allocators: split allocators and pagelocker

Pagelocker is only needed for secure (usually wallet) operations, so don't make
the zero-after-free allocator depend on it.

1 files changed, 62 insertions, 0 deletions

diff --git a/src/support/allocators/secure.h b/src/support/allocators/secure.h
new file mode 100644
index 0000000000..7a74d87bb4
--- /dev/null
+++ b/src/support/allocators/secure.h
@@ -0,0 +1,62 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2013 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_ALLOCATORS_SECURE_H
+#define BITCOIN_ALLOCATORS_SECURE_H
+
+#include "support/pagelocker.h"
+
+#include <string>
+
+//
+// Allocator that locks its contents from being paged
+// out of memory and clears its contents before deletion.
+//
+template <typename T>
+struct secure_allocator : public std::allocator<T> {
+    // MSVC8 default copy constructor is broken
+    typedef std::allocator<T> base;
+    typedef typename base::size_type size_type;
+    typedef typename base::difference_type difference_type;
+    typedef typename base::pointer pointer;
+    typedef typename base::const_pointer const_pointer;
+    typedef typename base::reference reference;
+    typedef typename base::const_reference const_reference;
+    typedef typename base::value_type value_type;
+    secure_allocator() throw() {}
+    secure_allocator(const secure_allocator& a) throw() : base(a) {}
+    template <typename U>
+    secure_allocator(const secure_allocator<U>& a) throw() : base(a)
+    {
+    }
+    ~secure_allocator() throw() {}
+    template <typename _Other>
+    struct rebind {
+        typedef secure_allocator<_Other> other;
+    };
+
+    T* allocate(std::size_t n, const void* hint = 0)
+    {
+        T* p;
+        p = std::allocator<T>::allocate(n, hint);
+        if (p != NULL)
+            LockedPageManager::Instance().LockRange(p, sizeof(T) * n);
+        return p;
+    }
+
+    void deallocate(T* p, std::size_t n)
+    {
+        if (p != NULL) {
+            memory_cleanse(p, sizeof(T) * n);
+            LockedPageManager::Instance().UnlockRange(p, sizeof(T) * n);
+        }
+        std::allocator<T>::deallocate(p, n);
+    }
+};
+
+// This is exactly like std::string, but with a custom allocator.
+typedef std::basic_string<char, std::char_traits<char>, secure_allocator<char> > SecureString;
+
+#endif // BITCOIN_ALLOCATORS_SECURE_H