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# Copyright 1999-2011 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
from _emerge.SubProcess import SubProcess
import sys
from portage.cache.mappings import slot_dict_class
import portage
from portage import _encodings
from portage import _unicode_encode
from portage import os
from portage.const import BASH_BINARY
import fcntl
import errno
import gzip
class SpawnProcess(SubProcess):
"""
Constructor keyword args are passed into portage.process.spawn().
The required "args" keyword argument will be passed as the first
spawn() argument.
"""
_spawn_kwarg_names = ("env", "opt_name", "fd_pipes",
"uid", "gid", "groups", "umask", "logfile",
"path_lookup", "pre_exec")
__slots__ = ("args",) + \
_spawn_kwarg_names + ("_log_file_real", "_selinux_type",)
_file_names = ("log", "process", "stdout")
_files_dict = slot_dict_class(_file_names, prefix="")
def _start(self):
if self.fd_pipes is None:
self.fd_pipes = {}
fd_pipes = self.fd_pipes
self._files = self._files_dict()
files = self._files
master_fd, slave_fd = self._pipe(fd_pipes)
fcntl.fcntl(master_fd, fcntl.F_SETFL,
fcntl.fcntl(master_fd, fcntl.F_GETFL) | os.O_NONBLOCK)
files.process = master_fd
logfile = None
if self._can_log(slave_fd):
logfile = self.logfile
null_input = None
if not self.background or 0 in fd_pipes:
# Subclasses such as AbstractEbuildProcess may have already passed
# in a null file descriptor in fd_pipes, so use that when given.
pass
else:
# TODO: Use job control functions like tcsetpgrp() to control
# access to stdin. Until then, use /dev/null so that any
# attempts to read from stdin will immediately return EOF
# instead of blocking indefinitely.
null_input = os.open('/dev/null', os.O_RDWR)
fd_pipes[0] = null_input
fd_pipes.setdefault(0, sys.stdin.fileno())
fd_pipes.setdefault(1, sys.stdout.fileno())
fd_pipes.setdefault(2, sys.stderr.fileno())
# flush any pending output
for fd in fd_pipes.values():
if fd == sys.stdout.fileno():
sys.stdout.flush()
if fd == sys.stderr.fileno():
sys.stderr.flush()
if logfile is not None:
fd_pipes_orig = fd_pipes.copy()
fd_pipes[1] = slave_fd
fd_pipes[2] = slave_fd
files.log = open(_unicode_encode(logfile,
encoding=_encodings['fs'], errors='strict'), mode='ab')
if logfile.endswith('.gz'):
self._log_file_real = files.log
files.log = gzip.GzipFile(filename='', mode='ab',
fileobj=files.log)
portage.util.apply_secpass_permissions(logfile,
uid=portage.portage_uid, gid=portage.portage_gid,
mode=0o660)
if not self.background:
files.stdout = os.dup(fd_pipes_orig[1])
output_handler = self._output_handler
else:
# Create a dummy pipe so the scheduler can monitor
# the process from inside a poll() loop.
fd_pipes[self._dummy_pipe_fd] = slave_fd
if self.background:
fd_pipes[1] = slave_fd
fd_pipes[2] = slave_fd
output_handler = self._dummy_handler
kwargs = {}
for k in self._spawn_kwarg_names:
v = getattr(self, k)
if v is not None:
kwargs[k] = v
kwargs["fd_pipes"] = fd_pipes
kwargs["returnpid"] = True
kwargs.pop("logfile", None)
self._reg_id = self.scheduler.register(files.process,
self._registered_events, output_handler)
self._registered = True
retval = self._spawn(self.args, **kwargs)
os.close(slave_fd)
if null_input is not None:
os.close(null_input)
if isinstance(retval, int):
# spawn failed
self._unregister()
self._set_returncode((self.pid, retval))
self.wait()
return
self.pid = retval[0]
portage.process.spawned_pids.remove(self.pid)
def _can_log(self, slave_fd):
return True
def _pipe(self, fd_pipes):
"""
@type fd_pipes: dict
@param fd_pipes: pipes from which to copy terminal size if desired.
"""
return os.pipe()
def _spawn(self, args, **kwargs):
spawn_func = portage.process.spawn
if self._selinux_type is not None:
spawn_func = portage.selinux.spawn_wrapper(spawn_func,
self._selinux_type)
# bash is an allowed entrypoint, while most binaries are not
if args[0] != BASH_BINARY:
args = [BASH_BINARY, "-c", "exec \"$@\"", args[0]] + args
return spawn_func(args, **kwargs)
def _output_handler(self, fd, event):
files = self._files
while True:
buf = self._read_buf(fd, event)
if buf is None:
# not a POLLIN event, EAGAIN, etc...
break
if not buf:
# EOF
self._unregister()
self.wait()
break
else:
if not self.background:
write_successful = False
failures = 0
while True:
try:
if not write_successful:
os.write(files.stdout, buf)
write_successful = True
break
except OSError as e:
if e.errno != errno.EAGAIN:
raise
del e
failures += 1
if failures > 50:
# Avoid a potentially infinite loop. In
# most cases, the failure count is zero
# and it's unlikely to exceed 1.
raise
# This means that a subprocess has put an inherited
# stdio file descriptor (typically stdin) into
# O_NONBLOCK mode. This is not acceptable (see bug
# #264435), so revert it. We need to use a loop
# here since there's a race condition due to
# parallel processes being able to change the
# flags on the inherited file descriptor.
# TODO: When possible, avoid having child processes
# inherit stdio file descriptors from portage
# (maybe it can't be avoided with
# PROPERTIES=interactive).
fcntl.fcntl(files.stdout, fcntl.F_SETFL,
fcntl.fcntl(files.stdout,
fcntl.F_GETFL) ^ os.O_NONBLOCK)
files.log.write(buf)
files.log.flush()
self._unregister_if_appropriate(event)
return True
def _dummy_handler(self, fd, event):
"""
This method is mainly interested in detecting EOF, since
the only purpose of the pipe is to allow the scheduler to
monitor the process from inside a poll() loop.
"""
while True:
buf = self._read_buf(fd, event)
if buf is None:
# not a POLLIN event, EAGAIN, etc...
break
if not buf:
# EOF
self._unregister()
self.wait()
break
self._unregister_if_appropriate(event)
return True
def _unregister(self):
super(SpawnProcess, self)._unregister()
if self._log_file_real is not None:
# Avoid "ResourceWarning: unclosed file" since python 3.2.
self._log_file_real.close()
self._log_file_real = None
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