Path: utzoo!attcan!uunet!know!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!thyme!kaleb
From: kaleb@thyme.jpl.nasa.gov (Kaleb Keithley	)
Newsgroups: comp.unix.questions
Subject: Re: alloca, malloc and friends
Keywords: alloca, malloc
Message-ID: <1990Oct25.152414.8221@thyme.jpl.nasa.gov>
Date: 25 Oct 90 15:24:14 GMT
References: <6793@suns302.cel.co.uk>
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 22

In article <6793@suns302.cel.co.uk> ir@cel.co.uk (ian reid) writes:
>
>The problem is that there is no way that this memory can be returned to the 
>operating system, at least no way documented on the sbrk(2) manual page which is
>where I would expect to find it, after all free(3) is documented on the malloc
>page.  free simply returns the memory to the pool managed by malloc not to the
>operating system, the documented behaviour.

sbrk may be passed a negative number, effectively shrinking the data segment
size, although no implementation of malloc/free that I know of will do this.

You could always roll your own malloc/free that does return free'd memory
to the system this way.  Good starting points are any of the malloc/free
sources in gnu emacs, perl, or gwm.  All three of these are based on the
4.3 bsd malloc/free, massaged by Caltech, and then polished by Stallman,
Wall, and Nahaboo respectively.

-- 
Kaleb Keithley                      Jet Propulsion Labs
kaleb@thyme.jpl.nasa.gov

causing trouble again.