/*

  zip_algorithm_deflate.c -- deflate (de)compression routines

  Copyright (C) 2017-2025 Dieter Baron and Thomas Klausner

  This file is part of libzip, a library to manipulate ZIP archives.

  The authors can be contacted at <info@libzip.org>

  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. 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.

  3. The names of the authors may not be used to endorse or promote

     products derived from this software without specific prior

     written permission.

  THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHORS 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.

*/

#include "zipint.h"

#include <limits.h>

#include <stdlib.h>

#include <zlib.h>

struct ctx {

    zip_error_t *error;

    bool compress;

    int level;

    int mem_level;

    bool end_of_input;

    z_stream zstr;

};

static zip_uint64_t maximum_compressed_size(zip_uint64_t uncompressed_size) {

    /* max deflate size increase: size + ceil(size/16k)*5+6 */

    zip_uint64_t compressed_size = uncompressed_size + (uncompressed_size + 16383) / 16384 * 5 + 6;

    if (compressed_size < uncompressed_size) {

        return ZIP_UINT64_MAX;

    }

    return compressed_size;

}

static void *allocate(bool compress, zip_uint32_t compression_flags, zip_error_t *error) {

    struct ctx *ctx;

    if ((ctx = (struct ctx *)malloc(sizeof(*ctx))) == NULL) {

        zip_error_set(error, ZIP_ET_SYS, errno);

        return NULL;

    }

    ctx->error = error;

    ctx->compress = compress;

    if (compression_flags >= 1 && compression_flags <= 9) {

        ctx->level = (int)compression_flags;

    }

    else {

        ctx->level = Z_BEST_COMPRESSION;

    }

    ctx->mem_level = compression_flags == TORRENTZIP_COMPRESSION_FLAGS ? TORRENTZIP_MEM_LEVEL : MAX_MEM_LEVEL;

    ctx->end_of_input = false;

    ctx->zstr.zalloc = Z_NULL;

    ctx->zstr.zfree = Z_NULL;

    ctx->zstr.opaque = NULL;

    return ctx;

}

static void *compress_allocate(zip_uint16_t method, zip_uint32_t compression_flags, zip_error_t *error) {

    (void)method;

    return allocate(true, compression_flags, error);

}

static void *decompress_allocate(zip_uint16_t method, zip_uint32_t compression_flags, zip_error_t *error) {

    (void)method;

    return allocate(false, compression_flags, error);

}

static void deallocate(void *ud) {

    struct ctx *ctx = (struct ctx *)ud;

    free(ctx);

}

static zip_uint16_t general_purpose_bit_flags(void *ud) {

    struct ctx *ctx = (struct ctx *)ud;

    if (!ctx->compress) {

        return 0;

    }

    if (ctx->level < 3) {

        return 2 << 1;

    }

    else if (ctx->level > 7) {

        return 1 << 1;

    }

    return 0;

}

static bool start(void *ud, zip_stat_t *st, zip_file_attributes_t *attributes) {

    struct ctx *ctx = (struct ctx *)ud;

    int ret;

    (void)st;

    (void)attributes;

    ctx->zstr.avail_in = 0;

    ctx->zstr.next_in = NULL;

    ctx->zstr.avail_out = 0;

    ctx->zstr.next_out = NULL;

    if (ctx->compress) {

        /* negative value to tell zlib not to write a header */

        ret = deflateInit2(&ctx->zstr, ctx->level, Z_DEFLATED, -MAX_WBITS, ctx->mem_level, Z_DEFAULT_STRATEGY);

    }

    else {

        ret = inflateInit2(&ctx->zstr, -MAX_WBITS);

    }

    if (ret != Z_OK) {

        zip_error_set(ctx->error, ZIP_ER_ZLIB, ret);

        return false;

    }

    return true;

}

static bool end(void *ud) {

    struct ctx *ctx = (struct ctx *)ud;

    int err;

    if (ctx->compress) {

        err = deflateEnd(&ctx->zstr);

    }

    else {

        err = inflateEnd(&ctx->zstr);

    }

    if (err != Z_OK) {

        zip_error_set(ctx->error, ZIP_ER_ZLIB, err);

        return false;

    }

    return true;

}

static bool input(void *ud, zip_uint8_t *data, zip_uint64_t length) {

    struct ctx *ctx = (struct ctx *)ud;

    if (length > UINT_MAX || ctx->zstr.avail_in > 0) {

        zip_error_set(ctx->error, ZIP_ER_INVAL, 0);

        return false;

    }

    ctx->zstr.avail_in = (uInt)length;

    ctx->zstr.next_in = (Bytef *)data;

    return true;

}

static bool end_of_input(void *ud) {

    struct ctx *ctx = (struct ctx *)ud;

    ctx->end_of_input = true;

    return ctx->zstr.avail_in != 0;

}

static zip_compression_status_t process(void *ud, zip_uint8_t *data, zip_uint64_t *length) {

    struct ctx *ctx = (struct ctx *)ud;

    uInt avail_out;

    int ret;

    avail_out = (uInt)ZIP_MIN(UINT_MAX, *length);

    ctx->zstr.avail_out = avail_out;

    ctx->zstr.next_out = (Bytef *)data;

    if (ctx->compress) {

        ret = deflate(&ctx->zstr, ctx->end_of_input ? Z_FINISH : 0);

    }

    else {

        ret = inflate(&ctx->zstr, Z_SYNC_FLUSH);

    }

    *length = avail_out - ctx->zstr.avail_out;

    switch (ret) {

    case Z_OK:

        return ZIP_COMPRESSION_OK;

    case Z_STREAM_END:

        return ZIP_COMPRESSION_END;

    case Z_BUF_ERROR:

        if (ctx->zstr.avail_in == 0) {

            return ZIP_COMPRESSION_NEED_DATA;

        }

        /* fallthrough */

    default:

        zip_error_set(ctx->error, ZIP_ER_ZLIB, ret);

        return ZIP_COMPRESSION_ERROR;

    }

}

/* clang-format off */

zip_compression_algorithm_t zip_algorithm_deflate_compress = {

    maximum_compressed_size,

    compress_allocate,

    deallocate,

    general_purpose_bit_flags,

    20,

    start,

    end,

    input,

    end_of_input,

    process

};

zip_compression_algorithm_t zip_algorithm_deflate_decompress = {

    maximum_compressed_size,

    decompress_allocate,

    deallocate,

    general_purpose_bit_flags,

    20,

    start,

    end,

    input,

    end_of_input,

    process

};

/* clang-format on */