utils/wvgzip.cc

   1 /*
   2  * Worldvisions Weaver Software:
   3  *   Copyright (C) 1997-2002 Net Integration Technologies, Inc.
   4  *
   5  * Gzip encoder/decoder based on zlib.
   6  */
   7 #include "wvgzip.h"
   8 #include <zlib.h>
   9 #include <assert.h>
  10
  11 #define ZBUFSIZE 10240
  12
  13
  14 WvGzipEncoder::WvGzipEncoder(Mode _mode, size_t _out_limit) :
  15     out_limit(_out_limit), tmpbuf(ZBUFSIZE), mode(_mode)
  16 {
  17     ignore_decompression_errors = false;
  18     full_flush = false;
  19     init();
  20 }
  21
  22
  23 WvGzipEncoder::~WvGzipEncoder()
  24 {
  25     close();
  26 }
  27
  28
  29 void WvGzipEncoder::init()
  30 {
  31     zstr = new z_stream;
  32     memset(zstr, 0, sizeof(*zstr));
  33     zstr->zalloc = Z_NULL;
  34     zstr->zfree = Z_NULL;
  35     zstr->opaque = NULL;
  36     zstr->msg = NULL;
  37
  38     int retval;
  39     if (mode == Deflate)
  40         retval = deflateInit(zstr, Z_BEST_SPEED);
  41     else
  42         retval = inflateInit(zstr);
  43
  44     if (retval != Z_OK)
  45     {
  46         seterror("error %s initializing gzip %s: %s", retval,
  47             mode == Deflate ? "compressor" : "decompressor",
  48             zstr->msg ? zstr->msg : "unknown");
  49         return;
  50     }
  51     zstr->next_in = zstr->next_out = NULL;
  52     zstr->avail_in = zstr->avail_out = 0;
  53 }
  54
  55 void WvGzipEncoder::close()
  56 {
  57     if (mode == Deflate)
  58         deflateEnd(zstr);
  59     else
  60         inflateEnd(zstr);
  61
  62     delete zstr;
  63
  64 }
  65
  66 bool WvGzipEncoder::_encode(WvBuf &inbuf, WvBuf &outbuf, bool flush)
  67 {
  68     bool success;
  69     output = 0;
  70     for (;;)
  71     {
  72         size_t starting_size = inbuf.used();
  73         prepare(& inbuf);
  74         bool alldata = inbuf.used() == 0;
  75         success = process(outbuf, flush && alldata, false);
  76         if (zstr->avail_in != 0)
  77         {
  78             // unget unused data
  79             inbuf.unget(zstr->avail_in);
  80             zstr->avail_in = 0;
  81         }
  82         if (! success)
  83             return false;
  84         if (alldata || (starting_size == inbuf.used()) ||
  85             (out_limit && (output >= out_limit)))
  86             return true;
  87     }
  88 }
  89
  90
  91 bool WvGzipEncoder::_finish(WvBuf &outbuf)
  92 {
  93     prepare(NULL);
  94     return process(outbuf, false, true);
  95 }
  96
  97
  98 bool WvGzipEncoder::_reset()
  99 {
 100     close();
 101     init();
 102     return true;
 103 }
 104
 105
 106 void WvGzipEncoder::prepare(WvBuf *inbuf)
 107 {
 108     assert(zstr->avail_in == 0);
 109     if (inbuf && inbuf->used() != 0)
 110     {
 111         size_t avail = inbuf->optgettable();
 112         zstr->avail_in = avail;
 113         zstr->next_in = const_cast<Bytef*>(
 114             (const Bytef*)inbuf->get(avail));
 115     }
 116     else
 117     {
 118         zstr->avail_in = 0;
 119         zstr->next_in = (Bytef*)""; // so it's not NULL
 120     }
 121 }
 122
 123
 124 bool WvGzipEncoder::process(WvBuf &outbuf, bool flush, bool finish)
 125 {
 126     int flushmode = finish ? Z_FINISH :
 127         flush ? (full_flush ? Z_FULL_FLUSH : Z_SYNC_FLUSH) : Z_NO_FLUSH;
 128     int retval;
 129     do
 130     {
 131         // process the next chunk
 132         tmpbuf.zap();
 133         size_t avail_out = tmpbuf.free();
 134         if (out_limit)
 135             avail_out = tmpbuf.free() < (out_limit - output) ? tmpbuf.free()
 136                 : (out_limit - output);
 137
 138         zstr->avail_out = avail_out;
 139         zstr->next_out = tmpbuf.alloc(avail_out);
 140         if (mode == Deflate)
 141             retval = deflate(zstr, flushmode);
 142         else
 143             retval = inflate(zstr, flushmode);
 144         tmpbuf.unalloc(zstr->avail_out);
 145
 146         output += avail_out - zstr->avail_out;
 147
 148         // consume pending output
 149         outbuf.merge(tmpbuf);
 150
 151         if (retval == Z_DATA_ERROR && mode == Inflate
 152             && ignore_decompression_errors)
 153             retval = inflateSync(zstr);
 154     } while (retval == Z_OK && (!out_limit || (out_limit > output)));
 155
 156     if (retval == Z_STREAM_END)
 157         setfinished();
 158     else if (retval != Z_OK && retval != Z_BUF_ERROR &&
 159              !(retval == Z_DATA_ERROR && mode == Inflate
 160                && ignore_decompression_errors))
 161     {
 162         seterror("error %s during gzip %s: %s", retval,
 163             mode == Deflate ? "compression" : "decompression",
 164             zstr->msg ? zstr->msg : "unknown");
 165         return false;
 166     }
 167
 168     return true;
 169 }
 170