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Re: [libvirt] [PATCHv2 13/13] Run radvd for virtual networks with IPv6 addresses



On 12/22/2010 11:58 AM, Laine Stump wrote:
> Running an instance of the router advertisement daemon (radvd) allows
> guests using the virtual network to automatically acquire an IPv6
> address and default route. Note that acquiring an address only works
> for networks with a prefix length of exactly 64 - radvd is still run
> in other circumstances, and still advertises routes, but autoconf will
> not work because it requires exactly 64 bits of address info from the
> network prefix.
> 
> This patch avoids a race condition with the pidfile by manually
> daemonizing radvd rather than allowing it to daemonize itself, then
> creating our own pidfile (in addition to radvd's own file, which is
> unnecessary). This is accomplished by exec'ing it with "--debug 1" in
> the commandline, and using virCommand's features to fork, create a
> pidfile, and detach from the newly forked process.

As a reminder, have you filed a bug report against radvd about their
anti-social daemonizing behavior?

> +    cmd = virCommandNewArgList(RADVD, "--debug", "1",
> +                               "--config", configfile,
> +                               "--pidfile", NULL);
> +    virCommandAddArgFormat(cmd, "%s-bin", pidfile);
> +
> +    virCommandSetPidFile(cmd, pidfile);
> +    virCommandDaemonize(cmd);
> +
> +    if (virCommandRun(cmd, NULL) < 0)
> +        goto cleanup;
> +
> +    if (virFileReadPid(NETWORK_PID_DIR, radvdpidbase,
> +                       &network->radvdPid) < 0)
> +        goto cleanup;
> +
> +    ret = 0;
> +cleanup:
> +    virCommandFree(cmd);
> +    VIR_FREE(configfile);
> +    VIR_FREE(configstr);
> +    virBufferFreeAndReset(&configbuf);
> +    VIR_FREE(radvdpidbase);
> +    VIR_FREE(pidfile);

Should we also unlink() pidfile or pidfile-bin at any point?

>  static int
> -networkEnableIpForwarding(void)
> +networkEnableIpForwarding(int enableIPv4, int enableIPv6)

s/int/bool/

ACK with those nits addressed.

-- 
Eric Blake   eblake redhat com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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