| """Selector eventloop for Unix with signal handling.""" |
| |
| import errno |
| import fcntl |
| import os |
| import signal |
| import socket |
| import stat |
| import subprocess |
| import sys |
| |
| |
| from . import base_subprocess |
| from . import constants |
| from . import events |
| from . import protocols |
| from . import selector_events |
| from . import tasks |
| from . import transports |
| from .log import logger |
| |
| |
| __all__ = ['SelectorEventLoop', 'STDIN', 'STDOUT', 'STDERR'] |
| |
| STDIN = 0 |
| STDOUT = 1 |
| STDERR = 2 |
| |
| |
| if sys.platform == 'win32': # pragma: no cover |
| raise ImportError('Signals are not really supported on Windows') |
| |
| |
| class SelectorEventLoop(selector_events.BaseSelectorEventLoop): |
| """Unix event loop |
| |
| Adds signal handling to SelectorEventLoop |
| """ |
| |
| def __init__(self, selector=None): |
| super().__init__(selector) |
| self._signal_handlers = {} |
| self._subprocesses = {} |
| |
| def _socketpair(self): |
| return socket.socketpair() |
| |
| def close(self): |
| handler = self._signal_handlers.get(signal.SIGCHLD) |
| if handler is not None: |
| self.remove_signal_handler(signal.SIGCHLD) |
| super().close() |
| |
| def add_signal_handler(self, sig, callback, *args): |
| """Add a handler for a signal. UNIX only. |
| |
| Raise ValueError if the signal number is invalid or uncatchable. |
| Raise RuntimeError if there is a problem setting up the handler. |
| """ |
| self._check_signal(sig) |
| try: |
| # set_wakeup_fd() raises ValueError if this is not the |
| # main thread. By calling it early we ensure that an |
| # event loop running in another thread cannot add a signal |
| # handler. |
| signal.set_wakeup_fd(self._csock.fileno()) |
| except ValueError as exc: |
| raise RuntimeError(str(exc)) |
| |
| handle = events.make_handle(callback, args) |
| self._signal_handlers[sig] = handle |
| |
| try: |
| signal.signal(sig, self._handle_signal) |
| except OSError as exc: |
| del self._signal_handlers[sig] |
| if not self._signal_handlers: |
| try: |
| signal.set_wakeup_fd(-1) |
| except ValueError as nexc: |
| logger.info('set_wakeup_fd(-1) failed: %s', nexc) |
| |
| if exc.errno == errno.EINVAL: |
| raise RuntimeError('sig {} cannot be caught'.format(sig)) |
| else: |
| raise |
| |
| def _handle_signal(self, sig, arg): |
| """Internal helper that is the actual signal handler.""" |
| handle = self._signal_handlers.get(sig) |
| if handle is None: |
| return # Assume it's some race condition. |
| if handle._cancelled: |
| self.remove_signal_handler(sig) # Remove it properly. |
| else: |
| self._add_callback_signalsafe(handle) |
| |
| def remove_signal_handler(self, sig): |
| """Remove a handler for a signal. UNIX only. |
| |
| Return True if a signal handler was removed, False if not. |
| """ |
| self._check_signal(sig) |
| try: |
| del self._signal_handlers[sig] |
| except KeyError: |
| return False |
| |
| if sig == signal.SIGINT: |
| handler = signal.default_int_handler |
| else: |
| handler = signal.SIG_DFL |
| |
| try: |
| signal.signal(sig, handler) |
| except OSError as exc: |
| if exc.errno == errno.EINVAL: |
| raise RuntimeError('sig {} cannot be caught'.format(sig)) |
| else: |
| raise |
| |
| if not self._signal_handlers: |
| try: |
| signal.set_wakeup_fd(-1) |
| except ValueError as exc: |
| logger.info('set_wakeup_fd(-1) failed: %s', exc) |
| |
| return True |
| |
| def _check_signal(self, sig): |
| """Internal helper to validate a signal. |
| |
| Raise ValueError if the signal number is invalid or uncatchable. |
| Raise RuntimeError if there is a problem setting up the handler. |
| """ |
| if not isinstance(sig, int): |
| raise TypeError('sig must be an int, not {!r}'.format(sig)) |
| |
| if not (1 <= sig < signal.NSIG): |
| raise ValueError( |
| 'sig {} out of range(1, {})'.format(sig, signal.NSIG)) |
| |
| def _make_read_pipe_transport(self, pipe, protocol, waiter=None, |
| extra=None): |
| return _UnixReadPipeTransport(self, pipe, protocol, waiter, extra) |
| |
| def _make_write_pipe_transport(self, pipe, protocol, waiter=None, |
| extra=None): |
| return _UnixWritePipeTransport(self, pipe, protocol, waiter, extra) |
| |
| @tasks.coroutine |
| def _make_subprocess_transport(self, protocol, args, shell, |
| stdin, stdout, stderr, bufsize, |
| extra=None, **kwargs): |
| self._reg_sigchld() |
| transp = _UnixSubprocessTransport(self, protocol, args, shell, |
| stdin, stdout, stderr, bufsize, |
| extra=None, **kwargs) |
| self._subprocesses[transp.get_pid()] = transp |
| yield from transp._post_init() |
| return transp |
| |
| def _reg_sigchld(self): |
| if signal.SIGCHLD not in self._signal_handlers: |
| self.add_signal_handler(signal.SIGCHLD, self._sig_chld) |
| |
| def _sig_chld(self): |
| try: |
| # Because of signal coalescing, we must keep calling waitpid() as |
| # long as we're able to reap a child. |
| while True: |
| try: |
| pid, status = os.waitpid(-1, os.WNOHANG) |
| except ChildProcessError: |
| break # No more child processes exist. |
| if pid == 0: |
| break # All remaining child processes are still alive. |
| elif os.WIFSIGNALED(status): |
| # A child process died because of a signal. |
| returncode = -os.WTERMSIG(status) |
| elif os.WIFEXITED(status): |
| # A child process exited (e.g. sys.exit()). |
| returncode = os.WEXITSTATUS(status) |
| else: |
| # A child exited, but we don't understand its status. |
| # This shouldn't happen, but if it does, let's just |
| # return that status; perhaps that helps debug it. |
| returncode = status |
| transp = self._subprocesses.get(pid) |
| if transp is not None: |
| transp._process_exited(returncode) |
| except Exception: |
| logger.exception('Unknown exception in SIGCHLD handler') |
| |
| def _subprocess_closed(self, transport): |
| pid = transport.get_pid() |
| self._subprocesses.pop(pid, None) |
| |
| |
| def _set_nonblocking(fd): |
| flags = fcntl.fcntl(fd, fcntl.F_GETFL) |
| flags = flags | os.O_NONBLOCK |
| fcntl.fcntl(fd, fcntl.F_SETFL, flags) |
| |
| |
| class _UnixReadPipeTransport(transports.ReadTransport): |
| |
| max_size = 256 * 1024 # max bytes we read in one eventloop iteration |
| |
| def __init__(self, loop, pipe, protocol, waiter=None, extra=None): |
| super().__init__(extra) |
| self._extra['pipe'] = pipe |
| self._loop = loop |
| self._pipe = pipe |
| self._fileno = pipe.fileno() |
| mode = os.fstat(self._fileno).st_mode |
| if not (stat.S_ISFIFO(mode) or stat.S_ISSOCK(mode)): |
| raise ValueError("Pipe transport is for pipes/sockets only.") |
| _set_nonblocking(self._fileno) |
| self._protocol = protocol |
| self._closing = False |
| self._loop.add_reader(self._fileno, self._read_ready) |
| self._loop.call_soon(self._protocol.connection_made, self) |
| if waiter is not None: |
| self._loop.call_soon(waiter.set_result, None) |
| |
| def _read_ready(self): |
| try: |
| data = os.read(self._fileno, self.max_size) |
| except (BlockingIOError, InterruptedError): |
| pass |
| except OSError as exc: |
| self._fatal_error(exc) |
| else: |
| if data: |
| self._protocol.data_received(data) |
| else: |
| self._closing = True |
| self._loop.remove_reader(self._fileno) |
| self._loop.call_soon(self._protocol.eof_received) |
| self._loop.call_soon(self._call_connection_lost, None) |
| |
| def pause_reading(self): |
| self._loop.remove_reader(self._fileno) |
| |
| def resume_reading(self): |
| self._loop.add_reader(self._fileno, self._read_ready) |
| |
| def close(self): |
| if not self._closing: |
| self._close(None) |
| |
| def _fatal_error(self, exc): |
| # should be called by exception handler only |
| logger.exception('Fatal error for %s', self) |
| self._close(exc) |
| |
| def _close(self, exc): |
| self._closing = True |
| self._loop.remove_reader(self._fileno) |
| self._loop.call_soon(self._call_connection_lost, exc) |
| |
| def _call_connection_lost(self, exc): |
| try: |
| self._protocol.connection_lost(exc) |
| finally: |
| self._pipe.close() |
| self._pipe = None |
| self._protocol = None |
| self._loop = None |
| |
| |
| class _UnixWritePipeTransport(transports.WriteTransport): |
| |
| def __init__(self, loop, pipe, protocol, waiter=None, extra=None): |
| super().__init__(extra) |
| self._extra['pipe'] = pipe |
| self._loop = loop |
| self._pipe = pipe |
| self._fileno = pipe.fileno() |
| mode = os.fstat(self._fileno).st_mode |
| is_socket = stat.S_ISSOCK(mode) |
| is_pipe = stat.S_ISFIFO(mode) |
| if not (is_socket or is_pipe): |
| raise ValueError("Pipe transport is for pipes/sockets only.") |
| _set_nonblocking(self._fileno) |
| self._protocol = protocol |
| self._buffer = [] |
| self._conn_lost = 0 |
| self._closing = False # Set when close() or write_eof() called. |
| |
| # On AIX, the reader trick only works for sockets. |
| # On other platforms it works for pipes and sockets. |
| # (Exception: OS X 10.4? Issue #19294.) |
| if is_socket or not sys.platform.startswith("aix"): |
| self._loop.add_reader(self._fileno, self._read_ready) |
| |
| self._loop.call_soon(self._protocol.connection_made, self) |
| if waiter is not None: |
| self._loop.call_soon(waiter.set_result, None) |
| |
| def _read_ready(self): |
| # Pipe was closed by peer. |
| self._close() |
| |
| def write(self, data): |
| assert isinstance(data, bytes), repr(data) |
| if not data: |
| return |
| |
| if self._conn_lost or self._closing: |
| if self._conn_lost >= constants.LOG_THRESHOLD_FOR_CONNLOST_WRITES: |
| logger.warning('pipe closed by peer or ' |
| 'os.write(pipe, data) raised exception.') |
| self._conn_lost += 1 |
| return |
| |
| if not self._buffer: |
| # Attempt to send it right away first. |
| try: |
| n = os.write(self._fileno, data) |
| except (BlockingIOError, InterruptedError): |
| n = 0 |
| except Exception as exc: |
| self._conn_lost += 1 |
| self._fatal_error(exc) |
| return |
| if n == len(data): |
| return |
| elif n > 0: |
| data = data[n:] |
| self._loop.add_writer(self._fileno, self._write_ready) |
| |
| self._buffer.append(data) |
| |
| def _write_ready(self): |
| data = b''.join(self._buffer) |
| assert data, 'Data should not be empty' |
| |
| self._buffer.clear() |
| try: |
| n = os.write(self._fileno, data) |
| except (BlockingIOError, InterruptedError): |
| self._buffer.append(data) |
| except Exception as exc: |
| self._conn_lost += 1 |
| # Remove writer here, _fatal_error() doesn't it |
| # because _buffer is empty. |
| self._loop.remove_writer(self._fileno) |
| self._fatal_error(exc) |
| else: |
| if n == len(data): |
| self._loop.remove_writer(self._fileno) |
| if self._closing: |
| self._loop.remove_reader(self._fileno) |
| self._call_connection_lost(None) |
| return |
| elif n > 0: |
| data = data[n:] |
| |
| self._buffer.append(data) # Try again later. |
| |
| def can_write_eof(self): |
| return True |
| |
| # TODO: Make the relationships between write_eof(), close(), |
| # abort(), _fatal_error() and _close() more straightforward. |
| |
| def write_eof(self): |
| if self._closing: |
| return |
| assert self._pipe |
| self._closing = True |
| if not self._buffer: |
| self._loop.remove_reader(self._fileno) |
| self._loop.call_soon(self._call_connection_lost, None) |
| |
| def close(self): |
| if not self._closing: |
| # write_eof is all what we needed to close the write pipe |
| self.write_eof() |
| |
| def abort(self): |
| self._close(None) |
| |
| def _fatal_error(self, exc): |
| # should be called by exception handler only |
| logger.exception('Fatal error for %s', self) |
| self._close(exc) |
| |
| def _close(self, exc=None): |
| self._closing = True |
| if self._buffer: |
| self._loop.remove_writer(self._fileno) |
| self._buffer.clear() |
| self._loop.remove_reader(self._fileno) |
| self._loop.call_soon(self._call_connection_lost, exc) |
| |
| def _call_connection_lost(self, exc): |
| try: |
| self._protocol.connection_lost(exc) |
| finally: |
| self._pipe.close() |
| self._pipe = None |
| self._protocol = None |
| self._loop = None |
| |
| |
| class _UnixSubprocessTransport(base_subprocess.BaseSubprocessTransport): |
| |
| def _start(self, args, shell, stdin, stdout, stderr, bufsize, **kwargs): |
| stdin_w = None |
| if stdin == subprocess.PIPE: |
| # Use a socket pair for stdin, since not all platforms |
| # support selecting read events on the write end of a |
| # socket (which we use in order to detect closing of the |
| # other end). Notably this is needed on AIX, and works |
| # just fine on other platforms. |
| stdin, stdin_w = self._loop._socketpair() |
| self._proc = subprocess.Popen( |
| args, shell=shell, stdin=stdin, stdout=stdout, stderr=stderr, |
| universal_newlines=False, bufsize=bufsize, **kwargs) |
| if stdin_w is not None: |
| stdin.close() |
| self._proc.stdin = open(stdin_w.detach(), 'rb', buffering=bufsize) |