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1   package nom.tam.fits.compress;
2   
3   /*
4    * #%L
5    * nom.tam FITS library
6    * %%
7    * Copyright (C) 1996 - 2024 nom-tam-fits
8    * %%
9    * This is free and unencumbered software released into the public domain.
10   *
11   * Anyone is free to copy, modify, publish, use, compile, sell, or
12   * distribute this software, either in source code form or as a compiled
13   * binary, for any purpose, commercial or non-commercial, and by any
14   * means.
15   *
16   * In jurisdictions that recognize copyright laws, the author or authors
17   * of this software dedicate any and all copyright interest in the
18   * software to the public domain. We make this dedication for the benefit
19   * of the public at large and to the detriment of our heirs and
20   * successors. We intend this dedication to be an overt act of
21   * relinquishment in perpetuity of all present and future rights to this
22   * software under copyright law.
23   *
24   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
27   * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
28   * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
29   * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
30   * OTHER DEALINGS IN THE SOFTWARE.
31   * #L%
32   */
33  
34  import java.io.IOException;
35  import java.io.InputStream;
36  import java.util.logging.Logger;
37  
38  import nom.tam.fits.FitsException;
39  
40  /**
41   * (<i>for internal use</i>) BZIP2 (<code>.bz2</code>) input stream decompression with a preference for using an
42   * external system command. You can use this class to decompress files that have been compressed with the UNIX
43   * <b>bzip2</b> tool and have the characteristic <code>.bz2</code> file name extension. It effectively provides the same
44   * functionality as {@link BZip2CompressionProvider}, but has a preference for calling on the system <b>bzip2</b>
45   * command first to do the lifting. If that fails it will call on {@link CompressionManager} to provide a suitable
46   * decompressor (which will give it {@link BZip2CompressionProvider}). Since the <b>bzip2</b> tool is UNIX-specific, it
47   * is not entirely portable. It also requires the environment variable <code>BZIP_DECOMPRESSOR</code> to be set to
48   * provide the system executable to use. As a result, you are probably better off relying on the mentioned other classes
49   * directly for this functionality.
50   * 
51   * @see        CompressionManager
52   * 
53   * @deprecated Use {@link ZCompressionProvider}, or the more generic {@link CompressionManager} with a preference toward
54   *                 using the system command if possible, instead.
55   */
56  @Deprecated
57  public class ExternalBZip2CompressionProvider implements ICompressProvider {
58  
59      private static final int PRIORITY = 10;
60  
61      private static final Logger LOG = Logger.getLogger(ExternalBZip2CompressionProvider.class.getName());
62  
63      private InputStream bunzipper(final InputStream compressed) throws IOException, FitsException {
64          String cmd = getBzip2Cmd();
65          // Allow the user to have already specified the - option.
66          if (cmd.indexOf(" -") < 0) {
67              cmd += " -";
68          }
69          String[] flds = cmd.split(" +");
70          Process proc;
71          try {
72              proc = new ProcessBuilder(flds).start();
73              return new CloseIS(proc, compressed);
74          } catch (Exception e) {
75              ICompressProvider next = CompressionManager.nextCompressionProvider('B', 'Z', this);
76              if (next != null) {
77                  LOG.warning("Error initiating BZIP decompression: " + e.getMessage() + " trying alternative decompressor");
78                  return next.decompress(compressed);
79              }
80              throw new FitsException("Error initiating BZIP decompression: " + e);
81          }
82      }
83  
84      /**
85       * Returns the system command to use for decompressing <code>.bz2</code> compressed files. It requires the
86       * <code>BZIP_DECOMPRESSOR</code> environment variable to be set to inform us as to what executable (including path)
87       * should be used. If there is no such environment variable set, it will return <code>null</code>
88       * 
89       * @return The system command for decompressing <code>.bz2</code> files, or <code>null</code> if there is no
90       *             <code>BZIP_DECOMPRESSOR</code> environment variable that could inform us.
91       */
92      public String getBzip2Cmd() {
93          return System.getProperty("BZIP_DECOMPRESSOR", System.getenv("BZIP_DECOMPRESSOR"));
94      }
95  
96      @Override
97      public InputStream decompress(InputStream in) throws IOException, FitsException {
98          return bunzipper(in);
99      }
100 
101     @Override
102     public int priority() {
103         return PRIORITY;
104     }
105 
106     @Override
107     public boolean provides(int mag1, int mag2) {
108         return mag1 == 'B' && mag2 == 'Z' && getBzip2Cmd() != null;
109     }
110 }