Add third_party/pexpect

third_party/pexpect/notes/my_forkpty.py

Index: third_party/pexpect/notes/my_forkpty.py
diff --git a/third_party/pexpect/notes/my_forkpty.py b/third_party/pexpect/notes/my_forkpty.py
new file mode 100644
index 0000000000000000000000000000000000000000..f2bef23bd68243c4ba3c06e3e415154e0e7e4d96
--- /dev/null
+++ b/third_party/pexpect/notes/my_forkpty.py
@@ -0,0 +1,89 @@
+import os, fcntl, termios
+import time
+
+def my_forkpty():
+
+    (master_fd, slave_fd) = os.openpty()
+
+    if (master_fd < 0  or  slave_fd < 0):
+        raise ExceptionPexpect("Forkpty failed")
+
+    # slave_name = ptsname(master_fd);
+
+    pid = os.fork();
+    if pid == -1:
+        raise ExceptionPexpect("Forkpty failed")
+    elif pid == 0: # Child
+        if hasattr(termios, 'TIOCNOTTY'):
+        #        Some platforms require an explicit detach of the
+        #        current controlling tty before closing stdin, stdout, stderr.
+        #        OpenBSD says that this is obsolete, but doesn't hurt.
+            try:
+                fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
+            except:
+                pass
+            else: #if fd >= 0:
+                fcntl.ioctl(fd, termios.TIOCNOTTY, 0)
+                os.close(fd)
+
+        # The setsid() system call will place the process into its own session
+        # which has the effect of disassociating it from the controlling terminal.
+        # This is known to be true for OpenBSD.
+        os.setsid()
+        # except:            return posix_error();
+
+        # Verify that we are disconnected from the controlling tty.
+        try:
+            fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
+            os.close(fd)
+            raise ExceptionPexpect("Forkpty failed")
+        except:
+            pass
+        if 'TIOCSCTTY' in dir(termios):
+            # Make the pseudo terminal the controlling terminal for this process
+            # (the process must not currently have a controlling terminal).
+            if fcntl.ioctl(slave_fd, termios.TIOCSCTTY, '') < 0:
+                raise ExceptionPexpect("Forkpty failed")
+
+#        # Verify that we can open to the slave pty file. */
+#        fd = os.open(slave_name, os.O_RDWR);
+#        if fd < 0:
+#            raise ExceptionPexpect("Forkpty failed")
+#        else:
+#            os.close(fd);
+
+        # Verify that we now have a controlling tty.
+        fd = os.open("/dev/tty", os.O_WRONLY)
+        if fd < 0:
+            raise ExceptionPexpect("This process could not get a controlling tty.")
+        else:
+            os.close(fd)
+
+        os.close(master_fd)
+        os.dup2(slave_fd, 0)
+        os.dup2(slave_fd, 1)
+        os.dup2(slave_fd, 2)
+        if slave_fd > 2:
+            os.close(slave_fd)
+        pid = 0
+
+    else:
+        # PARENT 
+        os.close(slave_fd);
+
+    if pid == -1:
+        raise ExceptionPexpect("This process could not get a controlling tty.")
+#    if (pid == 0)
+#        PyOS_AfterFork();
+
+    return (pid, master_fd)
+
+pid, fd = my_forkpty ()
+if pid == 0: # child
+    print 'I am not a robot!'
+else:
+    print '(pid, fd) = (%d, %d)' % (pid, fd)
+    time.sleep(1) # Give the child a chance to print.
+    print 'Robots always say:', os.read(fd,100)
+    os.close(fd)
+