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Subject [jira] [Commented] (COMPRESS-277) IOUtils.skip does not work as advertised
Date Fri, 25 Apr 2014 23:35:17 GMT


BELUGA BEHR commented on COMPRESS-277:

Yes! Sorry!  I will move to a new ticket! I was confused in that I thought this had direct
changes to the TarInputStream class.  Thanks for bringing these issues to light!

I do admit that the code I suggested was a bit confusing, but I am trying to help you.  IOUtils#skip()
from the commons-io package does not call the stream's skip method, it only calls the stream's
read.  You may get better results with the approach I suggested because it allows you to just
skip the 'skip' process all together and just pass in a large read buffer allowing for fewer

> IOUtils.skip does not work as advertised
> ----------------------------------------
>                 Key: COMPRESS-277
>                 URL:
>             Project: Commons Compress
>          Issue Type: Bug
>    Affects Versions: 1.8
>            Reporter: Fabian Lange
>             Fix For: 1.9
>         Attachments:
> I am trying to feed a TarInputStream from a CipherInputStream.
> It does not work, because IOUtils.skip() does not adhere to the contract it claims in
> "     * <p>This method will only skip less than the requested number of
>      * bytes if the end of the input stream has been reached.</p>"
> However it does:
>             long skipped = input.skip(numToSkip);
>             if (skipped == 0) {
>                 break;
>             }
> And the input stream javadoc says:
> "     * This may result from any of a number of conditions; reaching end of file
>      * before <code>n</code> bytes have been skipped is only one possibility."
> In the case of CipherInputStream, it stops at the end of each byte buffer.
> If you check the IOUtils from colleagues at commons-io, they have considered this case
in IOUtils.skip() where they use a read to skip through the stream.
> An optimized version could combine trying to skip, then read then trying to skip again.

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