n_zlib.c

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/*
 * Nilorea Library
 * Copyright (C) 2005-2026 Castagnier Mickael
 *
 * 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.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#include "nilorea/n_zlib.h"
#include "nilorea/n_log.h"
#include "limits.h"
 
#ifndef __windows__
#include <arpa/inet.h>
#else
#include "nilorea/n_windows.h"
#endif
 
size_t GetMaxCompressedLen(size_t nLenSrc) {
    size_t n16kBlocks = (nLenSrc + 16383) / 16384;  // round up any fraction of a block
    return (nLenSrc + 6 + (n16kBlocks * 5));
} /* GetMaxCompressedLen */
 
size_t CompressData(unsigned char* abSrc, size_t nLenSrc, unsigned char* abDst, size_t nLenDst) {
    __n_assert(abSrc, return 0);
    __n_assert(abDst, return 0);
 
    if (nLenSrc == 0) {
        n_log(LOG_ERR, "nLenSrc == 0");
        return 0;
    }
    if (nLenDst == 0) {
        n_log(LOG_ERR, "nLenDst == 0");
        return 0;
    }
    if (nLenSrc > UINT_MAX) {
        n_log(LOG_ERR, "nLenSrc is bigger than UINT_MAX");
        return 0;
    }
    if (nLenDst > UINT_MAX) {
        n_log(LOG_ERR, "nLenDst is bigger than UINT_MAX");
        return 0;
    }
 
    z_stream zInfo;
    memset(&zInfo, 0, sizeof(zInfo));
    zInfo.total_in = zInfo.avail_in = (unsigned int)nLenSrc;
    zInfo.total_out = zInfo.avail_out = (unsigned int)nLenDst;
    zInfo.next_in = (unsigned char*)abSrc;
    zInfo.next_out = abDst;
 
    int nErr = 0;
    size_t nRet = 0;
    nErr = deflateInit(&zInfo, Z_DEFAULT_COMPRESSION);  // zlib function
    switch (nErr) {
        case Z_OK:
            // all is fine
            break;
        default:
            n_log(LOG_ERR, "%s on string %p size %zu", zError(nErr), abSrc, nLenSrc);
            return 0;
    }
    nErr = deflate(&zInfo, Z_FINISH);  // zlib function
    if (nErr == Z_STREAM_END) {
        nRet = zInfo.total_out;
    } else {
        n_log(LOG_ERR, "%s on string %p size %zu", zError(nErr), abSrc, nLenSrc);
    }
    deflateEnd(&zInfo);  // zlib function
    return nRet;
} /* CompressData */
 
size_t UncompressData(unsigned char* abSrc, size_t nLenSrc, unsigned char* abDst, size_t nLenDst) {
    __n_assert(abSrc, return 0);
    __n_assert(abDst, return 0);
 
    if (nLenSrc == 0) {
        n_log(LOG_ERR, "nLenSrc == 0");
        return 0;
    }
    if (nLenDst == 0) {
        n_log(LOG_ERR, "nLenDst == 0");
        return 0;
    }
    if (nLenSrc > UINT_MAX) {
        n_log(LOG_ERR, "nLenSrc is bigger than UINT_MAX");
        return 0;
    }
    if (nLenDst > UINT_MAX) {
        n_log(LOG_ERR, "nLenDst is bigger than UINT_MAX");
        return 0;
    }
 
    z_stream zInfo;
    memset(&zInfo, 0, sizeof(zInfo));
    zInfo.total_in = zInfo.avail_in = (unsigned int)nLenSrc;
    zInfo.total_out = zInfo.avail_out = (unsigned int)nLenDst;
    zInfo.next_in = (unsigned char*)abSrc;
    zInfo.next_out = abDst;
 
    int nErr = 0;
    size_t nRet = 0;
    nErr = inflateInit(&zInfo);  // zlib function
    switch (nErr) {
        case Z_OK:
            // all is fine
            break;
        default:
            n_log(LOG_ERR, "%s on string %p size %zu", zError(nErr), abSrc, nLenSrc);
            return 0;
    }
    nErr = inflate(&zInfo, Z_FINISH);  // zlib function
    if (nErr == Z_STREAM_END) {
        nRet = zInfo.total_out;
    } else {
        n_log(LOG_ERR, "%s on string %p size %zu", zError(nErr), abSrc, nLenSrc);
    }
    inflateEnd(&zInfo);  // zlib function
    return nRet;         // -1 or len of output
} /* UncompressData */
 
N_STR* zip_nstr(N_STR* src) {
    __n_assert(src, return NULL);
    __n_assert(src->data, return NULL);
 
    if (src->length == 0) {
        n_log(LOG_ERR, "length of src == 0");
        return NULL;
    }
    if (src->written == 0) {
        n_log(LOG_ERR, "written of src == 0");
        return NULL;
    }
    if (src->length > UINT_MAX) {
        n_log(LOG_ERR, "length of src > UINT_MAX");
        return NULL;
    }
    if (src->written > UINT_MAX) {
        n_log(LOG_ERR, "written of src > UINT_MAX");
        return NULL;
    }
 
    /* storage for original string size + zipped string  + padding */
    size_t zip_max_size = GetMaxCompressedLen(src->length);
 
    N_STR* zipped = new_nstr(4 + zip_max_size);
 
    __n_assert(zipped, return NULL);
    __n_assert(zipped->data, return NULL);
 
    /* copying size */
    uint32_t src_length = htonl((uint32_t)src->length);
    memcpy(zipped->data, &src_length, sizeof(uint32_t));
    char* dataptr = zipped->data + 4;
 
    size_t compressed_size = CompressData((unsigned char*)src->data, src->written, (unsigned char*)dataptr, zip_max_size);
    if (compressed_size == 0) {
        free_nstr(&zipped);
        n_log(LOG_ERR, "unable to zip string %p  %zu/%zu bytes", src->data, src->written, src->length);
        return NULL;
    }
    zipped->written = 4 + compressed_size;
    n_log(LOG_DEBUG, "zip :%zu original: %zu", zipped->written, src->length);
 
    return zipped;
} /* zip_nstr */
 
N_STR* unzip_nstr(N_STR* src) {
    __n_assert(src, return NULL);
    __n_assert(src->data, return NULL);
 
    if (src->length == 0) {
        n_log(LOG_ERR, "length of src == 0");
        return NULL;
    }
    if (src->written == 0) {
        n_log(LOG_ERR, "written of src == 0");
        return NULL;
    }
 
    if (src->written < 4) {
        n_log(LOG_ERR, "compressed data too short");
        return NULL;
    }
 
    uint32_t original_size = 0;
    memcpy(&original_size, src->data, sizeof(uint32_t));
    original_size = ntohl(original_size);
    if (original_size == 0) {
        n_log(LOG_ERR, "original_size == 0");
        return NULL;
    }
    if (original_size > 256 * 1024 * 1024) {
        n_log(LOG_ERR, "decompressed size too large: %u", original_size);
        return NULL;
    }
    /* storage for original string size + zipped string  + padding */
    N_STR* unzipped = new_nstr(original_size);
    __n_assert(unzipped, return NULL);
    __n_assert(unzipped->data, return NULL);
 
    /* copying size */
    unzipped->written = UncompressData(((unsigned char*)src->data) + 4, src->written - 4, (unsigned char*)unzipped->data, original_size);
    if (unzipped->written == 0) {
        n_log(LOG_ERR, "unable to unzip string %p  %zu/%zu bytes", unzipped->data, unzipped->written, unzipped->length);
        free_nstr(&unzipped);
        return NULL;
    }
    n_log(LOG_DEBUG, "Size: zip: %zu => unzip :%zu original:%u", src->written, unzipped->written, original_size);
 
    return unzipped;
} /* unzip_nstr */