[libvirt] [PATCH 1/2] util: Add function to check if string contains some chars

[Sławek Kapłoński]

Hello,


-- 
Best regards / Pozdrawiam
Sławek Kapłoński
slawek at kaplonski.pl

On Wed, 19 Oct 2016, Michal Privoznik wrote:

> On 19.10.2016 03:55, Sławek Kapłoński wrote:
> > Tue, 18 Oct 2016, Michal Privoznik wrote:
> >> > On 14.10.2016 04:53, Sławek Kapłoński wrote:
> >>> > > This new function can be used to check if e.g. name of XML node
> >>> > > don't contains forbidden chars like "/" or new-line.
> >>> > > ---
> >>> > >  src/conf/network_conf.c  | 2 +-
> >>> > >  src/libvirt_private.syms | 1 +
> >>> > >  src/util/virstring.c     | 9 +++++++++
> >>> > >  src/util/virstring.h     | 1 +
> >>> > >  4 files changed, 12 insertions(+), 1 deletion(-)
> >>> > > 
> >>> > > diff --git a/src/conf/network_conf.c b/src/conf/network_conf.c
> >>> > > index aa39776..949d138 100644
> >>> > > --- a/src/conf/network_conf.c
> >>> > > +++ b/src/conf/network_conf.c
> >>> > > @@ -2117,7 +2117,7 @@ virNetworkDefParseXML(xmlXPathContextPtr ctxt)
> >>> > >          goto error;
> >>> > >      }
> >>> > >  
> >>> > > -    if (strchr(def->name, '/')) {
> >>> > > +    if (virStringHasChars(def->name, "/")) {
> >>> > >          virReportError(VIR_ERR_XML_ERROR,
> >>> > >                         _("name %s cannot contain '/'"), def->name);
> >> > 
> >> > Usually, in one patch we introduce a function and then in a subsequent
> >> > one we switch the rest of the code into using it. But okay, I can live
> >> > with this too.
> >> > 
> >>> > >          goto error;
> >>> > > diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> >>> > > index 55b6a24..6f41234 100644
> >>> > > --- a/src/libvirt_private.syms
> >>> > > +++ b/src/libvirt_private.syms
> >>> > > @@ -2435,6 +2435,7 @@ virStringEncodeBase64;
> >>> > >  virStringFreeList;
> >>> > >  virStringFreeListCount;
> >>> > >  virStringGetFirstWithPrefix;
> >>> > > +virStringHasChars;
> >>> > >  virStringHasControlChars;
> >>> > >  virStringIsEmpty;
> >>> > >  virStringIsPrintable;
> >>> > > diff --git a/src/util/virstring.c b/src/util/virstring.c
> >>> > > index 4a70620..7799d87 100644
> >>> > > --- a/src/util/virstring.c
> >>> > > +++ b/src/util/virstring.c
> >>> > > @@ -975,6 +975,15 @@ virStringStripIPv6Brackets(char *str)
> >>> > >  }
> >>> > >  
> >>> > >  
> >>> > > +bool
> >>> > > +virStringHasChars(const char *str, const char *chars)
> >>> > > +{
> >>> > > +    if (strpbrk(str, chars))
> >>> > > +        return true;
> >>> > > +    return false;
> >>> > > +}
> >> > 
> >> > This, however, makes not much sense. I mean, this function has no added
> >> > value to pain strpbrk(). What I suggested in one of previous reviews was
> >> > that this function should report an error too. In that case, it will
> >> > immediately have added value and thus it will be handy to use it.
> >> > Perhaps you are afraid that error message might change in some cases?
> >> > That's okay, we don't make any promises about error messages.
> >> > 
> > I agree that in fact it don't have too much sense but I'm not sure that
> > it would be good to report error here. First of all, it could be that in
> > some cases it could be used to check if function have required chars so
> > there is no easy way to check which result is error in fact.
> 
> Well, even if we did want to check for that, strpbrk() is no help there.
> I mean, you cannot use it to check if a string contains only allowed
> characters and nothing more.
> 
> > Second thing (maybe here I'm wrong) places where I wanted to use this
> > function are reporting error VIR_ERR_XML_ERROR and I'm not sure it is
> > good place to report such error in "string lib".
> 
> That's why I initially suggested for this function to be in virxml.c
> (and thus have a slightly different name to reflect the submodule it is in).
> 
> > So maybe better solution would be just use strbprk (or strchr) in
> > src/network/bridge_driver.c to check if name contains \n char and not
> > introduce any new function to such check? What You think about that?
> 
> Well, then again - I don't think we should limit ourselves to network
> driver really. Other drivers suffer from the same problem, don't they? I
> mean, sure - we can just use strpbrk() here and copy it all over the
> place to different drivers, but I think having a small function just for
> that would be more convenient.
> Moreover, we already have some small, one purpose functions in virxml,
> for instance:  virXMLPickShellSafeComment, virXMLSaveFile,
> virXMLPropString, and others.

Ok, that makes sense. I will add this function to virxml.c then and will
rename it. Then it should be fine to report error message also in such
function. Once again, thx for help with that.

> 
> Michal
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