
    Bool progress;
    EState* s;
    if (strm == nullptr)
        return BZ_PARAM_ERROR;
    s = (EState*)strm->state;
    if (s == nullptr)
        return BZ_PARAM_ERROR;
    if (s->strm != strm)
        return BZ_PARAM_ERROR;

preswitch:
    switch (s->mode) {
        case BZ_M_IDLE: return BZ_SEQUENCE_ERROR;

        case BZ_M_RUNNING:
            if (action == BZ_RUN) {
                progress = handle_compress(strm);
                return progress ? BZ_RUN_OK : BZ_PARAM_ERROR;
            }
            else if (action == BZ_FLUSH) {
                s->avail_in_expect = strm->avail_in;
                s->mode = BZ_M_FLUSHING;
                goto preswitch;
            }
            else if (action == BZ_FINISH) {
                s->avail_in_expect = strm->avail_in;
                s->mode = BZ_M_FINISHING;
                goto preswitch;
            }
            else
                return BZ_PARAM_ERROR;

        case BZ_M_FLUSHING:
            if (action != BZ_FLUSH)
                return BZ_SEQUENCE_ERROR;
            if (s->avail_in_expect != s->strm->avail_in)
                return BZ_SEQUENCE_ERROR;
            progress = handle_compress(strm);
            if (s->avail_in_expect > 0 || !isempty_RL(s) || s->state_out_pos < s->numZ)
                return BZ_FLUSH_OK;
            s->mode = BZ_M_RUNNING;
            return BZ_RUN_OK;

        case BZ_M_FINISHING:
            if (action != BZ_FINISH)
                return BZ_SEQUENCE_ERROR;
            if (s->avail_in_expect != s->strm->avail_in)
                return BZ_SEQUENCE_ERROR;
            progress = handle_compress(strm);
            if (!progress)
                return BZ_SEQUENCE_ERROR;
            if (s->avail_in_expect > 0 || !isempty_RL(s) || s->state_out_pos < s->numZ)
                return BZ_FINISH_OK;
            s->mode = BZ_M_IDLE;
            return BZ_STREAM_END;
    }
    return BZ_OK; /*--not reached--*/
}

/*---------------------------------------------------*/
int BZ_API(BZ2_bzCompressEnd)(bz_stream* strm) {
    EState* s;
    if (strm == nullptr)
        return BZ_PARAM_ERROR;
    s = (EState*)strm->state;
    if (s == nullptr)
        return BZ_PARAM_ERROR;
    if (s->strm != strm)
        return BZ_PARAM_ERROR;

    if (s->arr1 != nullptr)
        BZFREE(s->arr1);
    if (s->arr2 != nullptr)
        BZFREE(s->arr2);
    if (s->ftab != nullptr)
        BZFREE(s->ftab);
    BZFREE(strm->state);

    strm->state = nullptr;

    return BZ_OK;
}

/*---------------------------------------------------*/
/*--- Decompression stuff                         ---*/
/*---------------------------------------------------*/

/*---------------------------------------------------*/
int BZ_API(BZ2_bzDecompressInit)(bz_stream* strm, int verbosity, int small) {
    DState* s;

    if (!bz_config_ok())
        return BZ_CONFIG_ERROR;

    if (strm == nullptr)
        return BZ_PARAM_ERROR;
    if (small != 0 && small != 1)
        return BZ_PARAM_ERROR;
    if (verbosity < 0 || verbosity > 4)
        return BZ_PARAM_ERROR;

    if (strm->bzalloc == nullptr)
        strm->bzalloc = default_bzalloc;
    if (strm->bzfree == nullptr)
        strm->bzfree = default_bzfree;

    s = (DState*)BZALLOC(sizeof(DState));
    if (s == nullptr)
        return BZ_MEM_ERROR;
    s->strm = strm;
    strm->state = s;
    s->state = BZ_X_MAGIC_1;
    s->bsLive = 0;
    s->bsBuff = 0;
    s->calculatedCombinedCRC = 0;
    strm->total_in_lo32 = 0;
    strm->total_in_hi32 = 0;
    strm->total_out_lo32 = 0;
    strm->total_out_hi32 = 0;
    s->smallDecompress = (Bool)small;
    s->ll4 = nullptr;
    s->ll16 = nullptr;
    s->tt = nullptr;
    s->currBlockNo = 0;
    s->verbosity = verbosity;

    return BZ_OK;
}

/*---------------------------------------------------*/
/* Return  True iff data corruption is discovered.
   Returns False if there is no problem.
*/
static Bool unRLE_obuf_to_output_FAST(DState* s) {
    UChar k1;

    if (s->blockRandomised) {
        while (True) {
            /* try to finish existing run */
            while (True) {
                if (s->strm->avail_out == 0)
                    return False;
                if (s->state_out_len == 0)
                    break;
                *((UChar*)(s->strm->next_out)) = s->state_out_ch;
                BZ_UPDATE_CRC(s->calculatedBlockCRC, s->state_out_ch);
                s->state_out_len--;
                s->strm->next_out++;
                s->strm->avail_out--;
                s->strm->total_out_lo32++;
                if (s->strm->total_out_lo32 == 0)
                    s->strm->total_out_hi32++;
            }

            /* can a new run be started? */
            if (s->nblock_used == s->save_nblock + 1)
                return False;

            /* Only caused by corrupt data stream? */
            if (s->nblock_used > s->save_nblock + 1)
                return True;

            s->state_out_len = 1;
            s->state_out_ch = s->k0;
            BZ_GET_FAST(k1);
            BZ_RAND_UPD_MASK;
            k1 ^= BZ_RAND_MASK;
            s->nblock_used++;
            if (s->nblock_used == s->save_nblock + 1)
                continue;
            if (k1 != s->k0) {
                s->k0 = k1;
                continue;
            };

            s->state_out_len = 2;
            BZ_GET_FAST(k1);
            BZ_RAND_UPD_MASK;
            k1 ^= BZ_RAND_MASK;
            s->nblock_used++;
            if (s->nblock_used == s->save_nblock + 1)
                continue;
            if (k1 != s->k0) {
                s->k0 = k1;
                continue;
            };

            s->state_out_len = 3;
            BZ_GET_FAST(k1);
            BZ_RAND_UPD_MASK;
            k1 ^= BZ_RAND_MASK;
            s->nblock_used++;
            if (s->nblock_used == s->save_nblock + 1)
                continue;
            if (k1 != s->k0) {
                s->k0 = k1;
                continue;
            };

            BZ_GET_FAST(k1);
            BZ_RAND_UPD_MASK;
            k1 ^= BZ_RAND_MASK;
            s->nblock_used++;
            s->state_out_len = ((Int32)k1) + 4;
            BZ_GET_FAST(s->k0);
            BZ_RAND_UPD_MASK;
            s->k0 ^= BZ_RAND_MASK;
            s->nblock_used++;
        }
    }
    else {
        /* restore */
        UInt32 c_calculatedBlockCRC = s->calculatedBlockCRC;
        UChar c_state_out_ch = s->state_out_ch;
        Int32 c_state_out_len = s->state_out_len;
        Int32 c_nblock_used = s->nblock_used;
        Int32 c_k0 = s->k0;
        UInt32* c_tt = s->tt;
        UInt32 c_tPos = s->tPos;
        char* cs_next_out = s->strm->next_out;
        unsigned int cs_avail_out = s->strm->avail_out;
        Int32 ro_blockSize100k = s->blockSize100k;
        /* end restore */

        UInt32 avail_out_INIT = cs_avail_out;
        Int32 s_save_nblockPP = s->save_nblock + 1;
        unsigned int total_out_lo32_old;

        while (True) {
            /* try to finish existing run */
            if (c_state_out_len > 0) {
                while (True) {
                    if (cs_avail_out == 0)
                        goto return_notr;
                    if (c_state_out_len == 1)
                        break;
                    *((UChar*)(cs_next_out)) = c_state_out_ch;
                    BZ_UPDATE_CRC(c_calculatedBlockCRC, c_state_out_ch);
                    c_state_out_len--;
                    cs_next_out++;
                    cs_avail_out--;
                }
            s_state_out_len_eq_one : {
                if (cs_avail_out == 0) {
                    c_state_out_len = 1;
                    goto return_notr;
                };
                *((UChar*)(cs_next_out)) = c_state_out_ch;
                BZ_UPDATE_CRC(c_calculatedBlockCRC, c_state_out_ch);
                cs_next_out++;
                cs_avail_out--;
            }
            }
            /* Only caused by corrupt data stream? */
            if (c_nblock_used > s_save_nblockPP)
                return True;

            /* can a new run be started? */
            if (c_nblock_used == s_save_nblockPP) {
                c_state_out_len = 0;
                goto return_notr;
            };
            c_state_out_ch = c_k0;
            BZ_GET_FAST_C(k1);
            c_nblock_used++;
            if (k1 != c_k0) {
                c_k0 = k1;
                goto s_state_out_len_eq_one;
            };
            if (c_nblock_used == s_save_nblockPP)
                goto s_state_out_len_eq_one;

            c_state_out_len = 2;
            BZ_GET_FAST_C(k1);
            c_nblock_used++;
            if (c_nblock_used == s_save_nblockPP)
                continue;
            if (k1 != c_k0) {
                c_k0 = k1;
                continue;
            };

            c_state_out_len = 3;
            BZ_GET_FAST_C(k1);
            c_nblock_used++;
            if (c_nblock_used == s_save_nblockPP)
                continue;
            if (k1 != c_k0) {
                c_k0 = k1;
                continue;
            };

            BZ_GET_FAST_C(k1);
            c_nblock_used++;
            c_state_out_len = ((Int32)k1) + 4;
            BZ_GET_FAST_C(c_k0);
            c_nblock_used++;
        }

    return_notr:
        total_out_lo32_old = s->strm->total_out_lo32;
        s->strm->total_out_lo32 += (avail_out_INIT - cs_avail_out);
        if (s->strm->total_out_lo32 < total_out_lo32_old)
            s->strm->total_out_hi32++;

        /* save */
        s->calculatedBlockCRC = c_calculatedBlockCRC;
        s->state_out_ch = c_state_out_ch;
        s->state_out_len = c_state_out_len;
        s->nblock_used = c_nblock_used;
        s->k0 = c_k0;
        s->tt = c_tt;
        s->tPos = c_tPos;
        s->strm->next_out = cs_next_out;
        s->strm->avail_out = cs_avail_out;
        /* end save */
    }
    return False;
}

/*---------------------------------------------------*/
Int32 BZ2_indexIntoF(Int32 indx, Int32* cftab) {
    Int32 nb, na, mid;
    nb = 0;
    na = 256;
    do {
        mid = (nb + na) >> 1;
        if (indx >= cftab[mid])
            nb = mid;
        else
            na = mid;
    } while (na - nb != 1);
    return nb;
}

/*---------------------------------------------------*/
/* Return  True iff data corruption is discovered.
   Returns False if there is no problem.
*/
static Bool unRLE_obuf_to_output_SMALL(DState* s) {
    UChar k1;

    if (s->blockRandomised) {
        while (True) {
            /* try to finish existing run */
            while (True) {
                if (s->strm->avail_out == 0)
                    return False;
                if (s->state_out_len == 0)
                    break;
                *((UChar*)(s->strm->next_out)) = s->state_out_ch;
                BZ_UPDATE_CRC(s->calculatedBlockCRC, s->state_out_ch);
                s->state_out_len--;
                s->strm->next_out++;
                s->strm->avail_out--;
                s->strm->total_out_lo32++;
                if (s->strm->total_out_lo32 == 0)
                    s->strm->total_out_hi32++;
            }

            /* can a new run be started? */
            if (s->nblock_used == s->save_nblock + 1)
                return False;

            /* Only caused by corrupt data stream? */
            if (s->nblock_used > s->save_nblock + 1)
                return True;

            s->state_out_len = 1;
            s->state_out_ch = s->k0;
            BZ_GET_SMALL(k1);
            BZ_RAND_UPD_MASK;
            k1 ^= BZ_RAND_MASK;
            s->nblock_used++;
            if (s->nblock_used == s->save_nblock + 1)
                continue;
            if (k1 != s->k0) {
                s->k0 = k1;
                continue;
            };

            s->state_out_len = 2;
            BZ_GET_SMALL(k1);
            BZ_RAND_UPD_MASK;
            k1 ^= BZ_RAND_MASK;
            s->nblock_used++;
            if (s->nblock_used == s->save_nblock + 1)
                continue;
            if (k1 != s->k0) {
                s->k0 = k1;
                continue;
            };

            s->state_out_len = 3;
            BZ_GET_SMALL(k1);
            BZ_RAND_UPD_MASK;
            k1 ^= BZ_RAND_MASK;
            s->nblock_used++;
            if (s->nblock_used == s->save_nblock + 1)
                continue;
            if (k1 != s->k0) {
                s->k0 = k1;
                continue;
            };

            BZ_GET_SMALL(k1);
            BZ_RAND_UPD_MASK;
            k1 ^= BZ_RAND_MASK;
            s->nblock_used++;
            s->state_out_len = ((Int32)k1) + 4;
            BZ_GET_SMALL(s->k0);
            BZ_RAND_UPD_MASK;
            s->k0 ^= BZ_RAND_MASK;
            s->nblock_used++;
        }
    }
    else {
        while (True) {
            /* try to finish existing run */
            while (True) {
                if (s->strm->avail_out == 0)
                    return False;
                if (s->state_out_len == 0)
                    break;
                *((UChar*)(s->strm->next_out)) = s->state_out_ch;
                BZ_UPDATE_CRC(s->calculatedBlockCRC, s->state_out_ch);
                s->state_out_len--;
                s->strm->next_out++;
                s->strm->avail_out--;
                s->strm->total_out_lo32++;
                if (s->strm->total_out_lo32 == 0)
                    s->strm->total_out_hi32++;
            }

            /* can a new run be started? */
            if (s->nblock_used == s->save_nblock + 1)
                return False;

            /* Only caused by corrupt data stream? */
            if (s->nblock_used > s->save_nblock + 1)
                return True;

            s->state_out_len = 1;
            s->state_out_ch = s->k0;
            BZ_GET_SMALL(k1);
            s->nblock_used++;
            if (s->nblock_used == s->save_nblock + 1)
                continue;
            if (k1 != s->k0) {
                s->k0 = k1;
                continue;
            };

            s->state_out_len = 2;
            BZ_GET_SMALL(k1);
            s->nblock_used++;
            if (s->nblock_used == s->save_nblock + 1)
                continue;
            if (k1 != s->k0) {
                s->k0 = k1;
                continue;
            };

            s->state_out_len = 3;
            BZ_GET_SMALL(k1);
            s->nblock_used++;
            if (s->nblock_used == s->save_nblock + 1)
                continue;
            if (k1 != s->k0) {
                s->k0 = k1;
                continue;
            };

            BZ_GET_SMALL(k1);
            s->nblock_used++;
            s->state_out_len = ((Int32)k1) + 4;
            BZ_GET_SMALL(s->k0);
            s->nblock_used++;
        }
    }
}

/*---------------------------------------------------*/
int BZ_API(BZ2_bzDecompress)(bz_stream* strm) {
    Bool corrupt;
    DState* s;
    if (strm == nullptr)
        return BZ_PARAM_ERROR;
    s = (DState*)strm->state;
    if (s == nullptr)
        return BZ_PARAM_ERROR;
    if (s->strm != strm)
        return BZ_PARAM_ERROR;

    while (True) {
        if (s->state == BZ_X_IDLE)
            return BZ_SEQUENCE_ERROR;
        if (s->state == BZ_X_OUTPUT) {
            if (s->smallDecompress)
                corrupt = unRLE_obuf_to_output_SMALL(s);
            else
                corrupt = unRLE_obuf_to_output_FAST(s);
            if (corrupt)
                return BZ_DATA_ERROR;
            if (s->nblock_used == s->save_nblock + 1 && s->state_out_len == 0) {
                BZ_FINALISE_CRC(s->calculatedBlockCRC);
                if (s->verbosity >= 3)
                    VPrintf2(" {0x%08x, 0x%08x}", s->storedBlockCRC, s->calculatedBlockCRC);
                if (s->verbosity >= 2)
                    VPrintf0("]");
                if (s->calculatedBlockCRC != s->storedBlockCRC)
                    return BZ_DATA_ERROR;
                s->calculatedCombinedCRC =
                    (s->calculatedCombinedCRC << 1) | (s->calculatedCombinedCRC >> 31);
                s->calculatedCombinedCRC ^= s->calculatedBlockCRC;
                s->state = BZ_X_BLKHDR_1;
            }
            else {
                return BZ_OK;
            }
        }
        if (s->state >= BZ_X_MAGIC_1) {
            Int32 r = BZ2_decompress(s);
            if (r == BZ_STREAM_END) {
                if (s->verbosity >= 3)
                    VPrintf2("\n    combined CRCs: stored = 0x%08x, computed = 0x%08x",
                             s->storedCombinedCRC,
                             s->calculatedCombinedCRC);
                if (s->calculatedCombinedCRC != s->storedCombinedCRC)
                    return BZ_DATA_ERROR;
                return r;
            }
            if (s->state != BZ_X_OUTPUT)
                return r;
        }
    }

    AssertH(0, 6001);

    return 0; /*NOTREACHED*/
}

/*---------------------------------------------------*/
int BZ_API(BZ2_bzDecompressEnd)(bz_stream* strm) {
    DState* s;
    if (strm == nullptr)
        return BZ_PARAM_ERROR;
    s = (DState*)strm->state;
    if (s == nullptr)
        return BZ_PARAM_ERROR;
    if (s->strm != strm)
        return BZ_PARAM_ERROR;

    if (s->tt != nullptr)
        BZFREE(s->tt);
    if (s->ll16 != nullptr)
        BZFREE(s->ll16);
    if (s->ll4 != nullptr)
        BZFREE(s->ll4);

    BZFREE(strm->state);
    strm->state = nullptr;

    return BZ_OK;
}

#ifndef BZ_NO_STDIO
/*---------------------------------------------------*/
/*--- File I/O stuff                              ---*/
/*---------------------------------------------------*/

#define BZ_SETERR(eee)          \
    {                           \
        if (bzerror != nullptr) \
            *bzerror = eee;     \
        if (bzf != nullptr)     \
            bzf->lastErr = eee; \
    }

typedef struct {
    FILE* handle;
    Char buf[BZ_MAX_UNUSED];
    Int32 bufN;
    Bool writing;
    bz_stream strm;
    Int32 lastErr;
    Bool initialisedOk;
} bzFile;

/*---------------------------------------------*/
static Bool myfeof(FILE* f) {
    Int32 c = fgetc(f);
    if (c == EOF)
        return True;
    ungetc(c, f);
    return False;
}

/*---------------------------------------------------*/
BZFILE* BZ_API(
    BZ2_bzWriteOpen)(int* bzerror, FILE* f, int blockSize100k, int verbosity, int workFactor) {
    Int32 ret;
    bzFile* bzf = nullptr;

    BZ_SETERR(BZ_OK);

    if (f == nullptr || (blockSize100k < 1 || blockSize100k > 9) ||
        (workFactor < 0 || workFactor > 250) || (verbosity < 0 || verbosity > 4)) {
        BZ_SETERR(BZ_PARAM_ERROR);
        return nullptr;
    };

    if (ferror(f)) {
        BZ_SETERR(BZ_IO_ERROR);
        return nullptr;
    };

    bzf = (bzFile*)malloc(sizeof(bzFile));
    if (bzf == nullptr) {
        BZ_SETERR(BZ_MEM_ERROR);
        return nullptr;
    };

    BZ_SETERR(BZ_OK);
    bzf->initialisedOk = False;
    bzf->bufN = 0;
    bzf->handle = f;
    bzf->writing = True;
    bzf->strm.bzalloc = nullptr;
    bzf->strm.bzfree = nullptr;
    bzf->strm.opaque = nullptr;

    if (workFactor == 0)
        workFactor = 30;
    ret = BZ2_bzCompressInit(&(bzf->strm), blockSize100k, verbosity, workFactor);
    if (ret != BZ_OK) {
        BZ_SETERR(ret);
        free(bzf);
        return nullptr;
    };

    bzf->strm.avail_in = 0;
    bzf->initialisedOk = True;
    return bzf;
}

/*---------------------------------------------------*/
void BZ_API(BZ2_bzWrite)(int* bzerror, BZFILE* b, void* buf, int len) {
    Int32 n, n2, ret;
    bzFile* bzf = (bzFile*)b;

    BZ_SETERR(BZ_OK);
    if (bzf == nullptr || buf == nullptr || len < 0) {
        BZ_SETERR(BZ_PARAM_ERROR);
        return;
    };
    if (!(bzf->writing)) {
        BZ_SETERR(BZ_SEQUENCE_ERROR);
        return;
    };
    if (ferror(bzf->handle)) {
        BZ_SETERR(BZ_IO_ERROR);
        return;
    };

    if (len == 0) {
        BZ_SETERR(BZ_OK);
        return;
    };

    bzf->strm.avail_in = len;
    bzf->strm.next_in = (char*)buf;

    while (True) {
        bzf->strm.avail_out = BZ_MAX_UNUSED;
        bzf->strm.next_out = bzf->buf;
        ret = BZ2_bzCompress(&(bzf->strm), BZ_RUN);
        if (ret != BZ_RUN_OK) {
            BZ_SETERR(ret);
            return;
        };

        if (bzf->strm.avail_out < BZ_MAX_UNUSED) {
            n = BZ_MAX_UNUSED - bzf->strm.avail_out;
            n2 = fwrite((void*)(bzf->buf), sizeof(UChar), n, bzf->handle);
            if (n != n2 || ferror(bzf->handle)) {
                BZ_SETERR(BZ_IO_ERROR);
                return;
            };
        }

        if (bzf->strm.avail_in == 0) {
            BZ_SETERR(BZ_OK);
            return;
        };
    }
}

/*---------------------------------------------------*/
void BZ_API(BZ2_bzWriteClose)(int* bzerror,
                              BZFILE* b,
                              int abandon,
                              unsigned int* nbytes_in,
                              unsigned int* nbytes_out) {
    BZ2_bzWriteClose64(bzerror, b, abandon, nbytes_in, nullptr, nbytes_out, nullptr);
}

void BZ_API(BZ2_bzWriteClose64)(int* bzerror,
                                BZFILE* b,
                                int abandon,
                                unsigned int* nbytes_in_lo32,
                                unsigned int* nbytes_in_hi32,
                                unsigned int* nbytes_out_lo32,
                                unsigned int* nbytes_out_hi32) {
    Int32 n, n2, ret;
    bzFile* bzf = (bzFile*)b;

    if (bzf == nullptr) {
        BZ_SETERR(BZ_OK);
        return;
    };
    if (!(bzf->writing)) {
        BZ_SETERR(BZ_SEQUENCE_ERROR);
        return;
    };
    if (ferror(bzf->handle)) {
        BZ_SETERR(BZ_IO_ERROR);
        return;
    };

    if (nbytes_in_lo32 != nullptr)
        *nbytes_in_lo32 = 0;
    if (nbytes_in_hi32 != nullptr)
        *nbytes_in_hi32 = 0;
    if (nbytes_out_lo32 != nullptr)
        *nbytes_out_lo32 = 0;
    if (nbytes_out_hi32 != nullptr)
        *nbytes_out_hi32 = 0;

    if ((!abandon) && bzf->lastErr == BZ_OK) {
        while (True) {
            bzf->strm.avail_out = BZ_MAX_UNUSED;
            bzf->strm.next_out = bzf->buf;
            ret = BZ2_bzCompress(&(bzf->strm), BZ_FINISH);
            if (ret != BZ_FINISH_OK && ret != BZ_STREAM_END) {
                BZ_SETERR(ret);
                return;
            };

            if (bzf->strm.avail_out < BZ_MAX_UNUSED) {
                n = BZ_MAX_UNUSED - bzf->strm.avail_out;
                n2 = fwrite((void*)(bzf->buf), sizeof(UChar), n, bzf->handle);
                if (n != n2 || ferror(bzf->handle)) {
                    BZ_SETERR(BZ_IO_ERROR);
                    return;
                };
            }

            if (ret == BZ_STREAM_END)
                break;
        }
    }

    if (!abandon && !ferror(bzf->handle)) {
        fflush(bzf->handle);
        if (ferror(bzf->handle)) {
            BZ_SETERR(BZ_IO_ERROR);
            return;
        };
    }

    if (nbytes_in_lo32 != nullptr)
        *nbytes_in_lo32 = bzf->strm.total_in_lo32;
    if (nbytes_in_hi32 != nullptr)
        *nbytes_in_hi32 = bzf->strm.total_in_hi32;
    if (nbytes_out_lo32 != nullptr)
        *nbytes_out_lo32 = bzf->strm.total_out_lo32;
    if (nbytes_out_hi32 != nullptr)
        *nbytes_out_hi32 = bzf->strm.total_out_hi32;

    BZ_SETERR(BZ_OK);
    BZ2_bzCompressEnd(&(bzf->strm));
    free(bzf);
}

/*---------------------------------------------------*/
BZFILE* BZ_API(
    BZ2_bzReadOpen)(int* bzerror, FILE* f, int verbosity, int small, void* unused, int nUnused) {
    bzFile* bzf = nullptr;
    int ret;

    BZ_SETERR(BZ_OK);

    if (f == nullptr || (small != 0 && small != 1) || (verbosity < 0 || verbosity > 4) ||
        (unused == nullptr && nUnused != 0) ||
        (unused != nullptr && (nUnused < 0 || nUnused > BZ_MAX_UNUSED))) {
        BZ_SETERR(BZ_PARAM_ERROR);
        return nullptr;
    };

    if (ferror(f)) {
        BZ_SETERR(BZ_IO_ERROR);
        return nullptr;
    };

    bzf = (bzFile*)malloc(sizeof(bzFile));
    if (bzf == nullptr) {
        BZ_SETERR(BZ_MEM_ERROR);
        return nullptr;
    };

    BZ_SETERR(BZ_OK);

    bzf->initialisedOk = False;
    bzf->handle = f;
    bzf->bufN = 0;
    bzf->writing = False;
    bzf->strm.bzalloc = nullptr;
    bzf->strm.bzfree = nullptr;
    bzf->strm.opaque = nullptr;

    while (nUnused > 0) {
        bzf->buf[bzf->bufN] = *((UChar*)(unused));
        bzf->bufN++;
        unused = ((void*)(1 + ((UChar*)(unused))));
        nUnused--;
    }

    ret = BZ2_bzDecompressInit(&(bzf->strm), verbosity, small);
    if (ret != BZ_OK) {
        BZ_SETERR(ret);
        free(bzf);
        return nullptr;
    };

    bzf->strm.avail_in = bzf->bufN;
    bzf->strm.next_in = bzf->buf;

    bzf->initialisedOk = True;
    return bzf;
}

/*---------------------------------------------------*/
void BZ_API(BZ2_bzReadClose)(int* bzerror, BZFILE* b) {
    bzFile* bzf = (bzFile*)b;

    BZ_SETERR(BZ_OK);
    if (bzf == nullptr) {
        BZ_SETERR(BZ_OK);
        return;
    };

    if (bzf->writing) {
        BZ_SETERR(BZ_SEQUENCE_ERROR);
        return;
    };

    if (bzf->initialisedOk)
        (void)BZ2_bzDecompressEnd(&(bzf->strm));
    free(bzf);
}

/*---------------------------------------------------*/
int BZ_API(BZ2_bzRead)(int* bzerror, BZFILE* b, void* buf, int len) {
    Int32 n, ret;
    bzFile* bzf = (bzFile*)b;

    BZ_SETERR(BZ_OK);

    if (bzf == nullptr || buf == nullptr || len < 0) {
        BZ_SETERR(BZ_PARAM_ERROR);
        return 0;
    };

    if (bzf->writing) {
        BZ_SETERR(BZ_SEQUENCE_ERROR);
        return 0;
    };

    if (len == 0) {
        BZ_SETERR(BZ_OK);
        return 0;
    };

    bzf->strm.avail_out = len;
    bzf->strm.next_out = (char*)buf;

    while (True) {
        if (ferror(bzf->handle)) {
            BZ_SETERR(BZ_IO_ERROR);
            return 0;
        };

        if (bzf->strm.avail_in == 0 && !myfeof(bzf->handle)) {
            n = fread(bzf->buf, sizeof(UChar), BZ_MAX_UNUSED, bzf->handle);
            if (ferror(bzf->handle)) {
                BZ_SETERR(BZ_IO_ERROR);
                return 0;
            };
            bzf->bufN = n;
            bzf->strm.avail_in = bzf->bufN;
            bzf->strm.next_in = bzf->buf;
        }

        ret = BZ2_bzDecompress(&(bzf->strm));

        if (ret != BZ_OK && ret != BZ_STREAM_END) {
            BZ_SETERR(ret);
            return 0;
        };

        if (ret == BZ_OK && myfeof(bzf->handle) && bzf->strm.avail_in == 0 &&
            bzf->strm.avail_out > 0) {
            BZ_SETERR(BZ_UNEXPECTED_EOF);
            return 0;
        };

        if (ret == BZ_STREAM_END) {
            BZ_SETERR(BZ_STREAM_END);
            return len - bzf->strm.avail_out;
        };
        if (bzf->strm.avail_out == 0) {
            BZ_SETERR(BZ_OK);
            return len;
        };
    }

    return 0; /*not reached*/
}

/*---------------------------------------------------*/
void BZ_API(BZ2_bzReadGetUnused)(int* bzerror, BZFILE* b, void** unused, int* nUnused) {
    bzFile* bzf = (bzFile*)b;
    if (bzf == nullptr) {
        BZ_SETERR(BZ_PARAM_ERROR);
        return;
    };
    if (bzf->lastErr != BZ_STREAM_END) {
        BZ_SETERR(BZ_SEQUENCE_ERROR);
        return;
    };
    if (unused == nullptr || nUnused == nullptr) {
        BZ_SETERR(BZ_PARAM_ERROR);
        return;
    };

    BZ_SETERR(BZ_OK);
    *nUnused = bzf->strm.avail_in;
    *unused = bzf->strm.next_in;
}
#endif

/*---------------------------------------------------*/
/*--- Misc convenience stuff                      ---*/
/*---------------------------------------------------*/

/*---------------------------------------------------*/
int BZ_API(BZ2_bzBuffToBuffCompress)(char* dest,
                                     unsigned int* destLen,
                                     char* source,
                                     unsigned int sourceLen,
                                     int blockSize100k,
                                     int verbosity,
                                     int workFactor) {
    bz_stream strm;
    int ret;

    if (dest == nullptr || destLen == nullptr || source == nullptr || blockSize100k < 1 ||
        blockSize100k > 9 || verbosity < 0 || verbosity > 4 || workFactor < 0 || workFactor > 250)
        return BZ_PARAM_ERROR;

    if (workFactor == 0)
        workFactor = 30;
    strm.bzalloc = nullptr;
    strm.bzfree = nullptr;
    strm.opaque = nullptr;
    ret = BZ2_bzCompressInit(&strm, blockSize100k, verbosity, workFactor);
    if (ret != BZ_OK)
        return ret;

    strm.next_in = source;
    strm.next_out = dest;
    strm.avail_in = sourceLen;
    strm.avail_out = *destLen;

    ret = BZ2_bzCompress(&strm, BZ_FINISH);
    if (ret == BZ_FINISH_OK)
        goto output_overflow;
    if (ret != BZ_STREAM_END)
        goto errhandler;

    /* normal termination */
    *destLen -= strm.avail_out;
    BZ2_bzCompressEnd(&strm);
    return BZ_OK;

output_overflow:
    BZ2_bzCompressEnd(&strm);
    return BZ_OUTBUFF_FULL;

errhandler:
    BZ2_bzCompressEnd(&strm);
    return ret;
}

/*---------------------------------------------------*/
int BZ_API(BZ2_bzBuffToBuffDecompress)(char* dest,
                                       unsigned int* destLen,
                                       char* source,
                                       unsigned int sourceLen,
                                       int small,
                                       int verbosity) {
    bz_stream strm;
    int ret;

    if (dest == nullptr || destLen == nullptr || source == nullptr || (small != 0 && small != 1) ||
        verbosity < 0 || verbosity > 4)
        return BZ_PARAM_ERROR;

    strm.bzalloc = nullptr;
    strm.bzfree = nullptr;
    strm.opaque = nullptr;
    ret = BZ2_bzDecompressInit(&strm, verbosity, small);
    if (ret != BZ_OK)
        return ret;

    strm.next_in = source;
    strm.next_out = dest;
    strm.avail_in = sourceLen;
    strm.avail_out = *destLen;

    ret = BZ2_bzDecompress(&strm);
    if (ret == BZ_OK)
        goto output_overflow_or_eof;
    if (ret != BZ_STREAM_END)
        goto errhandler;

    /* normal termination */
    *destLen -= strm.avail_out;
    BZ2_bzDecompressEnd(&strm);
    return BZ_OK;

output_overflow_or_eof:
    if (strm.avail_out > 0) {
        BZ2_bzDecompressEnd(&strm);
        return BZ_UNEXPECTED_EOF;
    }
    else {
        BZ2_bzDecompressEnd(&strm);
        return BZ_OUTBUFF_FULL;
    };

errhandler:
    BZ2_bzDecompressEnd(&strm);
    return ret;
}

/*---------------------------------------------------*/
/*--
   Code contributed by Yoshioka Tsuneo (tsuneo@rr.iij4u.or.jp)
   to support better zlib compatibility.
   This code is not _officially_ part of libbzip2 (yet);
   I haven't tested it, documented it, or considered the
   threading-safeness of it.
   If this code breaks, please contact both Yoshioka and me.
--*/
/*---------------------------------------------------*/

/*---------------------------------------------------*/
/*--
   return version like "0.9.5d, 4-Sept-1999".
--*/
const char* BZ_API(BZ2_bzlibVersion)(void) {
    return BZ_VERSION;
}

#ifndef BZ_NO_STDIO
/*---------------------------------------------------*/

#if defined(_WIN32) || defined(OS2) || defined(MSDOS)
#include <fcntl.h>
#include <io.h>
#define SET_BINARY_MODE(file) setmode(fileno(file), O_BINARY)
#else
#define SET_BINARY_MODE(file)
#endif
static BZFILE* bzopen_or_bzdopen(const char* path, /* no use when bzdopen */
                                 int fd, /* no use when bzdopen */
                                 const char* mode,
                                 int open_mode) /* bzopen: 0, bzdopen:1 */
{
    int bzerr;
    char unused[BZ_MAX_UNUSED];
    int blockSize100k = 9;
    int writing = 0;
    char mode2[10] = "";
    FILE* fp = nullptr;
    BZFILE* bzfp = nullptr;
    int verbosity = 0;
    int workFactor = 30;
    int smallMode = 0;
    int nUnused = 0;

    if (mode == nullptr)
        return nullptr;
    while (*mode) {
        switch (*mode) {
            case 'r': writing = 0; break;
            case 'w': writing = 1; break;
            case 's': smallMode = 1; break;
            default:
                if (isdigit((int)(*mode))) {
                    blockSize100k = *mode - BZ_HDR_0;
                }
        }
        mode++;
    }
    strcat(mode2, writing ? "w" : "r");
    strcat(mode2, "b"); /* binary mode */

    if (open_mode == 0) {
        if (path == nullptr || strcmp(path, "") == 0) {
            fp = (writing ? stdout : stdin);
            SET_BINARY_MODE(fp);
        }
        else {
            fp = fopen(path, mode2);
        }
    }
    else {
#ifdef BZ_STRICT_ANSI
        fp = nullptr;
#else
        fp = fdopen(fd, mode2);
#endif
    }
    if (fp == nullptr)
        return nullptr;

    if (writing) {
        /* Guard against total chaos and anarchy -- JRS */
        if (blockSize100k < 1)
            blockSize100k = 1;
        if (blockSize100k > 9)
            blockSize100k = 9;
        bzfp = BZ2_bzWriteOpen(&bzerr, fp, blockSize100k, verbosity, workFactor);
    }
    else {
        bzfp = BZ2_bzReadOpen(&bzerr, fp, verbosity, smallMode, unused, nUnused);
    }
    if (bzfp == nullptr) {
        if (fp != stdin && fp != stdout)
            fclose(fp);
        return nullptr;
    }
    return bzfp;
}

/*---------------------------------------------------*/
/*--
   open file for read or write.
      ex) bzopen("file","w9")
      case path="" or nullptr => use stdin or stdout.
--*/
BZFILE* BZ_API(BZ2_bzopen)(const char* path, const char* mode) {
    return bzopen_or_bzdopen(path, -1, mode, /*bzopen*/ 0);
}

/*---------------------------------------------------*/
BZFILE* BZ_API(BZ2_bzdopen)(int fd, const char* mode) {
    return bzopen_or_bzdopen(nullptr, fd, mode, /*bzdopen*/ 1);
}

/*---------------------------------------------------*/
int BZ_API(BZ2_bzread)(BZFILE* b, void* buf, int len) {
    int bzerr, nread;
    if (((bzFile*)b)->lastErr == BZ_STREAM_END)
        return 0;
    nread = BZ2_bzRead(&bzerr, b, buf, len);
    if (bzerr == BZ_OK || bzerr == BZ_STREAM_END) {
        return nread;
    }
    else {
        return -1;
    }
}

/*---------------------------------------------------*/
int BZ_API(BZ2_bzwrite)(BZFILE* b, void* buf, int len) {
    int bzerr;

    BZ2_bzWrite(&bzerr, b, buf, len);
    if (bzerr == BZ_OK) {
        return len;
    }
    else {
        return -1;
    }
}

/*---------------------------------------------------*/
int BZ_API(BZ2_bzflush)(BZFILE* b) {
    /* do nothing now... */
    return 0;
}

/*---------------------------------------------------*/
void BZ_API(BZ2_bzclose)(BZFILE* b) {
    int bzerr;
    FILE* fp;

    if (b == nullptr) {
        return;
    }
    fp = ((bzFile*)b)->handle;
    if (((bzFile*)b)->writing) {
        BZ2_bzWriteClose(&bzerr, b, 0, nullptr, nullptr);
        if (bzerr != BZ_OK) {
            BZ2_bzWriteClose(nullptr, b, 1, nullptr, nullptr);
        }
    }
    else {
        BZ2_bzReadClose(&bzerr, b);
    }
    if (fp != stdin && fp != stdout) {
        fclose(fp);
    }
}

/*---------------------------------------------------*/
/*--
   return last error code 
--*/
static const char* bzerrorstrings[] = {
    "OK",
    "SEQUENCE_ERROR",
    "PARAM_ERROR",
    "MEM_ERROR",
    "DATA_ERROR",
    "DATA_ERROR_MAGIC",
    "IO_ERROR",
    "UNEXPECTED_EOF",
    "OUTBUFF_FULL",
    "CONFIG_ERROR",
    "???" /* for future */
    ,
    "???" /* for future */
    ,
    "???" /* for future */
    ,
    "???" /* for future */
    ,
    "???" /* for future */
    ,
    "???" /* for future */
};

const char* BZ_API(BZ2_bzerror)(BZFILE* b, int* errnum) {
    int err = ((bzFile*)b)->lastErr;

    if (err > 0)
        err = 0;
    *errnum = err;
    return bzerrorstrings[err * -1];
}
#endif

/*-------------------------------------------------------------*/
/*--- end                                           bzlib.c ---*/
/*-------------------------------------------------------------*/
