Support for specifying allocator added

Author: Christopher Dawes

include/json/allocator.h

@@ -0,0 +1,60 @@
+// Copyright 2015 Baptiste Lepilleur
+// Distributed under MIT license, or public domain if desired and
+// recognized in your jurisdiction.
+// See file LICENSE for detail or copy at https://raw.githubusercontent.com/open-source-parsers/jsoncpp/master/LICENSE
+#ifndef CPPTL_JSON_ALLOCATOR_H_INCLUDED
+#define CPPTL_JSON_ALLOCATOR_H_INCLUDED
+
+#include <cstring> // std::memset
+#include <cstddef> // std::size_t, std::ptrdiff_t
+#include <utility> // std::forward
+
+#if !defined(JSON_IS_AMALGAMATION)
+#include "config.h"
+#endif // if !defined(JSON_IS_AMALGAMATION)
+
+namespace Json {
+
+/**
+ * This class is used for de-allocating memory securely, allocation happens
+ * in the normal manner however it's important that de-allocation explicitly
+ * overwrites the memory with 0s to ensure the memory cannot be "sniffed"
+ */
+template<typename T>
+class JSON_API SecureAllocator {
+  public:
+    // Type definitions
+    using value_type      = T;
+    using pointer         = T*;
+    using const_pointer   = const T*;
+    using reference       = T&;
+    using const_reference = const T&;
+    using size_type       = std::size_t;
+    using difference_type = std::ptrdiff_t;
+
+    /**
+     * Release memory which was allocated for N items at pointer P.
+     *
+     * The memory block is filled with zeroes before being released.
+     * The pointer argument is tagged as "volatile" to prevent the
+     * compiler optimizing out this critical step.
+     */
+    void deallocate(volatile pointer p, size_type n) {
+      std::fill_n((volatile char*)p, n * sizeof(value_type), 0);
+      std::allocator<T>::deallocate(p, n);
+    }
+};
+
+template<typename T, typename U>
+bool operator==(const SecureAllocator<T>&, const SecureAllocator<U>&) {
+  return true;
+}
+
+template<typename T, typename U>
+bool operator!=(const SecureAllocator<T>&, const SecureAllocator<U>&) {
+  return false;
+}
+
+} //end namespace Json
+
+#endif // CPPTL_JSON_ALLOCATOR_H_INCLUDED

include/json/config.h

@@ -113,6 +113,13 @@
 #define JSONCPP_DEPRECATED(message)
 #endif // if !defined(JSONCPP_DEPRECATED)
 
+//We may want to have different presets for the default allocator and
+//string
+//#define JSONCPP_DEFAULT_CHAR_TRAITS = std::char_traits<char>
+//#define JSONCPP_DEFAULT_ALLOCATOR = std::allocator<char>
+#define JSONCPP_DEFAULT_CHAR_TRAITS
+#define JSONCPP_DEFAULT_ALLOCATOR
+
 namespace Json {
 typedef int Int;
 typedef unsigned int UInt;

include/json/forwards.h

@@ -13,10 +13,13 @@
 namespace Json {
 
 // writer.h
+template<typename _Traits, typename _Alloc>
 class FastWriter;
+template<typename _Traits, typename _Alloc>
 class StyledWriter;
 
-// reader.h
+// reader_declaration.h
+template<typename _Traits, typename _Alloc>
 class Reader;
 
 // features.h
@@ -25,11 +28,17 @@ class Features;
 // value.h
 typedef unsigned int ArrayIndex;
 class StaticString;
+template<typename _Traits, typename _Alloc>
 class Path;
+template<typename _Traits, typename _Alloc>
 class PathArgument;
+template<typename _Traits, typename _Alloc>
 class Value;
+template<typename _Traits, typename _Alloc>
 class ValueIteratorBase;
+template<typename _Traits, typename _Alloc>
 class ValueIterator;
+template<typename _Traits, typename _Alloc>
 class ValueConstIterator;
 
 } // namespace Json