Re: os.execute and the dreaded Windows console

[Chris <coderight@...>]

On Mon, Sep 8, 2008 at 7:03 PM, Fabio Mascarenhas <mascarenhas@acm.org> wrote:
> This is not really the same as os.execute, because CreateProcess is
> asynchronous. You also need to release the process and thread handles
> that Windows creates for the new process. Check

Yes, I should have mentioned my code was more of a starting example
than a full featured extension library.  Here is something with a
little more functionality (returns exit code and useful error
messages, etc):

#ifdef _WIN32
static void PushFormatWinError(lua_State* L, DWORD err)
{
   TCHAR* msgbuf;
   FormatMessage(
      FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
      NULL, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
      (LPTSTR)&msgbuf, 0, NULL);
   /* FIXME: doesn't handle UNICODE */
   lua_pushstring(L, msgbuf);
   LocalFree(msgbuf);
}

static int CreateProcess_(lua_State* L)
{
   size_t len;
   const char* cmd0 = luaL_checklstring(L, 1, &len);
   char* cmd = lua_newuserdata(L, len + 1);
   STARTUPINFO start;
   PROCESS_INFORMATION info;
   DWORD exitcode;

   strcpy(cmd, cmd0);
   memset(&start, 0x00, sizeof(start));
   start.cb = sizeof(start);

   if (!CreateProcess(NULL, cmd, NULL, NULL, FALSE,
      CREATE_NO_WINDOW, NULL, NULL, &start, &info))
   {
      PushFormatWinError(L, GetLastError());
      lua_error(L);
   }

   WaitForSingleObject(info.hProcess, INFINITE);
   GetExitCodeProcess(info.hProcess, &exitcode);
   CloseHandle(info.hProcess);
   CloseHandle(info.hThread);
   lua_pushinteger(L, exitcode);
   return 1;
}
#endif /* _WIN32 */


Technically I don't think you need to close the handles because as it
is those CloseHandle calls returns errors (I assume because the
process is dead).


> "...something like io.popen or whatever with some work" is a little
> bit of an understatement :-), see
> http://msdn.microsoft.com/en-us/library/ms682499(VS.85).aspx on how to
> do it.

Well I specifically didn't say how much work so I don't see how that
can be an understatement.  ;)

CR