Date: Mon, 14 Jan 2013 18:30:25 +0400 From: Vasily Kulikov <segoon@...nwall.com> To: musl@...ts.openwall.com Subject: Re: musl as a framework to test applications' compatibility with POSIX (was: NULL) On Mon, Jan 14, 2013 at 09:03 -0500, Rich Felker wrote: > On Mon, Jan 14, 2013 at 12:45:27PM +0400, Vasily Kulikov wrote: > > In musl libc it can be implemented as -DI_WANT_TO_DETECT_GCCISMS. > > At the very least, this would have to be a macro in the reserved > namespace. However, I'm skeptical of using musl as a tool for checking > this, especially since the check only works on 64-bit systems and does > not help the compiler produce a warning/error, but only causes random, > hard-to-diagnose crashes. It looks like cppcheck is adding (or has > already added?) a test for incorrectly passing NULL to variadic > functions, which is probably where the check belongs. My thought related to this specific bug was a bit more complex: 1) on each call of a variadic function save the list of all types 2) on each call to va_arg(ap, T) check whether the current argument was pushed as T in the saved list It would catch not only NULL/(void *)NULL, but also int/long or void*/long bugs. Now I see that while it is possible to implement (2) in libc redefining va_XXX() macros, but it looks like (1) has to be implemented in compiler. So, yeah, it is not a musl issue. Thanks, -- Vasily Kulikov http://www.openwall.com - bringing security into open computing environments
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