title: Using zlib to create a gzip file using zpipe.c example
body: <p>All,</p>
  
  <p>I am just trying to get the zpipe demo working using dev-c++ where I have all the zlib code imported and using the zpipe.c as an example.  Everything compiles and runs.  If I try to create a gzip file using the commented out call to deflateInit2 it creates with now errors, but is corrupted when unzipping with 7zip.  If I use the standard zlib headers to create the file, when I use the corresponding call to inflate it give me a return of -3/Z_DATA_ERROR indicating my defalte data is corrupted.  Everything points to something being wrong in the def unction, but its pretty much exactly the example. </p>
  
  <p>Any ideas??  Thanks so much in advance! </p>
  
  <pre><code>int main(int argc, char **argv)
  {
       int ret;
       FILE *source;
       FILE *zip;
       FILE *zipped;
       FILE *back;
  
       source = fopen ("C:\\Users\\schmoudm\\Pictures\\caela.jpg", "r");
       zip = fopen ("C:\\Core\\RD\\test.gz", "w");
  
       printf ("calling def \n");
       ret = def(source, zip, Z_DEFAULT_COMPRESSION);
       printf("def return: %i \n", ret);
       fclose(source);
       fclose(zip);
  
       if (ret == 0) {
          printf ("setting up inf \n");
          zipped = fopen ("C:\\Core\\RD\\test.gz", "r"); 
          back = fopen ("C:\\Core\\RD\\zlibout.txt", "w"); 
          printf ("calling inf \n");
          ret = inf(zipped, back); 
          printf("inf return: %i \n", ret);  
          zerr(ret);
       }
  
      fclose(source);
      fclose(zip);
  
      printf("DONE!");
      system("PAUSE");
      return 0;
  }
  
  int def(FILE *source, FILE *dest, int level)
  {
      int ret, flush;
      unsigned have;
      z_stream strm;
      unsigned char in[CHUNK];
      unsigned char out[CHUNK];
  
      /* allocate deflate state */
      strm.zalloc = Z_NULL;
      strm.zfree = Z_NULL;
      strm.opaque = Z_NULL;
  
      ret = deflateInit(&amp;strm, Z_DEFAULT_COMPRESSION);
      //ret = deflateInit2(&amp;strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, (15+16), 8,       Z_DEFAULT_STRATEGY);
      if (ret != Z_OK)
          return ret;
  
      /* compress until end of file */
      do {
          strm.avail_in = fread(in, 1, CHUNK, source);
          printf("available in: %u \n", strm.avail_in);  
          if (ferror(source)) {
              (void)deflateEnd(&amp;strm);
              return Z_ERRNO;
          }
          flush = feof(source) ? Z_FINISH : Z_NO_FLUSH;
          strm.next_in = in;
  
          /* run deflate() on input until output buffer not full, finish
             compression if all of source has been read in */
          do {
              strm.avail_out = CHUNK;
              strm.next_out = out;
              ret = deflate(&amp;strm, flush);    /* no bad return value */
              assert(ret != Z_STREAM_ERROR);  /* state not clobbered */
              have = CHUNK - strm.avail_out;
              if (fwrite(out, 1, have, dest) != have || ferror(dest)) {
                  (void)deflateEnd(&amp;strm);
                  return Z_ERRNO;
              }
          } while (strm.avail_out == 0);
          assert(strm.avail_in == 0);     /* all input will be used */
  
          /* done when last data in file processed */
      } while (flush != Z_FINISH);
      assert(ret == Z_STREAM_END);        /* stream will be complete */
  
      /* clean up and return */
      (void)deflateEnd(&amp;strm);
      return Z_OK;
  }
  </code></pre>