virxml: Add virXMLPropTristateBool

Convenience function to return the value of a yes / no XML attribute.

Signed-off-by: Tim Wiederhake <twiederh@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

src/libvirt_private.syms

@@ -3550,6 +3550,7 @@ virXMLParseHelper;
 virXMLPickShellSafeComment;
 virXMLPropString;
 virXMLPropStringLimit;
+virXMLPropTristateBool;
 virXMLSaveFile;
 virXMLValidateAgainstSchema;
 virXMLValidatorFree;

src/util/virxml.c

@@ -558,6 +558,50 @@ virXMLNodeContentString(xmlNodePtr node)
 }
 
 
+/**
+ * virXMLPropTristateBool:
+ * @node: XML dom node pointer
+ * @name: Name of the property (attribute) to get
+ * @flags: Bitwise or of virXMLPropFlags
+ * @result: The returned value
+ *
+ * Convenience function to return value of a yes / no 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
+virXMLPropTristateBool(xmlNodePtr node,
+                       const char* name,
+                       virXMLPropFlags flags,
+                       virTristateBool *result)
+{
+    g_autofree char *tmp = NULL;
+    int val;
+
+    if (!(tmp = virXMLPropString(node, name))) {
+        if (!(flags & VIR_XML_PROP_REQUIRED))
+            return 0;
+
+        virReportError(VIR_ERR_XML_ERROR,
+                       _("Missing required attribute '%s' in element '%s'"),
+                       name, node->name);
+        return -1;
+    }
+
+    if ((val = virTristateBoolTypeFromString(tmp)) <= 0) {
+        virReportError(VIR_ERR_XML_ERROR,
+                       _("Invalid value for attribute '%s' in element '%s': '%s'. Expected 'yes' or 'no'"),
+                       name, node->name, tmp);
+        return -1;
+    }
+
+    *result = val;
+    return 1;
+}
+
+
 /**
  * virXPathBoolean:
  * @xpath: the XPath string to evaluate

src/util/virxml.h

@@ -28,10 +28,18 @@
 #include <libxml/relaxng.h>
 
 #include "virbuffer.h"
+#include "virenum.h"
 
 xmlXPathContextPtr virXMLXPathContextNew(xmlDocPtr xml)
     G_GNUC_WARN_UNUSED_RESULT;
 
+
+typedef enum {
+    VIR_XML_PROP_OPTIONAL = 0, /* Attribute may be absent */
+    VIR_XML_PROP_REQUIRED = 1 << 0, /* Attribute may not be absent */
+} virXMLPropFlags;
+
+
 int
 virXPathBoolean(const char *xpath,
                 xmlXPathContextPtr ctxt);
@@ -95,6 +103,13 @@ virXMLPropStringLimit(xmlNodePtr node,
 char *
 virXMLNodeContentString(xmlNodePtr node);
 
+int
+virXMLPropTristateBool(xmlNodePtr node,
+                       const char *name,
+                       virXMLPropFlags flags,
+                       virTristateBool *result)
+    ATTRIBUTE_NONNULL(0) ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3);
+
 /* Internal function; prefer the macros below.  */
 xmlDocPtr
 virXMLParseHelper(int domcode,