lib/zlib/compress.c
author EKR <ekr@rtfm.com>
Fri, 02 Dec 2016 16:32:09 +0100
changeset 12940 433172d35f525c82db3eb0b583f40e93a7d3a7c8
parent 10685 6c43fe3ab5dd41803bbd6705979f73275d7668f6
child 15480 91f3f0749d0b5c659b41b9be57ff8f9d8ef43553
permissions -rw-r--r--
Bug 1321809 - Only increment the advertised extensions when appending rather than on both passes. r=mt Differential Revision: https://nss-review.dev.mozaws.net/D111

/* compress.c -- compress a memory buffer
 * Copyright (C) 1995-2005 Jean-loup Gailly.
 * 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 (dest, destLen, source, sourceLen, level)
    Bytef *dest;
    uLongf *destLen;
    const Bytef *source;
    uLong sourceLen;
    int level;
{
    z_stream stream;
    int err;

    stream.next_in = (Bytef*)source;
    stream.avail_in = (uInt)sourceLen;
#ifdef MAXSEG_64K
    /* Check for source > 64K on 16-bit machine: */
    if ((uLong)stream.avail_in != sourceLen) return Z_BUF_ERROR;
#endif
    stream.next_out = dest;
    stream.avail_out = (uInt)*destLen;
    if ((uLong)stream.avail_out != *destLen) return Z_BUF_ERROR;

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

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

    err = deflate(&stream, Z_FINISH);
    if (err != Z_STREAM_END) {
        deflateEnd(&stream);
        return err == Z_OK ? Z_BUF_ERROR : err;
    }
    *destLen = stream.total_out;

    err = deflateEnd(&stream);
    return err;
}

/* ===========================================================================
 */
int ZEXPORT compress (dest, destLen, source, sourceLen)
    Bytef *dest;
    uLongf *destLen;
    const Bytef *source;
    uLong 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.
 */
uLong ZEXPORT compressBound (sourceLen)
    uLong sourceLen;
{
    return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
           (sourceLen >> 25) + 13;
}