[jira] [Resolved] (ARROW-4018) [C++] RLE decoder may not big-endian compatible

["Antoine Pitrou (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-4018?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Antoine Pitrou resolved ARROW-4018.
-----------------------------------
    Fix Version/s: 1.0.0
       Resolution: Fixed

Issue resolved by pull request 7144
[https://github.com/apache/arrow/pull/7144]

> [C++] RLE decoder may not big-endian compatible
> -----------------------------------------------
>
>                 Key: ARROW-4018
>                 URL: https://issues.apache.org/jira/browse/ARROW-4018
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: C++
>    Affects Versions: 0.11.1
>            Reporter: Antoine Pitrou
>            Assignee: Kazuaki Ishizaki
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.0.0
>
>          Time Spent: 1h
>  Remaining Estimate: 0h
>
> This issue was found by Coverity. The {{RleDecoder::NextCounts}} method has the following code to fetch the repeated literal in repeated runs:
> {code:c++}
>     bool result =
>         bit_reader_.GetAligned<T>(static_cast<int>(BitUtil::CeilDiv(bit_width_, 8)),
>                                   reinterpret_cast<T*>(&current_value_));
> {code}
> Coverity says this:
> bq. Pointer "&this->current_value_" points to an object whose effective type is "unsigned long long" (64 bits, unsigned) but is dereferenced as a narrower "unsigned int" (32 bits, unsigned). This may lead to unexpected results depending on machine endianness.
> bq. 
> In addition, it's not obvious whether {{current_value_}} also needs byte-swapping (presumably, at least in the Parquet file format, it's supposed to be stored in little-endian format in the RLE bitstream).



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