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From: mike@thor.acc.stolaf.edu (Mike Haertel)
Newsgroups: comp.std.c,comp.lang.c
Subject: Re: Common malloc/free practice violates ANSI standard ?
Message-ID: <7366@thor.acc.stolaf.edu>
Date: 15 Oct 89 17:42:16 GMT
References: <1989Oct14.043811.669@anucsd.oz>
Reply-To: mike@thor.stolaf.edu ()
Followup-To: comp.std.c
Organization: St. Olaf College, Northfield, MN
Lines: 17

In article <1989Oct14.043811.669@anucsd.oz> bdm@anucsd.oz (Brendan McKay) writes:
>* assigning a void* to an OBJ* involves rounding up to an even address

The standard doesn't say anything about "rounding" pointers.
Assigning a misaligned void* to an OBJ* might well cause a trap when
the OBJ* is dereferenced.  Or even when the void* is just assigned to it!

>* malloc allocates sufficient space so that it will cover an object of
>  type OBJ even when the void* value returned is rounded up to even.
>  (Thus, sometimes it actually allocates one more cell than it is asked for.)

No!  The pointer returned by malloc() always has the most pessimistic
necessary alignment.
-- 
Mike Haertel <mike@stolaf.edu>
``There's nothing remarkable about it.  All one has to do is hit the right
  keys at the right time and the instrument plays itself.'' -- J. S. Bach