Date: Fri, 9 Aug 2002 08:34:59 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: joel@ie.cuhk.edu.hk Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Problem using fopen with ip_dummynet.c Message-ID: <20020809073459.GC86506@happy-idiot-talk.infracaninophi> In-Reply-To: <1028865572.3d533e24d682a@eng-ser4.erg.cuhk.edu.hk> References: <1028865572.3d533e24d682a@eng-ser4.erg.cuhk.edu.hk>
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On Fri, Aug 09, 2002 at 11:59:32AM +0800, joel@ie.cuhk.edu.hk wrote:
> I am trying to monitor the buffer size by using ipfw and I am modifying the
> ip_dummynet.c file.
>
> I have included #include <stdio.h> at the top of the code.
> Then,I have file and started logging information in it.
>
> But when i want to compile I get the following error message :
>
> ip_dummynet.o: In function `move_pkt':
> ip_dummynet.o(.text+0x51d): undefined reference to `fopen'
> ip_dummynet.o(.text+0x531): undefined reference to `__sF'
> ip_dummynet.o(.text+0x536): undefined reference to `fprintf'
> ip_dummynet.o(.text+0x5ac): undefined reference to `fprintf'
> ip_dummynet.o(.text+0x5b8): undefined reference to `fclose'
>
> Can anyone explain me the reason of this problem? I would be extremely
> grateful.
You're trying to use userland libc style code in the kernel --- as you
have discovered, that doesn't work.
One approach that should work is to use the sysctl(8) mechanism to
save the buffer size at some MIB from within the kernel, and then
write a userland process to monitor the value of the sysctl. If you
hunt around in the ipfw code (which uses sysctl(8) quite a bit), you
should be able to glean sufficient examples to be able to code that
up.
Cheers,
Matthew
--
Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks
Savill Way
Tel: +44 1628 476614 Marlow
Fax: +44 0870 0522645 Bucks., SL7 1TH UK
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