// Copyright https://code.google.com/p/mman-win32/
//
// Licensed under the MIT License;
// You may obtain a copy of the License at
//
// https://opensource.org/licenses/MIT

#ifndef _MMAN_WIN32_H
#define _MMAN_WIN32_H

// Allow use of features specific to Windows XP or later.
#ifndef _WIN32_WINNT
// Change this to the appropriate value to target other versions of Windows.
#define _WIN32_WINNT 0x0501

#endif

#include <sys/types.h>
#include <windows.h>
#include <errno.h>
#include <io.h>

#define PROT_NONE       0
#define PROT_READ       1
#define PROT_WRITE      2
#define PROT_EXEC       4

#define MAP_FILE        0
#define MAP_SHARED      1
#define MAP_PRIVATE     2
#define MAP_TYPE        0xf
#define MAP_FIXED       0x10
#define MAP_ANONYMOUS   0x20
#define MAP_ANON        MAP_ANONYMOUS

#define MAP_FAILED      ((void *)-1)

/* Flags for msync. */
#define MS_ASYNC        1
#define MS_SYNC         2
#define MS_INVALIDATE   4

#ifndef FILE_MAP_EXECUTE
#define FILE_MAP_EXECUTE    0x0020
#endif

static int __map_mman_error(const DWORD err, const int deferr) {
  if (err == 0)
    return 0;
  //TODO: implement
  return err;
}

static DWORD __map_mmap_prot_page(const int prot) {
  DWORD protect = 0;

  if (prot == PROT_NONE)
    return protect;

  if ((prot & PROT_EXEC) != 0) {
    protect = ((prot & PROT_WRITE) != 0) ?
        PAGE_EXECUTE_READWRITE : PAGE_EXECUTE_READ;
  } else {
    protect = ((prot & PROT_WRITE) != 0) ?
        PAGE_READWRITE : PAGE_READONLY;
  }

  return protect;
}

static DWORD __map_mmap_prot_file(const int prot) {
  DWORD desiredAccess = 0;

  if (prot == PROT_NONE)
    return desiredAccess;

  if ((prot & PROT_READ) != 0)
    desiredAccess |= FILE_MAP_READ;
  if ((prot & PROT_WRITE) != 0)
    desiredAccess |= FILE_MAP_WRITE;
  if ((prot & PROT_EXEC) != 0)
    desiredAccess |= FILE_MAP_EXECUTE;

  return desiredAccess;
}

void* mmap(void *addr, size_t len, int prot, int flags, int fildes, off_t off) {
  HANDLE fm, h;

  void * map = MAP_FAILED;

#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable: 4293)
#endif

  const DWORD dwFileOffsetLow = (sizeof(off_t) <= sizeof(DWORD)) ?
      (DWORD)off : (DWORD)(off & 0xFFFFFFFFL);
  const DWORD dwFileOffsetHigh = (sizeof(off_t) <= sizeof(DWORD)) ?
      (DWORD)0 : (DWORD)((off >> 32) & 0xFFFFFFFFL);
  const DWORD protect = __map_mmap_prot_page(prot);
  const DWORD desiredAccess = __map_mmap_prot_file(prot);

  const off_t maxSize = off + (off_t)len;

  const DWORD dwMaxSizeLow = (sizeof(off_t) <= sizeof(DWORD)) ?
      (DWORD)maxSize : (DWORD)(maxSize & 0xFFFFFFFFL);
  const DWORD dwMaxSizeHigh = (sizeof(off_t) <= sizeof(DWORD)) ?
      (DWORD)0 : (DWORD)((maxSize >> 32) & 0xFFFFFFFFL);

#ifdef _MSC_VER
#pragma warning(pop)
#endif

  errno = 0;

  if (len == 0
      /* Unsupported flag combinations */
      || (flags & MAP_FIXED) != 0
      /* Usupported protection combinations */
      || prot == PROT_EXEC) {
    errno = EINVAL;
    return MAP_FAILED;
  }

  h = ((flags & MAP_ANONYMOUS) == 0) ?
      (HANDLE)_get_osfhandle(fildes) : INVALID_HANDLE_VALUE;

  if ((flags & MAP_ANONYMOUS) == 0 && h == INVALID_HANDLE_VALUE) {
    errno = EBADF;
    return MAP_FAILED;
  }

  fm = CreateFileMapping(h, NULL, protect, dwMaxSizeHigh, dwMaxSizeLow, NULL);

  if (fm == NULL) {
    errno = __map_mman_error(GetLastError(), EPERM);
    return MAP_FAILED;
  }

  map = MapViewOfFile(fm, desiredAccess, dwFileOffsetHigh, dwFileOffsetLow, len);

  CloseHandle(fm);

  if (map == NULL) {
    errno = __map_mman_error(GetLastError(), EPERM);
    return MAP_FAILED;
  }

  return map;
}

int munmap(void *addr, size_t len) {
  if (UnmapViewOfFile(addr))
    return 0;

  errno =  __map_mman_error(GetLastError(), EPERM);

  return -1;
}

int mprotect(void *addr, size_t len, int prot) {
  DWORD newProtect = __map_mmap_prot_page(prot);
  DWORD oldProtect = 0;

  if (VirtualProtect(addr, len, newProtect, &oldProtect))
    return 0;

  errno =  __map_mman_error(GetLastError(), EPERM);

  return -1;
}

int msync(void *addr, size_t len, int flags) {
  if (FlushViewOfFile(addr, len))
    return 0;

  errno =  __map_mman_error(GetLastError(), EPERM);

  return -1;
}

int mlock(const void *addr, size_t len) {
  if (VirtualLock((LPVOID)addr, len))
    return 0;

  errno = __map_mman_error(GetLastError(), EPERM);

  return -1;
}

int munlock(const void *addr, size_t len) {
  if (VirtualUnlock((LPVOID)addr, len))
    return 0;

  errno =  __map_mman_error(GetLastError(), EPERM);

  return -1;
}

#endif
