On 4/21/06, Andrew Haley <aph@xxxxxxxxxxx> wrote:> Thibaud GUERIN writes:> > On 4/20/06, Andrew Haley <aph@xxxxxxxxxx> wrote:> > > Thibaud GUERIN writes:> > > >> > > >> > > > Not clear in the first message, (and maybe not in this one too..), sorry> > > >> > > >> > > > This asm inline was something like a "test/patch code".> > > >> > > > I try to have a simple :> > > >> > > > char **ap = (char **)(&fmt);> > >> > > I don't think that's legal. (Actually, I'm not perfectly sure it's> > > not legal, but I think not.) Also, I have no idea why you're trying> > > to do such a thing.> >> > as i'm compiling with :> > -Wall -Werror -nostdinc -Wstrict-aliasing=2> > it will not compile if it wasn't (i think, not sure too...)>> That is not true. We don't gurantee to generate an error for all> invalid source.>> > > > working, It didn't :> > > > ap was equal to &fmt BUT *ap wasn't equal to fmt (don't kown why...)> > >> > > I'm sure that's impossible. :-)> >> > it wasn't belive me... and it's driving me crasy since days....> >> > > > so i try by my self... to do :> > > >> > > > ap = &fmt;> > > > *ap = fmt;> > > >> > > > in asm inline.... (dirty i know...)> > > >> > > > problem is :> > > > With this asm code in the binary *s is equal to fmt> > > > Without this asm code in the binary *s isn't equal to fmt> > > >> > > >> > > > All the 's' variable stuffs are from my debug...> > > > Again :> > > > My only aim is to have an 'ap = &fmt' valid (->ap = &fmt AND *ap = fmt)> > >> > > So why not do the obvious> > >> > > const char **ap = &fmt ;> > >> > > ?> >> > because i need to do some :> > ap++;> > to get the next args in stack, as my end aim is to do re-write a printf...>> So why not use va_list? That's what va_list is for.>> > > > The resulting asm was here to help you to understand wath's wrong ....> > > > I'm looking for some days now without answer...> > >> > > You're still not explaining yourself. You have a const char* arg that> > > you are trying to alter, but instead of doing it the obvious way with> > > an assignment, you're taking the address of the arg, casting the> > > resulting pointer to a different pointer type, and then overwriting> > > the arg through the resulting pointer.> > >> > > What's the point of all this?> >> > i'm not trying to alter an (const char*) but to get the args in my> > stack by getting some pointers on it, as in all va_args fonctions....>> Trying to do all this stuff behind the compiler's back is likely to> break things. Use va_list.>> Andrew.> quote :I'm compiling with (to run on my VM):-std=gnu99 -Wall -Werror -nostdinc -Wstrict-aliasing=2 -fno-builtin -I../include -I../ no-builtin .... I'm doing that because the va_list wasn't working too... (i come tothat dirty code by simplifing the code to found the root of theproblem) And my final aim is to have a printf without any deps form any parentsystem (no use of standard includes, ....) --Thibaud
