Execute CLR assembly in the current process and redirect its output to file. Can be compiled and used as a Python module.

pyd-executeassembly.nim

import winim/clr
import os
import nimpy

#Create dup handles
proc dup(oldfd: FileHandle): FileHandle {.importc, header: "unistd.h".}
proc dup2(oldfd: FileHandle, newfd: FileHandle): cint {.importc,
    header: "unistd.h".}



# thanks Clonk from https://forum.nim-lang.org/t/6909
proc executeassembly(assembly_bytes: openarray[byte], args: openarray[string], tmpname: string) : string {.exportpy.} =
  # input redirection begins
  let tmpFileName = getTempDir() & tmpname
  
  var stdout_fileno = stdout.getFileHandle()
  var stdout_dupfd = dup(stdout_fileno)
  
  var tmp_file: File = open(tmpFileName, fmWrite)
  var tmp_file_fd: FileHandle = tmp_file.getFileHandle()
  
  # dup2 tmp_file_fd to stdout_fileno -> writing to stdout_fileno now writes to tmp_file
  discard dup2(tmp_file_fd, stdout_fileno)
  
  #actual execution
  var dotnetargs = toCLRVariant(args, VT_BSTR)
  var assembly = load(assembly_bytes)
  assembly.EntryPoint.Invoke(nil, toCLRVariant([dotnetargs]))

  # input redirection ends
  tmp_file.flushFile()
  tmp_file.close()
  discard dup2(stdout_dupfd, stdout_fileno)

  result = readFile(tmpFileName)