pym/_emerge/SubProcess.py

   1 # Copyright 1999-2012 Gentoo Foundation
   2 # Distributed under the terms of the GNU General Public License v2
   3
   4 from portage import os
   5 from _emerge.AbstractPollTask import AbstractPollTask
   6 import signal
   7 import errno
   8
   9 class SubProcess(AbstractPollTask):
  10
  11         __slots__ = ("pid",) + \
  12                 ("_files", "_reg_id")
  13
  14         # A file descriptor is required for the scheduler to monitor changes from
  15         # inside a poll() loop. When logging is not enabled, create a pipe just to
  16         # serve this purpose alone.
  17         _dummy_pipe_fd = 9
  18
  19         # This is how much time we allow for waitpid to succeed after
  20         # we've sent a kill signal to our subprocess.
  21         _cancel_timeout = 1000 # 1 second
  22
  23         def _poll(self):
  24                 if self.returncode is not None:
  25                         return self.returncode
  26                 if self.pid is None:
  27                         return self.returncode
  28                 if self._registered:
  29                         return self.returncode
  30
  31                 try:
  32                         # With waitpid and WNOHANG, only check the
  33                         # first element of the tuple since the second
  34                         # element may vary (bug #337465).
  35                         retval = os.waitpid(self.pid, os.WNOHANG)
  36                 except OSError as e:
  37                         if e.errno != errno.ECHILD:
  38                                 raise
  39                         del e
  40                         retval = (self.pid, 1)
  41
  42                 if retval[0] == 0:
  43                         return None
  44                 self._set_returncode(retval)
  45                 self.wait()
  46                 return self.returncode
  47
  48         def _cancel(self):
  49                 if self.isAlive():
  50                         try:
  51                                 os.kill(self.pid, signal.SIGTERM)
  52                         except OSError as e:
  53                                 if e.errno != errno.ESRCH:
  54                                         raise
  55
  56         def isAlive(self):
  57                 return self.pid is not None and \
  58                         self.returncode is None
  59
  60         def _wait(self):
  61
  62                 if self.returncode is not None:
  63                         return self.returncode
  64
  65                 if self._registered:
  66                         if self.cancelled:
  67                                 timeout = self._cancel_timeout
  68                                 self.scheduler.schedule(self._reg_id, timeout=timeout)
  69                                 if self._registered:
  70                                         try:
  71                                                 os.kill(self.pid, signal.SIGKILL)
  72                                         except OSError as e:
  73                                                 if e.errno != errno.ESRCH:
  74                                                         raise
  75                                                 del e
  76                                         self.scheduler.schedule(self._reg_id, timeout=timeout)
  77                                         if self._registered:
  78                                                 self._orphan_process_warn()
  79                         else:
  80                                 while self._registered:
  81                                         self.scheduler.iteration()
  82                         self._unregister()
  83                         if self.returncode is not None:
  84                                 return self.returncode
  85
  86                 try:
  87                         # With waitpid and WNOHANG, only check the
  88                         # first element of the tuple since the second
  89                         # element may vary (bug #337465).
  90                         wait_retval = os.waitpid(self.pid, os.WNOHANG)
  91                 except OSError as e:
  92                         if e.errno != errno.ECHILD:
  93                                 raise
  94                         del e
  95                         self._set_returncode((self.pid, 1 << 8))
  96                 else:
  97                         if wait_retval[0] != 0:
  98                                 self._set_returncode(wait_retval)
  99                         else:
 100                                 try:
 101                                         wait_retval = os.waitpid(self.pid, 0)
 102                                 except OSError as e:
 103                                         if e.errno != errno.ECHILD:
 104                                                 raise
 105                                         del e
 106                                         self._set_returncode((self.pid, 1 << 8))
 107                                 else:
 108                                         self._set_returncode(wait_retval)
 109
 110                 return self.returncode
 111
 112         def _orphan_process_warn(self):
 113                 pass
 114
 115         def _unregister(self):
 116                 """
 117                 Unregister from the scheduler and close open files.
 118                 """
 119
 120                 self._registered = False
 121
 122                 if self._reg_id is not None:
 123                         self.scheduler.unregister(self._reg_id)
 124                         self._reg_id = None
 125
 126                 if self._files is not None:
 127                         for f in self._files.values():
 128                                 if isinstance(f, int):
 129                                         os.close(f)
 130                                 else:
 131                                         f.close()
 132                         self._files = None
 133
 134         def _set_returncode(self, wait_retval):
 135                 """
 136                 Set the returncode in a manner compatible with
 137                 subprocess.Popen.returncode: A negative value -N indicates
 138                 that the child was terminated by signal N (Unix only).
 139                 """
 140
 141                 pid, status = wait_retval
 142
 143                 if os.WIFSIGNALED(status):
 144                         retval = - os.WTERMSIG(status)
 145                 else:
 146                         retval = os.WEXITSTATUS(status)
 147
 148                 self.returncode = retval
 149