Hi all, I recently read this 3 part blog article by the architect of llvm/clang, which I highly recommend:
<http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html> <http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html> <http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_21.html> In short, clang has two compiler flags that catch undefined behaviour. He described them thusly: "Clang has an experimental -fcatch-undefined-behavior mode that inserts runtime checks to find violations like shift amounts out of range, some simple array out of range errors, etc. This is limited because it slows down the application's runtime and it can't help you with random pointer dereferences (like Valgrind can), but it can find other important bugs. Clang also fully supports the -ftrapv flag (not to be confused with -fwrapv) which causes signed integer overflow bugs to trap at runtime (GCC also has this flag, but it is completely unreliable/buggy in my experience)." For fun, I enabled these flags on the VTK project and ran its unit tests. Some tests now crash, in freetype code. Example: ftcbasic.c 360 if ( (FT_ULong)(type->flags - FT_INT_MIN) > FT_UINT_MAX ) (gdb) p type->flags $1 = 4 On my system, INT_MIN is (-2147483647-1) and so this is in fact an overflow. I might one day have time to submit patches, but I though I'd point out this tool incase any of you would like to take a stab at it. Cheers, -- ____________________________________________________________ Sean McBride, B. Eng s...@rogue-research.com Rogue Research www.rogue-research.com Mac Software Developer Montréal, Québec, Canada _______________________________________________ Freetype-devel mailing list Freetype-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/freetype-devel
