Re: tlug: gcc misplacing pointers?

["Damian Foo" <damianfm@example.com>]

Dear Scott,


-----Original Message-----
From: Scott Stone <sstone@example.com>
To: Tokyo Linux Users' Group <tlug@example.com>
Date: Wednesday, March 04, 1998 12:43 PM
Subject: tlug: gcc misplacing pointers?


>
>I had the strangest thing happen.. on two separate machines, with 2
>different versions of libc and gcc, even..:
>
>I had a program that would segfault every time a certain function was run.
>The function had lines like:
>
>char *s0;
>
>s0=(char *)malloc(80);
>
>(and then proceeded to do operations on s0).
>

I would assume that where other operations that you had executed somehow
overwritten your registery pointers to the s0 (malloc). Check to assure that
all operations on the declared vars are not overlapped or mishandled. Hope
it helps !!


>Anyway, it would segfault upon leaving the function in '_libc_free()',
>according to gdb.  What was weird, though is that if I set the breakpoint
>one line past the malloc statement, and said 'print s0', it would say, 'no
>symbol s0 in current context'.
>
>Changing s0 to be 'char s0[200]' and removing the malloc line fixed the
>problem.
>
>Any idea why gcc would 'lose' the pointer to s0 like that?
>
>--------------------------------------------------
>Scott M. Stone <sstone@example.com, sstone@example.com>
>               <sstone@example.com>
>Linux Developer/Systems Administrator for Pacific HiTech, Inc.
>http://www.pht.com http://armadillo.pht.co.jp
>http://www.pht.co.jp         http://www.turbolinux.com
>
>
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---------------------------------------------------------------
Next TLUG Nomikai: 11 March Wed 1998 Tengu TokyoEkiMae 19:30
Chuo-ku, Kyobashi 1-1-6, EchiZenYa Bld. B1/B2 03-3275-3691
Next TLUG Meeting: 11 April 1998 Saturday, Tokyo Station
Featuring Tague Griffith of Netscape i18n talking on source code
---------------------------------------------------------------
a word from the sponsor:
TWICS - Japan's First Public-Access Internet System
www.twics.com  info@example.com  Tel:03-3351-5977  Fax:03-3353-6096