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The Windows Access Control Model: Part 2

, 27 Jun 2005
This second part of the Access Control series will program with the basic Access Control structures.
boost.zip
boost
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stdlib
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mpl
aux_
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bcc
bcc551
gcc
msvc60
msvc70
mwcw
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range_c
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arithmetic
detail
array
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config
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userfun.zip
ATL
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UserFun.exe
LowLevel
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LowLevel.exe
2000
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2000.exe
whoami.zip
Whoami
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Whoami.exe
/*
 *
 * Copyright (c) 1998-2002
 * Dr John Maddock
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Dr John Maddock makes no representations
 * about the suitability of this software for any purpose.
 * It is provided "as is" without express or implied warranty.
 *
 */

 /*
  *   LOCATION:    see http://www.boost.org for most recent version.
  *   FILE         regex_raw_buffer.hpp
  *   VERSION      see <boost/version.hpp>
  *   DESCRIPTION: Raw character buffer for regex code.
  *                Note this is an internal header file included
  *                by regex.hpp, do not include on its own.
  */

#ifndef BOOST_REGEX_RAW_BUFFER_HPP
#define BOOST_REGEX_RAW_BUFFER_HPP

#ifndef BOOST_REGEX_CONFIG_HPP
#include <boost/regex/config.hpp>
#endif

namespace boost{
   namespace re_detail{

#ifdef __BORLANDC__
   #pragma option push -a8 -b -Vx -Ve -pc
#endif

struct empty_padding{};

union padding
{
   void* p;
   unsigned int i;
};

template <int N>
struct padding3
{
   enum{
      padding_size = 8,
      padding_mask = 7
   };
};

template<>
struct padding3<2>
{
   enum{
      padding_size = 2,
      padding_mask = 1
   };
};

template<>
struct padding3<4>
{
   enum{
      padding_size = 4,
      padding_mask = 3
   };
};

template<>
struct padding3<8>
{
   enum{
      padding_size = 8,
      padding_mask = 7
   };
};

template<>
struct padding3<16>
{
   enum{
      padding_size = 16,
      padding_mask = 15
   };
};

enum{
   padding_size = padding3<sizeof(padding)>::padding_size,
   padding_mask = padding3<sizeof(padding)>::padding_mask
};

//
// class raw_storage
// basically this is a simplified vector<unsigned char>
// this is used by reg_expression for expression storage
//

template <class Allocator>
class raw_storage
{
public:
   typedef Allocator allocator_type;
   typedef typename boost::detail::rebind_allocator<unsigned char, allocator_type>::type alloc_inst_type;
   typedef typename alloc_inst_type::size_type                                size_type;
   typedef typename alloc_inst_type::pointer                                  pointer;
private:
   //
   // empty member optimisation:
   struct alloc_data : public alloc_inst_type
   {
      typename alloc_inst_type::pointer last;
      alloc_data(const Allocator& a) : alloc_inst_type(a){}
   } alloc_inst;
   pointer start, end;
public:

   raw_storage(const Allocator& a = Allocator());
   raw_storage(size_type n, const Allocator& a = Allocator());

   ~raw_storage()
   {
      alloc_inst.deallocate(start, (alloc_inst.last - start));
   }

   void BOOST_REGEX_CALL resize(size_type n);
   
   void* BOOST_REGEX_CALL extend(size_type n)
   {
      if(size_type(alloc_inst.last - end) < n)
         resize(n + (end - start));
      register void* result = end;
      end += n;
      return result;
   }

   void* BOOST_REGEX_CALL insert(size_type pos, size_type n);

   size_type BOOST_REGEX_CALL size()
   {
      return end - start;
   }

   size_type BOOST_REGEX_CALL capacity()
   {
      return alloc_inst.last - start;
   }

   void* BOOST_REGEX_CALL data()const
   {
      return start;
   }

   size_type BOOST_REGEX_CALL index(void* ptr)
   {
      return reinterpret_cast<unsigned char*>(ptr) - reinterpret_cast<unsigned char*>(data());
   }

   void BOOST_REGEX_CALL clear()
   {
      end = start;
   }

   void BOOST_REGEX_CALL align()
   {
      // move end up to a boundary:
      end = reinterpret_cast<unsigned char*>(start) + (((reinterpret_cast<unsigned char*>(end) - reinterpret_cast<unsigned char*>(start)) + padding_mask) & ~padding_mask);
   }

   Allocator BOOST_REGEX_CALL allocator()const;
};

template <class Allocator>
raw_storage<Allocator>::raw_storage(const Allocator& a)
  : alloc_inst(a)
{
  start = end = alloc_inst.allocate(1024);
  BOOST_REGEX_NOEH_ASSERT(start)
  alloc_inst.last = start + 1024;
}

template <class Allocator>
raw_storage<Allocator>::raw_storage(size_type n, const Allocator& a)
  : alloc_inst(a)
{
  start = end = alloc_inst.allocate(n);
  BOOST_REGEX_NOEH_ASSERT(start)
  alloc_inst.last = start + n;
}

template <class Allocator>
Allocator BOOST_REGEX_CALL raw_storage<Allocator>::allocator()const
{
  return alloc_inst;
}

template <class Allocator>
void BOOST_REGEX_CALL raw_storage<Allocator>::resize(size_type n)
{
   register size_type newsize = (alloc_inst.last - start) * 2;
   register size_type datasize = end - start;
   if(newsize < n)
      newsize = n;
   // extend newsize to WORD/DWORD boundary:
   newsize = (newsize + padding_mask) & ~(padding_mask);

   // allocate and copy data:
   register unsigned char* ptr = alloc_inst.allocate(newsize);
   BOOST_REGEX_NOEH_ASSERT(ptr)
   std::memcpy(ptr, start, datasize);

   // get rid of old buffer:
   alloc_inst.deallocate(start, (alloc_inst.last - start));

   // and set up pointers:
   start = ptr;
   end = ptr + datasize;
   alloc_inst.last = ptr + newsize;
}

template <class Allocator>
void* BOOST_REGEX_CALL raw_storage<Allocator>::insert(size_type pos, size_type n)
{
   jm_assert(pos <= size_type(end - start));
   if(size_type(alloc_inst.last - end) < n)
      resize(n + (end - start));
   register void* result = start + pos;
   std::memmove(start + pos + n, start + pos, (end - start) - pos);
   end += n;
   return result;
}

#ifdef __BORLANDC__
  #pragma option pop
#endif

} // namespace re_detail
} // namespace boost

#endif





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About the Author

oshah
Web Developer
United States United States
Mr. Shah is a reclusive C++/C# developer lurking somewhere in the depths of the city of London. He learnt physics at Kings' College London and obtained a Master in Science there. Having earned an MCAD, he teeters on the brink of transitioning from C++ to C#, unsure of which language to jump to. Fortunately, he also knows how to use .NET interop to merge code between the two languages (which means he won't have to make the choice anytime soon).
 
His interests (apart from programming) are walking, football (the real one!), philosophy, history, retro-gaming, strategy gaming, and any good game in general.
 
He maintains a website / blog / FAQ / junk at shexec32.serveftp.net, where he places the best answers he's written to the questions you've asked. If you can find him, maybe you can hire Mr. Shah to help you with anything C++[/CLI]/C#/.NET related Smile | :) .

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