/*************************************************
* Memory Mapping Allocator Source File           *
* (C) 1999-2004 The Botan Project                *
*************************************************/

#ifndef _XOPEN_SOURCE
  #define _XOPEN_SOURCE 500
#endif
#ifndef _XOPEN_SOURCE_EXTENDED
  #define _XOPEN_SOURCE_EXTENDED 1
#endif

#include <botan/mmap_mem.h>
#include <cstring>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>

namespace Botan {

/*************************************************
* Memory Map a File into Memory                  *
*************************************************/
void* MemoryMapping_Allocator::alloc_block(u32bit n) const
   {
   const std::string path = "/tmp/botan_XXXXXX";

   char* filepath = new char[path.length() + 1];
   std::strcpy(filepath, path.c_str());

   mode_t old_umask = umask(077);
   int fd = mkstemp(filepath);
   umask(old_umask);

   if(fd == -1)
      throw Exception("MemoryMapping_Allocator: Could not create file");
   if(unlink(filepath))
      throw Exception("MemoryMapping_Allocator: Could not unlink file " +
                      std::string(filepath));
   delete[] filepath;

   lseek(fd, n-1, SEEK_SET);
   if(write(fd, "\0", 1) != 1)
      throw Exception("MemoryMapping_Allocator: Could not write to file");
   void* ptr = mmap(0, n, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
   if(ptr == (void*)MAP_FAILED)
      throw Exception("MemoryMapping_Allocator: Could not map file");
   if(close(fd))
      throw Exception("MemoryMapping_Allocator: Could not close file");

   return ptr;
   }

/*************************************************
* Remove a Memory Mapping                        *
*************************************************/
void MemoryMapping_Allocator::dealloc_block(void* ptr, u32bit n) const
   {
   if(ptr == 0) return;

   const u32bit OVERWRITE_PASSES = 12;
   const byte PATTERNS[] = { 0x00, 0xFF, 0xAA, 0x55, 0x73, 0x8C, 0x5F, 0xA0,
                             0x6E, 0x91, 0x30, 0xCF, 0xD3, 0x2C, 0xAC, 0x53 };

   for(u32bit j = 0; j != OVERWRITE_PASSES; j++)
      {
      std::memset(ptr, PATTERNS[j % sizeof(PATTERNS)], n);
      if(msync(ptr, n, MS_SYNC))
         throw Exception("MemoryMapping_Allocator: Sync operation failed");
      }
   std::memset(ptr, 0, n);
   if(msync(ptr, n, MS_SYNC))
      throw Exception("MemoryMapping_Allocator: Sync operation failed");

   if(munmap(ptr, n))
      throw Exception("MemoryMapping_Allocator: Could not unmap file");
   }

}
