Change the KVP string storage type from char* to const char*.

Because we don't want to be able to get a pointer to the KvpValue and
change its contents without using KvpValue::set().

src/backend/xml/sixtp-dom-generators.cpp

@@ -262,7 +262,7 @@ add_kvp_value_node(xmlNodePtr node, const gchar *tag, KvpValue* val)
     {
     case KVP_TYPE_STRING:
     {
-	auto newstr = g_strdup(val->get<char*>());
+	auto newstr = g_strdup(val->get<const char*>());
         val_node = xmlNewTextChild(node, NULL, BAD_CAST tag,
 				   checked_char_cast (newstr));
 	g_free (newstr);

src/core-utils/gnc-features.c

@@ -124,7 +124,7 @@ gchar *gnc_features_test_unknown (QofBook *book)
 	g_list_free(features_list);
 	return msg;
     }
-
+    g_hash_table_unref (features_used);
     return NULL;
 }
 

src/libqof/qof/kvp-value.cpp

@@ -80,7 +80,7 @@ KvpValueImpl::get_type() const noexcept
         return KvpValueType::KVP_TYPE_DOUBLE;
     else if (datastore.type() == typeid(gnc_numeric))
         return KvpValueType::KVP_TYPE_NUMERIC;
-    else if (datastore.type() == typeid(gchar *))
+    else if (datastore.type() == typeid(const gchar *))
         return KvpValueType::KVP_TYPE_STRING;
     else if (datastore.type() == typeid(GncGUID *))
         return KvpValueType::KVP_TYPE_GUID;
@@ -202,7 +202,7 @@ struct to_string_visitor : boost::static_visitor<void>
         output << ")";
     }
 
-    void operator()(char * val)
+    void operator()(const char * val)
     {
         output << "KVP_VALUE_STRING(" << val << ")";
     }
@@ -243,7 +243,7 @@ struct compare_visitor : boost::static_visitor<int>
         return 0;
     }
 };
-template <> int compare_visitor::operator()(char * const & one, char * const & two) const
+template <> int compare_visitor::operator()(const char * const & one, const char * const & two) const
 {
     return strcmp(one, two);
 }
@@ -337,8 +337,8 @@ KvpValueImpl::~KvpValueImpl() noexcept
 void
 KvpValueImpl::duplicate(const KvpValueImpl& other) noexcept
 {
-    if (other.datastore.type() == typeid(gchar *))
-        this->datastore = g_strdup(other.get<gchar *>());
+    if (other.datastore.type() == typeid(const gchar *))
+        this->datastore = g_strdup(other.get<const gchar *>());
     else if (other.datastore.type() == typeid(GncGUID*))
         this->datastore = guid_copy(other.get<GncGUID *>());
     else if (other.datastore.type() == typeid(GList*))

src/libqof/qof/kvp-value.hpp

@@ -108,7 +108,7 @@ struct KvpValueImpl
         int64_t,
         double,
         gnc_numeric,
-        char *,
+        const char*,
         GncGUID *,
         Timespec,
         GList *,

src/libqof/qof/kvp_frame.cpp

@@ -1050,12 +1050,12 @@ kvp_value_get_numeric(const KvpValue * ovalue)
     return value->get<gnc_numeric>();
 }
 
-char *
+const char *
 kvp_value_get_string(const KvpValue * ovalue)
 {
     if (!ovalue) return {};
     const KvpValueImpl * value {static_cast<const KvpValueImpl *>(ovalue)};
-    return value->get<char*>();
+    return value->get<const char*>();
 }
 
 GncGUID *

src/libqof/qof/kvp_frame.h

@@ -528,7 +528,7 @@ gnc_numeric kvp_value_get_numeric(const KvpValue * value);
 
 /** Value accessor. This one is non-copying -- the caller can modify
  * the value directly. */
-char        * kvp_value_get_string(const KvpValue * value);
+const char* kvp_value_get_string(const KvpValue * value);
 
 /** Value accessor. This one is non-copying -- the caller can modify
  * the value directly. */

src/libqof/qof/qofbook.cpp

@@ -1068,7 +1068,7 @@ static void commit_err (G_GNUC_UNUSED QofInstance *inst, QofBackendError errcode
 static void
 add_feature_to_hash (const gchar *key, KvpValue *value, gpointer user_data)
 {
-    gchar *descr = kvp_value_get_string (value);
+    gchar *descr = g_strdup(kvp_value_get_string (value));
     g_hash_table_insert (*(GHashTable**)user_data, (gchar*)key, descr);
 }
 
@@ -1076,7 +1076,8 @@ GHashTable *
 qof_book_get_features (QofBook *book)
 {
     KvpFrame *frame = qof_instance_get_slots (QOF_INSTANCE (book));
-    GHashTable *features = g_hash_table_new (g_str_hash, g_str_equal);
+    GHashTable *features = g_hash_table_new_full (g_str_hash, g_str_equal,
+                                                  NULL, g_free);
 
     frame = kvp_frame_get_frame (frame, GNC_FEATURES);
     kvp_frame_for_each_slot (frame, &add_feature_to_hash, &features);