util: json: Introduce virJSONValueObjectAppendStringPrintf

Add a variant similar to virJSONValueObjectAppendString which also
formats more complex value strings with printf syntax.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

src/libvirt_private.syms

@@ -2361,6 +2361,7 @@ virJSONValueObjectAppendNumberLong;
 virJSONValueObjectAppendNumberUint;
 virJSONValueObjectAppendNumberUlong;
 virJSONValueObjectAppendString;
+virJSONValueObjectAppendStringPrintf;
 virJSONValueObjectCreate;
 virJSONValueObjectCreateVArgs;
 virJSONValueObjectDeflatten;

src/util/virjson.c

@@ -649,6 +649,23 @@ virJSONValueObjectAppendString(virJSONValuePtr object,
 }
 
 
+int
+virJSONValueObjectAppendStringPrintf(virJSONValuePtr object,
+                                     const char *key,
+                                     const char *fmt,
+                                     ...)
+{
+    va_list ap;
+    g_autofree char *str = NULL;
+
+    va_start(ap, fmt);
+    str = g_strdup_vprintf(fmt, ap);
+    va_end(ap);
+
+    return virJSONValueObjectInsertString(object, key, str, false);
+}
+
+
 int
 virJSONValueObjectPrependString(virJSONValuePtr object,
                                 const char *key,

src/util/virjson.h

@@ -127,6 +127,8 @@ int virJSONValueObjectGetBoolean(virJSONValuePtr object, const char *key, bool *
 int virJSONValueObjectIsNull(virJSONValuePtr object, const char *key);
 
 int virJSONValueObjectAppendString(virJSONValuePtr object, const char *key, const char *value);
+int virJSONValueObjectAppendStringPrintf(virJSONValuePtr object, const char *key, const char *fmt, ...)
+    G_GNUC_PRINTF(3, 4);
 int virJSONValueObjectPrependString(virJSONValuePtr object, const char *key, const char *value);
 int virJSONValueObjectAppendNumberInt(virJSONValuePtr object, const char *key, int number);
 int virJSONValueObjectAppendNumberUint(virJSONValuePtr object, const char *key, unsigned int number);