[HADOOP-8614] IOUtils#skipFully hangs forever on EOF

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0.0-alpha
• Fix Version/s: 0.23.3, 2.0.2-alpha
• Target Version/s: 2.0.2-alpha
• Hadoop Flags: Reviewed
• Assignee: Colin P. McCabe
• Reporter: Colin P. McCabe
• Created: 23/Jul/12 18:30
• Updated: 11/Oct/12 17:45
• Resolved: 29/Aug/12 21:15

Description

IOUtils#skipFully contains this code:

  public static void skipFully(InputStream in, long len) throws IOException {
    while (len > 0) {
      long ret = in.skip(len);
      if (ret < 0) {
        throw new IOException( "Premature EOF from inputStream");
      }
      len -= ret;
    }
  }

The Java documentation is silent about what exactly skip is supposed to do in the event of EOF. However, I looked at both InputStream#skip and ByteArrayInputStream#skip, and they both simply return 0 on EOF (no exception). So it seems safe to assume that this is the standard Java way of doing things in an InputStream.

Currently IOUtils#skipFully will loop forever if you ask it to skip past EOF!

Issue Links

• blocks: HDFS-3707 TestFSInputChecker: improper use of skip