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Re: [Xen-devel] [PATCH] xl: avoid creating domains with duplicate names

To: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] xl: avoid creating domains with duplicate names
From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Date: Wed, 26 Jan 2011 10:31:36 +0000
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Stefano Stabellini <Stefano.Stabellini@xxxxxxxxxxxxx>
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On Tue, 25 Jan 2011, Ian Jackson wrote:
> Stefano Stabellini writes ("[Xen-devel] [PATCH] xl: avoid creating domains 
> with duplicate names"):
> > Do not create the domain if another domain with the same name is already
> > running.
> Thanks.  I approve of the principle of this patch, but:
> > +    e = libxl_name_to_domid(&ctx, c_info->name, &domid_e);
> > +    if (!e) {
> You should explicitly check the actual error return value of
> libxl_name_to_domid and check that it is the expected error code, and
> not some other error code meaning "general failure" or something.
> I went to look at the code for libxl_name_to_domid and it returns,
> entirely ad-hoc, -1 (which is now ERROR_VERSION), for "no such
> domain".
> IMO it should return ERROR_INVAL.
> I grepped the libxl source for "-1" and found that this practice is
> widespread.  At this stage of the release I don't want to risk
> breaking everything by changing them all (since something may compare
> with -1, or something).
> So I suggest the attached fixup patch, and then a revised version of
> your patch.  What do you think?

I think is a good idea.

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