Re: Fwd: [glennrp/libpng] Undefined behaviour in pngutil.c (#149)
Glenn Randers-Pehrson <[email protected]>
| Newsgroups | gmane.comp.graphics.png.devel |
|---|---|
| Message-ID | <CA+PdXcv=o9aKx3ZjbtuLDmrcfV=3M+vKOs4F0v7mNmCwAi2aHQ@mail.gmail.com> |
On Mon, Jan 2, 2017 at 10:36 PM, John Bowler < [email protected]> wrote: > On Mon, Jan 2, 2017 at 4:40 PM, Glenn Randers-Pehrson <[email protected]> > wrote: > >> This bug report is correct. >> > > Yes, tricky maintainer feature; the 'options' field is entirely internal > so can be changed in maintenance releases. Doing this does, I think, work: > > unsigned option : PNG_OPTION_LAST * 2; > > (I didn't check the current code, but something along those lines will > work.) > > That means the compiler will barf if PNG_OPTION_LAST ever gets set to > something out of range for the base type and therefore guarantees that > neither the undefined behavior nor the current result (the new option is > always off) happens. > libpng17 is better anyhow; the "options" member is gone and replaced with individual "png_ptr->someflag" bytes. Glenn ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ png-mng-implement mailing list png-mng-implement-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org https://lists.sourceforge.net/lists/listinfo/png-mng-implement