my_mmap.c

/* Copyright (C) 2000-2003 MySQL AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#include "mysys_priv.h"

#ifdef HAVE_SYS_MMAN_H

/*
  system msync() only syncs mmap'ed area to fs cache.
  fsync() is required to really sync to disc
*/
int my_msync(int fd, void *addr, size_t len, int flags)
{
  msync(addr, len, flags);
  return my_sync(fd, MYF(0));
}

#else
#ifdef __WIN__

static SECURITY_ATTRIBUTES mmap_security_attributes=
  {sizeof(SECURITY_ATTRIBUTES), 0, TRUE};

int my_getpagesize(void)
{
  SYSTEM_INFO si;
  GetSystemInfo(&si);
  return si.dwPageSize;
}

void *my_mmap(void *addr, size_t len, int prot,
               int flags, int fd, my_off_t offset)
{
  DWORD flProtect=0;
  HANDLE hFileMap;
  LPVOID ptr;

  flProtect|=SEC_COMMIT;

  hFileMap=CreateFileMapping(fd, NULL, &mmap_security_attributes,
                             PAGE_READWRITE, 0, len, 0);
  if (hFileMap == 0)
    return MAP_FAILED;

  ptr=MapViewOfFile(hFileMap,
                    flags & PROT_WRITE ? FILE_MAP_WRITE : FILE_MAP_READ,
                    (DWORD)(offset >> 32), (DWORD)offset, len);

  /*
    MSDN explicitly states that it's possible to close File Mapping Object
    even when a view is not unmapped - then the object will be held open
    implicitly until unmap, as every view stores internally a handler of
    a corresponding File Mapping Object
   */
  CloseHandle(hFileMap);

  if (ptr)
    return ptr;

  return MAP_FAILED;
}

int my_munmap(void *addr, size_t len)
{
  return UnmapViewOfFile(addr) ? 0 : -1;
}

int my_msync(int fd, void *addr, size_t len, int flags)
{
  return FlushViewOfFile(addr, len) ? 0 : -1;
}

#endif

#ifndef __WIN__
#warning "no mmap!"
#endif

#endif