Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!news.albasani.net!newsfeed.straub-nv.de!dedekind.zen.co.uk!zen.net.uk!hamilton.zen.co.uk!prichard.zen.co.uk.POSTED!not-for-mail
Newsgroups: comp.unix.programmer
From: Geoff Clare <geoff@clare.See-My-Signature.invalid>
Subject: Re: Avoiding recursive stack overflow in C on Unix/Linux?
References: <iptr5l$tkb$1@speranza.aioe.org> <iptsc8$83f$2@news.httrack.net>
User-Agent: XPN/1.2.6 (Street Spirit ; Linux)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Date: Thu, 5 May 2011 13:40:01 +0100
Message-ID: <1eia98-ftk.ln1@leafnode-msgid.gclare.org.uk>
Lines: 33
Organization: Zen Internet
NNTP-Posting-Host: e3d53073.news.zen.co.uk
X-Trace: DXC=KVPU04332TPQfPBdY>`=OX0g@SS;SF6nWRiiCXJE[K>W>16WA4J_G?RJmKn^0gjVoQ\Gn1>W@EXmV
X-Complaints-To: abuse@zen.co.uk
Xref: x330-a1.tempe.blueboxinc.net comp.unix.programmer:312

Xavier Roche wrote:

> On 05/05/2011 11:37 AM, boltar2003@boltar.world wrote:
>> If a program recurses too deeply there's always a chance that it could
>> run out of stack space and die with a SIGSEGV. Is there any API that can
>> tell you how much stack space is left or some other method to prevent this
>> in C/C++? I realise I could catch the signal but thats a pretty damn ugly
>> way to do it.
>
> There is no portable way to find the stack bottom/size ; I am not even 
> sure what getrlimit(RLIMIT_STACK) returns exactly (current thread stack 
> size ? main thread stack size ? default stack size ?)

Here is what the POSIX/SUS standard says about RLIMIT_STACK:

    This is the maximum size of the initial thread's stack, in bytes.
    The implementation does not automatically grow the stack beyond
    this limit. If this limit is exceeded, SIGSEGV shall be generated
    for the thread. If the thread is blocking SIGSEGV, or the process
    is ignoring or catching SIGSEGV and has not made arrangements to
    use an alternate stack, the disposition of SIGSEGV shall be set to
    SIG_DFL before it is generated.

So it is just for the initial thread (which I assume is what you meant
by "main thread").  Created threads each have their own stack size
which can be set in the thread attributes.

If the OP is contemplating catching the SIGSEGV he should take note of
the part about using an alternate stack (for the catching function).

-- 
Geoff Clare <netnews@gclare.org.uk>