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https://issues.apache.org/jira/browse/ARROW-2790?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated ARROW-2790:
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Labels: pull-request-available (was: )
> [C++] Buffers contain uninitialized memory
> ------------------------------------------
>
> Key: ARROW-2790
> URL: https://issues.apache.org/jira/browse/ARROW-2790
> Project: Apache Arrow
> Issue Type: New Feature
> Components: C++
> Affects Versions: 0.9.0
> Reporter: Dimitri Vorona
> Priority: Major
> Labels: pull-request-available
>
> Hi,
> currently, buffers can contain uninitalized memory when built with buffer
> builders. This happens in two ways:
> # The most common implementation of AppendNull(s) adds a null-bit to the
> null-map and increments the lengths, leaving chunks of data values untouched
> # The padding is never initialized
> This can lead to a number of problems, some of more or less theoretical
> nature, but it's worth fixing just to make valgrind happy again and allow it
> to run in CI :) Also, leaking uninitialized memory over a wire is never nice,
> and currently problem 1. ist never mitigated by the ipc writers (although the
> problem 2 ist).
> This PR changes the behaviour of AppendNull(s) for the affected builders and
> adds a lot of checks to ensure the correct initialization. Most of the test
> succeed the current master, but cause valgrind warnings, if the buffer
> builders aren't patched.
> I decided not to test explicitly if the nulled/padded memory is really 0,
> just that it can be read without errors, since the specs don't specify exact
> values.
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