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List:       koffice-devel
Subject:    Re: KTempFile wierdness
From:       Werner Trobin <trobin () kde ! org>
Date:       2001-05-31 5:38:07
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David Faure wrote:
> 
> On Thursday 31 May 2001 00:48, shaheed wrote:
> > Drat and double drat. I found a problem with the OLEFilter handling of
> > embedded objects. The problem is as follows:
> >
> > 1. koFilterManager creates a KTempFile to receive the output from a "file"
> > filter. It uses defaults for the name "KTempFile tempFile;" near line 434.
> >
> > 2. The OLEFilter decides the top level MS Word contains an embedded file, and
> > invokes koFilterManager to handle it (near line 156).
> >
> > 3. This is a recursive call back to step 1, and results in a temporary file
> > of the same name as step 1 being created.
> >
> > 4. The OLEFilter embeds the returned data from step 3 into the file from step
> > 1 and tidies up by deleting the file from step 3, and also therefore the file
> > for step 1.
> >
> > Result: /me totally confused for several hours!
> >
> > Now, this used to work many months ago, so perhaps the behaviour of KTempFile
> > been changed? The new code uses the fakes.c vesion of mkstemps: but somehow
> > the check for exclusivity seems to be broken.
> >
> > Any clues? It would be really good to fix this before the next version of
> > kdelibs, so that koffice can use it!
> 
> The analysis of what happens is correct, but not the blame assignment.
> The reason why the two calls to KoFilterManager end up with the same tempfile name
> isn't due to a bug in KTempFile, but due to this :
> 
>             KTempFile tempFile; // create with default file prefix, extension and mode
>             if (tempFile.status() != 0)
>                 return QString::null;
>             d->tempfname=tempFile.name();
> 
> See the last line ? This stores the name into KoFilterManager !!!
> Basically, it's not re-entrant as it is, and you use it in a re-entrant way....
> 
>     QString tempfname; // yes, ugly :)
> 
> Apparently someone knew it was a hack :)

Yeah, sorry for that one :}

> Ah, the reason why this changed recently is that the MSWord filter got converted to
> a "bulletproof" one. i.e. it runs out of process. And that's the case where it uses
> this string (see KoFilterManager::receivedStdout).

Hmmm, I implemeted the wrapper and tested it with the WinWord filter, but
it doesn't use the bulletproof mode right now (I didn't commit the changed
.desktop file).

Ciao,
Werner

-- 
Werner Trobin - trobin@kde.org
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