Make default double serializer ignore userdata again

The user might want to use the userdata for something different, so the
serializer should ignore it by default.

Explicitly setting the serializer to json_object_double_to_json_string will
still make it interpret the userdata as a format string.

.gitignore

@@ -41,6 +41,7 @@
 /tests/test_parse
 /tests/test_cast
 /tests/test_charcase
+/tests/test_double_serializer
 /tests/test_locale
 /tests/test_null
 /tests/test_printbuf

json_object.c

@@ -54,6 +54,7 @@ static struct json_object* json_object_new(enum json_type o_type);
 
 static json_object_to_json_string_fn json_object_object_to_json_string;
 static json_object_to_json_string_fn json_object_boolean_to_json_string;
+static json_object_to_json_string_fn json_object_double_to_json_string_default;
 static json_object_to_json_string_fn json_object_int_to_json_string;
 static json_object_to_json_string_fn json_object_string_to_json_string;
 static json_object_to_json_string_fn json_object_array_to_json_string;
@@ -261,7 +262,7 @@ void json_object_set_serializer(json_object *jso,
 			jso->_to_json_string = &json_object_boolean_to_json_string;
 			break;
 		case json_type_double:
-			jso->_to_json_string = &json_object_double_to_json_string;
+			jso->_to_json_string = &json_object_double_to_json_string_default;
 			break;
 		case json_type_int:
 			jso->_to_json_string = &json_object_int_to_json_string;
@@ -643,10 +644,11 @@ int64_t json_object_get_int64(const struct json_object *jso)
 
 /* json_object_double */
 
-int json_object_double_to_json_string(struct json_object* jso,
-				      struct printbuf *pb,
-				      int level,
-				      int flags)
+static int json_object_double_to_json_string_format(struct json_object* jso,
+						    struct printbuf *pb,
+						    int level,
+						    int flags,
+						    const char *format)
 {
   char buf[128], *p, *q;
   int size;
@@ -663,7 +665,7 @@ int json_object_double_to_json_string(struct json_object* jso,
       size = snprintf(buf, sizeof(buf), "-Infinity");
   else
     size = snprintf(buf, sizeof(buf),
-        jso->_userdata ? (const char*) jso->_userdata : "%.17g", jso->o.c_double);
+        format ? format : "%.17g", jso->o.c_double);
 
   p = strchr(buf, ',');
   if (p) {
@@ -685,12 +687,30 @@ int json_object_double_to_json_string(struct json_object* jso,
   return size;
 }
 
+static int json_object_double_to_json_string_default(struct json_object* jso,
+						     struct printbuf *pb,
+						     int level,
+						     int flags)
+{
+	return json_object_double_to_json_string_format(jso, pb, level, flags,
+							NULL);
+}
+
+int json_object_double_to_json_string(struct json_object* jso,
+				      struct printbuf *pb,
+				      int level,
+				      int flags)
+{
+	return json_object_double_to_json_string_format(jso, pb, level, flags,
+							jso->_userdata);
+}
+
 struct json_object* json_object_new_double(double d)
 {
 	struct json_object *jso = json_object_new(json_type_double);
 	if (!jso)
 		return NULL;
-	jso->_to_json_string = &json_object_double_to_json_string;
+	jso->_to_json_string = &json_object_double_to_json_string_default;
 	jso->o.c_double = d;
 	return jso;
 }

tests/Makefile.am

@@ -11,6 +11,7 @@ TESTS+= testReplaceExisting.test
 TESTS+= test_parse_int64.test
 TESTS+= test_null.test
 TESTS+= test_cast.test
+TESTS+= test_double_serializer.test
 TESTS+= test_parse.test
 TESTS+= test_locale.test
 TESTS+= test_charcase.test
@@ -22,7 +23,7 @@ check_PROGRAMS=
 check_PROGRAMS += $(TESTS:.test=)
 
 # Note: handled by test1.test
-check_PROGRAMS += test1Formatted 
+check_PROGRAMS += test1Formatted
 test1Formatted_SOURCES = test1.c parse_flags.c
 test1Formatted_CPPFLAGS = -DTEST_FORMATTED
 

tests/test_double_serializer.c

@@ -0,0 +1,31 @@
+/*
+* Tests if the format string for double serialization is handled correctly
+*/
+
+#include <stdio.h>
+#include "config.h"
+
+#include "json_object.h"
+#include "json_object_private.h"
+
+int main()
+{
+	struct json_object *obj = json_object_new_double(0.5);
+
+	printf("Test default serializer:\n");
+	printf("obj.to_string(standard)=%s\n", json_object_to_json_string(obj));
+
+	printf("Test default serializer with custom userdata:\n");
+	obj->_userdata = "test";
+	printf("obj.to_string(userdata)=%s\n", json_object_to_json_string(obj));
+
+	printf("Test explicit serializer with custom userdata:\n");
+	json_object_set_serializer(obj, json_object_double_to_json_string, "test", NULL);
+	printf("obj.to_string(custom)=%s\n", json_object_to_json_string(obj));
+
+	printf("Test reset serializer:\n");
+	json_object_set_serializer(obj, NULL, NULL, NULL);
+	printf("obj.to_string(reset)=%s\n", json_object_to_json_string(obj));
+
+	json_object_put(obj);
+}

tests/test_double_serializer.expected

@@ -0,0 +1,8 @@
+Test default serializer:
+obj.to_string(standard)=0.5
+Test default serializer with custom userdata:
+obj.to_string(userdata)=0.5
+Test explicit serializer with custom userdata:
+obj.to_string(custom)=test
+Test reset serializer:
+obj.to_string(reset)=0.5

tests/test_double_serializer.test

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+# Common definitions
+if test -z "$srcdir"; then
+    srcdir="${0%/*}"
+    test "$srcdir" = "$0" && srcdir=.
+    test -z "$srcdir" && srcdir=.
+fi
+. "$srcdir/test-defs.sh"
+
+run_output_test test_double_serializer
+exit $?