ELDK glibc fcntl(socketFd, F_SETFL, flags) causes Seg Fault

ELDK glibc fcntl(socketFd, F_SETFL, flags) causes Seg Fault

[Daniel Ng]

Hi,

My application Seg Faults when I try to set flags for my socket fd.

First, I get the fd by calling socket():
fd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);

Then I try getting the fd flags:
fcntl(fd, F_GETFL, flags)

Then I try setting the flags:
flags |= O_NONBLOCK;
fcntl( fd, F_SETFL, flags );

-I get consistent Seg Faults on the last line above.

-I also checked fd, which is a sensible value. 
I can even successfully connect() with it.

-The problem happens regardless of what value 'flags' is set to


My embedded target details-

-powerpc8272
-ELDK v4
-the application uses glibc


Any ideas why I'm getting these Seg Faults?

Cheers,
Daniel

Re: ELDK glibc fcntl(socketFd, F_SETFL, flags) causes Seg Fault

[Wolfgang Denk]

In message <loom.20070201T073939-302@post.gmane.org> you wrote:
> 
> My application Seg Faults when I try to set flags for my socket fd.
> 
> First, I get the fd by calling socket():
> fd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
> 
> Then I try getting the fd flags:
> fcntl(fd, F_GETFL, flags)

Provide some working / crashing test code, i. e. a complete C program
with declarations etc.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de
There's an old story about the person who wished his computer were as
easy to use as his telephone. That wish has come  true,  since  I  no
longer know how to use my telephone.

RE: ELDK glibc fcntl(socketFd, F_SETFL, flags) causes Seg Fault

[Christopher Dumoulin]

If that's your exact code, I notice you're not checking if the socket()
call succeeded. You may be calling fcntl with an invalid socket handle.

The first place I'd look is to make sure you've included 'Networking
Support', 'Unix domain sockets', maybe 'TCP/IP networking', and whatever
else you might need, when you configure your kernel.

---------------------------------------------------------------------
Message: 6
Date: Fri, 02 Feb 2007 08:30:18 +0100
From: Wolfgang Denk <wd@denx.de>
Subject: Re: ELDK glibc fcntl(socketFd, F_SETFL, flags) causes Seg
	Fault
To: Daniel Ng <daniel_ng11@lycos.com>
Cc: linuxppc-embedded@ozlabs.org
Message-ID: <20070202073018.C8710352B86@atlas.denx.de>
Content-Type: text/plain; charset=ISO-8859-1

In message <loom.20070201T073939-302@post.gmane.org> you wrote:
> 
> My application Seg Faults when I try to set flags for my socket fd.
> 
> First, I get the fd by calling socket():
> fd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
> 
> Then I try getting the fd flags:
> fcntl(fd, F_GETFL, flags)

Provide some working / crashing test code, i. e. a complete C program
with declarations etc.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de
There's an old story about the person who wished his computer were as
easy to use as his telephone. That wish has come  true,  since  I  no
longer know how to use my telephone.


------------------------------

_______________________________________________

RE: ELDK glibc fcntl(socketFd,F_SETFL, flags) causes Seg Fault

[Edward Jubenville]

> Then I try getting the fd flags:
> fcntl(fd, F_GETFL, flags)

Don't you really need to do this...

  flags = fcntl(fd, F_GETFL, 0)

to get the correct initial state of the flags?

Ed Jubenville

Re: ELDK glibc fcntl(socketFd, F_SETFL, flags) causes Seg Fault

[Magnus Hjorth]

Daniel Ng wrote:
> Hi,
>
> My application Seg Faults when I try to set flags for my socket fd.
>
> Then I try getting the fd flags:
> fcntl(fd, F_GETFL, flags)
>   
Shouldn't it be &flags ??

-- 

Magnus Hjorth, M.Sc.
Omnisys Instruments AB
Gruvgatan 8
SE-421 30  Västra Frölunda, SWEDEN
Phone: +46 31 734 34 09
Fax: +46 31 734 34 29
http://www.omnisys.se 

Re: ELDK glibc fcntl(socketFd, F_SETFL, flags) causes Seg Fault

[Daniel Ng]

Thanks for your help everyone, I figured it out.

The cause of the problem seems to be unrelated to the F_SETFL- it just happened 
to seg fault at that point all the time.

Cheers,
Daniel