powerline/scripts/powerline-daemon

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#!/usr/bin/env python
# vim:fileencoding=utf-8:noet
from __future__ import (unicode_literals, division, absolute_import, print_function)
import socket
import os
import errno
import sys
from argparse import ArgumentParser
from select import select
from signal import signal, SIGTERM
from time import sleep
from functools import partial
from io import BytesIO
from powerline.shell import ShellPowerline
from powerline.commands.main import finish_args, write_output
from powerline.lib.monotonic import monotonic
from powerline.lib.encoding import get_preferred_output_encoding, get_preferred_arguments_encoding, get_unicode_writer
from powerline.commands.main import get_argparser as get_main_argparser
from powerline.commands.daemon import get_argparser as get_daemon_argparser
is_daemon = False
use_filesystem = not sys.platform.lower().startswith('linux')
address = None
pidfile = None
class NonInteractiveArgParser(ArgumentParser):
def print_usage(self, file=None):
raise Exception(self.format_usage())
def print_help(self, file=None):
raise Exception(self.format_help())
def exit(self, status=0, message=None):
pass
def error(self, message):
raise Exception(self.format_usage())
parser = get_main_argparser(NonInteractiveArgParser)
EOF = b'EOF\0\0'
powerlines = {}
logger = None
config_loader = None
home = os.path.expanduser('~')
class PowerlineDaemon(ShellPowerline):
def get_log_handler(self):
if not is_daemon:
import logging
return logging.StreamHandler()
return super(PowerlineDaemon, self).get_log_handler()
def render(args, environ, cwd):
global logger
global config_loader
cwd = cwd or environ.get('PWD', '/')
segment_info = {
'getcwd': lambda: cwd,
'home': environ.get('HOME', home),
'environ': environ,
'args': args,
}
key = (
args.ext[0],
args.renderer_module,
tuple(args.config_override) if args.config_override else None,
tuple(args.theme_override) if args.theme_override else None,
tuple(args.config_path) if args.config_path else None,
environ.get('POWERLINE_THEME_OVERRIDES', ''),
environ.get('POWERLINE_CONFIG_OVERRIDES', ''),
environ.get('POWERLINE_CONFIG_PATHS', ''),
)
finish_args(environ, args)
powerline = None
try:
powerline = powerlines[key]
except KeyError:
try:
powerline = powerlines[key] = PowerlineDaemon(
args,
logger=logger,
config_loader=config_loader,
run_once=False,
)
if logger is None:
logger = powerline.logger
if config_loader is None:
config_loader = powerline.config_loader
except SystemExit:
# Somebody thought raising system exit was a good idea,
return ''
except Exception as e:
if powerline:
powerline.pl.exception('Failed to render {0}: {1}', str(key), str(e))
else:
return 'Failed to render {0}: {1}'.format(str(key), str(e))
s = BytesIO()
write_output(args, powerline, segment_info, get_unicode_writer(stream=s))
s.seek(0)
return s.read()
def eintr_retry_call(func, *args, **kwargs):
while True:
try:
return func(*args, **kwargs)
except EnvironmentError as e:
if getattr(e, 'errno', None) == errno.EINTR:
continue
raise
def do_read(conn, timeout=2.0):
''' Read data from the client. If the client fails to send data within
timeout seconds, abort. '''
read = []
end_time = monotonic() + timeout
while not read or not read[-1].endswith(b'\0\0'):
r, w, e = select((conn,), (), (conn,), timeout)
if e:
return
if monotonic() > end_time:
return
if not r:
continue
x = eintr_retry_call(conn.recv, 4096)
if x:
read.append(x)
else:
break
return b''.join(read)
def do_write(conn, result):
try:
eintr_retry_call(conn.sendall, result)
except Exception:
pass
def safe_bytes(o, encoding=get_preferred_output_encoding()):
'''Return bytes instance without ever throwing an exception.'''
try:
try:
# We are assuming that o is a unicode object
return o.encode(encoding, 'replace')
except Exception:
# Object may have defined __bytes__ (python 3) or __str__ method
# (python 2)
# This also catches problem with non_ascii_bytes.encode('utf-8')
# that first tries to decode to UTF-8 using ascii codec (and fails
# in this case) and then encode to given encoding: errors= argument
# is not used in the first stage.
return bytes(o)
except Exception as e:
return safe_bytes(str(e), encoding)
def parse_args(req, encoding=get_preferred_arguments_encoding()):
args = [x.decode(encoding) for x in req.split(b'\0') if x]
numargs = int(args[0], 16)
shell_args = parser.parse_args(args[1:numargs + 1])
cwd = args[numargs + 1]
environ = dict(((k, v) for k, v in (x.partition('=')[0::2] for x in args[numargs + 2:])))
return shell_args, environ, cwd
def do_render(req):
try:
return safe_bytes(render(*parse_args(req)))
except Exception as e:
return safe_bytes(str(e))
def do_one(sock, read_sockets, write_sockets, result_map):
r, w, e = select(
tuple(read_sockets) + (sock,),
tuple(write_sockets),
tuple(read_sockets) + tuple(write_sockets) + (sock,),
60.0
)
if sock in e:
# We cannot accept any more connections, so we exit
raise SystemExit(1)
for s in e:
# Discard all broken connections to clients
s.close()
read_sockets.discard(s)
write_sockets.discard(s)
for s in r:
if s == sock:
# A client wants to connect
conn, _ = eintr_retry_call(sock.accept)
read_sockets.add(conn)
else:
# A client has sent some data
read_sockets.discard(s)
req = do_read(s)
if req == EOF:
raise SystemExit(0)
elif req:
ans = do_render(req)
result_map[s] = ans
write_sockets.add(s)
else:
s.close()
for s in w:
# A client is ready to receive the result
write_sockets.discard(s)
result = result_map.pop(s)
try:
do_write(s, result)
finally:
s.close()
def main_loop(sock):
sock.listen(1)
sock.setblocking(0)
read_sockets, write_sockets = set(), set()
result_map = {}
try:
while True:
do_one(sock, read_sockets, write_sockets, result_map)
except KeyboardInterrupt:
raise SystemExit(0)
return 0
def daemonize(stdin=os.devnull, stdout=os.devnull, stderr=os.devnull):
try:
pid = os.fork()
if pid > 0:
# exit first parent
sys.exit(0)
except OSError as e:
sys.stderr.write("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))
sys.exit(1)
# decouple from parent environment
os.chdir("/")
os.setsid()
os.umask(0)
# do second fork
try:
pid = os.fork()
if pid > 0:
# exit from second parent
sys.exit(0)
except OSError as e:
sys.stderr.write("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))
sys.exit(1)
# Redirect standard file descriptors.
si = open(stdin, 'rb')
so = open(stdout, 'a+b')
se = open(stderr, 'a+b', 0)
os.dup2(si.fileno(), sys.stdin.fileno())
os.dup2(so.fileno(), sys.stdout.fileno())
os.dup2(se.fileno(), sys.stderr.fileno())
global is_daemon
is_daemon = True
def check_existing():
if use_filesystem:
# We cannot bind if the socket file already exists so remove it, we
# already have a lock on pidfile, so this should be safe.
try:
os.unlink(address)
except EnvironmentError:
pass
sock = socket.socket(family=socket.AF_UNIX)
try:
sock.bind(address)
except socket.error as e:
if getattr(e, 'errno', None) == errno.EADDRINUSE:
return None
raise
return sock
def kill_daemon():
sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
try:
try:
eintr_retry_call(sock.connect, address)
except socket.error:
return False
else:
eintr_retry_call(sock.sendall, EOF)
finally:
sock.close()
return True
def cleanup_lockfile(fd, *args):
try:
# Remove the directory entry for the lock file
os.unlink(pidfile)
# Close the file descriptor
os.close(fd)
except EnvironmentError:
pass
if args:
# Called in signal handler
raise SystemExit(1)
def lockpidfile():
import fcntl
import atexit
import stat
fd = os.open(
pidfile,
os.O_WRONLY | os.O_CREAT,
stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH
)
try:
fcntl.lockf(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
except EnvironmentError:
os.close(fd)
return None
os.lseek(fd, 0, os.SEEK_SET)
os.ftruncate(fd, 0)
os.write(fd, ('%d' % os.getpid()).encode('ascii'))
os.fsync(fd)
cleanup = partial(cleanup_lockfile, fd)
signal(SIGTERM, cleanup)
atexit.register(cleanup)
return fd
def main():
global address
global pidfile
parser = get_daemon_argparser()
args = parser.parse_args()
if args.socket:
address = args.socket
if not use_filesystem:
address = '\0' + address
else:
if use_filesystem:
address = '/tmp/powerline-ipc-%d'
else:
# Use the abstract namespace for sockets rather than the filesystem
# (Available only in linux)
address = '\0powerline-ipc-%d'
address = address % os.getuid()
if use_filesystem:
pidfile = address + '.pid'
if args.kill:
if args.foreground or args.replace:
parser.error('--kill and --foreground/--replace cannot be used together')
if kill_daemon():
if not args.quiet:
print ('Kill command sent to daemon, if it does not die in a couple of seconds use kill to kill it')
raise SystemExit(0)
else:
if not args.quiet:
print ('No running daemon found')
raise SystemExit(1)
if args.replace:
while kill_daemon():
if not args.quiet:
print ('Kill command sent to daemon, waiting for daemon to exit, press Ctrl-C to terminate wait and exit')
sleep(2)
if use_filesystem and not args.foreground:
# We must daemonize before creating the locked pidfile, unfortunately,
# this means further print statements are discarded
daemonize()
if use_filesystem:
# Create a locked pid file containing the daemons PID
if lockpidfile() is None:
if not args.quiet:
sys.stderr.write(
'The daemon is already running. Use %s -k to kill it.\n' % (
os.path.basename(sys.argv[0])))
raise SystemExit(1)
# Bind to address or bail if we cannot bind
sock = check_existing()
if sock is None:
if not args.quiet:
sys.stderr.write(
'The daemon is already running. Use %s -k to kill it.\n' % (
os.path.basename(sys.argv[0])))
raise SystemExit(1)
if args.foreground:
return main_loop(sock)
if not use_filesystem:
# We daemonize on linux
daemonize()
main_loop(sock)
if __name__ == '__main__':
main()