/* demonstrate polling wakeup */

#include <unistd.h>
#include <pty.h>
#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

static int master, slave;

int main(void) {
  int r;

  r = openpty(&master,&slave,0,0,0);
  fprintf(stdout,"openpty=%d master=%d slave=%d\n", r, master, slave);
  assert(!r);
  
  r = fcntl(master, F_GETFL);  assert(r>=0);
  r = fcntl(master, F_SETFL, r | O_NONBLOCK);

  char buf[400];
  int i;
  for (i=0; i<sizeof(buf)-2; i+=2)
    sprintf(buf+i, "%02x", i);
  buf[sizeof(buf)-2]= '\r';
  buf[sizeof(buf)-1]= '\n';
  
  fd_set writefds;
  for (;;) {
    FD_ZERO(&writefds);
    FD_SET(master, &writefds);
    fprintf(stdout,"select\n");
    r= select(master+1, 0,&writefds,0, 0);
    if (r==-1) {
      fprintf(stdout,"select-fail %s\n", strerror(errno));
      continue;
    }
    assert(r==1);
    assert(FD_ISSET(master, &writefds));

    fprintf(stdout,"write\n");
    r= write(master,buf,sizeof(buf));
    if (r==-1) {
      fprintf(stdout,"write-fail %s\n", strerror(errno));
      continue;
    }
    assert(r>=0 && r<=sizeof(buf));
    fprintf(stdout,"wrote %d\n",r);
  }
}