[Libreoffice-commits] core.git: desktop/source

[julien2412]

Norbert Thiebaud wrote
> On Wed, Feb 20, 2013 at 7:54 AM, julien2412 <

> serval2412@

> > wrote:
>>
>> Yes I meant it, why? Is it wrong?
>> if "pReceiveBuffer" is initialized with 0 for the (sc_nCSASeqLength + 1)
>> elements thanks to = {0} initialization, what obvious thing did I miss?
>> Why
>> "pReceiveBuffer[nBytes-1] = 0;" would need to stay?
> 
> Ok since I added that particular code,  let me explain
> 
>> -            if (nBytes > 0)
>> -            {
>> -                pReceiveBuffer[nBytes-1] = 0;
>> -            }
> 
> was needed because the loop before can exit under 2 conditions:
> the normal one where  a[nBytes - 1] is already 0
> or the 'non-normal' one when the recv return 0 (or -1 for that matter)
> which mean the pipe got interrupted prematurely, in which case the
> buffer would _not_ be 0-terminated
> which was relyied upon later.
> 
> there is also the case where recv bail out before reading anything at
> that point nByte = 0 si of course we do not want to do a[nByte - 1]
> and for that case a[0] is set to 0;
> 
> initializing the whole buffer is a waste in all case but the corner
> case where the pipe get broken.
> 
> Note: it is clearly not expected that the pipe close with receiving
> a\0 as last character... ortherwise we would already be segfaulting a
> lot due to the code aftert that that _assume_ that the buffer is a
> 0-terminated string.
> so there is no particular danger that a valid character would be
> overwritten in normal expected cases.

Thank you Norbert for the explanation.
As I indicated in my previous message, I would have been ready to revert my
commit but it seems Stephan fixed the whole thing, see
https://gerrit.libreoffice.org/gitweb?p=core.git;a=commitdiff;h=b6ff19fba3a1a6d65134539a71d7a8df0e35d4ff.

Julien
PS : I thought I had found something useful but I must definitely forget
about {0} initialization since it must be used far more carefully than I
expected :-)



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