[jira] [Updated] (TIKA-1430) CHM parser gets faulty text (fix found)

["Hong-Thai Nguyen (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TIKA-1430?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hong-Thai Nguyen updated TIKA-1430:
-----------------------------------
    Fix Version/s: 1.7

> CHM parser gets faulty text (fix found)
> ---------------------------------------
>
>                 Key: TIKA-1430
>                 URL: https://issues.apache.org/jira/browse/TIKA-1430
>             Project: Tika
>          Issue Type: Bug
>          Components: parser
>    Affects Versions: 1.5, 1.6
>         Environment: Windows 7; JDK 7 or 8
>            Reporter: Bin Hawking
>            Priority: Critical
>             Fix For: 1.7
>
>
> Get partially wrong text out of a CHM file, including the chm files in tika-parsers/src/test/resources/test-documents/testChm*.chm
> I tried 1.6 and 1.5. Same bad. I wonder why no one complained before? 
> I checked the source code. The cause is obvious:
> When tika decompresses the LZX, the first block is done well, but as to the 2nd block and later on, Tika uses previous content as the compressed data. see in org.apache.tika.parser.chm.lzx.ChmLzxBlock
> """
>                 if (prevBlock != null
>                         && prevBlock.getState().getBlockLength() > prevBlock
>                                 .getState().getBlockRemaining())
>                     setChmSection(new ChmSection(prevBlock.getContent()));
> //                   NOTE: the dataSegment to be decompressed is not kept
>                 else
>                     setChmSection(new ChmSection(dataSegment));
> """
> My fix:
> 1.	Add a prevcontent member variable in ChmSection class, so that dataSegment and prevBlock.getContent() are both kept in it.
> 2.	In ChmLzxBlock.extractContent() when invoking decompressXXXXBlock(), pass ChmSection.prevcontent if exists, instead of ChmSection.data.
> Now, I tried some chm files, and got the correct looking texts. 
> BTW. The unit test should be tougher, as in this case some small text (the first block) is decompressed correctly.



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