/*************************************************
* Secure Memory Buffers Header File              *
* (C) 1999-2004 The Botan Project                *
*************************************************/

#ifndef BOTAN_SECURE_MEMORY_BUFFERS_H__
#define BOTAN_SECURE_MEMORY_BUFFERS_H__

#include <botan/allocate.h>
#include <botan/config.h>
#include <botan/mem_ops.h>
#include <algorithm>

namespace Botan {

/*************************************************
* Variable Length Memory Buffer                  *
*************************************************/
template<typename T>
class MemoryRegion
   {
   public:
      u32bit size() const { return used; }
      u32bit bits() const { return 8*used; }
      u32bit is_empty() const { return (used == 0); }
      u32bit has_items() const { return (used != 0); }

      operator T* () { return buf; }
      operator const T* () const { return buf; }

      T* begin() { return buf; }
      const T* begin() const { return buf; }

      T* end() { return (buf + size()); }
      const T* end() const { return (buf + size()); }

      bool operator==(const MemoryRegion<T>& in) const
         {
         if(size() == in.size() && std::equal(begin(), end(), in.begin()))
            return true;
         return false;
         }

      bool operator<(const MemoryRegion<T>&) const;

      bool operator!=(const MemoryRegion<T>& in) const
         { return (!(*this == in)); }
      MemoryRegion<T>& operator=(const MemoryRegion<T>& in)
         { if(this != &in) set(in); return (*this); }

      void copy(const T in[], u32bit n)
         { copy_mem(buf, in, std::min(size(), n)); }
      void copy(u32bit off, const T in[], u32bit n)
         { copy_mem(buf + off, in, std::min(size() - off, n)); }

      void set(const T in[], u32bit n)    { create(n); copy(in, n); }
      void set(const MemoryRegion<T>& in) { set(in.begin(), in.size()); }

      void append(const T data[], u32bit n)
         { grow_by(n); copy(size() - n, data, n); }
      void append(T x) { append(&x, 1); }
      void append(const MemoryRegion<T>& x) { append(x.begin(), x.size()); }

      void clear() { clear_mem(buf, allocated); }
      void destroy() { create(0); }

      void create(u32bit);
      void grow_to(u32bit) const;
      void grow_by(u32bit n) const { grow_to(n + size()); }
      void swap(MemoryRegion<T>&);

      ~MemoryRegion() { deallocate(buf, allocated); }
   protected:
      MemoryRegion() { buf = 0; alloc = 0; used = allocated = 0; }
      MemoryRegion(const MemoryRegion<T>& copy)
         {
         buf = 0;
         used = allocated = 0;
         alloc = copy.alloc;
         set(copy.buf, copy.used);
         }

      void init(bool lock, u32bit size = 0)
         { alloc = get_allocator(lock ? "default" : "malloc"); create(size); }
   private:
      T* allocate(u32bit n) const { return (T*)alloc->allocate(sizeof(T)*n); }
      void deallocate(T* p, u32bit n) const
         { alloc->deallocate(p, sizeof(T)*n); }

      mutable T* buf;
      mutable u32bit used;
      mutable u32bit allocated;
      const SecureAllocator* alloc;
   };

/*************************************************
* Create a new buffer                            *
*************************************************/
template<typename T>
void MemoryRegion<T>::create(u32bit n)
   {
   if(n <= allocated) { clear(); used = n; return; }
   deallocate(buf, allocated);
   buf = allocate(n);
   allocated = used = n;
   }

/*************************************************
* Increase the size of the buffer                *
*************************************************/
template<typename T>
void MemoryRegion<T>::grow_to(u32bit n) const
   {
   const u32bit VECTOR_OVER_ALLOCATE = BOTAN_VECTOR_OVER_ALLOCATE;

   if(n <= used) return;
   if(n <= allocated)
      {
      clear_mem(buf + used, n - used);
      used = n;
      return;
      }
   T* new_buf = allocate(n + VECTOR_OVER_ALLOCATE);
   copy_mem(new_buf, buf, used);
   deallocate(buf, allocated);
   buf = new_buf;
   used = n;
   allocated = n + VECTOR_OVER_ALLOCATE;
   }

/*************************************************
* Compare this buffer with another one           *
*************************************************/
template<typename T>
bool MemoryRegion<T>::operator<(const MemoryRegion<T>& in) const
   {
   if(size() < in.size()) return true;
   if(size() > in.size()) return false;

   for(u32bit j = 0; j != size(); j++)
      {
      if(buf[j] < in[j]) return true;
      if(buf[j] > in[j]) return false;
      }

   return false;
   }

/*************************************************
* Swap this buffer with another one              *
*************************************************/
template<typename T>
void MemoryRegion<T>::swap(MemoryRegion<T>& x)
   {
   std::swap(buf, x.buf);
   std::swap(used, x.used);
   std::swap(allocated, x.allocated);
   std::swap(alloc, x.alloc);
   }

/*************************************************
* Unlocked Variable Length Buffer                *
*************************************************/
template<typename T>
class MemoryVector : public MemoryRegion<T>
   {
   public:
      MemoryVector<T>& operator=(const MemoryRegion<T>& in)
         { if(this != &in) set(in); return (*this); }

      MemoryVector(u32bit n = 0) { MemoryRegion<T>::init(false, n); }
      MemoryVector(const T in[], u32bit n)
         { MemoryRegion<T>::init(false); set(in, n); }
      MemoryVector(const MemoryRegion<T>& in)
         { MemoryRegion<T>::init(false); set(in); }
      MemoryVector(const MemoryRegion<T>& in1, const MemoryRegion<T>& in2)
         { MemoryRegion<T>::init(false); set(in1); append(in2); }
   };

/*************************************************
* Locked Variable Length Buffer                  *
*************************************************/
template<typename T>
class SecureVector : public MemoryRegion<T>
   {
   public:
      SecureVector<T>& operator=(const MemoryRegion<T>& in)
         { if(this != &in) set(in); return (*this); }

      SecureVector(u32bit n = 0) { MemoryRegion<T>::init(true, n); }
      SecureVector(const T in[], u32bit n)
         { MemoryRegion<T>::init(true); set(in, n); }
      SecureVector(const MemoryRegion<T>& in)
         { MemoryRegion<T>::init(true); set(in); }
      SecureVector(const MemoryRegion<T>& in1, const MemoryRegion<T>& in2)
         { MemoryRegion<T>::init(true); set(in1); append(in2); }
   };

/*************************************************
* Locked Fixed Length Buffer                     *
*************************************************/
template<typename T, u32bit L>
class SecureBuffer : public MemoryRegion<T>
   {
   public:
      SecureBuffer<T,L>& operator=(const SecureBuffer<T,L>& in)
         { if(this != &in) set(in); return (*this); }

      SecureBuffer() { MemoryRegion<T>::init(true, L); }
      SecureBuffer(const T in[], u32bit n)
         { MemoryRegion<T>::init(true, L); copy(in, n); }
   private:
      SecureBuffer<T, L>& operator=(const MemoryRegion<T>& in)
         { if(this != &in) set(in); return (*this); }
   };

}

#endif
