text: # -*- test-case-name: twisted.test.test_process -*-
  # Copyright (c) Twisted Matrix Laboratories.
  # See LICENSE for details.
  
  """
  UNIX Process management.
  
  Do NOT use this module directly - use reactor.spawnProcess() instead.
  
  Maintainer: Itamar Shtull-Trauring
  """
  
  from __future__ import division, absolute_import, print_function
  
  from twisted.python.runtime import platform
  
  if platform.isWindows():
      raise ImportError(("twisted.internet.process does not work on Windows. "
                         "Use the reactor.spawnProcess() API instead."))
  
  import errno
  import gc
  import os
  import io
  import select
  import signal
  import stat
  import sys
  import traceback
  
  try:
      import pty
  except ImportError:
      pty = None
  
  try:
      import fcntl, termios
  except ImportError:
      fcntl = None
  
  from zope.interface import implementer
  
  from twisted.python import log, failure
  from twisted.python.util import switchUID
  from twisted.python.compat import items, range, _PY3
  from twisted.internet import fdesc, abstract, error
  from twisted.internet.main import CONNECTION_LOST, CONNECTION_DONE
  from twisted.internet._baseprocess import BaseProcess
  from twisted.internet.interfaces import IProcessTransport
  
  # Some people were importing this, which is incorrect, just keeping it
  # here for backwards compatibility:
  ProcessExitedAlready = error.ProcessExitedAlready
  
  reapProcessHandlers = {}
  
  def reapAllProcesses():
      """
      Reap all registered processes.
      """
      # Coerce this to a list, as reaping the process changes the dictionary and
      # causes a "size changed during iteration" exception
      for process in list(reapProcessHandlers.values()):
          process.reapProcess()
  
  
  
  def registerReapProcessHandler(pid, process):
      """
      Register a process handler for the given pid, in case L{reapAllProcesses}
      is called.
  
      @param pid: the pid of the process.
      @param process: a process handler.
      """
      if pid in reapProcessHandlers:
          raise RuntimeError("Try to register an already registered process.")
      try:
          auxPID, status = os.waitpid(pid, os.WNOHANG)
      except:
          log.msg('Failed to reap %d:' % pid)
          log.err()
          auxPID = None
      if auxPID:
          process.processEnded(status)
      else:
          # if auxPID is 0, there are children but none have exited
          reapProcessHandlers[pid] = process
  
  
  
  def unregisterReapProcessHandler(pid, process):
      """
      Unregister a process handler previously registered with
      L{registerReapProcessHandler}.
      """
      if not (pid in reapProcessHandlers
              and reapProcessHandlers[pid] == process):
          raise RuntimeError("Try to unregister a process not registered.")
      del reapProcessHandlers[pid]
  
  
  
  def detectLinuxBrokenPipeBehavior():
      """
      On some Linux version, write-only pipe are detected as readable. This
      function is here to check if this bug is present or not.
  
      See L{ProcessWriter.doRead} for a more detailed explanation.
  
      @return: C{True} if Linux pipe behaviour is broken.
      @rtype : L{bool}
      """
      r, w = os.pipe()
      os.write(w, b'a')
      reads, writes, exes = select.select([w], [], [], 0)
      if reads:
          # Linux < 2.6.11 says a write-only pipe is readable.
          brokenPipeBehavior = True
      else:
          brokenPipeBehavior = False
      os.close(r)
      os.close(w)
      return brokenPipeBehavior
  
  
  
  brokenLinuxPipeBehavior = detectLinuxBrokenPipeBehavior()
  
  
  
  class ProcessWriter(abstract.FileDescriptor):
      """
      (Internal) Helper class to write into a Process's input pipe.
  
      I am a helper which describes a selectable asynchronous writer to a
      process's input pipe, including stdin.
  
      @ivar enableReadHack: A flag which determines how readability on this
          write descriptor will be handled.  If C{True}, then readability may
          indicate the reader for this write descriptor has been closed (ie,
          the connection has been lost).  If C{False}, then readability events
          are ignored.
      """
      connected = 1
      ic = 0
      enableReadHack = False
  
      def __init__(self, reactor, proc, name, fileno, forceReadHack=False):
          """
          Initialize, specifying a Process instance to connect to.
          """
          abstract.FileDescriptor.__init__(self, reactor)
          fdesc.setNonBlocking(fileno)
          self.proc = proc
          self.name = name
          self.fd = fileno
  
          if not stat.S_ISFIFO(os.fstat(self.fileno()).st_mode):
              # If the fd is not a pipe, then the read hack is never
              # applicable.  This case arises when ProcessWriter is used by
              # StandardIO and stdout is redirected to a normal file.
              self.enableReadHack = False
          elif forceReadHack:
              self.enableReadHack = True
          else:
              # Detect if this fd is actually a write-only fd. If it's
              # valid to read, don't try to detect closing via read.
              # This really only means that we cannot detect a TTY's write
              # pipe being closed.
              try:
                  os.read(self.fileno(), 0)
              except OSError:
                  # It's a write-only pipe end, enable hack
                  self.enableReadHack = True
  
          if self.enableReadHack:
              self.startReading()
  
  
      def fileno(self):
          """
          Return the fileno() of my process's stdin.
          """
          return self.fd
  
  
      def writeSomeData(self, data):
          """
          Write some data to the open process.
          """
          rv = fdesc.writeToFD(self.fd, data)
          if rv == len(data) and self.enableReadHack:
              # If the send buffer is now empty and it is necessary to monitor
              # this descriptor for readability to detect close, try detecting
              # readability now.
              self.startReading()
          return rv
  
  
      def write(self, data):
          self.stopReading()
          abstract.FileDescriptor.write(self, data)
  
  
      def doRead(self):
          """
          The only way a write pipe can become "readable" is at EOF, because the
          child has closed it, and we're using a reactor which doesn't
          distinguish between readable and closed (such as the select reactor).
  
          Except that's not true on linux < 2.6.11. It has the following
          characteristics: write pipe is completely empty => POLLOUT (writable in
          select), write pipe is not completely empty => POLLIN (readable in
          select), write pipe's reader closed => POLLIN|POLLERR (readable and
          writable in select)
  
          That's what this funky code is for. If linux was not broken, this
          function could be simply "return CONNECTION_LOST".
  
          BUG: We call select no matter what the reactor.
          If the reactor is pollreactor, and the fd is > 1024, this will fail.
          (only occurs on broken versions of linux, though).
          """
          if self.enableReadHack:
              if brokenLinuxPipeBehavior:
                  fd = self.fd
                  r, w, x = select.select([fd], [fd], [], 0)
                  if r and w:
                      return CONNECTION_LOST
              else:
                  return CONNECTION_LOST
          else:
              self.stopReading()
  
  
      def connectionLost(self, reason):
          """
          See abstract.FileDescriptor.connectionLost.
          """
          # At least on OS X 10.4, exiting while stdout is non-blocking can
          # result in data loss.  For some reason putting the file descriptor
          # back into blocking mode seems to resolve this issue.
          fdesc.setBlocking(self.fd)
  
          abstract.FileDescriptor.connectionLost(self, reason)
          self.proc.childConnectionLost(self.name, reason)
  
  
  
  class ProcessReader(abstract.FileDescriptor):
      """
      ProcessReader
  
      I am a selectable representation of a process's output pipe, such as
      stdout and stderr.
      """
      connected = True
  
      def __init__(self, reactor, proc, name, fileno):
          """
          Initialize, specifying a process to connect to.
          """
          abstract.FileDescriptor.__init__(self, reactor)
          fdesc.setNonBlocking(fileno)
          self.proc = proc
          self.name = name
          self.fd = fileno
          self.startReading()
  
  
      def fileno(self):
          """
          Return the fileno() of my process's stderr.
          """
          return self.fd
  
  
      def writeSomeData(self, data):
          # the only time this is actually called is after .loseConnection Any
          # actual write attempt would fail, so we must avoid that. This hack
          # allows us to use .loseConnection on both readers and writers.
          assert data == b""
          return CONNECTION_LOST
  
  
      def doRead(self):
          """
          This is called when the pipe becomes readable.
          """
          return fdesc.readFromFD(self.fd, self.dataReceived)
  
  
      def dataReceived(self, data):
          self.proc.childDataReceived(self.name, data)
  
  
      def loseConnection(self):
          if self.connected and not self.disconnecting:
              self.disconnecting = 1
              self.stopReading()
              self.reactor.callLater(0, self.connectionLost,
                                     failure.Failure(CONNECTION_DONE))
  
  
      def connectionLost(self, reason):
          """
          Close my end of the pipe, signal the Process (which signals the
          ProcessProtocol).
          """
          abstract.FileDescriptor.connectionLost(self, reason)
          self.proc.childConnectionLost(self.name, reason)
  
  
  
  class _BaseProcess(BaseProcess, object):
      """
      Base class for Process and PTYProcess.
      """
      status = None
      pid = None
  
      def reapProcess(self):
          """
          Try to reap a process (without blocking) via waitpid.
  
          This is called when sigchild is caught or a Process object loses its
          "connection" (stdout is closed) This ought to result in reaping all
          zombie processes, since it will be called twice as often as it needs
          to be.
  
          (Unfortunately, this is a slightly experimental approach, since
          UNIX has no way to be really sure that your process is going to
          go away w/o blocking.  I don't want to block.)
          """
          try:
              try:
                  pid, status = os.waitpid(self.pid, os.WNOHANG)
              except OSError as e:
                  if e.errno == errno.ECHILD:
                      # no child process
                      pid = None
                  else:
                      raise
          except:
              log.msg('Failed to reap %d:' % self.pid)
              log.err()
              pid = None
          if pid:
              self.processEnded(status)
              unregisterReapProcessHandler(pid, self)
  
  
      def _getReason(self, status):
          exitCode = sig = None
          if os.WIFEXITED(status):
              exitCode = os.WEXITSTATUS(status)
          else:
              sig = os.WTERMSIG(status)
          if exitCode or sig:
              return error.ProcessTerminated(exitCode, sig, status)
          return error.ProcessDone(status)
  
  
      def signalProcess(self, signalID):
          """
          Send the given signal C{signalID} to the process. It'll translate a
          few signals ('HUP', 'STOP', 'INT', 'KILL', 'TERM') from a string
          representation to its int value, otherwise it'll pass directly the
          value provided
  
          @type signalID: C{str} or C{int}
          """
          if signalID in ('HUP', 'STOP', 'INT', 'KILL', 'TERM'):
              signalID = getattr(signal, 'SIG%s' % (signalID,))
          if self.pid is None:
              raise ProcessExitedAlready()
          try:
              os.kill(self.pid, signalID)
          except OSError as e:
              if e.errno == errno.ESRCH:
                  raise ProcessExitedAlready()
              else:
                  raise
  
  
      def _resetSignalDisposition(self):
          # The Python interpreter ignores some signals, and our child
          # process will inherit that behaviour. To have a child process
          # that responds to signals normally, we need to reset our
          # child process's signal handling (just) after we fork and
          # before we execvpe.
          for signalnum in range(1, signal.NSIG):
              if signal.getsignal(signalnum) == signal.SIG_IGN:
                  # Reset signal handling to the default
                  signal.signal(signalnum, signal.SIG_DFL)
  
  
      def _fork(self, path, uid, gid, executable, args, environment, **kwargs):
          """
          Fork and then exec sub-process.
  
          @param path: the path where to run the new process.
          @type path: L{bytes} or L{unicode}
          @param uid: if defined, the uid used to run the new process.
          @type uid: L{int}
          @param gid: if defined, the gid used to run the new process.
          @type gid: L{int}
          @param executable: the executable to run in a new process.
          @type executable: L{str}
          @param args: arguments used to create the new process.
          @type args: L{list}.
          @param environment: environment used for the new process.
          @type environment: L{dict}.
          @param kwargs: keyword arguments to L{_setupChild} method.
          """
          collectorEnabled = gc.isenabled()
          gc.disable()
          try:
              self.pid = os.fork()
          except:
              # Still in the parent process
              if collectorEnabled:
                  gc.enable()
              raise
          else:
              if self.pid == 0:
                  # A return value of 0 from fork() indicates that we are now
                  # executing in the child process.
  
                  # Do not put *ANY* code outside the try block. The child
                  # process must either exec or _exit. If it gets outside this
                  # block (due to an exception that is not handled here, but
                  # which might be handled higher up), there will be two copies
                  # of the parent running in parallel, doing all kinds of damage.
  
                  # After each change to this code, review it to make sure there
                  # are no exit paths.
  
                  try:
                      # Stop debugging. If I am, I don't care anymore.
                      sys.settrace(None)
                      self._setupChild(**kwargs)
                      self._execChild(path, uid, gid, executable, args,
                                      environment)
                  except:
                      # If there are errors, try to write something descriptive
                      # to stderr before exiting.
  
                      # The parent's stderr isn't *necessarily* fd 2 anymore, or
                      # even still available; however, even libc assumes that
                      # write(2, err) is a useful thing to attempt.
  
                      try:
                          stderr = os.fdopen(2, 'wb')
                          msg = ("Upon execvpe {0} {1} in environment id {2}"
                                 "\n:").format(executable, str(args),
                                               id(environment))
  
                          if _PY3:
  
                              # On Python 3, print_exc takes a text stream, but
                              # on Python 2 it still takes a byte stream.  So on
                              # Python 3 we will wrap up the byte stream returned
                              # by os.fdopen using TextIOWrapper.
  
                              # We hard-code UTF-8 as the encoding here, rather
                              # than looking at something like
                              # getfilesystemencoding() or sys.stderr.encoding,
                              # because we want an encoding that will be able to
                              # encode the full range of code points.  We are
                              # (most likely) talking to the parent process on
                              # the other end of this pipe and not the filesystem
                              # or the original sys.stderr, so there's no point
                              # in trying to match the encoding of one of those
                              # objects.
  
                              stderr = io.TextIOWrapper(stderr, encoding="utf-8")
  
                          stderr.write(msg)
                          traceback.print_exc(file=stderr)
                          stderr.flush()
  
                          for fd in range(3):
                              os.close(fd)
                      except:
                          # Handle all errors during the error-reporting process
                          # silently to ensure that the child terminates.
                          pass
  
                  # See comment above about making sure that we reach this line
                  # of code.
                  os._exit(1)
  
          # we are now in parent process
          if collectorEnabled:
              gc.enable()
          self.status = -1 # this records the exit status of the child
  
  
      def _setupChild(self, *args, **kwargs):
          """
          Setup the child process. Override in subclasses.
          """
          raise NotImplementedError()
  
  
      def _execChild(self, path, uid, gid, executable, args, environment):
          """
          The exec() which is done in the forked child.
          """
          if path:
              os.chdir(path)
          if uid is not None or gid is not None:
              if uid is None:
                  uid = os.geteuid()
              if gid is None:
                  gid = os.getegid()
              # set the UID before I actually exec the process
              os.setuid(0)
              os.setgid(0)
              switchUID(uid, gid)
          os.execvpe(executable, args, environment)
  
  
      def __repr__(self):
          """
          String representation of a process.
          """
          return "<%s pid=%s status=%s>" % (self.__class__.__name__,
                                            self.pid, self.status)
  
  
  
  class _FDDetector(object):
      """
      This class contains the logic necessary to decide which of the available
      system techniques should be used to detect the open file descriptors for
      the current process. The chosen technique gets monkey-patched into the
      _listOpenFDs method of this class so that the detection only needs to occur
      once.
  
      @ivar listdir: The implementation of listdir to use. This gets overwritten
          by the test cases.
      @ivar getpid: The implementation of getpid to use, returns the PID of the
          running process.
      @ivar openfile: The implementation of open() to use, by default the Python
          builtin.
      """
      # So that we can unit test this
      listdir = os.listdir
      getpid = os.getpid
      openfile = open
  
      def __init__(self):
          self._implementations = [
              self._procFDImplementation, self._devFDImplementation,
              self._fallbackFDImplementation]
  
  
      def _listOpenFDs(self):
          """
          Return an iterable of file descriptors which I{may} be open in this
          process.
  
          This will try to return the fewest possible descriptors without missing
          any.
          """
          self._listOpenFDs = self._getImplementation()
          return self._listOpenFDs()
  
  
      def _getImplementation(self):
          """
          Pick a method which gives correct results for C{_listOpenFDs} in this
          runtime environment.
  
          This involves a lot of very platform-specific checks, some of which may
          be relatively expensive.  Therefore the returned method should be saved
          and re-used, rather than always calling this method to determine what it
          is.
  
          See the implementation for the details of how a method is selected.
          """
          for impl in self._implementations:
              try:
                  before = impl()
              except:
                  continue
              with self.openfile("/dev/null", "r"):
                  after = impl()
              if before != after:
                  return impl
          # If no implementation can detect the newly opened file above, then just
          # return the last one.  The last one should therefore always be one
          # which makes a simple static guess which includes all possible open
          # file descriptors, but perhaps also many other values which do not
          # correspond to file descriptors.  For example, the scheme implemented
          # by _fallbackFDImplementation is suitable to be the last entry.
          return impl
  
  
      def _devFDImplementation(self):
          """
          Simple implementation for systems where /dev/fd actually works.
          See: http://www.freebsd.org/cgi/man.cgi?fdescfs
          """
          dname = "/dev/fd"
          result = [int(fd) for fd in self.listdir(dname)]
          return result
  
  
      def _procFDImplementation(self):
          """
          Simple implementation for systems where /proc/pid/fd exists (we assume
          it works).
          """
          dname = "/proc/%d/fd" % (self.getpid(),)
          return [int(fd) for fd in self.listdir(dname)]
  
  
      def _fallbackFDImplementation(self):
          """
          Fallback implementation where either the resource module can inform us
          about the upper bound of how many FDs to expect, or where we just guess
          a constant maximum if there is no resource module.
  
          All possible file descriptors from 0 to that upper bound are returned
          with no attempt to exclude invalid file descriptor values.
          """
          try:
              import resource
          except ImportError:
              maxfds = 1024
          else:
              # OS-X reports 9223372036854775808. That's a lot of fds to close.
              # OS-X should get the /dev/fd implementation instead, so mostly
              # this check probably isn't necessary.
              maxfds = min(1024, resource.getrlimit(resource.RLIMIT_NOFILE)[1])
          return range(maxfds)
  
  
  
  detector = _FDDetector()
  
  def _listOpenFDs():
      """
      Use the global detector object to figure out which FD implementation to
      use.
      """
      return detector._listOpenFDs()
  
  
  
  @implementer(IProcessTransport)
  class Process(_BaseProcess):
      """
      An operating-system Process.
  
      This represents an operating-system process with arbitrary input/output
      pipes connected to it. Those pipes may represent standard input,
      standard output, and standard error, or any other file descriptor.
  
      On UNIX, this is implemented using fork(), exec(), pipe()
      and fcntl(). These calls may not exist elsewhere so this
      code is not cross-platform. (also, windows can only select
      on sockets...)
      """
      debug = False
      debug_child = False
  
      status = -1
      pid = None
  
      processWriterFactory = ProcessWriter
      processReaderFactory = ProcessReader
  
      def __init__(self,
                   reactor, executable, args, environment, path, proto,
                   uid=None, gid=None, childFDs=None):
          """
          Spawn an operating-system process.
  
          This is where the hard work of disconnecting all currently open
          files / forking / executing the new process happens.  (This is
          executed automatically when a Process is instantiated.)
  
          This will also run the subprocess as a given user ID and group ID, if
          specified.  (Implementation Note: this doesn't support all the arcane
          nuances of setXXuid on UNIX: it will assume that either your effective
          or real UID is 0.)
          """
          if not proto:
              assert 'r' not in childFDs.values()
              assert 'w' not in childFDs.values()
          _BaseProcess.__init__(self, proto)
  
          self.pipes = {}
          # keys are childFDs, we can sense them closing
          # values are ProcessReader/ProcessWriters
  
          helpers = {}
          # keys are childFDs
          # values are parentFDs
  
          if childFDs is None:
              childFDs = {0: "w", # we write to the child's stdin
                          1: "r", # we read from their stdout
                          2: "r", # and we read from their stderr
                          }
  
          debug = self.debug
          if debug: print("childFDs", childFDs)
  
          _openedPipes = []
          def pipe():
              r, w = os.pipe()
              _openedPipes.extend([r, w])
              return r, w
  
          # fdmap.keys() are filenos of pipes that are used by the child.
          fdmap = {} # maps childFD to parentFD
          try:
              for childFD, target in items(childFDs):
                  if debug: print("[%d]" % childFD, target)
                  if target == "r":
                      # we need a pipe that the parent can read from
                      readFD, writeFD = pipe()
                      if debug: print("readFD=%d, writeFD=%d" % (readFD, writeFD))
                      fdmap[childFD] = writeFD     # child writes to this
                      helpers[childFD] = readFD    # parent reads from this
                  elif target == "w":
                      # we need a pipe that the parent can write to
                      readFD, writeFD = pipe()
                      if debug: print("readFD=%d, writeFD=%d" % (readFD, writeFD))
                      fdmap[childFD] = readFD      # child reads from this
                      helpers[childFD] = writeFD   # parent writes to this
                  else:
                      assert type(target) == int, '%r should be an int' % (target,)
                      fdmap[childFD] = target      # parent ignores this
              if debug: print("fdmap", fdmap)
              if debug: print("helpers", helpers)
              # the child only cares about fdmap.values()
  
              self._fork(path, uid, gid, executable, args, environment, fdmap=fdmap)
          except:
              for pipe in _openedPipes:
                  os.close(pipe)
              raise
  
          # we are the parent process:
          self.proto = proto
  
          # arrange for the parent-side pipes to be read and written
          for childFD, parentFD in items(helpers):
              os.close(fdmap[childFD])
              if childFDs[childFD] == "r":
                  reader = self.processReaderFactory(reactor, self, childFD,
                                          parentFD)
                  self.pipes[childFD] = reader
  
              if childFDs[childFD] == "w":
                  writer = self.processWriterFactory(reactor, self, childFD,
                                          parentFD, forceReadHack=True)
                  self.pipes[childFD] = writer
  
          try:
              # the 'transport' is used for some compatibility methods
              if self.proto is not None:
                  self.proto.makeConnection(self)
          except:
              log.err()
  
          # The reactor might not be running yet.  This might call back into
          # processEnded synchronously, triggering an application-visible
          # callback.  That's probably not ideal.  The replacement API for
          # spawnProcess should improve upon this situation.
          registerReapProcessHandler(self.pid, self)
  
  
      def _setupChild(self, fdmap):
          """
          fdmap[childFD] = parentFD
  
          The child wants to end up with 'childFD' attached to what used to be
          the parent's parentFD. As an example, a bash command run like
          'command 2>&1' would correspond to an fdmap of {0:0, 1:1, 2:1}.
          'command >foo.txt' would be {0:0, 1:os.open('foo.txt'), 2:2}.
  
          This is accomplished in two steps::
  
              1. close all file descriptors that aren't values of fdmap.  This
                 means 0 .. maxfds (or just the open fds within that range, if
                 the platform supports '/proc/<pid>/fd').
  
              2. for each childFD::
  
                   - if fdmap[childFD] == childFD, the descriptor is already in
                     place.  Make sure the CLOEXEC flag is not set, then delete
                     the entry from fdmap.
  
                   - if childFD is in fdmap.values(), then the target descriptor
                     is busy. Use os.dup() to move it elsewhere, update all
                     fdmap[childFD] items that point to it, then close the
                     original. Then fall through to the next case.
  
                   - now fdmap[childFD] is not in fdmap.values(), and is free.
                     Use os.dup2() to move it to the right place, then close the
                     original.
          """
          debug = self.debug_child
          if debug:
              errfd = sys.stderr
              errfd.write("starting _setupChild\n")
  
          destList = fdmap.values()
          for fd in _listOpenFDs():
              if fd in destList:
                  continue
              if debug and fd == errfd.fileno():
                  continue
              try:
                  os.close(fd)
              except:
                  pass
  
          # at this point, the only fds still open are the ones that need to
          # be moved to their appropriate positions in the child (the targets
          # of fdmap, i.e. fdmap.values() )
  
          if debug: print("fdmap", fdmap, file=errfd)
          for child in sorted(fdmap.keys()):
              target = fdmap[child]
              if target == child:
                  # fd is already in place
                  if debug: print("%d already in place" % target, file=errfd)
                  fdesc._unsetCloseOnExec(child)
              else:
                  if child in fdmap.values():
                      # we can't replace child-fd yet, as some other mapping
                      # still needs the fd it wants to target. We must preserve
                      # that old fd by duping it to a new home.
                      newtarget = os.dup(child) # give it a safe home
                      if debug: print("os.dup(%d) -> %d" % (child, newtarget),
                                      file=errfd)
                      os.close(child) # close the original
                      for c, p in items(fdmap):
                          if p == child:
                              fdmap[c] = newtarget # update all pointers
                  # now it should be available
                  if debug: print("os.dup2(%d,%d)" % (target, child), file=errfd)
                  os.dup2(target, child)
  
          # At this point, the child has everything it needs. We want to close
          # everything that isn't going to be used by the child, i.e.
          # everything not in fdmap.keys(). The only remaining fds open are
          # those in fdmap.values().
  
          # Any given fd may appear in fdmap.values() multiple times, so we
          # need to remove duplicates first.
  
          old = []
          for fd in fdmap.values():
              if not fd in old:
                  if not fd in fdmap.keys():
                      old.append(fd)
          if debug: print("old", old, file=errfd)
          for fd in old:
              os.close(fd)
  
          self._resetSignalDisposition()
  
  
      def writeToChild(self, childFD, data):
          self.pipes[childFD].write(data)
  
  
      def closeChildFD(self, childFD):
          # for writer pipes, loseConnection tries to write the remaining data
          # out to the pipe before closing it
          # if childFD is not in the list of pipes, assume that it is already
          # closed
          if childFD in self.pipes:
              self.pipes[childFD].loseConnection()
  
  
      def pauseProducing(self):
          for p in self.pipes.itervalues():
              if isinstance(p, ProcessReader):
                  p.stopReading()
  
  
      def resumeProducing(self):
          for p in self.pipes.itervalues():
              if isinstance(p, ProcessReader):
                  p.startReading()
  
      # compatibility
      def closeStdin(self):
          """
          Call this to close standard input on this process.
          """
          self.closeChildFD(0)
  
  
      def closeStdout(self):
          self.closeChildFD(1)
  
  
      def closeStderr(self):
          self.closeChildFD(2)
  
  
      def loseConnection(self):
          self.closeStdin()
          self.closeStderr()
          self.closeStdout()
  
  
      def write(self, data):
          """
          Call this to write to standard input on this process.
  
          NOTE: This will silently lose data if there is no standard input.
          """
          if 0 in self.pipes:
              self.pipes[0].write(data)
  
  
      def registerProducer(self, producer, streaming):
          """
          Call this to register producer for standard input.
  
          If there is no standard input producer.stopProducing() will
          be called immediately.
          """
          if 0 in self.pipes:
              self.pipes[0].registerProducer(producer, streaming)
          else:
              producer.stopProducing()
  
  
      def unregisterProducer(self):
          """
          Call this to unregister producer for standard input."""
          if 0 in self.pipes:
              self.pipes[0].unregisterProducer()
  
  
      def writeSequence(self, seq):
          """
          Call this to write to standard input on this process.
  
          NOTE: This will silently lose data if there is no standard input.
          """
          if 0 in self.pipes:
              self.pipes[0].writeSequence(seq)
  
  
      def childDataReceived(self, name, data):
          self.proto.childDataReceived(name, data)
  
  
      def childConnectionLost(self, childFD, reason):
          # this is called when one of the helpers (ProcessReader or
          # ProcessWriter) notices their pipe has been closed
          os.close(self.pipes[childFD].fileno())
          del self.pipes[childFD]
          try:
              self.proto.childConnectionLost(childFD)
          except:
              log.err()
          self.maybeCallProcessEnded()
  
  
      def maybeCallProcessEnded(self):
          # we don't call ProcessProtocol.processEnded until:
          #  the child has terminated, AND
          #  all writers have indicated an error status, AND
          #  all readers have indicated EOF
          # This insures that we've gathered all output from the process.
          if self.pipes:
              return
          if not self.lostProcess:
              self.reapProcess()
              return
          _BaseProcess.maybeCallProcessEnded(self)
  
  
  
  @implementer(IProcessTransport)
  class PTYProcess(abstract.FileDescriptor, _BaseProcess):
      """
      An operating-system Process that uses PTY support.
      """
  
      status = -1
      pid = None
  
      def __init__(self, reactor, executable, args, environment, path, proto,
                   uid=None, gid=None, usePTY=None):
          """
          Spawn an operating-system process.
  
          This is where the hard work of disconnecting all currently open
          files / forking / executing the new process happens.  (This is
          executed automatically when a Process is instantiated.)
  
          This will also run the subprocess as a given user ID and group ID, if
          specified.  (Implementation Note: this doesn't support all the arcane
          nuances of setXXuid on UNIX: it will assume that either your effective
          or real UID is 0.)
          """
          if pty is None and not isinstance(usePTY, (tuple, list)):
              # no pty module and we didn't get a pty to use
              raise NotImplementedError(
                  "cannot use PTYProcess on platforms without the pty module.")
          abstract.FileDescriptor.__init__(self, reactor)
          _BaseProcess.__init__(self, proto)
  
          if isinstance(usePTY, (tuple, list)):
              masterfd, slavefd, _ = usePTY
          else:
              masterfd, slavefd = pty.openpty()
  
          try:
              self._fork(path, uid, gid, executable, args, environment,
                         masterfd=masterfd, slavefd=slavefd)
          except:
              if not isinstance(usePTY, (tuple, list)):
                  os.close(masterfd)
                  os.close(slavefd)
              raise
  
          # we are now in parent process:
          os.close(slavefd)
          fdesc.setNonBlocking(masterfd)
          self.fd = masterfd
          self.startReading()
          self.connected = 1
          self.status = -1
          try:
              self.proto.makeConnection(self)
          except:
              log.err()
          registerReapProcessHandler(self.pid, self)
  
  
      def _setupChild(self, masterfd, slavefd):
          """
          Set up child process after C{fork()} but before C{exec()}.
  
          This involves:
  
              - closing C{masterfd}, since it is not used in the subprocess
  
              - creating a new session with C{os.setsid}
  
              - changing the controlling terminal of the process (and the new
                session) to point at C{slavefd}
  
              - duplicating C{slavefd} to standard input, output, and error
  
              - closing all other open file descriptors (according to
                L{_listOpenFDs})
  
              - re-setting all signal handlers to C{SIG_DFL}
  
          @param masterfd: The master end of a PTY file descriptors opened with
              C{openpty}.
          @type masterfd: L{int}
  
          @param slavefd: The slave end of a PTY opened with C{openpty}.
          @type slavefd: L{int}
          """
          os.close(masterfd)
          os.setsid()
          fcntl.ioctl(slavefd, termios.TIOCSCTTY, '')
  
          for fd in range(3):
              if fd != slavefd:
                  os.close(fd)
  
          os.dup2(slavefd, 0) # stdin
          os.dup2(slavefd, 1) # stdout
          os.dup2(slavefd, 2) # stderr
  
          for fd in _listOpenFDs():
              if fd > 2:
                  try:
                      os.close(fd)
                  except:
                      pass
  
          self._resetSignalDisposition()
  
  
      def closeStdin(self):
          # PTYs do not have stdin/stdout/stderr. They only have in and out, just
          # like sockets. You cannot close one without closing off the entire PTY
          pass
  
  
      def closeStdout(self):
          pass
  
  
      def closeStderr(self):
          pass
  
  
      def doRead(self):
          """
          Called when my standard output stream is ready for reading.
          """
          return fdesc.readFromFD(
              self.fd,
              lambda data: self.proto.childDataReceived(1, data))
  
  
      def fileno(self):
          """
          This returns the file number of standard output on this process.
          """
          return self.fd
  
  
      def maybeCallProcessEnded(self):
          # two things must happen before we call the ProcessProtocol's
          # processEnded method. 1: the child process must die and be reaped
          # (which calls our own processEnded method). 2: the child must close
          # their stdin/stdout/stderr fds, causing the pty to close, causing
          # our connectionLost method to be called. #2 can also be triggered
          # by calling .loseConnection().
          if self.lostProcess == 2:
              _BaseProcess.maybeCallProcessEnded(self)
  
  
      def connectionLost(self, reason):
          """
          I call this to clean up when one or all of my connections has died.
          """
          abstract.FileDescriptor.connectionLost(self, reason)
          os.close(self.fd)
          self.lostProcess += 1
          self.maybeCallProcessEnded()
  
  
      def writeSomeData(self, data):
          """
          Write some data to the open process.
          """
          return fdesc.writeToFD(self.fd, data)
  