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Message-ID: <CAPW=hRTa=Xw5_H52UCKH1MZdfoexrdoRz+5xH7JLeWVTN25BWw@mail.gmail.com>
Date: Fri, 26 Oct 2012 11:01:47 +0800
From: Brian Wang <brian.wang.0721@...il.com>
To: musl@...ts.openwall.com
Subject: Re: Difference between -O2 and -g
On Fri, Oct 26, 2012 at 10:55 AM, Rich Felker <dalias@...ifal.cx> wrote:
> 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.
I am using a mildly patched one based on:
http://xorg.freedesktop.org/archive/individual/xserver/xorg-server-1.5.1.tar.bz2
The patch is about displaying a background ppm image and should be
after the error path.
The failed call is within dix/colormap.c:CreateColormap().
Thanks for helping. I really appreciate it.
Brian
--
brian
------------------
Cool-Karaoke - The smallest recording studio, in your palm, open-sourced
http://cool-idea.com.tw/
iMaGiNaTiOn iS mOrE iMpOrTaNt tHaN kNoWlEdGe
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