util: json: Add helper to reformat JSON strings

For use in test cases it will be helpful to allow reformatting JSON
strings. Add a wrapper on top of the parser and formatter to achieve
this.

src/libvirt_private.syms

@@ -1791,6 +1791,7 @@ virISCSIScanTargets;
 
 
 # util/virjson.h
+virJSONStringReformat;
 virJSONValueArrayAppend;
 virJSONValueArrayForeachSteal;
 virJSONValueArrayGet;

src/util/virjson.c

@@ -1918,3 +1918,32 @@ virJSONValueToString(virJSONValuePtr object ATTRIBUTE_UNUSED,
     return NULL;
 }
 #endif
+
+
+/**
+ * virJSONStringReformat:
+ * @jsonstr: string to reformat
+ * @pretty: use the pretty formatter
+ *
+ * Reformats a JSON string by passing it to the parser and then to the
+ * formatter. If @pretty is true the JSON is formatted for human eye
+ * compatibility.
+ *
+ * Returns the reformatted JSON string on success; NULL and a libvirt error on
+ * failure.
+ */
+char *
+virJSONStringReformat(const char *jsonstr,
+                      bool pretty)
+{
+    virJSONValuePtr json;
+    char *ret;
+
+    if (!(json = virJSONValueFromString(jsonstr)))
+        return NULL;
+
+    ret = virJSONValueToString(json, pretty);
+
+    virJSONValueFree(json);
+    return ret;
+}

src/util/virjson.h

@@ -181,4 +181,6 @@ int virJSONValueObjectForeachKeyValue(virJSONValuePtr object,
 
 virJSONValuePtr virJSONValueCopy(const virJSONValue *in);
 
+char *virJSONStringReformat(const char *jsonstr, bool pretty);
+
 #endif /* __VIR_JSON_H_ */