[Libreoffice-commits] core.git: initialize new member variables

[Chris Sherlock]

Hi all,

Unfortunately that was the case - I definitely went down the wrong path with that merge.

I've reverted it now - the commit can be found on http://cgit.freedesktop.org/libreoffice/core/commit/?id=b4b0cc2a5eef42434444e51fda4a13fc48183aa0

I need to check that UBSan tool more regularly.

But I definitely have to put my hand up for causing these errors. Apologies for this, I will do my level best not to let this occur again.

When I'm back home I've been meaning to send a post to the list summarising how font handling works and some ideas and questions around the code.

Thanks all (especially Caolon and Stephan)!

Chris

> On 12 Jan 2016, at 7:20 PM, Stephan Bergmann <sbergman at redhat.com> wrote:
> 
>> On 01/11/2016 06:29 PM, Caolán McNamara wrote:
>> commit c93a43c0c9113bc1c787fe6b3c5e58a8bfd80be0
>> Author: Caolán McNamara <caolanm at redhat.com>
>> Date:   Mon Jan 11 17:08:39 2016 +0000
>> 
>>     initialize new member variables
>> 
>>     Change-Id: I3839bc134b337ccb7cfdb2ee70524e4721c8f83c
>> 
>> diff --git a/vcl/source/font/fontattributes.cxx b/vcl/source/font/fontattributes.cxx
>> index be3ab68..49060f0 100644
>> --- a/vcl/source/font/fontattributes.cxx
>> +++ b/vcl/source/font/fontattributes.cxx
>> @@ -93,7 +93,18 @@ bool FontAttributes::CompareDeviceIndependentFontAttributes(const FontAttributes
>>  }
>> 
>>  FontAttributes::FontAttributes()
>> -    : mnWidth ( 0 )
>> +    : meWeight(WEIGHT_DONTKNOW)
>> +    , meItalic(ITALIC_DONTKNOW)
>> +    , meFamily(FAMILY_DONTKNOW)
>> +    , mePitch(PITCH_DONTKNOW)
>> +    , meWidthType(WIDTH_DONTKNOW)
>> +    , mbSymbolFlag(false)
>> +    , mnQuality(0)
>> +    , mbOrientation(false)
>> +    , mbDevice(false)
>> +    , mbSubsettable(false)
>> +    , mbEmbeddable(false)
>> +    , mnWidth ( 0 )
>>      , mnOrientation( 0 )
>>      , mnAscent( 0 )
>>      , mnDescent( 0 )
> [...]
> 
> Tools like UBSan or Valgrind's memcheck started to complain about reads of uninitialized members after a series of commits that merged font-related structs in VCL together.  What looked fishy is that those members had not been default-initialized in the original structs, the number of setter calls had not changed, and yet the code started to grow uninitialized reads of the members.  Without a clear understanding of what was going on, we were reluctant to blindly default-initialize those members now, as it might hide problems (at least from the eyes of UBSan and Valgrind) instead of fixing them.
> 
> Now, as I understand, Chris is going to revert those merges, as he came to the conclusion that they went in the wrong direction after all, and I assume that will obsolete the above potentially problematic commit anyway.