Allow format strings to be NULL in dmixml_Add*() functions

This bug was reported by Jan Hutař <jhutar@redhat.com> [1]

The implemented fix avoids assertions if the format strings to
dmixml_AddAttribute(), dmixml_AddTextChild() and dmixml_AddTextContent()
functions are NULL.  In these cases, it will result in an empty value
instead of returning NULL from these functions.

[1] <https://bugzilla.redhat.com/show_bug.cgi?id=583867>

1 files changed, 19 insertions, 5 deletions

diff --git a/src/dmixml.c b/src/dmixml.c
index ba285e8..3b05ad4 100644
--- a/src/dmixml.c
+++ b/src/dmixml.c
@@ -92,13 +92,18 @@ xmlAttr *dmixml_AddAttribute(xmlNode *node, const char *atrname, const char *fmt
         xmlAttr *res = NULL;
         va_list ap;
 
-        if( (node == NULL) || (atrname == NULL) || (fmt == NULL) ) {
+        if( (node == NULL) || (atrname == NULL) ) {
                 return NULL;
         }
 
         atrname_s = xmlCharStrdup(atrname);
         assert( atrname_s != NULL );
 
+	if( fmt == NULL ) {
+		res = xmlNewProp(node, atrname_s, NULL);
+		goto exit;
+	}
+
         va_start(ap, fmt);
         val_s = dmixml_buildstr(2048, fmt, ap);
         va_end(ap);
@@ -106,8 +111,9 @@ xmlAttr *dmixml_AddAttribute(xmlNode *node, const char *atrname, const char *fmt
         res = xmlNewProp(node, atrname_s,
                          (xmlStrcmp(val_s, (xmlChar *) "(null)") == 0 ? NULL : val_s));
 
-        free(atrname_s);
         free(val_s);
+ exit:
+        free(atrname_s);
 
         assert( res != NULL );
         return res;
@@ -129,13 +135,18 @@ xmlNode *dmixml_AddTextChild(xmlNode *node, const char *tagname, const char *fmt
         xmlNode *res = NULL;
         va_list ap;
 
-        if( (node == NULL) || (tagname == NULL) || (fmt == NULL) ) {
+        if( (node == NULL) || (tagname == NULL) ) {
                 return NULL;
         }
 
         tagname_s = xmlCharStrdup(tagname);
         assert( tagname_s != NULL );
 
+	if( fmt == NULL ) {
+		res = xmlNewChild(node, NULL, tagname_s, NULL);
+		goto exit;
+	}
+
         va_start(ap, fmt);
         val_s = dmixml_buildstr(2048, fmt, ap);
         va_end(ap);
@@ -144,8 +155,9 @@ xmlNode *dmixml_AddTextChild(xmlNode *node, const char *tagname, const char *fmt
         res = xmlNewTextChild(node, NULL, tagname_s,
                               (xmlStrcmp(val_s, (xmlChar *) "(null)") == 0 ? NULL : val_s));
 
-        free(tagname_s);
         free(val_s);
+ exit:
+        free(tagname_s);
 
         assert( res != NULL );
         return res;
@@ -165,7 +177,9 @@ xmlNode *dmixml_AddTextContent(xmlNode *node, const char *fmt, ...)
         va_list ap;
 
         if( (node == NULL) || (fmt == NULL) ) {
-                return NULL;
+                // Return node and not NULL, as node may not be NULL but fmt can be,
+                // thus doing a similar string check (val_s != "(null)") as later on
+                return node;
         }
 
         va_start(ap, fmt);