From owner-freebsd-emulation  Tue Aug 25 21:22:04 1998
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Date: Tue, 25 Aug 1998 22:32:24 +0200
From: freebsd-emulation@bland.fido.de (freebsd-emulation)
Reply-To: tobi@bland.fido.de (Tobias Ernst)
Subject: Linux termios problem
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Hello!

I am running FreeBSD 2.2.5 and seem to have a problem with the termios code of
the Linux emulation.

In order to implement something like "kbhit()" (a function to query if any
characters are waiting in the console input queue), I use code similar to the
following example program:

  #include <termios.h>
  #include <stdio.h>

  int main(void)
  {
      struct termios tios;
      char c;

      tcgetattr(0, &tios);
      tios.c_lflag &= ~(ICANON | ISIG);
      tios.c_lflag &= ~ECHO; 
      tios.c_cc[VMIN] = 0;
      tios.c_cc[VTIME] = 0;
      tcsetattr(0, 0, &tios);
      setbuf(stdin, NULL);
  
      c = getchar();
  
      return c;
  }

With the flags that I set, the getchar() function is supposed to return
immediately even if no character could be read. (In this case, it should return
EOF and I afterwards have to clear the errorflag from stdin, but this does not
matter for the test program).

The code from above works if I compile it natively for FreeBSD, and it works if
I compile it with the linux crossdevelopment package and run the executable on
a Linux box. However, it does not work if I try to run the resulting Linux
executable on FreeBSD in Linux emulation mode. There, the getchar() function
blocks for a very long time (minutes) before it returns.

Is this a bug in my code (if so, please tell me where), or is it a problem with
the Linux emulation of FreeBSD? 

Viele Gruesse,
Tobias

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