[json-glib] reader: Do more strict validation

[Emmanuele Bassi <ebassi src gnome org>]

commit 9f75475871cc8723e0a41d6c8971f741a405cb9f
Author: Emmanuele Bassi <ebassi linux intel com>
Date:   Fri Sep 9 14:00:36 2011 +0100

    reader: Do more strict validation
    
    JsonReader should perform more strict validation, and put itself in an
    error state whenever the user asks for values or information on nodes
    that are not there, or not of the right type.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=658632

 json-glib/json-reader.c |  177 ++++++++++++++++++++++++++++++++++++++++------
 json-glib/json-reader.h |   10 +++-
 2 files changed, 163 insertions(+), 24 deletions(-)
---
diff --git a/json-glib/json-reader.c b/json-glib/json-reader.c
index 73e0ea3..ddce658 100644
--- a/json-glib/json-reader.c
+++ b/json-glib/json-reader.c
@@ -571,10 +571,19 @@ json_reader_count_elements (JsonReader *reader)
   priv = reader->priv;
 
   if (priv->current_node == NULL)
-    return -1;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_NODE,
+                             _("No node available at the current position"));
+      return -1;
+    }
 
   if (!JSON_NODE_HOLDS_ARRAY (priv->current_node))
-    return -1;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_NO_ARRAY,
+                             _("The current position holds a '%s' and not an array"),
+                             json_node_type_get_name (JSON_NODE_TYPE (priv->current_node)));
+      return -1;
+    }
 
   return json_array_get_length (json_node_get_array (priv->current_node));
 }
@@ -715,10 +724,19 @@ json_reader_list_members (JsonReader *reader)
   priv = reader->priv;
 
   if (priv->current_node == NULL)
-    return NULL;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_NODE,
+                             _("No node available at the current position"));
+      return NULL;
+    }
 
   if (!JSON_NODE_HOLDS_OBJECT (priv->current_node))
-    return NULL;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_NO_OBJECT,
+                             _("The current position holds a '%s' and not an object"),
+                             json_node_type_get_name (JSON_NODE_TYPE (priv->current_node)));
+      return NULL;
+    }
 
   members = json_object_get_members (json_node_get_object (priv->current_node));
   if (members == NULL)
@@ -757,10 +775,19 @@ json_reader_count_members (JsonReader *reader)
   priv = reader->priv;
 
   if (priv->current_node == NULL)
-    return -1;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_NODE,
+                             _("No node available at the current position"));
+      return -1;
+    }
 
   if (!JSON_NODE_HOLDS_OBJECT (priv->current_node))
-    return -1;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_NO_OBJECT,
+                             _("The current position holds a '%s' and not an object"),
+                             json_node_type_get_name (JSON_NODE_TYPE (priv->current_node)));
+      return -1;
+    }
 
   return json_object_get_size (json_node_get_object (priv->current_node));
 }
@@ -780,14 +807,27 @@ json_reader_count_members (JsonReader *reader)
 JsonNode *
 json_reader_get_value (JsonReader *reader)
 {
+  JsonNode *node;
+
   g_return_val_if_fail (JSON_IS_READER (reader), NULL);
   json_reader_return_val_if_error_set (reader, NULL);
 
   if (reader->priv->current_node == NULL)
-    return NULL;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_NODE,
+                             _("No node available at the current position"));
+      return NULL;
+    }
 
-  if (!JSON_NODE_HOLDS_VALUE (reader->priv->current_node))
-    return NULL;
+  node = reader->priv->current_node;
+
+  if (!JSON_NODE_HOLDS_VALUE (node))
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_NO_VALUE,
+                             _("The current position holds a '%s' and not a value"),
+                             json_node_type_get_name (JSON_NODE_TYPE (node)));
+      return NULL;
+    }
 
   return reader->priv->current_node;
 }
@@ -805,14 +845,34 @@ json_reader_get_value (JsonReader *reader)
 gint64
 json_reader_get_int_value (JsonReader *reader)
 {
+  JsonNode *node;
+
   g_return_val_if_fail (JSON_IS_READER (reader), 0);
   json_reader_return_val_if_error_set (reader, 0);
 
   if (reader->priv->current_node == NULL)
-    return 0;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_NODE,
+                             _("No node available at the current position"));
+      return 0;
+    }
+
+  node = reader->priv->current_node;
+
+  if (!JSON_NODE_HOLDS_VALUE (node))
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_NO_VALUE,
+                             _("The current position holds a '%s' and not a value"),
+                             json_node_type_get_name (JSON_NODE_TYPE (node)));
+      return 0;
+    }
 
-  if (!JSON_NODE_HOLDS_VALUE (reader->priv->current_node))
-    return 0;
+  if (json_node_get_value_type (node) != G_TYPE_INT64)
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_TYPE,
+                             _("The current position does not hold an integer type"));
+      return 0;
+    }
 
   return json_node_get_int (reader->priv->current_node);
 }
@@ -830,14 +890,34 @@ json_reader_get_int_value (JsonReader *reader)
 gdouble
 json_reader_get_double_value (JsonReader *reader)
 {
+  JsonNode *node;
+
   g_return_val_if_fail (JSON_IS_READER (reader), 0.0);
   json_reader_return_val_if_error_set (reader, 0.0);
 
   if (reader->priv->current_node == NULL)
-    return 0.0;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_NODE,
+                             _("No node available at the current position"));
+      return 0.0;
+    }
+
+  node = reader->priv->current_node;
+
+  if (!JSON_NODE_HOLDS_VALUE (node))
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_NO_VALUE,
+                             _("The current position holds a '%s' and not a value"),
+                             json_node_type_get_name (JSON_NODE_TYPE (node)));
+      return 0.0;
+    }
 
-  if (!JSON_NODE_HOLDS_VALUE (reader->priv->current_node))
-    return 0.0;
+  if (json_node_get_value_type (node) != G_TYPE_DOUBLE)
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_TYPE,
+                             _("The current position does not hold a floating point type"));
+      return 0.0;
+    }
 
   return json_node_get_double (reader->priv->current_node);
 }
@@ -855,14 +935,34 @@ json_reader_get_double_value (JsonReader *reader)
 const gchar *
 json_reader_get_string_value (JsonReader *reader)
 {
+  JsonNode *node;
+
   g_return_val_if_fail (JSON_IS_READER (reader), NULL);
   json_reader_return_val_if_error_set (reader, NULL);
 
   if (reader->priv->current_node == NULL)
-    return NULL;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_NODE,
+                             _("No node available at the current position"));
+      return NULL;
+    }
 
-  if (!JSON_NODE_HOLDS_VALUE (reader->priv->current_node))
-    return NULL;
+  node = reader->priv->current_node;
+
+  if (!JSON_NODE_HOLDS_VALUE (node))
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_NO_VALUE,
+                             _("The current position holds a '%s' and not a value"),
+                             json_node_type_get_name (JSON_NODE_TYPE (node)));
+      return NULL;
+    }
+
+  if (json_node_get_value_type (node) != G_TYPE_STRING)
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_TYPE,
+                             _("The current position does not hold a string type"));
+      return NULL;
+    }
 
   return json_node_get_string (reader->priv->current_node);
 }
@@ -880,16 +980,36 @@ json_reader_get_string_value (JsonReader *reader)
 gboolean
 json_reader_get_boolean_value (JsonReader *reader)
 {
+  JsonNode *node;
+
   g_return_val_if_fail (JSON_IS_READER (reader), FALSE);
   json_reader_return_val_if_error_set (reader, FALSE);
 
   if (reader->priv->current_node == NULL)
-    return FALSE;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_NODE,
+                             _("No node available at the current position"));
+      return FALSE;
+    }
 
-  if (!JSON_NODE_HOLDS_VALUE (reader->priv->current_node))
-    return FALSE;
+  node = reader->priv->current_node;
+
+  if (!JSON_NODE_HOLDS_VALUE (node))
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_NO_VALUE,
+                             _("The current position holds a '%s' and not a value"),
+                             json_node_type_get_name (JSON_NODE_TYPE (node)));
+      return FALSE;
+    }
+
+  if (json_node_get_value_type (node) != G_TYPE_BOOLEAN)
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_TYPE,
+                             _("The current position does not hold a boolean type"));
+      return FALSE;
+    }
 
-  return json_node_get_boolean (reader->priv->current_node);
+  return json_node_get_boolean (node);
 }
 
 /**
@@ -909,7 +1029,11 @@ json_reader_get_null_value (JsonReader *reader)
   json_reader_return_val_if_error_set (reader, FALSE);
 
   if (reader->priv->current_node == NULL)
-    return FALSE;
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_NODE,
+                             _("No node available at the current position"));
+      return FALSE;
+    }
 
   return JSON_NODE_HOLDS_NULL (reader->priv->current_node);
 }
@@ -930,5 +1054,12 @@ json_reader_get_member_name (JsonReader *reader)
   g_return_val_if_fail (JSON_IS_READER (reader), NULL);
   json_reader_return_val_if_error_set (reader, NULL);
 
+  if (reader->priv->current_node == NULL)
+    {
+      json_reader_set_error (reader, JSON_READER_ERROR_INVALID_NODE,
+                             _("No node available at the current position"));
+      return FALSE;
+    }
+
   return reader->priv->current_member;
 }
diff --git a/json-glib/json-reader.h b/json-glib/json-reader.h
index 05d0735..6ee0b54 100644
--- a/json-glib/json-reader.h
+++ b/json-glib/json-reader.h
@@ -57,6 +57,11 @@ typedef struct _JsonReaderClass         JsonReaderClass;
  * @JSON_READER_ERROR_INVALID_INDEX: Index out of bounds
  * @JSON_READER_ERROR_NO_OBJECT: No object found at the current position
  * @JSON_READER_ERROR_INVALID_MEMBER: Member not found
+ * @JSON_READER_ERROR_INVALID_NODE: No valid node found at the current position
+ * @JSON_READER_ERROR_NO_VALUE: The node at the current position does not
+ *   hold a value
+ * @JSON_READER_ERROR_INVALID_TYPE: The node at the current position does not
+ *   hold a value of the desired type
  *
  * Error codes enumeration for #JsonReader errors
  *
@@ -66,7 +71,10 @@ typedef enum {
   JSON_READER_ERROR_NO_ARRAY,
   JSON_READER_ERROR_INVALID_INDEX,
   JSON_READER_ERROR_NO_OBJECT,
-  JSON_READER_ERROR_INVALID_MEMBER
+  JSON_READER_ERROR_INVALID_MEMBER,
+  JSON_READER_ERROR_INVALID_NODE,
+  JSON_READER_ERROR_NO_VALUE,
+  JSON_READER_ERROR_INVALID_TYPE
 } JsonReaderError;
 
 /**