CreateFileMapping2.nim

#[
    Author: Ward

    Example of CreateFileMapping

    References:
      https://docs.microsoft.com/en-us/windows/win32/memory/creating-named-shared-memory
]#

# This program may need to run as admin.

import winim/lean
import strformat

const BUF_SIZE = 256

block:
  let hMapFile = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE,
    "Global\\MyFileMappingObject")

  if hMapFile == 0:
    echo fmt"Could not open file mapping object ({GetLastError()})."
    quit()

  defer:
    CloseHandle(hMapFile)

  let pBuf = cast[LPSTR](MapViewOfFile(hMapFile, FILE_MAP_ALL_ACCESS, 0, 0, BUF_SIZE))
  if pBuf.isNil:
    echo fmt"Could not map view of file ({GetLastError()})."
    quit()

  # pBuf is LPSTR (pointer to multibyte character string) here,
  # convert it to nim string before pass into MessageBox.
  MessageBox(0, $pBuf, "Process2", MB_OK)