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May 2008
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2008.06.02 14:10 "Re: [gdal-dev] Problem with libTiff on Solaris 10", by Edward Lam
I'm anal here but I think it should really be: nTemp = (uint32)o->tdir_offset; _TIFFmemcpy(n, &nTemp, sizeof(uint32)); Looking at the original code snippet, the only way I can see the access be not aligned on a 4 byte boundary is if the _TIFFmalloc() (which maps to plain old malloc()) returns a pointer that is not 4-byte aligned in the first place. Or am I reading the code wrong? Cheers, -Edward Even Rouault wrote: > And I suspect that the "_TIFFmemcpy(n,&o->tdir_offset,4)" is also bogus as > tdir_offset is 64 bit large too. > That should be fixed too by the same method : > > nTemp = (uint32)o->tdir_offset; > _Tiffmemcpy(n, &nTemp, 4); > > Those problems are probably not seen on little endian machines as the first 4 > bytes contain the lowest 32 bit word, which is the one we want to put into > the n pointer... I'm also wondering why there's not a test to see if it must > be swabbed afterwards, as it's done for the tag, type and count fields. > > Le Saturday 31 May 2008 17:30:11 Even Rouault, vous avez écrit : >> Dan, >> >> Your fix is not the right one. But I recognize that my previous suggestion >> could lead into error. >> >> In fact, tdir_count field is a uint64 in libtiff 4.0. >> So the correct fix is : >> >> uint32 nTemp = (uint32)o->tdir_count; >> _Tiffmemcpy(n, &nTemp, 4); >> >> Even >> >> --------------------------------------------------------------------------- >> -------- >> >> RE: [Tiff] Re: [gdal-dev] Problem with libTiff on Solaris 10 >> De : >> Dan Greve <grevedan@hotmail.com> >> À : >> Bob Friesenhahn <bfriesen@simple.dallas.tx.us>, Even Rouault >> <even.rouault@mines-paris.org> >> CC : >> gdal-dev@lists.osgeo.org, tiff@lists.osgeo.org, Andy Cave >> <andy.cave@hamillroad.com>, mailing list <tiff@lists.maptools.org> >> Date : >> Aujourd'hui 16:49:15 >> >> Sure enough, the pointer n is not null, and throws a sigsegv fault. Aftern >> changing from >> >> *(uint32*)n=(uint32)o->tdir_count; TO >> >> _TIFFmemcpy(n, &o->tdir_count, 4) >> >> The execution passes this point, but where as *(uint32*)n should be 1, it >> is 0. This causes errors later in the GDALOpen call on the tiff dataset, >> which fails with error "TiffFetchNormalTag:incorrect count for >> "SamplesPerPixel". debugging continues.... >> >> -- Dan Greve >> -- Software Engineering >> -- Northrop Grumman Corp. >> _______________________________________________ >> gdal-dev mailing list >> gdal-dev@lists.osgeo.org >> http://lists.osgeo.org/mailman/listinfo/gdal-dev > > > > _______________________________________________ > Tiff mailing list: Tiff@lists.maptools.org > http://lists.maptools.org/mailman/listinfo/tiff > http://www.remotesensing.org/libtiff/