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Message-ID: <3E8E7721.FAAEF08F@eyal.emu.id.au>
Date: Sat, 05 Apr 2003 11:18:00 -0000
From: Eyal Lebedinsky <eyal@eyal.emu.id.au>
Organization: Eyal at Home
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To: "list, gcc" <gcc@gcc.gnu.org>, "Eigler, Frank Ch." <fche@redhat.com>
Subject: Re: mudflap: how do I give size for 'void *' objects? - example
References: <3E8CCC43.3F317393@eyal.emu.id.au>
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Eyal Lebedinsky wrote:
> 
> I have a problem where I get a large number of reported violations
> when accessing objects acquired through something like
>         p = shmat()
> where the size of the object is unknown (unless mudflap uses
> extra internal knowledge).

Here is a simple program that demonstrates the problem with ctime().
Note how the fprintf() works OK (no violation) but the strlen()
fails. I assume that mudflap has its own strlen() wrapper that
trips on the "foreign" pointer returned from ctime().

  -----------------------------------------------------
#!/bin/sh

mf="/usr/local/gcc-mudflap"

cat >zz.c <<EOF
#include <stdio.h>
#include <time.h>
#include <string.h>

int main ()
{
        time_t  t;
        char    *p;
        int     l;

        t = time (NULL);
        p = ctime (&t);

        fprintf (stderr, "%s", p);

        l = (int)strlen (p);

        return (0);
}
EOF

export LD_LIBRARY_PATH="$mf/lib"

 cc="$mf/bin/i686-pc-linux-gnu-gcc-3.5-tree-ssa -fmudflap -g -O0"
#cc="gcc"

test -f zz && rm zz
$cc -Wall -o zz zz.c
./zz
  -----------------------------------------------------

--
Eyal Lebedinsky (eyal@eyal.emu.id.au) <http://samba.org/eyal/>