Re: tlug: more gcc crap

["Andrew S. Howell" <andy@example.com>]

>>>>> "Scott" == Scott Stone <sstone@example.com> writes:

    Scott> Ok, suppose I have a variable:
    Scott> char *s0;
    Scott> it's been malloced with
    Scott> s0=(char *)malloc(80);
    Scott> The function it's in does:

    Scott> sprintf(s0,"some_text %s some_text",some_other_string_var);
    Scott> newtWinMessage("Title","Ok",s0);

If "some_other_string_var" is more than 80 characters, your in
trouble. Take a look with gdb and see how long it is, or try a strlen
of it. Its also possible that newtWinMessage is overwriting it.

    Scott> if (s0) free(s0);

    Scott> what the heck causes something like this?  It seems like
    Scott> the if clause would prevent this sort of crap.. it's acting
    Scott> like I'm trying to free an un-malloced pointer...

... which points to s0 being written past its end

You may have some luck by using gdb's watch command, 

`watch EXPR'
     Set a watchpoint for an expression.  GDB will break when EXPR is
     written into by the program and its value changes.  This can be

Andy

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