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List:       freebsd-hackers
Subject:    Re: Global variables in system programs
From:       Sebastian Huber <sebastian.huber () embedded-brains ! de>
Date:       2013-12-05 15:07:45
Message-ID: 52A096C1.9090400 () embedded-brains ! de
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Hello,

a small status update since some of my ROUTE(8) patches have been committed=
 to =

FreeBSD HEAD recently.

A library interface to the core network commands and utilities is useful, b=
ut =

it turned out that the ROUTE(8) program was just the most simple one to =

convert.  I tried to do this also with IFCONFIG(8), but gave up (it uses so=
me =

sort of module registry via linker sets, etc.).  I use now a different =

approach.  I initialize/destroy all global variables in a custom =

set-up/tear-down routine and protect the commands with a global mutex.  Cal=
ls =

to the error and exit functions are wrapped to use a long jump.  This works =

well so far with ROUTE(8), IFCONFIG(8), NETSTAT(1), PING(8) and PING6(8).

What really helps is adding static and const qualifiers whenever possible. =

Function static variables are a problem since they cannot be initialized wi=
th a =

single set-up/tear-down routine for a module.  Signals are also a problem i=
n a =

multi-threaded environment (used by PING6(8)).

-- =

Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber@embedded-brains.de
PGP     : Public key available on request.

Diese Nachricht ist keine gesch=E4ftliche Mitteilung im Sinne des EHUG.
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