Re: found a resource leak in file builtin-fast-export.c

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Am 09.07.2009, 15:01 Uhr, schrieb Johannes Schindelin <Johannes.Schindelin@xxxxxx>:

Hi,

On Thu, 9 Jul 2009, Thomas Rast wrote:

Johannes Schindelin wrote:
> On Thu, 9 Jul 2009, Thomas Rast wrote:
>
> > Martin Ettl wrote:
> > > -	if (ferror(f) || fclose(f))
> > > +	if (ferror(f))
> > >  		error("Unable to write marks file %s.", file);
> > > +  	fclose(f);
> >
> > You no longer check the error returned by fclose().  This is
> > important, because the FILE* API may buffer writes, and a write error
> > may only become apparent when fclose() flushes the file.
>
> Indeed. A better fix would be to replace the || by a |, but this must be
> accompanied by a comment so it does not get removed due to overzealous
> compiler warnings.

Are you allowed to do that?  IIRC using | no longer guarantees that
ferror() is called before fclose(), and my local 'man 3p fclose' says
that

       After the call to fclose(), any use of stream results in
       undefined behavior.

Good point.  So we really need something like

	err = ferror(f);
	err |= fclose(f); /* call fclose() even if there was an error */
	if (err)
		error...

I've made such a patch, to appear soon on the list (sorry for not Cc:'ing it).

--
Matthias Andree
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