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From "Julius Davies (JIRA)" <j...@apache.org>
Subject [jira] Updated: (CODEC-105) ArrayIndexOutOfBoundsException when doing multiple reads() on encoding b64InputStream
Date Sat, 22 Jan 2011 07:25:44 GMT

     [ https://issues.apache.org/jira/browse/CODEC-105?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Julius Davies updated CODEC-105:
--------------------------------

    Attachment: codec-105.patch

This fixes the bug by removing the "little optimization".   The fix is actually 99% code removal,
and it makes the overall base64 code a bit simpler, and should result in higher code-coverage
percentages, since I think this "little optimization" was hard to cover.

Mea culpa:  the "little optimization" was my own foolish idea from the beginning (it's there
in my original CODEC-69 patch), and I've felt funny about it for a long time.  Now that I
see it's even causing a real bug I'm very much +1 for purging it!!!   Sorry!

> ArrayIndexOutOfBoundsException when doing multiple reads() on encoding b64InputStream
> -------------------------------------------------------------------------------------
>
>                 Key: CODEC-105
>                 URL: https://issues.apache.org/jira/browse/CODEC-105
>             Project: Commons Codec
>          Issue Type: Bug
>    Affects Versions: 1.4
>         Environment: 64-bit Linux
>            Reporter: ZAK Magnus
>            Assignee: Julius Davies
>         Attachments: codec-105-junit-including-ASL2-license.patch, codec-105.patch
>
>
> When encoding a sizable stream byte by byte (so, just calling Base64InputStream.read()),
after 10920 successful read()s, this happens: 
> java.lang.ArrayIndexOutOfBoundsException: 2
>         at org.apache.commons.codec.binary.Base64.encode(Base64.java:502)
>         at org.apache.commons.codec.binary.Base64InputStream.read(Base64InputStream.java:157)
>         at org.apache.commons.codec.binary.Base64InputStream.read(Base64InputStream.java:109)
> Based on this, the necessary conditions seem to be that buffer = null and modulus = 2.
Then, if a read() is done, a single-byte buffer is used, whose length is doubled by resizeBuffer(),
but that still doesn't make it big enough to hold the 4 bytes written to it because modulus
was just incremented to 0. 
> Here's some sample code:
> import org.apache.commons.codec.binary.Base64InputStream;
> public class TestReads {
>     public static void main(String[] args) {
>         Base64InputStream b64stream = new Base64InputStream(System.in, true, 0, null);
>         int n = 0;
>         try {
>             while (b64stream.read() != -1) n++;
>         } catch (Exception x) {
>             System.out.println(n);
>             x.printStackTrace();
>         }
>     }
> }

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