/Lib/test/test_pty.py

  1import errno
  2import fcntl
  3import pty
  4import os
  5import sys
  6import signal
  7from test.test_support import verbose, TestSkipped, run_unittest
  8import unittest
  9
 10TEST_STRING_1 = "I wish to buy a fish license.\n"
 11TEST_STRING_2 = "For my pet fish, Eric.\n"
 12
 13if verbose:
 14    def debug(msg):
 15        print msg
 16else:
 17    def debug(msg):
 18        pass
 19
 20
 21def normalize_output(data):
 22    # Some operating systems do conversions on newline.  We could possibly
 23    # fix that by doing the appropriate termios.tcsetattr()s.  I couldn't
 24    # figure out the right combo on Tru64 and I don't have an IRIX box.
 25    # So just normalize the output and doc the problem O/Ses by allowing
 26    # certain combinations for some platforms, but avoid allowing other
 27    # differences (like extra whitespace, trailing garbage, etc.)
 28
 29    # This is about the best we can do without getting some feedback
 30    # from someone more knowledgable.
 31
 32    # OSF/1 (Tru64) apparently turns \n into \r\r\n.
 33    if data.endswith('\r\r\n'):
 34        return data.replace('\r\r\n', '\n')
 35
 36    # IRIX apparently turns \n into \r\n.
 37    if data.endswith('\r\n'):
 38        return data.replace('\r\n', '\n')
 39
 40    return data
 41
 42
 43# Marginal testing of pty suite. Cannot do extensive 'do or fail' testing
 44# because pty code is not too portable.
 45# XXX(nnorwitz):  these tests leak fds when there is an error.
 46class PtyTest(unittest.TestCase):
 47    def setUp(self):
 48        # isatty() and close() can hang on some platforms.  Set an alarm
 49        # before running the test to make sure we don't hang forever.
 50        self.old_alarm = signal.signal(signal.SIGALRM, self.handle_sig)
 51        signal.alarm(10)
 52
 53    def tearDown(self):
 54        # remove alarm, restore old alarm handler
 55        signal.alarm(0)
 56        signal.signal(signal.SIGALRM, self.old_alarm)
 57
 58    def handle_sig(self, sig, frame):
 59        self.fail("isatty hung")
 60
 61    def test_basic(self):
 62        try:
 63            debug("Calling master_open()")
 64            master_fd, slave_name = pty.master_open()
 65            debug("Got master_fd '%d', slave_name '%s'" %
 66                  (master_fd, slave_name))
 67            debug("Calling slave_open(%r)" % (slave_name,))
 68            slave_fd = pty.slave_open(slave_name)
 69            debug("Got slave_fd '%d'" % slave_fd)
 70        except OSError:
 71            # " An optional feature could not be imported " ... ?
 72            raise TestSkipped, "Pseudo-terminals (seemingly) not functional."
 73
 74        self.assertTrue(os.isatty(slave_fd), 'slave_fd is not a tty')
 75
 76        # Solaris requires reading the fd before anything is returned.
 77        # My guess is that since we open and close the slave fd
 78        # in master_open(), we need to read the EOF.
 79
 80        # Ensure the fd is non-blocking in case there's nothing to read.
 81        orig_flags = fcntl.fcntl(master_fd, fcntl.F_GETFL)
 82        fcntl.fcntl(master_fd, fcntl.F_SETFL, orig_flags | os.O_NONBLOCK)
 83        try:
 84            s1 = os.read(master_fd, 1024)
 85            self.assertEquals('', s1)
 86        except OSError, e:
 87            if e.errno != errno.EAGAIN:
 88                raise
 89        # Restore the original flags.
 90        fcntl.fcntl(master_fd, fcntl.F_SETFL, orig_flags)
 91
 92        debug("Writing to slave_fd")
 93        os.write(slave_fd, TEST_STRING_1)
 94        s1 = os.read(master_fd, 1024)
 95        self.assertEquals('I wish to buy a fish license.\n',
 96                          normalize_output(s1))
 97
 98        debug("Writing chunked output")
 99        os.write(slave_fd, TEST_STRING_2[:5])
100        os.write(slave_fd, TEST_STRING_2[5:])
101        s2 = os.read(master_fd, 1024)
102        self.assertEquals('For my pet fish, Eric.\n', normalize_output(s2))
103
104        os.close(slave_fd)
105        os.close(master_fd)
106
107
108    def test_fork(self):
109        debug("calling pty.fork()")
110        pid, master_fd = pty.fork()
111        if pid == pty.CHILD:
112            # stdout should be connected to a tty.
113            if not os.isatty(1):
114                debug("Child's fd 1 is not a tty?!")
115                os._exit(3)
116
117            # After pty.fork(), the child should already be a session leader.
118            # (on those systems that have that concept.)
119            debug("In child, calling os.setsid()")
120            try:
121                os.setsid()
122            except OSError:
123                # Good, we already were session leader
124                debug("Good: OSError was raised.")
125                pass
126            except AttributeError:
127                # Have pty, but not setsid()?
128                debug("No setsid() available?")
129                pass
130            except:
131                # We don't want this error to propagate, escaping the call to
132                # os._exit() and causing very peculiar behavior in the calling
133                # regrtest.py !
134                # Note: could add traceback printing here.
135                debug("An unexpected error was raised.")
136                os._exit(1)
137            else:
138                debug("os.setsid() succeeded! (bad!)")
139                os._exit(2)
140            os._exit(4)
141        else:
142            debug("Waiting for child (%d) to finish." % pid)
143            # In verbose mode, we have to consume the debug output from the
144            # child or the child will block, causing this test to hang in the
145            # parent's waitpid() call.  The child blocks after a
146            # platform-dependent amount of data is written to its fd.  On
147            # Linux 2.6, it's 4000 bytes and the child won't block, but on OS
148            # X even the small writes in the child above will block it.  Also
149            # on Linux, the read() will throw an OSError (input/output error)
150            # when it tries to read past the end of the buffer but the child's
151            # already exited, so catch and discard those exceptions.  It's not
152            # worth checking for EIO.
153            while True:
154                try:
155                    data = os.read(master_fd, 80)
156                except OSError:
157                    break
158                if not data:
159                    break
160                sys.stdout.write(data.replace('\r\n', '\n'))
161
162            ##line = os.read(master_fd, 80)
163            ##lines = line.replace('\r\n', '\n').split('\n')
164            ##if False and lines != ['In child, calling os.setsid()',
165            ##             'Good: OSError was raised.', '']:
166            ##    raise TestFailed("Unexpected output from child: %r" % line)
167
168            (pid, status) = os.waitpid(pid, 0)
169            res = status >> 8
170            debug("Child (%d) exited with status %d (%d)." % (pid, res, status))
171            if res == 1:
172                self.fail("Child raised an unexpected exception in os.setsid()")
173            elif res == 2:
174                self.fail("pty.fork() failed to make child a session leader.")
175            elif res == 3:
176                self.fail("Child spawned by pty.fork() did not have a tty as stdout")
177            elif res != 4:
178                self.fail("pty.fork() failed for unknown reasons.")
179
180            ##debug("Reading from master_fd now that the child has exited")
181            ##try:
182            ##    s1 = os.read(master_fd, 1024)
183            ##except os.error:
184            ##    pass
185            ##else:
186            ##    raise TestFailed("Read from master_fd did not raise exception")
187
188        os.close(master_fd)
189
190        # pty.fork() passed.
191
192def test_main(verbose=None):
193    run_unittest(PtyTest)
194
195if __name__ == "__main__":
196    test_main()