compress.c revision 17652 
1/* compress.c -- compress a memory buffer
2 * Copyright (C) 1995-1996 Jean-loup Gailly.
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */
5
6/* $Id: compress.c,v 1.10 1996/05/23 16:51:12 me Exp $ */
7
8#include "zlib.h"
9
10/* ===========================================================================
11     Compresses the source buffer into the destination buffer.  sourceLen is
12   the byte length of the source buffer. Upon entry, destLen is the total
13   size of the destination buffer, which must be at least 0.1% larger than
14   sourceLen plus 8 bytes. Upon exit, destLen is the actual size of the
15   compressed buffer.
16     This function can be used to compress a whole file at once if the
17   input file is mmap'ed.
18     compress returns Z_OK if success, Z_MEM_ERROR if there was not
19   enough memory, Z_BUF_ERROR if there was not enough room in the output
20   buffer.
21*/
22int compress (dest, destLen, source, sourceLen)
23    Bytef *dest;
24    uLongf *destLen;
25    const Bytef *source;
26    uLong sourceLen;
27{
28    z_stream stream;
29    int err;
30
31    stream.next_in = (Bytef*)source;
32    stream.avail_in = (uInt)sourceLen;
33#ifdef MAXSEG_64K
34    /* Check for source > 64K on 16-bit machine: */
35    if ((uLong)stream.avail_in != sourceLen) return Z_BUF_ERROR;
36#endif
37    stream.next_out = dest;
38    stream.avail_out = (uInt)*destLen;
39    if ((uLong)stream.avail_out != *destLen) return Z_BUF_ERROR;
40
41    stream.zalloc = (alloc_func)0;
42    stream.zfree = (free_func)0;
43    stream.opaque = (voidpf)0;
44
45    err = deflateInit(&stream, Z_DEFAULT_COMPRESSION);
46    if (err != Z_OK) return err;
47
48    err = deflate(&stream, Z_FINISH);
49    if (err != Z_STREAM_END) {
50        deflateEnd(&stream);
51        return err == Z_OK ? Z_BUF_ERROR : err;
52    }
53    *destLen = stream.total_out;
54
55    err = deflateEnd(&stream);
56    return err;
57}
58