Convenience function to return the value of an enum XML attribute.

Signed-off-by: Tim Wiederhake <twiederh@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/libvirt_private.syms b/src/libvirt_private.syms
index dc6c9191c8..79eb4dba50 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -3544,6 +3544,7 @@ virXMLNodeSanitizeNamespaces;
 virXMLNodeToString;
 virXMLParseHelper;
 virXMLPickShellSafeComment;
+virXMLPropEnum;
 virXMLPropInt;
 virXMLPropString;
 virXMLPropStringLimit;
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))) {
+        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;
+}
+
 /**
  * virXPathBoolean:
  * @xpath: the XPath string to evaluate
diff --git a/src/util/virxml.h b/src/util/virxml.h
index 82d5d16375..cbe4cc32dc 100644
--- a/src/util/virxml.h
+++ b/src/util/virxml.h
@@ -103,6 +103,11 @@ int               virXMLPropUInt(xmlNodePtr node,
                                  int base,
                                  virXMLPropFlags flags,
                                  unsigned int *result);
+int               virXMLPropEnum(xmlNodePtr node,
+                                 const char* name,
+                                 int (*strToInt)(const char*),
+                                 virXMLPropFlags flags,
+                                 unsigned int *result);
 
 /* Internal function; prefer the macros below.  */
 xmlDocPtr      virXMLParseHelper(int domcode,
-- 
2.26.2

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@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@redhat.com>