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Date: Thu, 25 Oct 2012 22:55:46 -0400
From: Rich Felker <dalias@...ifal.cx>
To: musl@...ts.openwall.com
Subject: Re: Difference between -O2 and -g

On Fri, Oct 26, 2012 at 10:47:57AM +0800, Brian Wang wrote:
> On Fri, Oct 26, 2012 at 10:32 AM, Rich Felker <dalias@...ifal.cx> wrote:
> > On Fri, Oct 26, 2012 at 10:04:46AM +0800, Brian Wang wrote:
> >> > One very simple way to get a picture of what's going on in a program
> >> > is to run it under strace. Try saving strace logs for both the working
> >> > version and the broken version and comparing them either manually or
> >> > with the diff utility (although the latter may be difficult unless you
> >> > filter out the addresses and other contnets that will naturally
> >> > differ, so it might be easier to visually inspect). If you don't
> >> > already have an strace built for your target, I think Aboriginal Linux
> >> > has static binaries you can use.
> >>
> >> I have previously built my static strace.
> >> I could not decipher what went wrong.  Please find the strace logs for
> >> the three binaries in question.
> >> The source code is basically the same, except for the musl ones,
> >> printf calls are sprinkled here and there
> >> as my desperate attempt.
> >
> > The good and bad traces diverge at this line, which only happens in
> > the good one:
> >
> > writev(2, [{"CreateColormap : good end\n", 26}, {NULL, 0}], 2) = 26
> >
> > So search the source for that string and see what condition is causing
> > that code to be reached or not reached.
> 
> Thank you for reading through them. :-)
> 
> The failed call (XaceHook) is:
> -----------
>     /*
>      * Security creation/labeling check
>      */
>     i = XaceHook(XACE_RESOURCE_ACCESS, clients[client], mid, RT_COLORMAP,
> 		 pmap, RT_NONE, NULL, DixCreateAccess);
>     if (i != Success) {
> 	fprintf(stderr, "%s : 9\n", __func__);
> 	FreeResource(mid, RT_NONE);
> 	return i;
>     }
> -----------

It would help a lot if I knew what source you were using, or at least
the part of the tree it corresponds to in the upstrea/latest X source
tree, so I could take a look at it.

Rich

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