ClickHouse/contrib/libzlib-ng/compress.c

/* compress.c -- compress a memory buffer
 * Copyright (C) 1995-2005, 2014 Jean-loup Gailly, Mark Adler.
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

/* @(#) $Id$ */

#define ZLIB_INTERNAL
#include "zlib.h"

/* ===========================================================================
     Compresses the source buffer into the destination buffer. The level
   parameter has the same meaning as in deflateInit.  sourceLen is the byte
   length of the source buffer. Upon entry, destLen is the total size of the
   destination buffer, which must be at least 0.1% larger than sourceLen plus
   12 bytes. Upon exit, destLen is the actual size of the compressed buffer.

     compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
   memory, Z_BUF_ERROR if there was not enough room in the output buffer,
   Z_STREAM_ERROR if the level parameter is invalid.
*/
int ZEXPORT compress2(unsigned char *dest, size_t *destLen, const unsigned char *source,
                        size_t sourceLen, int level) {
    z_stream stream;
    int err;
    const unsigned int max = (unsigned int)0 - 1;
    size_t left;

    left = *destLen;
    *destLen = 0;

    stream.zalloc = (alloc_func)0;
    stream.zfree = (free_func)0;
    stream.opaque = NULL;

    err = deflateInit(&stream, level);
    if (err != Z_OK)
        return err;

    stream.next_out = dest;
    stream.avail_out = 0;
    stream.next_in = (const unsigned char *)source;
    stream.avail_in = 0;

    do {
        if (stream.avail_out == 0) {
            stream.avail_out = left > (unsigned long)max ? max : (unsigned int)left;
            left -= stream.avail_out;
        }
        if (stream.avail_in == 0) {
            stream.avail_in = sourceLen > (unsigned long)max ? max : (unsigned int)sourceLen;
            sourceLen -= stream.avail_in;
        }
        err = deflate(&stream, sourceLen ? Z_NO_FLUSH : Z_FINISH);
    } while (err == Z_OK);

    *destLen = stream.total_out;
    deflateEnd(&stream);
    return err == Z_STREAM_END ? Z_OK : err;
}

/* ===========================================================================
 */
int ZEXPORT compress(unsigned char *dest, size_t *destLen, const unsigned char *source, size_t sourceLen) {
    return compress2(dest, destLen, source, sourceLen, Z_DEFAULT_COMPRESSION);
}

/* ===========================================================================
   If the default memLevel or windowBits for deflateInit() is changed, then
   this function needs to be updated.
 */
size_t ZEXPORT compressBound(size_t sourceLen) {
    return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + (sourceLen >> 25) + 13;
}