[gdal-dev] Losing access to dataset variables. Am I doing something really dumb?

[Even Rouault]

Selon Jorge Arevalo <jorgearevalo at libregis.org>:

> Hi Even,
>
> Thanks for your hints. About the memory leaking, apart from the obvious
> fact that CPLStrdup vars need to be freed, are you seeing something more?

No, that was indeed what I meant. Not much more that could leak in the snippet
;-)

>
>
> On Tue, Aug 12, 2014 at 9:48 AM, Even Rouault <even.rouault at mines-paris.org>
> wrote:
>
> > Hi Jorge,
> >
> > I don't see anything obviously wrong. Looking at the places where the
> > variables
> > might be nullified and running Valgrind would be my best advice.
> > Just wanted to mention that in the likely simplified below snippet, you
> > would
> > leak memory.
> >
> > Even
> >
> > > Hello,
> > >
> > > I have a stupid mistake in my code. This is the problem (very
> > simplified):
> > >
> > > postgisrasterdataset.cpp
> > >
> > > PostGISRasterDataset::IRasterIO(....)
> > > {
> > >     // Two attributes of my class, that inherits from GDALDataset
> > >     pszAttribute = CPLStrdup("foo");
> > >     pszAttribute2 = CPLStrdup("bar");
> > >
> > >     // Just delegates in default implementation
> > >     return GDALDataset::IRasterIO(...);
> > > }
> > >
> > >
> > > postgisrasterrasterband.cpp
> > >
> > > PostGISRasterRasterBand::IRasterIO(....)
> > > {
> > >     // Get pointer to dataset this rasterband belongs to
> > >     PostGISRasterDataset * poRDS = (PostGISRasterDataset *)poDS;
> > >
> > >     // Do some stuff with poRDS->pszAttribute and poRDS->pszAttribute2
> > >     // They're private vars, but PostGISRasterRasterBand and
> > >     // PostGISRasterDataset are friends. No problem here.
> > >
> > >     // Delegates in default implementation. So, this will result, at the
> > > end, in calls
> > >     // to my implementation of IReadBlock / IWriteBlock
> > >     return GDALRasterBand::IRasterIO(...);
> > > }
> > >
> > >
> > > PostGISRasterRasterBand::IWriteBlock(...)
> > > {
> > >     // Get pointer to dataset this rasterband belongs to
> > >     PostGISRasterDataset * poRDS = (PostGISRasterDataset *)poDS;
> > >
> > >     // Try to work with poRDS->pszAttribute and poRDS->pszAttribute2, but
> > >     // fails because they are NULL. Why??
> > > }
> > >
> > > Weirdest thing is the rest of cuestom attributes of my
> > PostGISRasterDataset
> > > class are accessible. And, of course, the poRDS pointer is always the
> > same
> > > (same mem address). Only problem is with those char * attributes. Looks
> > > like they're freed at some point  (or I'm doing something really wrong
> > from
> > > the point of view of C++, and I deserve a severe punishment for that).
> > >
> > > Any clues?
> > >
> > > Best regards,
> > >
> > > --
> > > Jorge Arevalo
> > >
> > > http://about.me/jorgeas80
> > >
> >
> >
> >
>


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