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

[jan iversen]

Sent from my iPad, please excuse any misspellings 

> On 12 Jan 2016, at 12:05, Chris Sherlock <chris.sherlock79 at gmail.com> wrote:
> 
> 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.
Even better would be to make a wiki page :-)

rgds
jan i
> 
> 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.
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