text: # Copyright (c) 2010-2012 OpenStack Foundation
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #    http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
  # implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  """WSGI tools for use with swift."""
  
  from __future__ import print_function
  
  import errno
  import inspect
  import os
  import signal
  import time
  import mimetools
  from swift import gettext_ as _
  from textwrap import dedent
  
  import eventlet
  import eventlet.debug
  from eventlet import greenio, GreenPool, sleep, wsgi, listen, Timeout
  from paste.deploy import loadwsgi
  from eventlet.green import socket, ssl, os as green_os
  from six import BytesIO
  from six import StringIO
  from six.moves.urllib.parse import unquote
  
  from swift.common import utils, constraints
  from swift.common.storage_policy import BindPortsCache
  from swift.common.swob import Request
  from swift.common.utils import capture_stdio, disable_fallocate, \
      drop_privileges, get_logger, NullLogger, config_true_value, \
      validate_configuration, get_hub, config_auto_int_value, \
      CloseableChain
  
  # Set maximum line size of message headers to be accepted.
  wsgi.MAX_HEADER_LINE = constraints.MAX_HEADER_SIZE
  
  try:
      import multiprocessing
      CPU_COUNT = multiprocessing.cpu_count() or 1
  except (ImportError, NotImplementedError):
      CPU_COUNT = 1
  
  
  class NamedConfigLoader(loadwsgi.ConfigLoader):
      """
      Patch paste.deploy's ConfigLoader so each context object will know what
      config section it came from.
      """
  
      def get_context(self, object_type, name=None, global_conf=None):
          context = super(NamedConfigLoader, self).get_context(
              object_type, name=name, global_conf=global_conf)
          context.name = name
          return context
  
  
  loadwsgi.ConfigLoader = NamedConfigLoader
  
  
  class ConfigDirLoader(NamedConfigLoader):
      """
      Read configuration from multiple files under the given path.
      """
  
      def __init__(self, conf_dir):
          # parent class uses filename attribute when building error messages
          self.filename = conf_dir = conf_dir.strip()
          defaults = {
              'here': os.path.normpath(os.path.abspath(conf_dir)),
              '__file__': os.path.abspath(conf_dir)
          }
          self.parser = loadwsgi.NicerConfigParser(conf_dir, defaults=defaults)
          self.parser.optionxform = str  # Don't lower-case keys
          utils.read_conf_dir(self.parser, conf_dir)
  
  
  def _loadconfigdir(object_type, uri, path, name, relative_to, global_conf):
      if relative_to:
          path = os.path.normpath(os.path.join(relative_to, path))
      loader = ConfigDirLoader(path)
      if global_conf:
          loader.update_defaults(global_conf, overwrite=False)
      return loader.get_context(object_type, name, global_conf)
  
  
  # add config_dir parsing to paste.deploy
  loadwsgi._loaders['config_dir'] = _loadconfigdir
  
  
  class ConfigString(NamedConfigLoader):
      """
      Wrap a raw config string up for paste.deploy.
  
      If you give one of these to our loadcontext (e.g. give it to our
      appconfig) we'll intercept it and get it routed to the right loader.
      """
  
      def __init__(self, config_string):
          self.contents = StringIO(dedent(config_string))
          self.filename = "string"
          defaults = {
              'here': "string",
              '__file__': "string",
          }
          self.parser = loadwsgi.NicerConfigParser("string", defaults=defaults)
          self.parser.optionxform = str  # Don't lower-case keys
          self.parser.readfp(self.contents)
  
  
  def wrap_conf_type(f):
      """
      Wrap a function whos first argument is a paste.deploy style config uri,
      such that you can pass it an un-adorned raw filesystem path (or config
      string) and the config directive (either config:, config_dir:, or
      config_str:) will be added automatically based on the type of entity
      (either a file or directory, or if no such entity on the file system -
      just a string) before passing it through to the paste.deploy function.
      """
      def wrapper(conf_path, *args, **kwargs):
          if os.path.isdir(conf_path):
              conf_type = 'config_dir'
          else:
              conf_type = 'config'
          conf_uri = '%s:%s' % (conf_type, conf_path)
          return f(conf_uri, *args, **kwargs)
      return wrapper
  
  
  appconfig = wrap_conf_type(loadwsgi.appconfig)
  
  
  def monkey_patch_mimetools():
      """
      mimetools.Message defaults content-type to "text/plain"
      This changes it to default to None, so we can detect missing headers.
      """
  
      orig_parsetype = mimetools.Message.parsetype
  
      def parsetype(self):
          if not self.typeheader:
              self.type = None
              self.maintype = None
              self.subtype = None
              self.plisttext = ''
          else:
              orig_parsetype(self)
      parsetype.patched = True
  
      if not getattr(mimetools.Message.parsetype, 'patched', None):
          mimetools.Message.parsetype = parsetype
  
  
  def get_socket(conf):
      """Bind socket to bind ip:port in conf
  
      :param conf: Configuration dict to read settings from
  
      :returns : a socket object as returned from socket.listen or
                 ssl.wrap_socket if conf specifies cert_file
      """
      try:
          bind_port = int(conf['bind_port'])
      except (ValueError, KeyError, TypeError):
          raise ConfigFilePortError()
      bind_addr = (conf.get('bind_ip', '0.0.0.0'), bind_port)
      address_family = [addr[0] for addr in socket.getaddrinfo(
          bind_addr[0], bind_addr[1], socket.AF_UNSPEC, socket.SOCK_STREAM)
          if addr[0] in (socket.AF_INET, socket.AF_INET6)][0]
      sock = None
      bind_timeout = int(conf.get('bind_timeout', 30))
      retry_until = time.time() + bind_timeout
      warn_ssl = False
      while not sock and time.time() < retry_until:
          try:
              sock = listen(bind_addr, backlog=int(conf.get('backlog', 4096)),
                            family=address_family)
              if 'cert_file' in conf:
                  warn_ssl = True
                  sock = ssl.wrap_socket(sock, certfile=conf['cert_file'],
                                         keyfile=conf['key_file'])
          except socket.error as err:
              if err.args[0] != errno.EADDRINUSE:
                  raise
              sleep(0.1)
      if not sock:
          raise Exception(_('Could not bind to %s:%s '
                            'after trying for %s seconds') % (
                                bind_addr[0], bind_addr[1], bind_timeout))
      sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
      # in my experience, sockets can hang around forever without keepalive
      sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
      sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
      if hasattr(socket, 'TCP_KEEPIDLE'):
          sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 600)
      if warn_ssl:
          ssl_warning_message = _('WARNING: SSL should only be enabled for '
                                  'testing purposes. Use external SSL '
                                  'termination for a production deployment.')
          get_logger(conf).warning(ssl_warning_message)
          print(ssl_warning_message)
      return sock
  
  
  class RestrictedGreenPool(GreenPool):
      """
      Works the same as GreenPool, but if the size is specified as one, then the
      spawn_n() method will invoke waitall() before returning to prevent the
      caller from doing any other work (like calling accept()).
      """
      def __init__(self, size=1024):
          super(RestrictedGreenPool, self).__init__(size=size)
          self._rgp_do_wait = (size == 1)
  
      def spawn_n(self, *args, **kwargs):
          super(RestrictedGreenPool, self).spawn_n(*args, **kwargs)
          if self._rgp_do_wait:
              self.waitall()
  
  
  def pipeline_property(name, **kwargs):
      """
      Create a property accessor for the given name.  The property will
      dig through the bound instance on which it was accessed for an
      attribute "app" and check that object for an attribute of the given
      name.  If the "app" object does not have such an attribute, it will
      look for an attribute "app" on THAT object and continue it's search
      from there.  If the named attribute cannot be found accessing the
      property will raise AttributeError.
  
      If a default kwarg is provided you get that instead of the
      AttributeError.  When found the attribute will be cached on instance
      with the property accessor using the same name as the attribute
      prefixed with a leading underscore.
      """
  
      cache_attr_name = '_%s' % name
  
      def getter(self):
          cached_value = getattr(self, cache_attr_name, None)
          if cached_value:
              return cached_value
          app = self  # first app is on self
          while True:
              app = getattr(app, 'app', None)
              if not app:
                  break
              try:
                  value = getattr(app, name)
              except AttributeError:
                  continue
              setattr(self, cache_attr_name, value)
              return value
          if 'default' in kwargs:
              return kwargs['default']
          raise AttributeError('No apps in pipeline have a '
                               '%s attribute' % name)
  
      return property(getter)
  
  
  class PipelineWrapper(object):
      """
      This class provides a number of utility methods for
      modifying the composition of a wsgi pipeline.
      """
  
      def __init__(self, context):
          self.context = context
  
      def __contains__(self, entry_point_name):
          try:
              self.index(entry_point_name)
              return True
          except ValueError:
              return False
  
      def startswith(self, entry_point_name):
          """
          Tests if the pipeline starts with the given entry point name.
  
          :param entry_point_name: entry point of middleware or app (Swift only)
  
          :returns: True if entry_point_name is first in pipeline, False
                    otherwise
          """
          try:
              first_ctx = self.context.filter_contexts[0]
          except IndexError:
              first_ctx = self.context.app_context
          return first_ctx.entry_point_name == entry_point_name
  
      def _format_for_display(self, ctx):
          # Contexts specified by pipeline= have .name set in NamedConfigLoader.
          if hasattr(ctx, 'name'):
              return ctx.name
          # This should not happen: a foreign context. Let's not crash.
          return "<unknown>"
  
      def __str__(self):
          parts = [self._format_for_display(ctx)
                   for ctx in self.context.filter_contexts]
          parts.append(self._format_for_display(self.context.app_context))
          return " ".join(parts)
  
      def create_filter(self, entry_point_name):
          """
          Creates a context for a filter that can subsequently be added
          to a pipeline context.
  
          :param entry_point_name: entry point of the middleware (Swift only)
  
          :returns: a filter context
          """
          spec = 'egg:swift#' + entry_point_name
          ctx = loadwsgi.loadcontext(loadwsgi.FILTER, spec,
                                     global_conf=self.context.global_conf)
          ctx.protocol = 'paste.filter_factory'
          ctx.name = entry_point_name
          return ctx
  
      def index(self, entry_point_name):
          """
          Returns the first index of the given entry point name in the pipeline.
  
          Raises ValueError if the given module is not in the pipeline.
          """
          for i, ctx in enumerate(self.context.filter_contexts):
              if ctx.entry_point_name == entry_point_name:
                  return i
          raise ValueError("%s is not in pipeline" % (entry_point_name,))
  
      def insert_filter(self, ctx, index=0):
          """
          Inserts a filter module into the pipeline context.
  
          :param ctx: the context to be inserted
          :param index: (optional) index at which filter should be
                        inserted in the list of pipeline filters. Default
                        is 0, which means the start of the pipeline.
          """
          self.context.filter_contexts.insert(index, ctx)
  
  
  def loadcontext(object_type, uri, name=None, relative_to=None,
                  global_conf=None):
      if isinstance(uri, loadwsgi.ConfigLoader):
          # bypass loadcontext's uri parsing and loader routing and
          # just directly return the context
          if global_conf:
              uri.update_defaults(global_conf, overwrite=False)
          return uri.get_context(object_type, name, global_conf)
      add_conf_type = wrap_conf_type(lambda x: x)
      return loadwsgi.loadcontext(object_type, add_conf_type(uri), name=name,
                                  relative_to=relative_to,
                                  global_conf=global_conf)
  
  
  def _add_pipeline_properties(app, *names):
      for property_name in names:
          if not hasattr(app, property_name):
              setattr(app.__class__, property_name,
                      pipeline_property(property_name))
  
  
  def loadapp(conf_file, global_conf=None, allow_modify_pipeline=True):
      """
      Loads a context from a config file, and if the context is a pipeline
      then presents the app with the opportunity to modify the pipeline.
      """
      global_conf = global_conf or {}
      ctx = loadcontext(loadwsgi.APP, conf_file, global_conf=global_conf)
      if ctx.object_type.name == 'pipeline':
          # give app the opportunity to modify the pipeline context
          app = ctx.app_context.create()
          func = getattr(app, 'modify_wsgi_pipeline', None)
          if func and allow_modify_pipeline:
              func(PipelineWrapper(ctx))
      return ctx.create()
  
  
  def run_server(conf, logger, sock, global_conf=None):
      # Ensure TZ environment variable exists to avoid stat('/etc/localtime') on
      # some platforms. This locks in reported times to the timezone in which
      # the server first starts running in locations that periodically change
      # timezones.
      os.environ['TZ'] = time.strftime("%z", time.gmtime())
  
      wsgi.HttpProtocol.default_request_version = "HTTP/1.0"
      # Turn off logging requests by the underlying WSGI software.
      wsgi.HttpProtocol.log_request = lambda *a: None
      # Redirect logging other messages by the underlying WSGI software.
      wsgi.HttpProtocol.log_message = \
          lambda s, f, *a: logger.error('ERROR WSGI: ' + f % a)
      wsgi.WRITE_TIMEOUT = int(conf.get('client_timeout') or 60)
  
      eventlet.hubs.use_hub(get_hub())
      # NOTE(sileht):
      #     monkey-patching thread is required by python-keystoneclient;
      #     monkey-patching select is required by oslo.messaging pika driver
      #         if thread is monkey-patched.
      eventlet.patcher.monkey_patch(all=False, socket=True, select=True,
                                    thread=True)
      eventlet_debug = config_true_value(conf.get('eventlet_debug', 'no'))
      eventlet.debug.hub_exceptions(eventlet_debug)
      wsgi_logger = NullLogger()
      if eventlet_debug:
          # let eventlet.wsgi.server log to stderr
          wsgi_logger = None
      # utils.LogAdapter stashes name in server; fallback on unadapted loggers
      if not global_conf:
          if hasattr(logger, 'server'):
              log_name = logger.server
          else:
              log_name = logger.name
          global_conf = {'log_name': log_name}
      app = loadapp(conf['__file__'], global_conf=global_conf)
      max_clients = int(conf.get('max_clients', '1024'))
      pool = RestrictedGreenPool(size=max_clients)
      try:
          # Disable capitalizing headers in Eventlet if possible.  This is
          # necessary for the AWS SDK to work with swift3 middleware.
          argspec = inspect.getargspec(wsgi.server)
          if 'capitalize_response_headers' in argspec.args:
              wsgi.server(sock, app, wsgi_logger, custom_pool=pool,
                          capitalize_response_headers=False)
          else:
              wsgi.server(sock, app, wsgi_logger, custom_pool=pool)
      except socket.error as err:
          if err[0] != errno.EINVAL:
              raise
      pool.waitall()
  
  
  class WorkersStrategy(object):
      """
      WSGI server management strategy object for a single bind port and listen
      socket shared by a configured number of forked-off workers.
  
      Used in :py:func:`run_wsgi`.
  
      :param dict conf: Server configuration dictionary.
      :param logger: The server's :py:class:`~swift.common.utils.LogAdaptor`
                     object.
      """
  
      def __init__(self, conf, logger):
          self.conf = conf
          self.logger = logger
          self.sock = None
          self.children = []
          self.worker_count = config_auto_int_value(conf.get('workers'),
                                                    CPU_COUNT)
  
      def loop_timeout(self):
          """
          We want to keep from busy-waiting, but we also need a non-None value so
          the main loop gets a chance to tell whether it should keep running or
          not (e.g. SIGHUP received).
  
          So we return 0.5.
          """
  
          return 0.5
  
      def bind_ports(self):
          """
          Bind the one listen socket for this strategy and drop privileges
          (since the parent process will never need to bind again).
          """
  
          try:
              self.sock = get_socket(self.conf)
          except ConfigFilePortError:
              msg = 'bind_port wasn\'t properly set in the config file. ' \
                  'It must be explicitly set to a valid port number.'
              return msg
          drop_privileges(self.conf.get('user', 'swift'))
  
      def no_fork_sock(self):
          """
          Return a server listen socket if the server should run in the
          foreground (no fork).
          """
  
          # Useful for profiling [no forks].
          if self.worker_count == 0:
              return self.sock
  
      def new_worker_socks(self):
          """
          Yield a sequence of (socket, opqaue_data) tuples for each server which
          should be forked-off and started.
  
          The opaque_data item for each socket will passed into the
          :py:meth:`log_sock_exit` and :py:meth:`register_worker_start` methods
          where it will be ignored.
          """
  
          while len(self.children) < self.worker_count:
              yield self.sock, None
  
      def post_fork_hook(self):
          """
          Perform any initialization in a forked-off child process prior to
          starting the wsgi server.
          """
  
          pass
  
      def log_sock_exit(self, sock, _unused):
          """
          Log a server's exit.
  
          :param socket sock: The listen socket for the worker just started.
          :param _unused: The socket's opaque_data yielded by
                          :py:meth:`new_worker_socks`.
          """
  
          self.logger.notice('Child %d exiting normally' % os.getpid())
  
      def register_worker_start(self, sock, _unused, pid):
          """
          Called when a new worker is started.
  
          :param socket sock: The listen socket for the worker just started.
          :param _unused: The socket's opaque_data yielded by new_worker_socks().
          :param int pid: The new worker process' PID
          """
  
          self.logger.notice('Started child %s' % pid)
          self.children.append(pid)
  
      def register_worker_exit(self, pid):
          """
          Called when a worker has exited.
  
          :param int pid: The PID of the worker that exited.
          """
  
          self.logger.error('Removing dead child %s' % pid)
          self.children.remove(pid)
  
      def shutdown_sockets(self):
          """
          Shutdown any listen sockets.
          """
  
          greenio.shutdown_safe(self.sock)
          self.sock.close()
  
  
  class PortPidState(object):
      """
      A helper class for :py:class:`ServersPerPortStrategy` to track listen
      sockets and PIDs for each port.
  
      :param int servers_per_port: The configured number of servers per port.
      :param logger: The server's :py:class:`~swift.common.utils.LogAdaptor`
      """
  
      def __init__(self, servers_per_port, logger):
          self.servers_per_port = servers_per_port
          self.logger = logger
          self.sock_data_by_port = {}
  
      def sock_for_port(self, port):
          """
          :param int port: The port whose socket is desired.
          :returns: The bound listen socket for the given port.
          """
  
          return self.sock_data_by_port[port]['sock']
  
      def port_for_sock(self, sock):
          """
          :param socket sock: A tracked bound listen socket
          :returns: The port the socket is bound to.
          """
  
          for port, sock_data in self.sock_data_by_port.items():
              if sock_data['sock'] == sock:
                  return port
  
      def _pid_to_port_and_index(self, pid):
          for port, sock_data in self.sock_data_by_port.items():
              for server_idx, a_pid in enumerate(sock_data['pids']):
                  if pid == a_pid:
                      return port, server_idx
  
      def port_index_pairs(self):
          """
          Returns current (port, server index) pairs.
  
          :returns: A set of (port, server_idx) tuples for currently-tracked
              ports, sockets, and PIDs.
          """
  
          current_port_index_pairs = set()
          for port, pid_state in self.sock_data_by_port.items():
              current_port_index_pairs |= set(
                  (port, i)
                  for i, pid in enumerate(pid_state['pids'])
                  if pid is not None)
          return current_port_index_pairs
  
      def track_port(self, port, sock):
          """
          Start tracking servers for the given port and listen socket.
  
          :param int port: The port to start tracking
          :param socket sock: The bound listen socket for the port.
          """
  
          self.sock_data_by_port[port] = {
              'sock': sock,
              'pids': [None] * self.servers_per_port,
          }
  
      def not_tracking(self, port):
          """
          Return True if the specified port is not being tracked.
  
          :param int port: A port to check.
          """
  
          return port not in self.sock_data_by_port
  
      def all_socks(self):
          """
          Yield all current listen sockets.
          """
  
          for orphan_data in self.sock_data_by_port.itervalues():
              yield orphan_data['sock']
  
      def forget_port(self, port):
          """
          Idempotently forget a port, closing the listen socket at most once.
          """
  
          orphan_data = self.sock_data_by_port.pop(port, None)
          if orphan_data:
              greenio.shutdown_safe(orphan_data['sock'])
              orphan_data['sock'].close()
              self.logger.notice('Closing unnecessary sock for port %d', port)
  
      def add_pid(self, port, index, pid):
          self.sock_data_by_port[port]['pids'][index] = pid
  
      def forget_pid(self, pid):
          """
          Idempotently forget a PID.  It's okay if the PID is no longer in our
          data structure (it could have been removed by the "orphan port" removal
          in :py:meth:`new_worker_socks`).
  
          :param int pid: The PID which exited.
          """
  
          port_server_idx = self._pid_to_port_and_index(pid)
          if port_server_idx is None:
              # This method can lose a race with the "orphan port" removal, when
              # a ring reload no longer contains a port.  So it's okay if we were
              # unable to find a (port, server_idx) pair.
              return
          dead_port, server_idx = port_server_idx
          self.logger.error('Removing dead child %d (PID: %s) for port %s',
                            server_idx, pid, dead_port)
          self.sock_data_by_port[dead_port]['pids'][server_idx] = None
  
  
  class ServersPerPortStrategy(object):
      """
      WSGI server management strategy object for an object-server with one listen
      port per unique local port in the storage policy rings.  The
      `servers_per_port` integer config setting determines how many workers are
      run per port.
  
      Used in :py:func:`run_wsgi`.
  
      :param dict conf: Server configuration dictionary.
      :param logger: The server's :py:class:`~swift.common.utils.LogAdaptor`
                     object.
      :param int servers_per_port: The number of workers to run per port.
      """
  
      def __init__(self, conf, logger, servers_per_port):
          self.conf = conf
          self.logger = logger
          self.servers_per_port = servers_per_port
          self.swift_dir = conf.get('swift_dir', '/etc/swift')
          self.ring_check_interval = int(conf.get('ring_check_interval', 15))
          self.port_pid_state = PortPidState(servers_per_port, logger)
  
          bind_ip = conf.get('bind_ip', '0.0.0.0')
          self.cache = BindPortsCache(self.swift_dir, bind_ip)
  
      def _reload_bind_ports(self):
          self.bind_ports = self.cache.all_bind_ports_for_node()
  
      def _bind_port(self, port):
          new_conf = self.conf.copy()
          new_conf['bind_port'] = port
          sock = get_socket(new_conf)
          self.port_pid_state.track_port(port, sock)
  
      def loop_timeout(self):
          """
          Return timeout before checking for reloaded rings.
  
          :returns: The time to wait for a child to exit before checking for
                    reloaded rings (new ports).
          """
  
          return self.ring_check_interval
  
      def bind_ports(self):
          """
          Bind one listen socket per unique local storage policy ring port.  Then
          do all the work of drop_privileges except the actual dropping of
          privileges (each forked-off worker will do that post-fork in
          :py:meth:`post_fork_hook`).
          """
  
          self._reload_bind_ports()
          for port in self.bind_ports:
              self._bind_port(port)
  
          # The workers strategy drops privileges here, which we obviously cannot
          # do if we want to support binding to low ports.  But we do want some
          # of the actions that drop_privileges did.
          try:
              os.setsid()
          except OSError:
              pass
          # In case you need to rmdir where you started the daemon:
          os.chdir('/')
          # Ensure files are created with the correct privileges:
          os.umask(0o22)
  
      def no_fork_sock(self):
          """
          This strategy does not support running in the foreground.
          """
  
          pass
  
      def new_worker_socks(self):
          """
          Yield a sequence of (socket, server_idx) tuples for each server which
          should be forked-off and started.
  
          Any sockets for "orphaned" ports no longer in any ring will be closed
          (causing their associated workers to gracefully exit) after all new
          sockets have been yielded.
  
          The server_idx item for each socket will passed into the
          :py:meth:`log_sock_exit` and :py:meth:`register_worker_start` methods.
          """
  
          self._reload_bind_ports()
          desired_port_index_pairs = set(
              (p, i) for p in self.bind_ports
              for i in range(self.servers_per_port))
  
          current_port_index_pairs = self.port_pid_state.port_index_pairs()
  
          if desired_port_index_pairs != current_port_index_pairs:
              # Orphan ports are ports which had object-server processes running,
              # but which no longer appear in the ring.  We'll kill them after we
              # start missing workers.
              orphan_port_index_pairs = current_port_index_pairs - \
                  desired_port_index_pairs
  
              # Fork off worker(s) for every port who's supposed to have
              # worker(s) but doesn't
              missing_port_index_pairs = desired_port_index_pairs - \
                  current_port_index_pairs
              for port, server_idx in sorted(missing_port_index_pairs):
                  if self.port_pid_state.not_tracking(port):
                      try:
                          self._bind_port(port)
                      except Exception as e:
                          self.logger.critical('Unable to bind to port %d: %s',
                                               port, e)
                          continue
                  yield self.port_pid_state.sock_for_port(port), server_idx
  
              for orphan_pair in orphan_port_index_pairs:
                  # For any port in orphan_port_index_pairs, it is guaranteed
                  # that there should be no listen socket for that port, so we
                  # can close and forget them.
                  self.port_pid_state.forget_port(orphan_pair[0])
  
      def post_fork_hook(self):
          """
          Called in each child process, prior to starting the actual wsgi server,
          to drop privileges.
          """
  
          drop_privileges(self.conf.get('user', 'swift'), call_setsid=False)
  
      def log_sock_exit(self, sock, server_idx):
          """
          Log a server's exit.
          """
  
          port = self.port_pid_state.port_for_sock(sock)
          self.logger.notice('Child %d (PID %d, port %d) exiting normally',
                             server_idx, os.getpid(), port)
  
      def register_worker_start(self, sock, server_idx, pid):
          """
          Called when a new worker is started.
  
          :param socket sock: The listen socket for the worker just started.
          :param server_idx: The socket's server_idx as yielded by
                             :py:meth:`new_worker_socks`.
          :param int pid: The new worker process' PID
          """
          port = self.port_pid_state.port_for_sock(sock)
          self.logger.notice('Started child %d (PID %d) for port %d',
                             server_idx, pid, port)
          self.port_pid_state.add_pid(port, server_idx, pid)
  
      def register_worker_exit(self, pid):
          """
          Called when a worker has exited.
  
          :param int pid: The PID of the worker that exited.
          """
  
          self.port_pid_state.forget_pid(pid)
  
      def shutdown_sockets(self):
          """
          Shutdown any listen sockets.
          """
  
          for sock in self.port_pid_state.all_socks():
              greenio.shutdown_safe(sock)
              sock.close()
  
  
  def run_wsgi(conf_path, app_section, *args, **kwargs):
      """
      Runs the server according to some strategy.  The default strategy runs a
      specified number of workers in pre-fork model.  The object-server (only)
      may use a servers-per-port strategy if its config has a servers_per_port
      setting with a value greater than zero.
  
      :param conf_path: Path to paste.deploy style configuration file/directory
      :param app_section: App name from conf file to load config from
      :returns: 0 if successful, nonzero otherwise
      """
      # Load configuration, Set logger and Load request processor
      try:
          (conf, logger, log_name) = \
              _initrp(conf_path, app_section, *args, **kwargs)
      except ConfigFileError as e:
          print(e)
          return 1
  
      servers_per_port = int(conf.get('servers_per_port', '0') or 0)
  
      # NOTE: for now servers_per_port is object-server-only; future work could
      # be done to test and allow it to be used for account and container
      # servers, but that has not been done yet.
      if servers_per_port and app_section == 'object-server':
          strategy = ServersPerPortStrategy(
              conf, logger, servers_per_port=servers_per_port)
      else:
          strategy = WorkersStrategy(conf, logger)
  
      error_msg = strategy.bind_ports()
      if error_msg:
          logger.error(error_msg)
          print(error_msg)
          return 1
  
      # Ensure the configuration and application can be loaded before proceeding.
      global_conf = {'log_name': log_name}
      if 'global_conf_callback' in kwargs:
          kwargs['global_conf_callback'](conf, global_conf)
      loadapp(conf_path, global_conf=global_conf)
  
      # set utils.FALLOCATE_RESERVE if desired
      reserve = int(conf.get('fallocate_reserve', 0))
      if reserve > 0:
          utils.FALLOCATE_RESERVE = reserve
      # redirect errors to logger and close stdio
      capture_stdio(logger)
  
      no_fork_sock = strategy.no_fork_sock()
      if no_fork_sock:
          run_server(conf, logger, no_fork_sock, global_conf=global_conf)
          return 0
  
      def kill_children(*args):
          """Kills the entire process group."""
          logger.error('SIGTERM received')
          signal.signal(signal.SIGTERM, signal.SIG_IGN)
          running[0] = False
          os.killpg(0, signal.SIGTERM)
  
      def hup(*args):
          """Shuts down the server, but allows running requests to complete"""
          logger.error('SIGHUP received')
          signal.signal(signal.SIGHUP, signal.SIG_IGN)
          running[0] = False
  
      running = [True]
      signal.signal(signal.SIGTERM, kill_children)
      signal.signal(signal.SIGHUP, hup)
  
      while running[0]:
          for sock, sock_info in strategy.new_worker_socks():
              pid = os.fork()
              if pid == 0:
                  signal.signal(signal.SIGHUP, signal.SIG_DFL)
                  signal.signal(signal.SIGTERM, signal.SIG_DFL)
                  strategy.post_fork_hook()
                  run_server(conf, logger, sock)
                  strategy.log_sock_exit(sock, sock_info)
                  return 0
              else:
                  strategy.register_worker_start(sock, sock_info, pid)
  
          # The strategy may need to pay attention to something in addition to
          # child process exits (like new ports showing up in a ring).
          #
          # NOTE: a timeout value of None will just instantiate the Timeout
          # object and not actually schedule it, which is equivalent to no
          # timeout for the green_os.wait().
          loop_timeout = strategy.loop_timeout()
  
          with Timeout(loop_timeout, exception=False):
              try:
                  pid, status = green_os.wait()
                  if os.WIFEXITED(status) or os.WIFSIGNALED(status):
                      strategy.register_worker_exit(pid)
              except OSError as err:
                  if err.errno not in (errno.EINTR, errno.ECHILD):
                      raise
              except KeyboardInterrupt:
                  logger.notice('User quit')
                  running[0] = False
                  break
  
      strategy.shutdown_sockets()
      logger.notice('Exited')
      return 0
  
  
  class ConfigFileError(Exception):
      pass
  
  
  class ConfigFilePortError(ConfigFileError):
      pass
  
  
  def _initrp(conf_path, app_section, *args, **kwargs):
      try:
          conf = appconfig(conf_path, name=app_section)
      except Exception as e:
          raise ConfigFileError("Error trying to load config from %s: %s" %
                                (conf_path, e))
  
      validate_configuration()
  
      # pre-configure logger
      log_name = conf.get('log_name', app_section)
      if 'logger' in kwargs:
          logger = kwargs.pop('logger')
      else:
          logger = get_logger(conf, log_name,
                              log_to_console=kwargs.pop('verbose', False),
                              log_route='wsgi')
  
      # disable fallocate if desired
      if config_true_value(conf.get('disable_fallocate', 'no')):
          disable_fallocate()
  
      monkey_patch_mimetools()
      return (conf, logger, log_name)
  
  
  def init_request_processor(conf_path, app_section, *args, **kwargs):
      """
      Loads common settings from conf
      Sets the logger
      Loads the request processor
  
      :param conf_path: Path to paste.deploy style configuration file/directory
      :param app_section: App name from conf file to load config from
      :returns: the loaded application entry point
      :raises ConfigFileError: Exception is raised for config file error
      """
      (conf, logger, log_name) = _initrp(conf_path, app_section, *args, **kwargs)
      app = loadapp(conf_path, global_conf={'log_name': log_name})
      return (app, conf, logger, log_name)
  
  
  class WSGIContext(object):
      """
      This class provides a means to provide context (scope) for a middleware
      filter to have access to the wsgi start_response results like the request
      status and headers.
      """
      def __init__(self, wsgi_app):
          self.app = wsgi_app
  
      def _start_response(self, status, headers, exc_info=None):
          """
          Saves response info without sending it to the remote client.
          Uses the same semantics as the usual WSGI start_response.
          """
          self._response_status = status
          self._response_headers = headers
          self._response_exc_info = exc_info
  
      def _app_call(self, env):
          """
          Ensures start_response has been called before returning.
          """
          self._response_status = None
          self._response_headers = None
          self._response_exc_info = None
          resp = self.app(env, self._start_response)
          # if start_response has been called, just return the iter
          if self._response_status is not None:
              return resp
          resp = iter(resp)
          try:
              first_chunk = next(resp)
          except StopIteration:
              return iter([])
          else:  # We got a first_chunk
              return CloseableChain([first_chunk], resp)
  
      def _get_status_int(self):
          """
          Returns the HTTP status int from the last called self._start_response
          result.
          """
          return int(self._response_status.split(' ', 1)[0])
  
      def _response_header_value(self, key):
          "Returns str of value for given header key or None"
          for h_key, val in self._response_headers:
              if h_key.lower() == key.lower():
                  return val
          return None
  
  
  def make_env(env, method=None, path=None, agent='Swift', query_string=None,
               swift_source=None):
      """
      Returns a new fresh WSGI environment.
  
      :param env: The WSGI environment to base the new environment on.
      :param method: The new REQUEST_METHOD or None to use the
                     original.
      :param path: The new path_info or none to use the original. path
                   should NOT be quoted. When building a url, a Webob
                   Request (in accordance with wsgi spec) will quote
                   env['PATH_INFO'].  url += quote(environ['PATH_INFO'])
      :param query_string: The new query_string or none to use the original.
                           When building a url, a Webob Request will append
                           the query string directly to the url.
                           url += '?' + env['QUERY_STRING']
      :param agent: The HTTP user agent to use; default 'Swift'. You
                    can put %(orig)s in the agent to have it replaced
                    with the original env's HTTP_USER_AGENT, such as
                    '%(orig)s StaticWeb'. You also set agent to None to
                    use the original env's HTTP_USER_AGENT or '' to
                    have no HTTP_USER_AGENT.
      :param swift_source: Used to mark the request as originating out of
                           middleware. Will be logged in proxy logs.
      :returns: Fresh WSGI environment.
      """
      newenv = {}
      for name in ('HTTP_USER_AGENT', 'HTTP_HOST', 'PATH_INFO',
                   'QUERY_STRING', 'REMOTE_USER', 'REQUEST_METHOD',
                   'SCRIPT_NAME', 'SERVER_NAME', 'SERVER_PORT',
                   'HTTP_ORIGIN', 'HTTP_ACCESS_CONTROL_REQUEST_METHOD',
                   'SERVER_PROTOCOL', 'swift.cache', 'swift.source',
                   'swift.trans_id', 'swift.authorize_override',
                   'swift.authorize', 'HTTP_X_USER_ID', 'HTTP_X_PROJECT_ID',
                   'HTTP_REFERER'):
          if name in env:
              newenv[name] = env[name]
      if method:
          newenv['REQUEST_METHOD'] = method
      if path:
          newenv['PATH_INFO'] = path
          newenv['SCRIPT_NAME'] = ''
      if query_string is not None:
          newenv['QUERY_STRING'] = query_string
      if agent:
          newenv['HTTP_USER_AGENT'] = (
              agent % {'orig': env.get('HTTP_USER_AGENT', '')}).strip()
      elif agent == '' and 'HTTP_USER_AGENT' in newenv:
          del newenv['HTTP_USER_AGENT']
      if swift_source:
          newenv['swift.source'] = swift_source
      newenv['wsgi.input'] = BytesIO()
      if 'SCRIPT_NAME' not in newenv:
          newenv['SCRIPT_NAME'] = ''
      return newenv
  
  
  def make_subrequest(env, method=None, path=None, body=None, headers=None,
                      agent='Swift', swift_source=None, make_env=make_env):
      """
      Makes a new swob.Request based on the current env but with the
      parameters specified.
  
      :param env: The WSGI environment to base the new request on.
      :param method: HTTP method of new request; default is from
                     the original env.
      :param path: HTTP path of new request; default is from the
                   original env. path should be compatible with what you
                   would send to Request.blank. path should be quoted and it
                   can include a query string. for example:
                   '/a%20space?unicode_str%E8%AA%9E=y%20es'
      :param body: HTTP body of new request; empty by default.
      :param headers: Extra HTTP headers of new request; None by
                      default.
      :param agent: The HTTP user agent to use; default 'Swift'. You
                    can put %(orig)s in the agent to have it replaced
                    with the original env's HTTP_USER_AGENT, such as
                    '%(orig)s StaticWeb'. You also set agent to None to
                    use the original env's HTTP_USER_AGENT or '' to
                    have no HTTP_USER_AGENT.
      :param swift_source: Used to mark the request as originating out of
                           middleware. Will be logged in proxy logs.
      :param make_env: make_subrequest calls this make_env to help build the
          swob.Request.
      :returns: Fresh swob.Request object.
      """
      query_string = None
      path = path or ''
      if path and '?' in path:
          path, query_string = path.split('?', 1)
      newenv = make_env(env, method, path=unquote(path), agent=agent,
                        query_string=query_string, swift_source=swift_source)
      if not headers:
          headers = {}
      if body:
          return Request.blank(path, environ=newenv, body=body, headers=headers)
      else:
          return Request.blank(path, environ=newenv, headers=headers)
  
  
  def make_pre_authed_env(env, method=None, path=None, agent='Swift',
                          query_string=None, swift_source=None):
      """Same as :py:func:`make_env` but with preauthorization."""
      newenv = make_env(
          env, method=method, path=path, agent=agent, query_string=query_string,
          swift_source=swift_source)
      newenv['swift.authorize'] = lambda req: None
      newenv['swift.authorize_override'] = True
      newenv['REMOTE_USER'] = '.wsgi.pre_authed'
      return newenv
  
  
  def make_pre_authed_request(env, method=None, path=None, body=None,
                              headers=None, agent='Swift', swift_source=None):
      """Same as :py:func:`make_subrequest` but with preauthorization."""
      return make_subrequest(
          env, method=method, path=path, body=body, headers=headers, agent=agent,
          swift_source=swift_source, make_env=make_pre_authed_env)
  