Return to BSD News archive
Xref: sserve comp.os.misc:3352 comp.unix.bsd:15042 comp.unix.internals:7795 comp.unix.programmer:20635
Newsgroups: comp.os.misc,comp.unix.bsd,comp.unix.internals,comp.unix.programmer,comp.unix.quest1ions
Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!bunyip.cc.uq.oz.au!munnari.oz.au!uunet!psinntp!relay1!unislc!rick
From: rick@unislc.slc.unisys.com (Rick Cohen)
Subject: Re: Question: What exactly does sbrk(0) do?
References: <36n65p$blf@sal-sun2.usc.edu>
Message-ID: <1994Oct5.165455.29421@unislc.slc.unisys.com>
Reply-To: rick@unislc.UUCP (Rick Cohen,D1V03,6359,CC 5231)
Organization: Unisys, Salt Lake City
Date: Wed, 5 Oct 1994 16:54:55 GMT
Keywords: Question: What exactly does sbrk(0) do?
Lines: 27
In article <36n65p$blf@sal-sun2.usc.edu> fabbroci@sal-sun2.usc.edu (Frank Fabbrocino) writes:
>From what I understand, calling sbrk(0) returns the size of the data segment
>in the executable. However, I can't find this call in our system documentation
>or my UNIX books (specifically, calling sbrk with 0). Since I can't look
>at the code for sbrk() since our system is proprietary :( and I can't find
>the code on BSD ftp sites :( does anyone know where I can get more info
>on that specific call of sbrk() with 0 as an arg? Do I even have the right
>info on what sbrk(0) does?
>
>Thanks in advance.
>
>Later,
>Frank
On my SVR4 system, the man page for sbrk(2) reads:
.
.
.
DIAGNOSTICS
Upon successful completion, brk returns a value of 0 and
sbrk returns the old break value. Otherwise, a value of -1
is returned and errno is set to indicate the error.
So, calling sbrk(0) is not a special case since adding 0 bytes doesn't
change anything.