[libvirt] [dbus PATCH 14/25] Implement FSFreeze method for Domain Interface

[Katerina Koukiou]

On Wed, 2018-04-18 at 09:42 +0200, Pavel Hrdina wrote:
> On Tue, Apr 17, 2018 at 02:04:33PM +0200, Katerina Koukiou wrote:
> > Signed-off-by: Katerina Koukiou <kkoukiou at redhat.com>
> > ---
> >  data/org.libvirt.Domain.xml |  7 +++++++
> >  src/domain.c                | 40
> > ++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 47 insertions(+)
> > 
> > diff --git a/data/org.libvirt.Domain.xml
> > b/data/org.libvirt.Domain.xml
> > index fb2bcce..66cf5e2 100644
> > --- a/data/org.libvirt.Domain.xml
> > +++ b/data/org.libvirt.Domain.xml
> > @@ -135,6 +135,13 @@
> >        <arg name="xml" type="s" direction="in"/>
> >        <arg name="flags" type="u" direction="in"/>
> >      </method>
> > +    <method name="FSFreeze">
> > +      <annotation name="org.gtk.GDBus.DocString"
> > +        value="See https://libvirt.org/html/libvirt-libvirt-domain
> > .html#virDomainFSFreeze"/>;
> > +      <arg name="mountpoints" type="as" direction="in"/>
> > +      <arg name="flags" type="u" direction="in"/>
> > +      <arg name="frozenFilesystems" type="u" direction="out"/>
> > +    </method>
> >      <method name="GetBlkioParameters">
> >        <annotation name="org.gtk.GDBus.DocString"
> >          value="See https://libvirt.org/html/libvirt-libvirt-domain
> > .html#virDomainGetBlkioParameters"/>;
> > diff --git a/src/domain.c b/src/domain.c
> > index 2fd8343..04115d1 100644
> > --- a/src/domain.c
> > +++ b/src/domain.c
> > @@ -693,6 +693,45 @@ virtDBusDomainDetachDevice(GVariant *inArgs,
> >          virtDBusUtilSetLastVirtError(error);
> >  }
> >  
> > +static void
> > +virtDBusDomainFSFreeze(GVariant *inArgs,
> > +                       GUnixFDList *inFDs G_GNUC_UNUSED,
> > +                       const gchar *objectPath,
> > +                       gpointer userData,
> > +                       GVariant **outArgs,
> > +                       GUnixFDList **outFDs G_GNUC_UNUSED,
> > +                       GError **error)
> > +{
> > +    virtDBusConnect *connect = userData;
> > +    g_autoptr(virDomain) domain = NULL;
> > +    g_autofree const gchar **mountpoints = NULL;
> > +    GVariantIter *iter;
> > +    gsize nmountpoints = 0;
> > +    guint flags;
> > +    gint ret;
> > +
> > +    g_variant_get(inArgs, "(asu)", &iter, &flags);
> > +
> > +    nmountpoints = g_variant_iter_n_children(iter);
> > +    if (nmountpoints) {
> > +        mountpoints = g_new0(const gchar*, nmountpoints + 1);
> > +        while (g_variant_iter_loop(iter, "s",
> > &mountpoints[nmountpoints-1]))
> > +            nmountpoints++;
> > +        nmountpoints--;
> > +        g_variant_iter_free(iter);
> > +    }
> 
> This code will not work for nmountpoints >= 2.
> 
> At the first line you get a number of mountpoints, let's say it's
> 2 ("/root", "/home").
> 
> Then you allocate nmountpoints + 1 array of strings, the array should
> have only nmountpoints elements.
> 
> The while loop is the place where it actually fails:
> 
> 1 cycle: g_variant_iter_loop(iter, "s", &mountpoints[3-1])
> 
>     - this will not fail because mountpoints[2] is still allocated
> 
> 2 cycle: g_variant_iter_loop(iter, "s", &mountpoints[4-1])
> 
>     - there the program crashes because mountpoints[3] is not
> allocated
> 
> Another issue here is that using "s" as signature makes a copy of the
> string and it needs to be freed, in this case "&s" would be better.
> 
> 
> One possible way how the code can look like:
> 
>     
>     const gchar **tmp;
> 
>     nmountpoints = g_variant_iter_n_children(iter);
>     if (nmountpoints > 0) {
>         mountpoints = g_new0(const gchar*, nmountpoints);
>         tmp = mountpoints;
>         while (g_variant_iter_loop(iter, "&s", tmp))
>             tmp++;
>         g_variant_iter_free(iter);
>     }
> 

I 'll need slight modification here: I 'll have to allocate
nmountpoints + 1 because else I am getting the following Error
after the last iteration.

free(): invalid next size (fast)

Thanks,
Katerina

> > +
> > +    domain = virtDBusDomainGetVirDomain(connect, objectPath,
> > error);
> > +    if (!domain)
> > +        return;
> > +
> > +    ret = virDomainFSFreeze(domain, (const gchar **)mountpoints,
> > nmountpoints, flags);
> 
> There is no need to typecast mountpoints and the line is too long.
> 
> > +    if (ret < 0)
> > +        virtDBusUtilSetLastVirtError(error);
> 
> Missing return.
> 
> Pavel