fcntl_problem.c

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>

void set(int fd) {
  int flags = fcntl(fd, F_GETFL);
  if (isatty(fd)) {
    flags |= O_NONBLOCK;
  } else {
    // flags &= ~O_NONBLOCK;
    return;
  }
  fcntl(fd, F_SETFL, flags);
}

int main() {
  set(0);
  set(1);
  set(2);

  char* str = "01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789\n01234567890123456789012345678901234567890123456789012345678901234567890123456789";
  int count = 1619;
  while (count > 0) {
    int written = write(1, str, count);
    if (written != -1) {
      count -= written;
    }
  }
  while(write(1, "\n", 1) != 1) {}
  return 0;
}