Making CreateProcess inherit the console of the calling process

Question

When I call CreateProcess in Windows, the new process doesn't seem to inherit the console of the calling process. I made a test program that runs "ruby xtest", xtest being a script that writes "hello" to standard output. I ran this test program from Emacs, and get no output. I also tried the following code calling GetStdHandle, but again, no output. Then I tried passing CREATE_NEW_CONSOLE in dwCreationFlags to CreateProcess, which made a whole new window with the Ruby output. Finally, I made a simple fork/exec test program and compiled it using Cygwin's GCC. This program worked: the Ruby output showed up in Emacs as expected. I tried to decipher the Cygwin source code in http://cygwin.com/cgi-bin/cvsweb.cgi/src/winsup/cygwin/spawn.cc?rev=1.268&content-type=text/x-cvsweb-markup&cvsroot=src but failed. So, how do you make the new process inherit the console of the parent process such that the output from the child shows up as expected?

STARTUPINFO si;
PROCESS_INFORMATION pi;
memset(&si, 0, sizeof(si));
memset(&pi, 0, sizeof(pi));
si.dwFlags |= STARTF_USESTDHANDLES;
si.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
si.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
si.hStdError = GetStdHandle(STD_ERROR_HANDLE);
if(!CreateProcess(0, "ruby xtest", 0, 0, 1, 0, 0, 0, &si, &pi)) die("CreateProcess");

Answer 1

I've done this by passing in pipes for hStdInput, hStdOutput, and hStdError and manually routing data from the hStdOutput and hStdError pipes to the console.

Answer 2

Not sure if debeige ever solved this, but I needed the same thing, but starting up another thread to listen to stdout output, just to put it on stdout seemed nuts to me.

The following works for me, and is slightly different than what he originally posted. I thought at first it wouldn't work if you don't set si.cb, but when I commented that in mine, it still worked, so... YMMV.

   STARTUPINFO siStartInfo;
   ZeroMemory( &siStartInfo, sizeof(STARTUPINFO) );
   siStartInfo.cb = sizeof(STARTUPINFO); 
   siStartInfo.hStdError = GetStdHandle(STD_OUTPUT_HANDLE); 
   siStartInfo.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE); 
   siStartInfo.hStdInput = g_hChildStd_IN_Rd;  // my outgoing pipe
   siStartInfo.dwFlags |= STARTF_USESTDHANDLES;

// Create the child process. 

   bSuccess = CreateProcess(
      NULL,         
      szCmdline,    
      NULL,         
      NULL,         
      TRUE,         
      0,            
      NULL,         
      NULL,         
      &siStartInfo, 
      &piProcInfo);