Review Request 127968: kshareddatacache: Fix invalid use of & to avoid unaligned reads

[Michael Pyne]

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Ship it!




This is an error upstream in the MurmurHash 1.0 aligned implementation (which still contains the error, see https://sites.google.com/site/murmurhash/MurmurHashAligned.cpp?attredirects=0 )

In our case KSharedDataCache will never pass an unaligned block into the hash function so 'align' was always 0 (and boolean false) anyways. So I concur with not bumping the cache version and agree with your patch. Thanks for taking a look!

- Michael Pyne


On May 19, 2016, 6:13 p.m., Fabian Vogt wrote:
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> https://git.reviewboard.kde.org/r/127968/
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> (Updated May 19, 2016, 6:13 p.m.)
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> Review request for KDE Frameworks, David Faure and Michael Pyne.
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> Repository: kcoreaddons
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> Description
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> That the & is wrong here is obvious:
> align can never be 2 inside the if condition as ```(2 & bool)``` is always false,
> yet the switch on align contains a case for 2.
> Instead it drops into the while loop for an 4-byte aligned pointer.
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> This doesn't change the returned values on platforms where unaligned reads
> are permitted, so I didn't bump the version.
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> Diffs
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>   src/lib/caching/kshareddatacache.cpp 50bbf64 
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> Diff: https://git.reviewboard.kde.org/r/127968/diff/
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> Testing
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> Ran make test, all passed.
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> Thanks,
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> Fabian Vogt
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>

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