[libvirt PATCH v5 5/8] virxml: Add virXMLPropEnum

[Peter Krempa]

On Thu, Apr 08, 2021 at 13:19:55 +0200, Tim Wiederhake wrote:
> Convenience function to return the value of an enum XML attribute.
> 
> Signed-off-by: Tim Wiederhake <twiederh at redhat.com>
> ---
>  src/libvirt_private.syms |  1 +
>  src/util/virxml.c        | 51 ++++++++++++++++++++++++++++++++++++++++
>  src/util/virxml.h        |  5 ++++
>  3 files changed, 57 insertions(+)

[...]

> diff --git a/src/util/virxml.c b/src/util/virxml.c
> index fba02900f5..8147266557 100644
> --- a/src/util/virxml.c
> +++ b/src/util/virxml.c
> @@ -774,6 +774,57 @@ virXMLPropUInt(xmlNodePtr node, const char* name, int base,
>  }
>  
>  
> +/**
> + * virXMLPropEnum:
> + * @node: XML dom node pointer
> + * @name: Name of the property (attribute) to get
> + * @strToInt: Conversion function to turn enum name to value. Expected to
> + *            return negative value on failure.
> + * @flags: Bitwise or of virXMLPropFlags
> + * @result: The returned value
> + *
> + * Convenience function to return value of an enum attribute.
> + *
> + * Returns 1 in case of success in which case @result is set,
> + *         or 0 if the attribute is not present,
> + *         or -1 and reports an error on failure.
> + */
> +int
> +virXMLPropEnum(xmlNodePtr node, const char* name, int (*strToInt)(const char*),
> +               virXMLPropFlags flags, unsigned int *result)
> +{
> +    g_autofree char *tmp = NULL;
> +    int ret;
> +
> +    if (!node || !name || !strToInt || !result) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR,
> +                       _("Invalid argument to %s"),
> +                       __FUNCTION__);
> +        return -1;
> +    }
> +
> +    if (!(tmp = virXMLPropString(node, name))) {
> +        if ((flags & VIR_XML_PROP_REQUIRED) != VIR_XML_PROP_REQUIRED)
> +            return 0;
> +
> +        virReportError(VIR_ERR_XML_ERROR,
> +                       _("Missing required attribute '%s' in element '%s'"),
> +                       name, node->name);
> +        return -1;
> +    }
> +
> +    ret = strToInt(tmp);
> +    if ((ret < 0) || ((flags & VIR_XML_PROP_NONZERO) && (ret == 0))) {

The parentheses in this condition make it confusing to read. I suggest

  if (ret < 0 ||
      ((flags & VIR_XML_PROP_NONZERO) && (ret == 0))) {


> +        virReportError(VIR_ERR_XML_ERROR,
> +                       _("Invalid value for attribute '%s' in element '%s': '%s'."),
> +                       name, node->name, NULLSTR(tmp));
> +        return -1;
> +    }
> +
> +    *result = ret;
> +    return 0;
> +}

Obviously relevant comments from previous patches apply too:

Reviewed-by: Peter Krempa <pkrempa at redhat.com>