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# -*- coding: utf-8 -*-
"""
celery.platforms
~~~~~~~~~~~~~~~~
Utilities dealing with platform specifics: signals, daemonization,
users, groups, and so on.
:copyright: (c) 2009 - 2012 by Ask Solem.
:license: BSD, see LICENSE for more details.
"""
from __future__ import absolute_import
from __future__ import with_statement
import atexit
import errno
import os
import platform as _platform
import shlex
import signal as _signal
import sys
from contextlib import contextmanager
from .local import try_import
from billiard import current_process
from kombu.utils.limits import TokenBucket
_setproctitle = try_import("setproctitle")
resource = try_import("resource")
pwd = try_import("pwd")
grp = try_import("grp")
EX_OK = getattr(os, "EX_OK", 0)
EX_FAILURE = 1
EX_UNAVAILABLE = getattr(os, "EX_UNAVAILABLE", 69)
EX_USAGE = getattr(os, "EX_USAGE", 64)
SYSTEM = _platform.system()
IS_OSX = SYSTEM == "Darwin"
IS_WINDOWS = SYSTEM == "Windows"
DAEMON_UMASK = 0
DAEMON_WORKDIR = "/"
DAEMON_REDIRECT_TO = getattr(os, "devnull", "/dev/null")
PIDFILE_FLAGS = os.O_CREAT | os.O_EXCL | os.O_WRONLY
PIDFILE_MODE = ((os.R_OK | os.W_OK) << 6) | ((os.R_OK) << 3) | ((os.R_OK))
_setps_bucket = TokenBucket(0.5) # 30/m, every 2 seconds
PIDLOCKED = """ERROR: Pidfile (%s) already exists.
Seems we're already running? (PID: %s)"""
def pyimplementation():
if hasattr(_platform, "python_implementation"):
return _platform.python_implementation()
elif sys.platform.startswith("java"):
return "Jython " + sys.platform
elif hasattr(sys, "pypy_version_info"):
v = ".".join(map(str, sys.pypy_version_info[:3]))
if sys.pypy_version_info[3:]:
v += "-" + "".join(map(str, sys.pypy_version_info[3:]))
return "PyPy " + v
else:
return "CPython"
class LockFailed(Exception):
"""Raised if a pidlock can't be acquired."""
pass
def get_fdmax(default=None):
"""Returns the maximum number of open file descriptors
on this system.
:keyword default: Value returned if there's no file
descriptor limit.
"""
fdmax = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
if fdmax == resource.RLIM_INFINITY:
return default
return fdmax
class PIDFile(object):
"""PID lock file.
This is the type returned by :func:`create_pidlock`.
**Should not be used directly, use the :func:`create_pidlock`
context instead**
"""
#: Path to the pid lock file.
path = None
def __init__(self, path):
self.path = os.path.abspath(path)
def acquire(self):
"""Acquire lock."""
try:
self.write_pid()
except OSError, exc:
raise LockFailed, LockFailed(str(exc)), sys.exc_info()[2]
return self
__enter__ = acquire
def is_locked(self):
"""Returns true if the pid lock exists."""
return os.path.exists(self.path)
def release(self, *args):
"""Release lock."""
self.remove()
__exit__ = release
def read_pid(self):
"""Reads and returns the current pid."""
try:
fh = open(self.path, "r")
except IOError, exc:
if exc.errno == errno.ENOENT:
return
raise
try:
line = fh.readline()
if line.strip() == line: # must contain '\n'
raise ValueError(
"Partially written or invalid pidfile %r" % (self.path))
finally:
fh.close()
try:
return int(line.strip())
except ValueError:
raise ValueError("PID file %r contents invalid." % self.path)
def remove(self):
"""Removes the lock."""
try:
os.unlink(self.path)
except OSError, exc:
if exc.errno in (errno.ENOENT, errno.EACCES):
return
raise
def remove_if_stale(self):
"""Removes the lock if the process is not running.
(does not respond to signals)."""
try:
pid = self.read_pid()
except ValueError, exc:
sys.stderr.write("Broken pidfile found. Removing it.\n")
self.remove()
return True
if not pid:
self.remove()
return True
try:
os.kill(pid, 0)
except os.error, exc:
if exc.errno == errno.ESRCH:
sys.stderr.write("Stale pidfile exists. Removing it.\n")
self.remove()
return True
return False
def write_pid(self):
pid = os.getpid()
content = "%d\n" % (pid, )
pidfile_fd = os.open(self.path, PIDFILE_FLAGS, PIDFILE_MODE)
pidfile = os.fdopen(pidfile_fd, "w")
try:
pidfile.write(content)
# flush and sync so that the re-read below works.
pidfile.flush()
try:
os.fsync(pidfile_fd)
except AttributeError: # pragma: no cover
pass
finally:
pidfile.close()
rfh = open(self.path)
try:
if rfh.read() != content:
raise LockFailed(
"Inconsistency: Pidfile content doesn't match at re-read")
finally:
rfh.close()
def create_pidlock(pidfile):
"""Create and verify pid file.
If the pid file already exists the program exits with an error message,
however if the process it refers to is not running anymore, the pid file
is deleted and the program continues.
The caller is responsible for releasing the lock before the program
exits.
:returns: :class:`PIDFile`.
**Example**:
.. code-block:: python
pidlock = create_pidlock("/var/run/app.pid")
"""
pidlock = PIDFile(pidfile)
if pidlock.is_locked() and not pidlock.remove_if_stale():
raise SystemExit(PIDLOCKED % (pidfile, pidlock.read_pid()))
pidlock.acquire()
atexit.register(pidlock.release)
return pidlock
class DaemonContext(object):
_is_open = False
workdir = DAEMON_WORKDIR
umask = DAEMON_UMASK
def __init__(self, pidfile=None, workdir=None, umask=None,
fake=False, **kwargs):
self.workdir = workdir or self.workdir
self.umask = self.umask if umask is None else umask
self.fake = fake
def open(self):
if not self._is_open:
if not self.fake:
self._detach()
os.chdir(self.workdir)
os.umask(self.umask)
for fd in reversed(range(get_fdmax(default=2048))):
with ignore_EBADF():
os.close(fd)
os.open(DAEMON_REDIRECT_TO, os.O_RDWR)
os.dup2(0, 1)
os.dup2(0, 2)
self._is_open = True
__enter__ = open
def close(self, *args):
if self._is_open:
self._is_open = False
__exit__ = close
def _detach(self):
if os.fork() == 0: # first child
os.setsid() # create new session
if os.fork() > 0: # second child
os._exit(0)
else:
os._exit(0)
return self
def detached(logfile=None, pidfile=None, uid=None, gid=None, umask=0,
workdir=None, fake=False, **opts):
"""Detach the current process in the background (daemonize).
:keyword logfile: Optional log file. The ability to write to this file
will be verified before the process is detached.
:keyword pidfile: Optional pid file. The pid file will not be created,
as this is the responsibility of the child. But the process will
exit if the pid lock exists and the pid written is still running.
:keyword uid: Optional user id or user name to change
effective privileges to.
:keyword gid: Optional group id or group name to change effective
privileges to.
:keyword umask: Optional umask that will be effective in the child process.
:keyword workdir: Optional new working directory.
:keyword fake: Don't actually detach, intented for debugging purposes.
:keyword \*\*opts: Ignored.
**Example**:
.. code-block:: python
import atexit
from celery.platforms import detached, create_pidlock
with detached(logfile="/var/log/app.log", pidfile="/var/run/app.pid",
uid="nobody"):
# Now in detached child process with effective user set to nobody,
# and we know that our logfile can be written to, and that
# the pidfile is not locked.
pidlock = create_pidlock("/var/run/app.pid").acquire()
atexit.register(pidlock.release)
# Run the program
program.run(logfile="/var/log/app.log")
"""
if not resource:
raise RuntimeError("This platform does not support detach.")
workdir = os.getcwd() if workdir is None else workdir
signals.reset("SIGCLD") # Make sure SIGCLD is using the default handler.
if not os.geteuid():
# no point trying to setuid unless we're root.
maybe_drop_privileges(uid=uid, gid=gid)
# Since without stderr any errors will be silently suppressed,
# we need to know that we have access to the logfile.
logfile and open(logfile, "a").close()
# Doesn't actually create the pidfile, but makes sure it's not stale.
pidfile and create_pidlock(pidfile)
return DaemonContext(umask=umask, workdir=workdir, fake=fake)
def parse_uid(uid):
"""Parse user id.
uid can be an integer (uid) or a string (user name), if a user name
the uid is taken from the password file.
"""
try:
return int(uid)
except ValueError:
try:
return pwd.getpwnam(uid).pw_uid
except (AttributeError, KeyError):
raise KeyError("User does not exist: %r" % (uid, ))
def parse_gid(gid):
"""Parse group id.
gid can be an integer (gid) or a string (group name), if a group name
the gid is taken from the password file.
"""
try:
return int(gid)
except ValueError:
try:
return grp.getgrnam(gid).gr_gid
except (AttributeError, KeyError):
raise KeyError("Group does not exist: %r" % (gid, ))
def _setgroups_hack(groups):
""":fun:`setgroups` may have a platform-dependent limit,
and it is not always possible to know in advance what this limit
is, so we use this ugly hack stolen from glibc."""
groups = groups[:]
while 1:
try:
return os.setgroups(groups)
except ValueError: # error from Python's check.
if len(groups) <= 1:
raise
groups[:] = groups[:-1]
except OSError, exc: # error from the OS.
if exc.errno != errno.EINVAL or len(groups) <= 1:
raise
groups[:] = groups[:-1]
def setgroups(groups):
max_groups = None
try:
max_groups = os.sysconf("SC_NGROUPS_MAX")
except Exception:
pass
try:
return _setgroups_hack(groups[:max_groups])
except OSError, exc:
if exc.errno != errno.EPERM:
raise
if any(group not in groups for group in os.getgroups()):
# we shouldn't be allowed to change to this group.
raise
def initgroups(uid, gid):
if not pwd: # pragma: no cover
return
username = pwd.getpwuid(uid)[0]
if hasattr(os, "initgroups"): # Python 2.7+
return os.initgroups(username, gid)
groups = [gr.gr_gid for gr in grp.getgrall()
if username in gr.gr_mem]
setgroups(groups)
def setegid(gid):
"""Set effective group id."""
gid = parse_gid(gid)
if gid != os.getegid():
os.setegid(gid)
def seteuid(uid):
"""Set effective user id."""
uid = parse_uid(uid)
if uid != os.geteuid():
os.seteuid(uid)
def setgid(gid):
os.setgid(parse_gid(gid))
def setuid(uid):
os.setuid(parse_uid(uid))
def maybe_drop_privileges(uid=None, gid=None):
"""Change process privileges to new user/group.
If UID and GID is specified, the real user/group is changed.
If only UID is specified, the real user is changed, and the group is
changed to the users primary group.
If only GID is specified, only the group is changed.
"""
uid = uid and parse_uid(uid)
gid = gid and parse_gid(gid)
if uid:
# If GID isn't defined, get the primary GID of the user.
if not gid and pwd:
gid = pwd.getpwuid(uid).pw_gid
# Must set the GID before initgroups(), as setgid()
# is known to zap the group list on some platforms.
setgid(gid)
initgroups(uid, gid)
# at last:
setuid(uid)
else:
gid and setgid(gid)
class Signals(object):
"""Convenience interface to :mod:`signals`.
If the requested signal is not supported on the current platform,
the operation will be ignored.
**Examples**:
.. code-block:: python
>>> from celery.platforms import signals
>>> signals["INT"] = my_handler
>>> signals["INT"]
my_handler
>>> signals.supported("INT")
True
>>> signals.signum("INT")
2
>>> signals.ignore("USR1")
>>> signals["USR1"] == signals.ignored
True
>>> signals.reset("USR1")
>>> signals["USR1"] == signals.default
True
>>> signals.update(INT=exit_handler,
... TERM=exit_handler,
... HUP=hup_handler)
"""
ignored = _signal.SIG_IGN
default = _signal.SIG_DFL
def supported(self, signal_name):
"""Returns true value if ``signal_name`` exists on this platform."""
try:
return self.signum(signal_name)
except AttributeError:
pass
def signum(self, signal_name):
"""Get signal number from signal name."""
if isinstance(signal_name, int):
return signal_name
if not isinstance(signal_name, basestring) \
or not signal_name.isupper():
raise TypeError("signal name must be uppercase string.")
if not signal_name.startswith("SIG"):
signal_name = "SIG" + signal_name
return getattr(_signal, signal_name)
def reset(self, *signal_names):
"""Reset signals to the default signal handler.
Does nothing if the platform doesn't support signals,
or the specified signal in particular.
"""
self.update((sig, self.default) for sig in signal_names)
def ignore(self, *signal_names):
"""Ignore signal using :const:`SIG_IGN`.
Does nothing if the platform doesn't support signals,
or the specified signal in particular.
"""
self.update((sig, self.ignored) for sig in signal_names)
def __getitem__(self, signal_name):
return _signal.getsignal(self.signum(signal_name))
def __setitem__(self, signal_name, handler):
"""Install signal handler.
Does nothing if the current platform doesn't support signals,
or the specified signal in particular.
"""
try:
_signal.signal(self.signum(signal_name), handler)
except (AttributeError, ValueError):
pass
def update(self, _d_=None, **sigmap):
"""Set signal handlers from a mapping."""
for signal_name, handler in dict(_d_ or {}, **sigmap).iteritems():
self[signal_name] = handler
signals = Signals()
get_signal = signals.signum # compat
install_signal_handler = signals.__setitem__ # compat
reset_signal = signals.reset # compat
ignore_signal = signals.ignore # compat
def strargv(argv):
arg_start = 2 if "manage" in argv[0] else 1
if len(argv) > arg_start:
return " ".join(argv[arg_start:])
return ""
def set_process_title(progname, info=None):
"""Set the ps name for the currently running process.
Only works if :mod:`setproctitle` is installed.
"""
proctitle = "[%s]" % progname
proctitle = "%s %s" % (proctitle, info) if info else proctitle
if _setproctitle:
_setproctitle.setproctitle(proctitle)
return proctitle
if os.environ.get("NOSETPS"): # pragma: no cover
def set_mp_process_title(*a, **k):
pass
else:
def set_mp_process_title(progname, info=None, hostname=None, # noqa
rate_limit=False):
"""Set the ps name using the multiprocessing process name.
Only works if :mod:`setproctitle` is installed.
"""
if not rate_limit or _setps_bucket.can_consume(1):
if hostname:
progname = "%s@%s" % (progname, hostname.split(".")[0])
return set_process_title(
"%s:%s" % (progname, current_process().name), info=info)
def shellsplit(s, posix=True):
# posix= option to shlex.split first available in Python 2.6+
lexer = shlex.shlex(s, posix=not IS_WINDOWS)
lexer.whitespace_split = True
lexer.commenters = ''
return list(lexer)
@contextmanager
def ignore_EBADF():
try:
yield
except OSError, exc:
if exc.errno != errno.EBADF:
raise
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