Stitch in a current version of zdaemon; several

bugfixes have piled up since this was last done.

src/zdaemon/DEPENDENCIES.cfg

+ZConfig

src/zdaemon/SETUP.cfg

+script  zdctl.py
+script  zdrun.py

src/zdaemon/__init__.py

+##############################################################################
+#
+# Copyright (c) 2001, 2002 Zope Corporation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+"""zdaemon -- a package to manage a daemon application."""

src/zdaemon/component.xml

+<component>
+
+  <!-- Note on logging configuration:
+
+       This schema component expects to use a section type named
+       "eventlog"; this type needs to be provided by some other
+       component that the top-level schema needs to import.
+
+       The import is not performed here to allow applications to
+       load the type from different components.
+    -->
+
+  <sectiontype name="runner">
+
+    <description>
+      This section describes the options for zdctl.py and zdrun.py.
+      The only required option is "program".  Many other options have
+      no default value specified in the schema; in some cases, the
+      program calculates a dynamic default, in others, the feature
+      associated with the option is disabled.
+
+      For those options that also have corresponding command-line
+      options, the command line option (short and long form) are given
+      here too.
+    </description>
+
+    <section name="*" type="ZConfig.logger.log"
+             attribute="eventlog"
+             required="no">
+      <description>
+        Log configuration for zdctl.py and zdrun.py.  These
+        applications will normally use the eventlog section at the top
+        level of the configuration, but will use this eventlog section
+        if it exists.
+
+        (This is done so that the combined schema for the runner and
+        the controlled application will write to the same logs by
+        default, but a separation of logs can be achieved if desired.)
+      </description>
+    </section>
+
+    <key name="program" datatype="string-list"
+         required="yes">
+      <description>
+        Command-line option: -p or --program (zdctl.py only).
+
+        This option gives the command used to start the subprocess
+        managed by zdrun.py.  This is currently a simple list of
+        whitespace-delimited words. The first word is the program
+        file, subsequent words are its command line arguments.  If the
+        program file contains no slashes, it is searched using $PATH.
+        (XXX There is no way to to include whitespace in the program
+        file or an argument, and under certain circumstances other
+        shell metacharacters are also a problem, e.g. the "foreground"
+        command of zdctl.py.)
+
+        NOTE: zdrun.py doesn't use this option; it uses its positional
+        arguments.  Rather, zdctl.py uses this option to determine the
+        positional argument with which to invoke zdrun.py.  (XXX This
+        could be better.)
+      </description>
+    </key>
+
+    <key name="python" datatype="existing-path"
+         required="no">
+      <description>
+        Path to the Python interpreter.  Used by zdctl.py to start the
+        zdrun.py process.  Defaults to sys.executable.
+      </description>
+    </key>
+
+    <key name="zdrun" datatype="existing-path"
+         required="no">
+      <description>
+        Path to the zdrun.py script.  Used by zdctl.py to start the
+        zdrun.py process.  Defaults to a file named "zdrun.py" in the
+        same directory as zdctl.py.
+      </description>
+    </key>
+
+    <key name="socket-name" datatype="existing-dirpath"
+         required="no"
+         default="zdsock">
+      <description>
+        Command-line option: -s or --socket-name.
+
+        The pathname of the Unix domain socket used for communication
+        between zdctl.py and zdrun.py.  The default is relative to the
+        current directory in which zdctl.py and zdrun.py are started.
+        You want to specify an absolute pathname here.
+      </description>
+    </key>
+
+    <key name="daemon" datatype="boolean"
+         required="no"
+         default="false">
+      <description>
+        Command-line option: -d or --daemon.
+
+        If this option is true, zdrun.py runs in the background as a
+        true daemon.  It forks a child process which becomes the
+        subprocess manager, while the parent exits (making the shell
+        that started it believe it is done).  The child process also
+        does the following:
+
+        - if the directory option is set, change into that directory
+
+        - redirect stdin, stdout and stderr to /dev/null
+
+        - call setsid() so it becomes a session leader
+
+        - call umask() with specified value
+      </description>
+    </key>
+
+    <key name="directory" datatype="existing-directory"
+         required="no">
+      <description>
+        Command-line option: -z or --directory.
+
+        If the daemon option is true, this option can specify a
+        directory into which zdrun.py changes as part of the
+        "daemonizing".  If the daemon option is false, this option is
+        ignored.
+      </description>
+    </key>
+
+    <key name="backoff-limit" datatype="integer"
+         required="no"
+         default="10">
+      <description>
+        Command-line option: -b or --backoff-limit.
+
+        When the subprocess crashes, zdrun.py inserts a one-second
+        delay before it restarts it.  When the subprocess crashes
+        again right away, the delay is incremented by one second, and
+        so on.  What happens when the delay has reached the value of
+        backoff-limit (in seconds), depends on the value of the
+        forever option.  If forever is false, zdrun.py gives up at
+        this point, and exits.  An always-crashing subprocess will
+        have been restarted exactly backoff-limit times in this case.
+        If forever is true, zdrun.py continues to attempt to restart
+        the process, keeping the delay at backoff-limit seconds.
+
+        If the subprocess stays up for more than backoff-limit
+        seconds, the delay is reset to 1 second.
+      </description>
+    </key>
+
+    <key name="forever" datatype="boolean"
+         required="no"
+         default="false">
+      <description>
+        Command-line option: -f or --forever.
+
+        If this option is true, zdrun.py will keep restarting a
+        crashing subprocess forever.  If it is false, it will give up
+        after backoff-limit crashes in a row.  See the description of
+        backoff-limit for details.
+      </description>
+    </key>
+
+    <key name="exit-codes" datatype="zdaemon.zdoptions.list_of_ints"
+         required="no"
+         default="0,2">
+      <description>
+        Command-line option: -x or --exit-codes.
+
+        If the subprocess exits with an exit status that is equal to
+        one of the integers in this list, zdrun.py will not restart
+        it.  The default list requires some explanation.  Exit status
+        0 is considered a willful successful exit; the ZEO and Zope
+        server processes use this exit status when they want to stop
+        without being restarted.  (Including in response to a
+        SIGTERM.)  Exit status 2 is typically issued for command line
+        syntax errors; in this case, restarting the program will not
+        help!
+
+        NOTE: this mechanism overrides the backoff-limit and forever
+        options; i.e. even if forever is true, a subprocess exit
+        status code in this list makes zdrun.py give up.  To disable
+        this, change the value to an empty list.
+      </description>
+    </key>
+
+    <key name="user" datatype="string"
+         required="no">
+      <description>
+        Command-line option: -u or --user.
+
+        When zdrun.py is started by root, this option specifies the
+        user as who the the zdrun.py process (and hence the daemon
+        subprocess) will run.  This can be a user name or a numeric
+        user id.  Both the user and the group are set from the
+        corresponding password entry, using setuid() and setgid().
+        This is done before zdrun.py does anything else besides
+        parsing its command line arguments.
+
+        NOTE: when zdrun.py is not started by root, specifying this
+        option is an error.  (XXX This may be a mistake.)
+
+        XXX The zdrun.py event log file may be opened *before*
+        setuid() is called.  Is this good or bad?
+      </description>
+    </key>
+
+    <key name="umask" datatype="zdaemon.zdoptions.octal_type"
+         required="no"
+         default="022">
+      <description>
+        Command-line option: -m or --umask.
+
+        When daemon mode is used, this option specifies the octal umask
+        of the subprocess.
+      </description>
+    </key>
+
+    <key name="hang-around" datatype="boolean"
+         required="no"
+         default="false">
+      <description>
+        If this option is true, the zdrun.py process will remain even
+        when the daemon subprocess is stopped.  In this case, zdctl.py
+        will restart zdrun.py as necessary.  If this option is false,
+        zdrun.py will exit when the daemon subprocess is stopped
+        (unless zdrun.py intends to restart it).
+      </description>
+    </key>
+
+    <key name="default-to-interactive" datatype="boolean"
+         required="no"
+         default="true">
+      <description>
+        If this option is true, zdctl.py enters interactive mode
+        when it is invoked without a positional command argument.  If
+        it is false, you must use the -i or --interactive command line
+        option to zdctl.py to enter interactive mode.
+      </description>
+    </key>
+
+    <key name="logfile" datatype="existing-dirpath"
+         required="no">
+      <description>
+        This option specifies a log file that is the default target of
+        the "logtail" zdctl.py command.
+
+        NOTE: This is NOT the log file to which zdrun.py writes its
+        logging messages!  That log file is specified by the
+        &lt;eventlog&gt; section.
+      </description>
+    </key>
+
+    <key name="transcript" datatype="existing-dirpath"
+         required="no">
+      <description>
+        The name of a file in which a transcript of all output from
+        the command being run will be written to when daemonized.
+
+        If not specified, output from the command will be discarded.
+
+        This only takes effect when the "daemon" option is enabled.
+      </description>
+    </key>
+
+    <key name="prompt" datatype="string"
+         required="no">
+       <description>
+         The prompt shown by the controller program.  The default must
+         be provided by the application.
+       </description>
+    </key>
+
+  </sectiontype>
+
+</component>

src/zdaemon/sample.conf

+# Sample config file for zdctl.py and zdrun.py (which share a schema).
+
+<runner>
+  # Harmless example
+  program       sleep 100
+  # Repeat the defaults
+  backoff-limit 10
+  daemon	True
+  forever	True
+  socket-name	zdsock
+  exit-codes	0,2
+  # user has no default
+  umask		022
+  directory	.
+  default-to-interactive True
+  hang-around   False
+</runner>
+
+<eventlog>
+  level info
+  <logfile>
+    path /tmp/zdrun.log
+  </logfile>
+</eventlog>

src/zdaemon/schema.xml

+<schema>
+
+  <description>
+    This schema describes various options that control zdctl.py and
+    zdrun.py.  zdrun.py is the "daemon process manager"; it runs a
+    subprocess in the background and restarts it when it crashes.
+    zdctl.py is the user interface to zdrun.py; it can tell zdrun.py
+    to start, stop or restart the subprocess, send it a signal, etc.
+
+    There are two sections: &lt;runner&gt; defines options unique
+    zdctl.py and zdrun.py, and &lt;eventlog&gt; defines a standard
+    event logging section used by zdrun.py.
+
+    More information about zdctl.py and zdrun.py can be found in the
+    file Doc/zdctl.txt.  This all is specific to Unix/Linux.
+  </description>
+
+  <import package="ZConfig.components.logger"/>
+
+  <import package="zdaemon"/>
+
+  <section name="*" type="runner" attribute="runner" required="yes" />
+
+  <section name="*" type="eventlog" attribute="eventlog" required="no" />
+
+</schema>

src/zdaemon/tests/__init__.py

+# This file is needed to make this a package.

src/zdaemon/tests/donothing.sh

+#!/bin/sh
+while [ "1" -ne "2" ]; do
+   sleep 10
+done
+
+    

src/zdaemon/tests/nokill.py

+#! /usr/bin/env python
+
+import signal
+
+signal.signal(signal.SIGTERM, signal.SIG_IGN)
+
+while 1:
+    signal.pause()

src/zdaemon/tests/parent.py

+import time
+import os
+import sys
+
+def main():
+    # dummy zdctl startup of zdrun
+    shutup()
+    file = os.path.normpath(os.path.abspath(sys.argv[0]))
+    dir = os.path.dirname(file)
+    zctldir = os.path.dirname(dir)
+    zdrun = os.path.join(zctldir, 'zdrun.py')
+    args = [sys.executable, zdrun]
+    args += ['-d', '-b', '10', '-s', os.path.join(dir, 'testsock'),
+             '-x', '0,2', '-z', dir, os.path.join(dir, 'donothing.sh')]
+    flag = os.P_NOWAIT
+    #cmd = ' '.join([sys.executable] + args)
+    #print cmd
+    os.spawnvp(flag, args[0], args)
+    while 1:
+        # wait to be signaled
+        time.sleep(1)
+
+def shutup():
+    os.close(0)
+    sys.stdin = sys.__stdin__ = open("/dev/null")
+    os.close(1)
+    sys.stdout = sys.__stdout__ = open("/dev/null", "w")
+    os.close(2)
+    sys.stderr = sys.__stderr__ = open("/dev/null", "w")
+
+if __name__ == '__main__':
+    main()

src/zdaemon/tests/testzdoptions.py

+##############################################################################
+#
+# Copyright (c) 2001, 2002 Zope Corporation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE
+#
+##############################################################################
+
+"""Test suite for zdaemon.zdoptions."""
+
+import os
+import sys
+import tempfile
+import unittest
+from StringIO import StringIO
+
+import ZConfig
+import zdaemon
+from zdaemon.zdoptions import ZDOptions
+
+class ZDOptionsTestBase(unittest.TestCase):
+
+    OptionsClass = ZDOptions
+
+    def save_streams(self):
+        self.save_stdout = sys.stdout
+        self.save_stderr = sys.stderr
+        sys.stdout = self.stdout = StringIO()
+        sys.stderr = self.stderr = StringIO()
+
+    def restore_streams(self):
+        sys.stdout = self.save_stdout
+        sys.stderr = self.save_stderr
+
+    def check_exit_code(self, options, args):
+        save_sys_stderr = sys.stderr
+        try:
+            sys.stderr = StringIO()
+            try:
+                options.realize(args)
+            except SystemExit, err:
+                self.assertEqual(err.code, 2)
+            else:
+                self.fail("SystemExit expected")
+        finally:
+            sys.stderr = save_sys_stderr
+
+
+class TestZDOptions(ZDOptionsTestBase):
+
+    input_args = ["arg1", "arg2"]
+    output_opts = []
+    output_args = ["arg1", "arg2"]
+
+    def test_basic(self):
+        progname = "progname"
+        doc = "doc"
+        options = self.OptionsClass()
+        options.positional_args_allowed = 1
+        options.schemadir = os.path.dirname(zdaemon.__file__)
+        options.realize(self.input_args, progname, doc)
+        self.assertEqual(options.progname, "progname")
+        self.assertEqual(options.doc, "doc")
+        self.assertEqual(options.options, self.output_opts)
+        self.assertEqual(options.args, self.output_args)
+
+    def test_configure(self):
+        configfile = os.path.join(os.path.dirname(zdaemon.__file__),
+                                  "sample.conf")
+        for arg in "-C", "--c", "--configure":
+            options = self.OptionsClass()
+            options.realize([arg, configfile])
+            self.assertEqual(options.configfile, configfile)
+
+    def test_help(self):
+        for arg in "-h", "--h", "--help":
+            options = self.OptionsClass()
+            try:
+                self.save_streams()
+                try:
+                    options.realize([arg])
+                finally:
+                    self.restore_streams()
+            except SystemExit, err:
+                self.assertEqual(err.code, 0)
+            else:
+                self.fail("%s didn't call sys.exit()" % repr(arg))
+
+    def test_unrecognized(self):
+        # Check that we get an error for an unrecognized option
+        self.check_exit_code(self.OptionsClass(), ["-/"])
+
+
+class TestBasicFunctionality(TestZDOptions):
+
+    def test_no_positional_args(self):
+        # Check that we get an error for positional args when they
+        # haven't been enabled.
+        self.check_exit_code(self.OptionsClass(), ["A"])
+
+    def test_positional_args(self):
+        options = self.OptionsClass()
+        options.positional_args_allowed = 1
+        options.realize(["A", "B"])
+        self.assertEqual(options.args, ["A", "B"])
+
+    def test_positional_args_empty(self):
+        options = self.OptionsClass()
+        options.positional_args_allowed = 1
+        options.realize([])
+        self.assertEqual(options.args, [])
+
+    def test_positional_args_unknown_option(self):
+        # Make sure an unknown option doesn't become a positional arg.
+        options = self.OptionsClass()
+        options.positional_args_allowed = 1
+        self.check_exit_code(options, ["-o", "A", "B"])
+
+    def test_conflicting_flags(self):
+        # Check that we get an error for flags which compete over the
+        # same option setting.
+        options = self.OptionsClass()
+        options.add("setting", None, "a", flag=1)
+        options.add("setting", None, "b", flag=2)
+        self.check_exit_code(options, ["-a", "-b"])
+
+    def test_handler_simple(self):
+        # Test that a handler is called; use one that doesn't return None.
+        options = self.OptionsClass()
+        options.add("setting", None, "a:", handler=int)
+        options.realize(["-a2"])
+        self.assertEqual(options.setting, 2)
+
+    def test_handler_side_effect(self):
+        # Test that a handler is called and conflicts are not
+        # signalled when it returns None.
+        options = self.OptionsClass()
+        L = []
+        options.add("setting", None, "a:", "append=", handler=L.append)
+        options.realize(["-a2", "--append", "3"])
+        self.assert_(options.setting is None)
+        self.assertEqual(L, ["2", "3"])
+
+    def test_handler_with_bad_value(self):
+        options = self.OptionsClass()
+        options.add("setting", None, "a:", handler=int)
+        self.check_exit_code(options, ["-afoo"])
+
+    def test_raise_getopt_errors(self):
+        options = self.OptionsClass()
+        # note that we do not add "a" to the list of options;
+        # if raise_getopt_errors was true, this test would error
+        options.realize(["-afoo"], raise_getopt_errs=False)
+        # check_exit_code realizes the options with raise_getopt_errs=True
+        self.check_exit_code(options, ['-afoo'])
+
+
+class EnvironmentOptions(ZDOptionsTestBase):
+
+    saved_schema = None
+
+    class OptionsClass(ZDOptions):
+        def __init__(self):
+            ZDOptions.__init__(self)
+            self.add("opt", "opt", "o:", "opt=",
+                     default=42, handler=int, env="OPT")
+
+        def load_schema(self):
+            # Doing this here avoids needing a separate file for the schema:
+            if self.schema is None:
+                if EnvironmentOptions.saved_schema is None:
+                    schema = ZConfig.loadSchemaFile(StringIO("""\
+                        <schema>
+                          <key name='opt' datatype='integer' default='12'/>
+                        </schema>
+                        """))
+                    EnvironmentOptions.saved_schema = schema
+                self.schema = EnvironmentOptions.saved_schema
+
+        def load_configfile(self):
+            if getattr(self, "configtext", None):
+                self.configfile = tempfile.mktemp()
+                f = open(self.configfile, 'w')
+                f.write(self.configtext)
+                f.close()
+                try:
+                    ZDOptions.load_configfile(self)
+                finally:
+                    os.unlink(self.configfile)
+            else:
+                ZDOptions.load_configfile(self)
+
+    # Save and restore the environment around each test:
+
+    def setUp(self):
+        self._oldenv = os.environ
+        env = {}
+        for k, v in os.environ.items():
+            env[k] = v
+        os.environ = env
+
+    def tearDown(self):
+        os.environ = self._oldenv
+
+    def create_with_config(self, text):
+        options = self.OptionsClass()
+        zdpkgdir = os.path.dirname(os.path.abspath(zdaemon.__file__))
+        options.schemadir = os.path.join(zdpkgdir, 'tests')
+        options.schemafile = "envtest.xml"
+        # configfile must be set for ZDOptions to use ZConfig:
+        if text:
+            options.configfile = "not used"
+            options.configtext = text
+        return options
+
+
+class TestZDOptionsEnvironment(EnvironmentOptions):
+
+    def test_with_environment(self):
+        os.environ["OPT"] = "2"
+        self.check_from_command_line()
+        options = self.OptionsClass()
+        options.realize([])
+        self.assertEqual(options.opt, 2)
+
+    def test_without_environment(self):
+        self.check_from_command_line()
+        options = self.OptionsClass()
+        options.realize([])
+        self.assertEqual(options.opt, 42)
+
+    def check_from_command_line(self):
+        for args in (["-o1"], ["--opt", "1"]):
+            options = self.OptionsClass()
+            options.realize(args)
+            self.assertEqual(options.opt, 1)
+
+    def test_with_bad_environment(self):
+        os.environ["OPT"] = "Spooge!"
+        # make sure the bad value is ignored if the command-line is used:
+        self.check_from_command_line()
+        options = self.OptionsClass()
+        try:
+            self.save_streams()
+            try:
+                options.realize([])
+            finally:
+                self.restore_streams()
+        except SystemExit, e:
+            self.assertEqual(e.code, 2)
+        else:
+            self.fail("expected SystemExit")
+
+    def test_environment_overrides_configfile(self):
+        options = self.create_with_config("opt 3")
+        options.realize([])
+        self.assertEqual(options.opt, 3)
+
+        os.environ["OPT"] = "2"
+        options = self.create_with_config("opt 3")
+        options.realize([])
+        self.assertEqual(options.opt, 2)
+
+
+class TestCommandLineOverrides(EnvironmentOptions):
+
+    def test_simple_override(self):
+        options = self.create_with_config("# empty config")
+        options.realize(["-X", "opt=-2"])
+        self.assertEqual(options.opt, -2)
+
+    def test_error_propogation(self):
+        self.check_exit_code(self.create_with_config("# empty"),
+                             ["-Xopt=1", "-Xopt=2"])
+        self.check_exit_code(self.create_with_config("# empty"),
+                             ["-Xunknown=foo"])
+
+
+def test_suite():
+    suite = unittest.TestSuite()
+    for cls in [TestBasicFunctionality,
+                TestZDOptionsEnvironment,
+                TestCommandLineOverrides]:
+        suite.addTest(unittest.makeSuite(cls))
+    return suite
+
+if __name__ == "__main__":
+    unittest.main(defaultTest='test_suite')

src/zdaemon/tests/testzdrun.py

+"""Test suite for zdrun.py."""
+
+import os
+import sys
+import time
+import signal
+import tempfile
+import unittest
+import socket
+
+from StringIO import StringIO
+
+import ZConfig
+
+from zdaemon import zdrun, zdctl
+
+
+class ConfiguredOptions:
+    """Options class that loads configuration from a specified string.
+
+    This always loads from the string, regardless of any -C option
+    that may be given.
+    """
+
+    def set_configuration(self, configuration):
+        self.__configuration = configuration
+        self.configfile = "<preloaded string>"
+
+    def load_configfile(self):
+        sio = StringIO(self.__configuration)
+        cfg = ZConfig.loadConfigFile(self.schema, sio, self.zconfig_options)
+        self.configroot, self.confighandlers = cfg
+
+
+class ConfiguredZDRunOptions(ConfiguredOptions, zdrun.ZDRunOptions):
+
+    def __init__(self, configuration):
+        zdrun.ZDRunOptions.__init__(self)
+        self.set_configuration(configuration)
+
+
+class ZDaemonTests(unittest.TestCase):
+
+    python = os.path.abspath(sys.executable)
+    assert os.path.exists(python)
+    here = os.path.abspath(os.path.dirname(__file__))
+    assert os.path.isdir(here)
+    nokill = os.path.join(here, "nokill.py")
+    assert os.path.exists(nokill)
+    parent = os.path.dirname(here)
+    zdrun = os.path.join(parent, "zdrun.py")
+    assert os.path.exists(zdrun)
+
+    ppath = os.pathsep.join(sys.path)
+
+    def setUp(self):
+        self.zdsock = tempfile.mktemp()
+        self.new_stdout = StringIO()
+        self.save_stdout = sys.stdout
+        sys.stdout = self.new_stdout
+        self.expect = ""
+
+    def tearDown(self):
+        sys.stdout = self.save_stdout
+        for sig in (signal.SIGTERM,
+                    signal.SIGHUP,
+                    signal.SIGINT,
+                    signal.SIGCHLD):
+            signal.signal(sig, signal.SIG_DFL)
+        try:
+            os.unlink(self.zdsock)
+        except os.error:
+            pass
+        output = self.new_stdout.getvalue()
+        self.assertEqual(self.expect, output)
+
+    def quoteargs(self, args):
+        for i in range(len(args)):
+            if " " in args[i]:
+                args[i] = '"%s"' % args[i]
+        return " ".join(args)
+
+    def rundaemon(self, args):
+        # Add quotes, in case some pathname contains spaces (e.g. Mac OS X)
+        args = self.quoteargs(args)
+        cmd = ('PYTHONPATH="%s" "%s" "%s" -d -s "%s" %s' %
+               (self.ppath, self.python, self.zdrun, self.zdsock, args))
+        os.system(cmd)
+        # When the daemon crashes, the following may help debug it:
+        ##os.system("PYTHONPATH=%s %s %s -s %s %s &" %
+        ##    (self.ppath, self.python, self.zdrun, self.zdsock, args))
+
+    def _run(self, args, cmdclass=None):
+        if type(args) is type(""):
+            args = args.split()
+        try:
+            zdctl.main(["-s", self.zdsock] + args, cmdclass=cmdclass)
+        except SystemExit:
+            pass
+
+    def testCmdclassOverride(self):
+        class MyCmd(zdctl.ZDCmd):
+            def do_sproing(self, rest):
+                print rest
+        self._run("-p echo sproing expected", cmdclass=MyCmd)
+        self.expect = "expected\n"
+
+    def testSystem(self):
+        self.rundaemon(["echo", "-n"])
+        self.expect = ""
+
+##     def testInvoke(self):
+##         self._run("echo -n")
+##         self.expect = ""
+
+##     def testControl(self):
+##         self.rundaemon(["sleep", "1000"])
+##         time.sleep(1)
+##         self._run("stop")
+##         time.sleep(1)
+##         self._run("exit")
+##         self.expect = "Sent SIGTERM\nExiting now\n"
+
+##     def testStop(self):
+##         self.rundaemon([self.python, self.nokill])
+##         time.sleep(1)
+##         self._run("stop")
+##         time.sleep(1)
+##         self._run("exit")
+##         self.expect = "Sent SIGTERM\nSent SIGTERM; will exit later\n"
+
+    def testHelp(self):
+        self._run("-h")
+        import __main__
+        self.expect = __main__.__doc__
+
+    def testOptionsSysArgv(self):
+        # Check that options are parsed from sys.argv by default
+        options = zdrun.ZDRunOptions()
+        save_sys_argv = sys.argv
+        try:
+            sys.argv = ["A", "B", "C"]
+            options.realize()
+        finally:
+            sys.argv = save_sys_argv
+        self.assertEqual(options.options, [])
+        self.assertEqual(options.args, ["B", "C"])
+
+    def testOptionsBasic(self):
+        # Check basic option parsing
+        options = zdrun.ZDRunOptions()
+        options.realize(["B", "C"], "foo")
+        self.assertEqual(options.options, [])
+        self.assertEqual(options.args, ["B", "C"])
+        self.assertEqual(options.progname, "foo")
+
+    def testOptionsHelp(self):
+        # Check that -h behaves properly
+        options = zdrun.ZDRunOptions()
+        try:
+            options.realize(["-h"], doc=zdrun.__doc__)
+        except SystemExit, err:
+            self.failIf(err.code)
+        else:
+            self.fail("SystemExit expected")
+        self.expect = zdrun.__doc__
+
+    def testSubprocessBasic(self):
+        # Check basic subprocess management: spawn, kill, wait
+        options = zdrun.ZDRunOptions()
+        options.realize(["sleep", "100"])
+        proc = zdrun.Subprocess(options)
+        self.assertEqual(proc.pid, 0)
+        pid = proc.spawn()
+        self.assertEqual(proc.pid, pid)
+        msg = proc.kill(signal.SIGTERM)
+        self.assertEqual(msg, None)
+        wpid, wsts = os.waitpid(pid, 0)
+        self.assertEqual(wpid, pid)
+        self.assertEqual(os.WIFSIGNALED(wsts), 1)
+        self.assertEqual(os.WTERMSIG(wsts), signal.SIGTERM)
+        proc.setstatus(wsts)
+        self.assertEqual(proc.pid, 0)
+
+    def testEventlogOverride(self):
+        # Make sure runner.eventlog is used if it exists
+        options = ConfiguredZDRunOptions("""\
+            <runner>
+              program /bin/true
+              <eventlog>
+                level 42
+              </eventlog>
+            </runner>
+
+            <eventlog>
+              level 35
+            </eventlog>
+            """)
+        options.realize(["/bin/true"])
+        self.assertEqual(options.config_logger.level, 42)
+
+    def testEventlogWithoutOverride(self):
+        # Make sure eventlog is used if runner.eventlog doesn't exist
+        options = ConfiguredZDRunOptions("""\
+            <runner>
+              program /bin/true
+            </runner>
+
+            <eventlog>
+              level 35
+            </eventlog>
+            """)
+        options.realize(["/bin/true"])
+        self.assertEqual(options.config_logger.level, 35)
+
+    def testRunIgnoresParentSignals(self):
+        # Spawn a process which will in turn spawn a zdrun process.
+        # We make sure that the zdrun process is still running even if
+        # its parent process receives an interrupt signal (it should
+        # not be passed to zdrun).
+        zdrun_socket = os.path.join(self.here, 'testsock')
+        zdctlpid = os.spawnvp(
+            os.P_NOWAIT,
+            sys.executable,
+            [sys.executable, os.path.join(self.here, 'parent.py')]
+            )
+        # Wait for it to start, but no longer than a minute.
+        deadline = time.time() + 60
+        is_started = False
+        while time.time() < deadline:
+             response = send_action('status\n', zdrun_socket)
+             if response is None:
+                 time.sleep(0.05)
+             else:
+                 is_started = True
+                 break
+        self.assert_(is_started, "spawned process failed to start in a minute")
+        # Kill it, and wait a little to ensure it's dead.
+        os.kill(zdctlpid, signal.SIGINT)
+        time.sleep(0.25)
+        # Make sure the child is still responsive.
+        response = send_action('status\n', zdrun_socket)
+        self.assert_(response is not None and '\n' in response)
+        # Kill the process.
+        send_action('exit\n', zdrun_socket)
+
+    def testUmask(self):
+        path = tempfile.mktemp()
+        # With umask 666, we should create a file that we aren't able
+        # to write.  If access says no, assume that umask works.
+        try:
+            touch_cmd = "/bin/touch"
+            if not os.path.exists(touch_cmd):
+                touch_cmd = "/usr/bin/touch" # Mac OS X
+            self.rundaemon(["-m", "666", touch_cmd, path])
+            for i in range(5):
+                if not os.path.exists(path):
+                    time.sleep(0.1)
+            self.assert_(os.path.exists(path))
+            self.assert_(not os.access(path, os.W_OK))
+        finally:
+            if os.path.exists(path):
+                os.remove(path)
+
+def send_action(action, sockname):
+    """Send an action to the zdrun server and return the response.
+
+    Return None if the server is not up or any other error happened.
+    """
+    sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+    try:
+        sock.connect(sockname)
+        sock.send(action + "\n")
+        sock.shutdown(1) # We're not writing any more
+        response = ""
+        while 1:
+            data = sock.recv(1000)
+            if not data:
+                break
+            response += data
+        sock.close()
+        return response
+    except socket.error, msg:
+        return None
+
+def test_suite():
+    suite = unittest.TestSuite()
+    if os.name == "posix":
+        suite.addTest(unittest.makeSuite(ZDaemonTests))
+    return suite
+
+if __name__ == '__main__':
+    __file__ = sys.argv[0]
+    unittest.main(defaultTest='test_suite')

src/zdaemon/zdctl.py

+#!python
+##############################################################################
+#
+# Copyright (c) 2001, 2002 Zope Corporation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+"""zdctl -- control an application run by zdaemon.
+
+Usage: python zdctl.py [-C URL] [-S schema.xml] [-h] [-p PROGRAM]
+       [zdrun-options] [action [arguments]]
+
+Options:
+-C/--configure URL -- configuration file or URL
+-S/--schema XML Schema -- XML schema for configuration file
+-h/--help -- print usage message and exit
+-b/--backoff-limit SECONDS -- set backoff limit to SECONDS (default 10)
+-d/--daemon -- run as a proper daemon; fork a subprocess, close files etc.
+-f/--forever -- run forever (by default, exit when backoff limit is exceeded)
+-h/--help -- print this usage message and exit
+-i/--interactive -- start an interactive shell after executing commands
+-l/--logfile -- log file to be read by logtail command
+-p/--program PROGRAM -- the program to run
+-s/--socket-name SOCKET -- Unix socket name for client (default "zdsock")
+-u/--user USER -- run as this user (or numeric uid)
+-m/--umask UMASK -- use this umask for daemon subprocess (default is 022)
+-x/--exit-codes LIST -- list of fatal exit codes (default "0,2")
+-z/--directory DIRECTORY -- directory to chdir to when using -d (default off)
+action [arguments] -- see below
+
+Actions are commands like "start", "stop" and "status".  If -i is
+specified or no action is specified on the command line, a "shell"
+interpreting actions typed interactively is started (unless the
+configuration option default_to_interactive is set to false).  Use the
+action "help" to find out about available actions.
+"""
+
+import os
+import re
+import cmd
+import sys
+import time
+import signal
+import socket
+import stat
+
+if __name__ == "__main__":
+    # Add the parent of the script directory to the module search path
+    # (but only when the script is run from inside the zdaemon package)
+    from os.path import dirname, basename, abspath, normpath
+    scriptdir = dirname(normpath(abspath(sys.argv[0])))
+    if basename(scriptdir).lower() == "zdaemon":
+        sys.path.append(dirname(scriptdir))
+
+from zdaemon.zdoptions import RunnerOptions
+
+
+def string_list(arg):
+    return arg.split()
+
+
+class ZDCtlOptions(RunnerOptions):
+
+    positional_args_allowed = 1
+
+    def __init__(self):
+        RunnerOptions.__init__(self)
+        self.add("schemafile", short="S:", long="schema=",
+                 default="schema.xml",
+                 handler=self.set_schemafile)
+        self.add("interactive", None, "i", "interactive", flag=1)
+        self.add("default_to_interactive", "runner.default_to_interactive",
+                 default=1)
+        self.add("program", "runner.program", "p:", "program=",
+                 handler=string_list,
+                 required="no program specified; use -p or -C")
+        self.add("logfile", "runner.logfile", "l:", "logfile=")
+        self.add("python", "runner.python")
+        self.add("zdrun", "runner.zdrun")
+        programname = os.path.basename(sys.argv[0])
+        base, ext = os.path.splitext(programname)
+        if ext == ".py":
+            programname = base
+        self.add("prompt", "runner.prompt", default=(programname + ">"))
+
+    def realize(self, *args, **kwds):
+        RunnerOptions.realize(self, *args, **kwds)
+
+        # Maybe the config file requires -i or positional args
+        if not self.args and not self.interactive:
+            if not self.default_to_interactive:
+                self.usage("either -i or an action argument is required")
+            self.interactive = 1
+
+        # Where's python?
+        if not self.python:
+            self.python = sys.executable
+
+        # Where's zdrun?
+        if not self.zdrun:
+            if __name__ == "__main__":
+                file = sys.argv[0]
+            else:
+                file = __file__
+            file = os.path.normpath(os.path.abspath(file))
+            dir = os.path.dirname(file)
+            self.zdrun = os.path.join(dir, "zdrun.py")
+
+    def set_schemafile(self, file):
+        self.schemafile = file
+
+
+
+class ZDCmd(cmd.Cmd):
+
+    def __init__(self, options):
+        self.options = options
+        self.prompt = self.options.prompt + ' '
+        cmd.Cmd.__init__(self)
+        self.get_status()
+        if self.zd_status:
+            m = re.search("(?m)^args=(.*)$", self.zd_status)
+            if m:
+                s = m.group(1)
+                args = eval(s, {"__builtins__": {}})
+                if args != self.options.program:
+                    print "WARNING! zdrun is managing a different program!"
+                    print "our program   =", self.options.program
+                    print "daemon's args =", args
+
+    def emptyline(self):
+        # We don't want a blank line to repeat the last command.
+        # Showing status is a nice alternative.
+        self.do_status()
+
+    def send_action(self, action):
+        """Send an action to the zdrun server and return the response.
+
+        Return None if the server is not up or any other error happened.
+        """
+        sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+        try:
+            sock.connect(self.options.sockname)
+            sock.send(action + "\n")
+            sock.shutdown(1) # We're not writing any more
+            response = ""
+            while 1:
+                data = sock.recv(1000)
+                if not data:
+                    break
+                response += data
+            sock.close()
+            return response
+        except socket.error, msg:
+            return None
+
+    def get_status(self):
+        self.zd_up = 0
+        self.zd_pid = 0
+        self.zd_status = None
+        resp = self.send_action("status")
+        if not resp:
+            return
+        m = re.search("(?m)^application=(\d+)$", resp)
+        if not m:
+            return
+        self.zd_up = 1
+        self.zd_pid = int(m.group(1))
+        self.zd_status = resp
+
+    def awhile(self, cond, msg):
+        try:
+            self.get_status()
+            while not cond():
+                sys.stdout.write(". ")
+                sys.stdout.flush()
+                time.sleep(1)
+                self.get_status()
+        except KeyboardInterrupt:
+            print "^C"
+        else:
+            print msg % self.__dict__
+
+    def help_help(self):
+        print "help          -- Print a list of available actions."
+        print "help <action> -- Print help for <action>."
+
+    def do_EOF(self, arg):
+        print
+        return 1
+
+    def help_EOF(self):
+        print "To quit, type ^D or use the quit command."
+
+    def do_start(self, arg):
+        self.get_status()
+        if not self.zd_up:
+            args = [
+                self.options.python,
+                self.options.zdrun,
+                ]
+            args += self._get_override("-S", "schemafile")
+            args += self._get_override("-C", "configfile")
+            args += self._get_override("-b", "backofflimit")
+            args += self._get_override("-d", "daemon", flag=1)
+            args += self._get_override("-f", "forever", flag=1)
+            args += self._get_override("-s", "sockname")
+            args += self._get_override("-u", "user")
+            args += self._get_override("-m", "umask")
+            args += self._get_override(
+                "-x", "exitcodes", ",".join(map(str, self.options.exitcodes)))
+            args += self._get_override("-z", "directory")
+            args.extend(self.options.program)
+            if self.options.daemon:
+                flag = os.P_NOWAIT
+            else:
+                flag = os.P_WAIT
+            os.spawnvp(flag, args[0], args)
+        elif not self.zd_pid:
+            self.send_action("start")
+        else:
+            print "daemon process already running; pid=%d" % self.zd_pid
+            return
+        self.awhile(lambda: self.zd_pid,
+                    "daemon process started, pid=%(zd_pid)d")
+
+    def _get_override(self, opt, name, svalue=None, flag=0):
+        value = getattr(self.options, name)
+        if value is None:
+            return []
+        configroot = self.options.configroot
+        if configroot is not None:
+            for n, cn in self.options.names_list:
+                if n == name and cn:
+                    v = configroot
+                    for p in cn.split("."):
+                        v = getattr(v, p, None)
+                        if v is None:
+                            break
+                    if v == value: # We didn't override anything
+                        return []
+                    break
+        if flag:
+            if value:
+                args = [opt]
+            else:
+                args = []
+        else:
+            if svalue is None:
+                svalue = str(value)
+            args = [opt, svalue]
+        return args
+
+    def help_start(self):
+        print "start -- Start the daemon process."
+        print "         If it is already running, do nothing."
+
+    def do_stop(self, arg):
+        self.get_status()
+        if not self.zd_up:
+            print "daemon manager not running"
+        elif not self.zd_pid:
+            print "daemon process not running"
+        else:
+            self.send_action("stop")
+            self.awhile(lambda: not self.zd_pid, "daemon process stopped")
+
+    def help_stop(self):
+        print "stop -- Stop the daemon process."
+        print "        If it is not running, do nothing."
+
+    def do_restart(self, arg):
+        self.get_status()
+        pid = self.zd_pid
+        if not pid:
+            self.do_start(arg)
+        else:
+            self.send_action("restart")
+            self.awhile(lambda: self.zd_pid not in (0, pid),
+                        "daemon process restarted, pid=%(zd_pid)d")
+
+    def help_restart(self):
+        print "restart -- Stop and then start the daemon process."
+
+    def do_kill(self, arg):
+        if not arg:
+            sig = signal.SIGTERM
+        else:
+            try:
+                sig = int(arg)
+            except: # int() can raise any number of exceptions
+                print "invalid signal number", `arg`
+                return
+        self.get_status()
+        if not self.zd_pid:
+            print "daemon process not running"
+            return
+        print "kill(%d, %d)" % (self.zd_pid, sig)
+        try:
+            os.kill(self.zd_pid, sig)
+        except os.error, msg:
+            print "Error:", msg
+        else:
+            print "signal %d sent to process %d" % (sig, self.zd_pid)
+
+    def help_kill(self):
+        print "kill [sig] -- Send signal sig to the daemon process."
+        print "              The default signal is SIGTERM."
+
+    def do_wait(self, arg):
+        self.awhile(lambda: not self.zd_pid, "daemon process stopped")
+        self.do_status()
+
+    def help_wait(self):
+        print "wait -- Wait for the daemon process to exit."
+
+    def do_status(self, arg=""):
+        if arg not in ["", "-l"]:
+            print "status argument must be absent or -l"
+            return
+        self.get_status()
+        if not self.zd_up:
+            print "daemon manager not running"
+        elif not self.zd_pid:
+            print "daemon manager running; daemon process not running"
+        else:
+            print "program running; pid=%d" % self.zd_pid
+        if arg == "-l" and self.zd_status:
+            print self.zd_status
+
+    def help_status(self):
+        print "status [-l] -- Print status for the daemon process."
+        print "               With -l, show raw status output as well."
+
+    def do_show(self, arg):
+        if not arg:
+            arg = "options"
+        try:
+            method = getattr(self, "show_" + arg)
+        except AttributeError, err:
+            print err
+            self.help_show()
+            return
+        method()
+
+    def show_options(self):
+        print "zdctl/zdrun options:"
+        print "schemafile:  ", repr(self.options.schemafile)
+        print "configfile:  ", repr(self.options.configfile)
+        print "interactive: ", repr(self.options.interactive)
+        print "default_to_interactive:",
+        print                  repr(self.options.default_to_interactive)
+        print "zdrun:       ", repr(self.options.zdrun)
+        print "python:      ", repr(self.options.python)
+        print "program:     ", repr(self.options.program)
+        print "backofflimit:", repr(self.options.backofflimit)
+        print "daemon:      ", repr(self.options.daemon)
+        print "forever:     ", repr(self.options.forever)
+        print "sockname:    ", repr(self.options.sockname)
+        print "exitcodes:   ", repr(self.options.exitcodes)
+        print "user:        ", repr(self.options.user)
+        print "umask:       ", oct(self.options.umask)
+        print "directory:   ", repr(self.options.directory)
+        print "logfile:     ", repr(self.options.logfile)
+        print "hang_around: ", repr(self.options.hang_around)
+
+    def show_python(self):
+        print "Python info:"
+        version = sys.version.replace("\n", "\n              ")
+        print "Version:     ", version
+        print "Platform:    ", sys.platform
+        print "Executable:  ", repr(sys.executable)
+        print "Arguments:   ", repr(sys.argv)
+        print "Directory:   ", repr(os.getcwd())
+        print "Path:"
+        for dir in sys.path:
+            print "    " + repr(dir)
+
+    def show_all(self):
+        self.show_options()
+        print
+        self.show_python()
+
+    def help_show(self):
+        print "show options -- show zdctl options"
+        print "show python -- show Python version and details"
+        print "show all -- show all of the above"
+
+    def complete_show(self, text, *ignored):
+        options = ["options", "python", "all"]
+        return [x for x in options if x.startswith(text)]
+
+    def do_logreopen(self, arg):
+        self.do_kill(str(signal.SIGUSR2))
+
+    def help_logreopen(self):
+        print "logreopen -- Send a SIGUSR2 signal to the daemon process."
+        print "             This is designed to reopen the log file."
+
+    def do_logtail(self, arg):
+        if not arg:
+            arg = self.options.logfile
+            if not arg:
+                print "No default log file specified; use logtail <logfile>"
+                return
+        try:
+            helper = TailHelper(arg)
+            helper.tailf()
+        except KeyboardInterrupt:
+            print
+        except IOError, msg:
+            print msg
+        except OSError, msg:
+            print msg
+
+    def help_logtail(self):
+        print "logtail [logfile] -- Run tail -f on the given logfile."
+        print "                     A default file may exist."
+        print "                     Hit ^C to exit this mode."
+
+    def do_shell(self, arg):
+        if not arg:
+            arg = os.getenv("SHELL") or "/bin/sh"
+        try:
+            os.system(arg)
+        except KeyboardInterrupt:
+            print
+
+    def help_shell(self):
+        print "shell [command] -- Execute a shell command."
+        print "                   Without a command, start an interactive sh."
+        print "An alias for this command is ! [command]"
+
+    def do_reload(self, arg):
+        if arg:
+            args = arg.split()
+            if self.options.configfile:
+                args = ["-C", self.options.configfile] + args
+        else:
+            args = None
+        options = ZDCtlOptions()
+        options.positional_args_allowed = 0
+        try:
+            options.realize(args)
+        except SystemExit:
+            print "Configuration not reloaded"
+        else:
+            self.options = options
+            if self.options.configfile:
+                print "Configuration reloaded from", self.options.configfile
+            else:
+                print "Configuration reloaded without a config file"
+
+    def help_reload(self):
+        print "reload [options] -- Reload the configuration."
+        print "    Without options, this reparses the command line."
+        print "    With options, this substitutes 'options' for the"
+        print "    command line, except that if no -C option is given,"
+        print "    the last configuration file is used."
+
+    def do_foreground(self, arg):
+        self.get_status()
+        pid = self.zd_pid
+        if pid:
+            print "To run the program in the foreground, please stop it first."
+            return
+        program = " ".join(self.options.program)
+        print program
+        try:
+            os.system(program)
+        except KeyboardInterrupt:
+            print
+
+    def do_fg(self, arg):
+        self.do_foreground(arg)
+
+    def help_foreground(self):
+        print "foreground -- Run the program in the forground."
+        print "fg -- an alias for foreground."
+
+    def help_fg(self):
+        self.help_foreground()
+
+    def do_quit(self, arg):
+        self.get_status()
+        if not self.zd_up:
+            print "daemon manager not running"
+        elif not self.zd_pid:
+            print "daemon process not running; stopping daemon manager"
+            self.send_action("exit")
+            self.awhile(lambda: not self.zd_up, "daemon manager stopped")
+        else:
+            print "daemon process and daemon manager still running"
+        return 1
+
+    def help_quit(self):
+        print "quit -- Exit the zdctl shell."
+        print "        If the daemon process is not running,"
+        print "        stop the daemon manager."
+
+
+class TailHelper:
+
+    MAX_BUFFSIZE = 1024
+
+    def __init__(self, fname):
+        self.f = open(fname, 'r')
+
+    def tailf(self):
+        sz, lines = self.tail(10)
+        for line in lines:
+            sys.stdout.write(line)
+            sys.stdout.flush()
+        while 1:
+            newsz = self.fsize()
+            bytes_added = newsz - sz
+            if bytes_added < 0:
+                sz = 0
+                print "==> File truncated <=="
+                bytes_added = newsz
+            if bytes_added > 0:
+                self.f.seek(-bytes_added, 2)
+                bytes = self.f.read(bytes_added)
+                sys.stdout.write(bytes)
+                sys.stdout.flush()
+                sz = newsz
+            time.sleep(1)
+
+    def tail(self, max=10):
+        self.f.seek(0, 2)
+        pos = sz = self.f.tell()
+
+        lines = []
+        bytes = []
+        num_bytes = 0
+
+        while 1:
+            if pos == 0:
+                break
+            self.f.seek(pos)
+            byte = self.f.read(1)
+            if byte == '\n':
+                if len(lines) == max:
+                    break
+                bytes.reverse()
+                line = ''.join(bytes)
+                line and lines.append(line)
+                bytes = []
+            bytes.append(byte)
+            num_bytes = num_bytes + 1
+            if num_bytes > self.MAX_BUFFSIZE:
+                break
+            pos = pos - 1
+        lines.reverse()
+        return sz, lines
+
+    def fsize(self):
+        return os.fstat(self.f.fileno())[stat.ST_SIZE]
+
+def main(args=None, options=None, cmdclass=ZDCmd):
+    if options is None:
+        options = ZDCtlOptions()
+    options.realize(args)
+    c = cmdclass(options)
+    if options.args:
+        c.onecmd(" ".join(options.args))
+    if options.interactive:
+        try:
+            import readline
+        except ImportError:
+            pass
+        print "program:", " ".join(options.program)
+        c.do_status()
+        c.cmdloop()
+
+if __name__ == "__main__":
+    main()

src/zdaemon/zdoptions.py

+##############################################################################
+#
+# Copyright (c) 2003 Zope Corporation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+
+"""Option processing for zdaemon and related code."""
+
+import os
+import sys
+import getopt
+
+import ZConfig
+
+class ZDOptions:
+
+    doc = None
+    progname = None
+    configfile = None
+    schemadir = None
+    schemafile = "schema.xml"
+    schema = None
+    confighandlers = None
+    configroot = None
+
+    # Class variable to control automatic processing of an <eventlog>
+    # section.  This should be the (possibly dotted) name of something
+    # accessible from configroot, typically "eventlog".
+    logsectionname = None
+    config_logger = None # The configured event logger, if any
+
+    # Class variable deciding whether positional arguments are allowed.
+    # If you want positional arguments, set this to 1 in your subclass.
+    positional_args_allowed = 0
+
+    def __init__(self):
+        self.names_list = []
+        self.short_options = []
+        self.long_options = []
+        self.options_map = {}
+        self.default_map = {}
+        self.required_map = {}
+        self.environ_map = {}
+        self.zconfig_options = []
+        self.add(None, None, "h", "help", self.help)
+        self.add("configfile", None, "C:", "configure=")
+        self.add(None, None, "X:", handler=self.zconfig_options.append)
+
+    def help(self, dummy):
+        """Print a long help message (self.doc) to stdout and exit(0).
+
+        Occurrences of "%s" in self.doc are replaced by self.progname.
+        """
+        doc = self.doc
+        if doc.find("%s") > 0:
+            doc = doc.replace("%s", self.progname)
+        print doc,
+        sys.exit(0)
+
+    def usage(self, msg):
+        """Print a brief error message to stderr and exit(2)."""
+        sys.stderr.write("Error: %s\n" % str(msg))
+        sys.stderr.write("For help, use %s -h\n" % self.progname)
+        sys.exit(2)
+
+    def remove(self,
+               name=None,               # attribute name on self
+               confname=None,           # name in ZConfig (may be dotted)
+               short=None,              # short option name
+               long=None,               # long option name
+               ):
+        """Remove all traces of name, confname, short and/or long."""
+        if name:
+            for n, cn in self.names_list[:]:
+                if n == name:
+                    self.names_list.remove((n, cn))
+            if self.default_map.has_key(name):
+                del self.default_map[name]
+            if self.required_map.has_key(name):
+                del self.required_map[name]
+        if confname:
+            for n, cn in self.names_list[:]:
+                if cn == confname:
+                    self.names_list.remove((n, cn))
+        if short:
+            key = "-" + short[0]
+            if self.options_map.has_key(key):
+                del self.options_map[key]
+        if long:
+            key = "--" + long
+            if key[-1] == "=":
+                key = key[:-1]
+            if self.options_map.has_key(key):
+                del self.options_map[key]
+
+    def add(self,
+            name=None,                  # attribute name on self
+            confname=None,              # name in ZConfig (may be dotted)
+            short=None,                 # short option name
+            long=None,                  # long option name
+            handler=None,               # handler (defaults to string)
+            default=None,               # default value
+            required=None,              # message if not provided
+            flag=None,                  # if not None, flag value
+            env=None,                   # if not None, environment variable
+            ):
+        """Add information about a configuration option.
+
+        This can take several forms:
+
+        add(name, confname)
+            Configuration option 'confname' maps to attribute 'name'
+        add(name, None, short, long)
+            Command line option '-short' or '--long' maps to 'name'
+        add(None, None, short, long, handler)
+            Command line option calls handler
+        add(name, None, short, long, handler)
+            Assign handler return value to attribute 'name'
+
+        In addition, one of the following keyword arguments may be given:
+
+        default=...  -- if not None, the default value
+        required=... -- if nonempty, an error message if no value provided
+        flag=...     -- if not None, flag value for command line option
+        env=...      -- if not None, name of environment variable that
+                        overrides the configuration file or default
+        """
+
+        if flag is not None:
+            if handler is not None:
+                raise ValueError, "use at most one of flag= and handler="
+            if not long and not short:
+                raise ValueError, "flag= requires a command line flag"
+            if short and short.endswith(":"):
+                raise ValueError, "flag= requires a command line flag"
+            if long and long.endswith("="):
+                raise ValueError, "flag= requires a command line flag"
+            handler = lambda arg, flag=flag: flag
+
+        if short and long:
+            if short.endswith(":") != long.endswith("="):
+                raise ValueError, "inconsistent short/long options: %r %r" % (
+                    short, long)
+
+        if short:
+            if short[0] == "-":
+                raise ValueError, "short option should not start with '-'"
+            key, rest = short[:1], short[1:]
+            if rest not in ("", ":"):
+                raise ValueError, "short option should be 'x' or 'x:'"
+            key = "-" + key
+            if self.options_map.has_key(key):
+                raise ValueError, "duplicate short option key '%s'" % key
+            self.options_map[key] = (name, handler)
+            self.short_options.append(short)
+
+        if long:
+            if long[0] == "-":
+                raise ValueError, "long option should not start with '-'"
+            key = long
+            if key[-1] == "=":
+                key = key[:-1]
+            key = "--" + key
+            if self.options_map.has_key(key):
+                raise ValueError, "duplicate long option key '%s'" % key
+            self.options_map[key] = (name, handler)
+            self.long_options.append(long)
+
+        if env:
+            self.environ_map[env] = (name, handler)
+
+        if name:
+            if not hasattr(self, name):
+                setattr(self, name, None)
+            self.names_list.append((name, confname))
+            if default is not None:
+                self.default_map[name] = default
+            if required:
+                self.required_map[name] = required
+
+    def realize(self, args=None, progname=None, doc=None,
+                raise_getopt_errs=True):
+        """Realize a configuration.
+
+        Optional arguments:
+
+        args     -- the command line arguments, less the program name
+                    (default is sys.argv[1:])
+
+        progname -- the program name (default is sys.argv[0])
+
+        doc      -- usage message (default is __main__.__doc__)
+        """
+
+         # Provide dynamic default method arguments
+        if args is None:
+            try:
+                args = sys.argv[1:]
+            except AttributeError:
+                args = ()
+
+        if progname is None:
+            try:
+                progname = sys.argv[0]
+            except (AttributeError, IndexError):
+                progname = 'zope'
+
+        if doc is None:
+            import __main__
+            doc = __main__.__doc__
+        self.progname = progname
+        self.doc = doc
+
+        self.options = []
+        self.args = []
+
+        # Call getopt
+        try:
+            self.options, self.args = getopt.getopt(
+                args, "".join(self.short_options), self.long_options)
+        except getopt.error, msg:
+            if raise_getopt_errs:
+                self.usage(msg)
+
+        # Check for positional args
+        if self.args and not self.positional_args_allowed:
+            self.usage("positional arguments are not supported")
+
+        # Process options returned by getopt
+        for opt, arg in self.options:
+            name, handler = self.options_map[opt]
+            if handler is not None:
+                try:
+                    arg = handler(arg)
+                except ValueError, msg:
+                    self.usage("invalid value for %s %r: %s" % (opt, arg, msg))
+            if name and arg is not None:
+                if getattr(self, name) is not None:
+                    self.usage("conflicting command line option %r" % opt)
+                setattr(self, name, arg)
+
+        # Process environment variables
+        for envvar in self.environ_map.keys():
+            name, handler = self.environ_map[envvar]
+            if name and getattr(self, name, None) is not None:
+                continue
+            if os.environ.has_key(envvar):
+                value = os.environ[envvar]
+                if handler is not None:
+                    try:
+                        value = handler(value)
+                    except ValueError, msg:
+                        self.usage("invalid environment value for %s %r: %s"
+                                   % (envvar, value, msg))
+                if name and value is not None:
+                    setattr(self, name, value)
+
+        if self.configfile is None:
+            self.configfile = self.default_configfile()
+        if self.zconfig_options and self.configfile is None:
+            self.usage("configuration overrides (-X) cannot be used"
+                       " without a configuration file")
+        if self.configfile is not None:
+            # Process config file
+            self.load_schema()
+            try:
+                self.load_configfile()
+            except ZConfig.ConfigurationError, msg:
+                self.usage(str(msg))
+
+        # Copy config options to attributes of self.  This only fills
+        # in options that aren't already set from the command line.
+        for name, confname in self.names_list:
+            if confname and getattr(self, name) is None:
+                parts = confname.split(".")
+                obj = self.configroot
+                for part in parts:
+                    if obj is None:
+                        break
+                    # Here AttributeError is not a user error!
+                    obj = getattr(obj, part)
+                setattr(self, name, obj)
+
+        # Process defaults
+        for name, value in self.default_map.items():
+            if getattr(self, name) is None:
+                setattr(self, name, value)
+
+        # Process required options
+        for name, message in self.required_map.items():
+            if getattr(self, name) is None:
+                self.usage(message)
+
+        if self.logsectionname:
+            self.load_logconf(self.logsectionname)
+
+    def default_configfile(self):
+        """Return the name of the default config file, or None."""
+        # This allows a default configuration file to be used without
+        # affecting the -C command line option; setting self.configfile
+        # before calling realize() makes the -C option unusable since
+        # then realize() thinks it has already seen the option.  If no
+        # -C is used, realize() will call this method to try to locate
+        # a configuration file.
+        return None
+
+    def load_schema(self):
+        if self.schema is None:
+            # Load schema
+            if self.schemadir is None:
+                self.schemadir = os.path.dirname(__file__)
+            self.schemafile = os.path.join(self.schemadir, self.schemafile)
+            self.schema = ZConfig.loadSchema(self.schemafile)
+
+    def load_configfile(self):
+        self.configroot, self.confighandlers = \
+            ZConfig.loadConfig(self.schema, self.configfile,
+                               self.zconfig_options)
+
+    def load_logconf(self, sectname="eventlog"):
+        parts = sectname.split(".")
+        obj = self.configroot
+        for p in parts:
+            if obj == None:
+                break
+            obj = getattr(obj, p)
+        self.config_logger = obj
+        if obj is not None:
+            obj.startup()
+
+
+class RunnerOptions(ZDOptions):
+
+    uid = gid = None
+
+    def __init__(self):
+        ZDOptions.__init__(self)
+        self.add("backofflimit", "runner.backoff_limit",
+                 "b:", "backoff-limit=", int, default=10)
+        self.add("daemon", "runner.daemon", "d", "daemon", flag=1, default=0)
+        self.add("forever", "runner.forever", "f", "forever",
+                 flag=1, default=0)
+        self.add("sockname", "runner.socket_name", "s:", "socket-name=",
+                 ZConfig.datatypes.existing_dirpath, default="zdsock")
+        self.add("exitcodes", "runner.exit_codes", "x:", "exit-codes=",
+                 list_of_ints, default=[0, 2])
+        self.add("user", "runner.user", "u:", "user=")
+        self.add("umask", "runner.umask", "m:", "umask=", octal_type,
+                 default=022)
+        self.add("directory", "runner.directory", "z:", "directory=",
+                 ZConfig.datatypes.existing_directory)
+        self.add("hang_around", "runner.hang_around", default=0)
+
+    def realize(self, *args, **kwds):
+        ZDOptions.realize(self, *args, **kwds)
+
+        # Additional checking of user option; set uid and gid
+        if self.user is not None:
+            import pwd
+            try:
+                uid = int(self.user)
+            except ValueError:
+                try:
+                    pwrec = pwd.getpwnam(self.user)
+                except KeyError:
+                    self.usage("username %r not found" % self.user)
+                uid = pwrec[2]
+            else:
+                try:
+                    pwrec = pwd.getpwuid(uid)
+                except KeyError:
+                    self.usage("uid %r not found" % self.user)
+            gid = pwrec[3]
+            self.uid = uid
+            self.gid = gid
+
+
+# ZConfig datatype
+
+def list_of_ints(arg):
+    if not arg:
+        return []
+    else:
+        return map(int, arg.split(","))
+
+def octal_type(arg):
+    return int(arg, 8)
+
+
+def _test():
+    # Stupid test program
+    z = ZDOptions()
+    z.add("program", "zdctl.program", "p:", "program=")
+    print z.names_list
+    z.realize()
+    names = z.names_list[:]
+    names.sort()
+    for name, confname in names:
+        print "%-20s = %.56r" % (name, getattr(z, name))
+
+if __name__ == "__main__":
+    __file__ = sys.argv[0]
+    _test()

src/zdaemon/zdrun.py

+#!python
+##############################################################################
+#
+# Copyright (c) 2001, 2002 Zope Corporation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE
+#
+##############################################################################
+"""zrdun -- run an application as a daemon.
+
+Usage: python zrdun.py [zrdun-options] program [program-arguments]
+
+Options:
+-C/--configure URL -- configuration file or URL
+-S/--schema XML Schema -- XML schema for configuration file
+-b/--backoff-limit SECONDS -- set backoff limit to SECONDS (default 10)
+-d/--daemon -- run as a proper daemon; fork a subprocess, setsid(), etc.
+-f/--forever -- run forever (by default, exit when backoff limit is exceeded)
+-h/--help -- print this usage message and exit
+-s/--socket-name SOCKET -- Unix socket name for client (default "zdsock")
+-u/--user USER -- run as this user (or numeric uid)
+-m/--umask UMASK -- use this umask for daemon subprocess (default is 022)
+-t/--transcript FILE -- transript of output from daemon-mode program
+-x/--exit-codes LIST -- list of fatal exit codes (default "0,2")
+-z/--directory DIRECTORY -- directory to chdir to when using -d (default off)
+program [program-arguments] -- an arbitrary application to run
+
+This daemon manager has two purposes: it restarts the application when
+it dies, and (when requested to do so with the -d option) it runs the
+application in the background, detached from the foreground tty
+session that started it (if any).
+
+Exit codes: if at any point the application exits with an exit status
+listed by the -x option, it is not restarted.  Any other form of
+termination (either being killed by a signal or exiting with an exit
+status not listed in the -x option) causes it to be restarted.
+
+Backoff limit: when the application exits (nearly) immediately after a
+restart, the daemon manager starts slowing down by delaying between
+restarts.  The delay starts at 1 second and is increased by one on
+each restart up to the backoff limit given by the -b option; it is
+reset when the application runs for more than the backoff limit
+seconds.  By default, when the delay reaches the backoff limit, the
+daemon manager exits (under the assumption that the application has a
+persistent fault).  The -f (forever) option prevents this exit; use it
+when you expect that a temporary external problem (such as a network
+outage or an overfull disk) may prevent the application from starting
+but you want the daemon manager to keep trying.
+"""
+
+"""
+XXX TO DO
+
+- Finish OO design -- use multiple classes rather than folding
+  everything into one class.
+
+- Add unit tests.
+
+- Add doc strings.
+
+"""
+
+import os
+import sys
+import time
+import errno
+import logging
+import socket
+import select
+import signal
+from stat import ST_MODE
+
+if __name__ == "__main__":
+    # Add the parent of the script directory to the module search path
+    # (but only when the script is run from inside the zdaemon package)
+    from os.path import dirname, basename, abspath, normpath
+    scriptdir = dirname(normpath(abspath(sys.argv[0])))
+    if basename(scriptdir).lower() == "zdaemon":
+        sys.path.append(dirname(scriptdir))
+
+from zdaemon.zdoptions import RunnerOptions
+
+
+class ZDRunOptions(RunnerOptions):
+
+    positional_args_allowed = 1
+    logsectionname = "runner.eventlog"
+    program = None
+
+    def __init__(self):
+        RunnerOptions.__init__(self)
+        self.add("schemafile", short="S:", long="schema=",
+                 default="schema.xml",
+                 handler=self.set_schemafile)
+        self.add("transcript", "runner.transcript", "t:", "transcript=",
+                 default="/dev/null")
+
+    def set_schemafile(self, file):
+        self.schemafile = file
+
+    def realize(self, *args, **kwds):
+        RunnerOptions.realize(self, *args, **kwds)
+        if self.args:
+            self.program = self.args
+        if not self.program:
+            self.usage("no program specified (use -C or positional args)")
+        if self.sockname:
+            # Convert socket name to absolute path
+            self.sockname = os.path.abspath(self.sockname)
+        if self.config_logger is None:
+            # This doesn't perform any configuration of the logging
+            # package, but that's reasonable in this case.
+            self.logger = logging.getLogger()
+        else:
+            self.logger = self.config_logger()
+
+    def load_logconf(self, sectname):
+        """Load alternate eventlog if the specified section isn't present."""
+        RunnerOptions.load_logconf(self, sectname)
+        if self.config_logger is None and sectname != "eventlog":
+            RunnerOptions.load_logconf(self, "eventlog")
+
+
+class Subprocess:
+
+    """A class to manage a subprocess."""
+
+    # Initial state; overridden by instance variables
+    pid = 0 # Subprocess pid; 0 when not running
+    lasttime = 0 # Last time the subprocess was started; 0 if never
+
+    def __init__(self, options, args=None):
+        """Constructor.
+
+        Arguments are a ZDRunOptions instance and a list of program
+        arguments; the latter's first item must be the program name.
+        """
+        if args is None:
+            args = options.args
+        if not args:
+            options.usage("missing 'program' argument")
+        self.options = options
+        self.args = args
+        self._set_filename(args[0])
+
+    def _set_filename(self, program):
+        """Internal: turn a program name into a file name, using $PATH."""
+        if "/" in program:
+            filename = program
+            try:
+                st = os.stat(filename)
+            except os.error:
+                self.options.usage("can't stat program %r" % program)
+        else:
+            path = get_path()
+            for dir in path:
+                filename = os.path.join(dir, program)
+                try:
+                    st = os.stat(filename)
+                except os.error:
+                    continue
+                mode = st[ST_MODE]
+                if mode & 0111:
+                    break
+            else:
+                self.options.usage("can't find program %r on PATH %s" %
+                                   (program, path))
+        if not os.access(filename, os.X_OK):
+            self.options.usage("no permission to run program %r" % filename)
+        self.filename = filename
+
+    def spawn(self):
+        """Start the subprocess.  It must not be running already.
+
+        Return the process id.  If the fork() call fails, return 0.
+        """
+        assert not self.pid
+        self.lasttime = time.time()
+        try:
+            pid = os.fork()
+        except os.error:
+            return 0
+        if pid != 0:
+            # Parent
+            self.pid = pid
+            self.options.logger.info("spawned process pid=%d" % pid)
+            return pid
+        else:
+            # Child
+            try:
+                # Close file descriptors except std{in,out,err}.
+                # XXX We don't know how many to close; hope 100 is plenty.
+                for i in range(3, 100):
+                    try:
+                        os.close(i)
+                    except os.error:
+                        pass
+                try:
+                    os.execv(self.filename, self.args)
+                except os.error, err:
+                    sys.stderr.write("can't exec %r: %s\n" %
+                                     (self.filename, err))
+            finally:
+                os._exit(127)
+            # Does not return
+
+    def kill(self, sig):
+        """Send a signal to the subprocess.  This may or may not kill it.
+
+        Return None if the signal was sent, or an error message string
+        if an error occurred or if the subprocess is not running.
+        """
+        if not self.pid:
+            return "no subprocess running"
+        try:
+            os.kill(self.pid, sig)
+        except os.error, msg:
+            return str(msg)
+        return None
+
+    def setstatus(self, sts):
+        """Set process status returned by wait() or waitpid().
+
+        This simply notes the fact that the subprocess is no longer
+        running by setting self.pid to 0.
+        """
+        self.pid = 0
+
+
+class Daemonizer:
+
+    def main(self, args=None):
+        self.options = ZDRunOptions()
+        self.options.realize(args)
+        self.logger = self.options.logger
+        self.set_uid()
+        self.run()
+
+    def set_uid(self):
+        if self.options.uid is None:
+            return
+        uid = os.geteuid()
+        if uid != 0 and uid != self.options.uid:
+            self.options.usage("only root can use -u USER to change users")
+        os.setgid(self.options.gid)
+        os.setuid(self.options.uid)
+
+    def run(self):
+        self.proc = Subprocess(self.options)
+        self.opensocket()
+        try:
+            self.setsignals()
+            if self.options.daemon:
+                self.daemonize()
+            self.runforever()
+        finally:
+            try:
+                os.unlink(self.options.sockname)
+            except os.error:
+                pass
+
+    mastersocket = None
+    commandsocket = None
+
+    def opensocket(self):
+        sockname = self.options.sockname
+        tempname = "%s.%d" % (sockname, os.getpid())
+        self.unlink_quietly(tempname)
+        while 1:
+            sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+            try:
+                sock.bind(tempname)
+                os.chmod(tempname, 0700)
+                try:
+                    os.link(tempname, sockname)
+                    break
+                except os.error:
+                    # Lock contention, or stale socket.
+                    self.checkopen()
+                    # Stale socket -- delete, sleep, and try again.
+                    msg = "Unlinking stale socket %s; sleep 1" % sockname
+                    sys.stderr.write(msg + "\n")
+                    self.logger.warn(msg)
+                    self.unlink_quietly(sockname)
+                    sock.close()
+                    time.sleep(1)
+                    continue
+            finally:
+                self.unlink_quietly(tempname)
+        sock.listen(1)
+        sock.setblocking(0)
+        self.mastersocket = sock
+
+    def unlink_quietly(self, filename):
+        try:
+            os.unlink(filename)
+        except os.error:
+            pass
+
+    def checkopen(self):
+        s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+        try:
+            s.connect(self.options.sockname)
+            s.send("status\n")
+            data = s.recv(1000)
+            s.close()
+        except socket.error:
+            pass
+        else:
+            while data.endswith("\n"):
+                data = data[:-1]
+            msg = ("Another zrdun is already up using socket %r:\n%s" %
+                   (self.options.sockname, data))
+            sys.stderr.write(msg + "\n")
+            self.logger.critical(msg)
+            sys.exit(1)
+
+    def setsignals(self):
+        signal.signal(signal.SIGTERM, self.sigexit)
+        signal.signal(signal.SIGHUP, self.sigexit)
+        signal.signal(signal.SIGINT, self.sigexit)
+        signal.signal(signal.SIGCHLD, self.sigchild)
+
+    def sigexit(self, sig, frame):
+        self.logger.critical("daemon manager killed by %s" % signame(sig))
+        sys.exit(1)
+
+    waitstatus = None
+
+    def sigchild(self, sig, frame):
+        try:
+            pid, sts = os.waitpid(-1, os.WNOHANG)
+        except os.error:
+            return
+        if pid:
+            self.waitstatus = pid, sts
+
+    def daemonize(self):
+
+        # To daemonize, we need to become the leader of our own session
+        # (process) group.  If we do not, signals sent to our
+        # parent process will also be sent to us.   This might be bad because
+        # signals such as SIGINT can be sent to our parent process during
+        # normal (uninteresting) operations such as when we press Ctrl-C in the
+        # parent terminal window to escape from a logtail command.
+        # To disassociate ourselves from our parent's session group we use
+        # os.setsid.  It means "set session id", which has the effect of
+        # disassociating a process from is current session and process group
+        # and setting itself up as a new session leader.
+        #
+        # Unfortunately we cannot call setsid if we're already a session group
+        # leader, so we use "fork" to make a copy of ourselves that is
+        # guaranteed to not be a session group leader.
+        #
+        # We also change directories, set stderr and stdout to null, and
+        # change our umask.
+        #
+        # This explanation was (gratefully) garnered from
+        # http://www.hawklord.uklinux.net/system/daemons/d3.htm
+
+        pid = os.fork()
+        if pid != 0:
+            # Parent
+            self.logger.debug("daemon manager forked; parent exiting")
+            os._exit(0)
+        # Child
+        self.logger.info("daemonizing the process")
+        if self.options.directory:
+            try:
+                os.chdir(self.options.directory)
+            except os.error, err:
+                self.logger.warn("can't chdir into %r: %s"
+                                 % (self.options.directory, err))
+            else:
+                self.logger.info("set current directory: %r"
+                                 % self.options.directory)
+        os.close(0)
+        sys.stdin = sys.__stdin__ = open("/dev/null")
+        os.close(1)
+        sys.stdout = sys.__stdout__ = open(self.options.transcript, "a", 0)
+        os.close(2)
+        sys.stderr = sys.__stderr__ = open(self.options.transcript, "a", 0)
+        os.setsid()
+        os.umask(self.options.umask)
+        # XXX Stevens, in his Advanced Unix book, section 13.3 (page
+        # 417) recommends calling umask(0) and closing unused
+        # file descriptors.  In his Network Programming book, he
+        # additionally recommends ignoring SIGHUP and forking again
+        # after the setsid() call, for obscure SVR4 reasons.
+
+    mood = 1 # 1: up, 0: down, -1: suicidal
+    delay = 0 # If nonzero, delay starting or killing until this time
+    killing = 0 # If true, send SIGKILL when delay expires
+    proc = None # Subprocess instance
+
+    def runforever(self):
+        self.logger.info("daemon manager started")
+        min_mood = not self.options.hang_around
+        while self.mood >= min_mood or self.proc.pid:
+            if self.mood > 0 and not self.proc.pid and not self.delay:
+                pid = self.proc.spawn()
+                if not pid:
+                    # Can't fork.  Try again later...
+                    self.delay = time.time() + self.backofflimit
+            if self.waitstatus:
+                self.reportstatus()
+            r, w, x = [self.mastersocket], [], []
+            if self.commandsocket:
+                r.append(self.commandsocket)
+            timeout = self.options.backofflimit
+            if self.delay:
+                timeout = max(0, min(timeout, self.delay - time.time()))
+                if timeout <= 0:
+                    self.delay = 0
+                    if self.killing and self.proc.pid:
+                        self.proc.kill(signal.SIGKILL)
+                        self.delay = time.time() + self.options.backofflimit
+            try:
+                r, w, x = select.select(r, w, x, timeout)
+            except select.error, err:
+                if err[0] != errno.EINTR:
+                    raise
+                r = w = x = []
+            if self.waitstatus:
+                self.reportstatus()
+            if self.commandsocket and self.commandsocket in r:
+                try:
+                    self.dorecv()
+                except socket.error, msg:
+                    self.logger.exception("socket.error in dorecv(): %s"
+                                          % str(msg))
+                    self.commandsocket = None
+            if self.mastersocket in r:
+                try:
+                    self.doaccept()
+                except socket.error, msg:
+                    self.logger.exception("socket.error in doaccept(): %s"
+                                          % str(msg))
+                    self.commandsocket = None
+        self.logger.info("Exiting")
+        sys.exit(0)
+
+    def reportstatus(self):
+        pid, sts = self.waitstatus
+        self.waitstatus = None
+        es, msg = decode_wait_status(sts)
+        msg = "pid %d: " % pid + msg
+        if pid != self.proc.pid:
+            msg = "unknown " + msg
+            self.logger.warn(msg)
+        else:
+            killing = self.killing
+            if killing:
+                self.killing = 0
+                self.delay = 0
+            else:
+                self.governor()
+            self.proc.setstatus(sts)
+            if es in self.options.exitcodes and not killing:
+                msg = msg + "; exiting now"
+                self.logger.info(msg)
+                sys.exit(es)
+            self.logger.info(msg)
+
+    backoff = 0
+
+    def governor(self):
+        # Back off if respawning too frequently
+        now = time.time()
+        if not self.proc.lasttime:
+            pass
+        elif now - self.proc.lasttime < self.options.backofflimit:
+            # Exited rather quickly; slow down the restarts
+            self.backoff += 1
+            if self.backoff >= self.options.backofflimit:
+                if self.options.forever:
+                    self.backoff = self.options.backofflimit
+                else:
+                    self.logger.critical("restarting too frequently; quit")
+                    sys.exit(1)
+            self.logger.info("sleep %s to avoid rapid restarts" % self.backoff)
+            self.delay = now + self.backoff
+        else:
+            # Reset the backoff timer
+            self.backoff = 0
+            self.delay = 0
+
+    def doaccept(self):
+        if self.commandsocket:
+            # Give up on previous command socket!
+            self.sendreply("Command superseded by new command")
+            self.commandsocket.close()
+            self.commandsocket = None
+        self.commandsocket, addr = self.mastersocket.accept()
+        self.commandbuffer = ""
+
+    def dorecv(self):
+        data = self.commandsocket.recv(1000)
+        if not data:
+            self.sendreply("Command not terminated by newline")
+            self.commandsocket.close()
+            self.commandsocket = None
+        self.commandbuffer += data
+        if "\n" in self.commandbuffer:
+            self.docommand()
+            self.commandsocket.close()
+            self.commandsocket = None
+        elif len(self.commandbuffer) > 10000:
+            self.sendreply("Command exceeds 10 KB")
+            self.commandsocket.close()
+            self.commandsocket = None
+
+    def docommand(self):
+        lines = self.commandbuffer.split("\n")
+        args = lines[0].split()
+        if not args:
+            self.sendreply("Empty command")
+            return
+        command = args[0]
+        methodname = "cmd_" + command
+        method = getattr(self, methodname, None)
+        if method:
+            method(args)
+        else:
+            self.sendreply("Unknown command %r; 'help' for a list" % args[0])
+
+    def cmd_start(self, args):
+        self.mood = 1 # Up
+        self.backoff = 0
+        self.delay = 0
+        self.killing = 0
+        if not self.proc.pid:
+            self.proc.spawn()
+            self.sendreply("Application started")
+        else:
+            self.sendreply("Application already started")
+
+    def cmd_stop(self, args):
+        self.mood = 0 # Down
+        self.backoff = 0
+        self.delay = 0
+        self.killing = 0
+        if self.proc.pid:
+            self.proc.kill(signal.SIGTERM)
+            self.sendreply("Sent SIGTERM")
+            self.killing = 1
+            self.delay = time.time() + self.options.backofflimit
+        else:
+            self.sendreply("Application already stopped")
+
+    def cmd_restart(self, args):
+        self.mood = 1 # Up
+        self.backoff = 0
+        self.delay = 0
+        self.killing = 0
+        if self.proc.pid:
+            self.proc.kill(signal.SIGTERM)
+            self.sendreply("Sent SIGTERM; will restart later")
+            self.killing = 1
+            self.delay = time.time() + self.options.backofflimit
+        else:
+            self.proc.spawn()
+            self.sendreply("Application started")
+
+    def cmd_exit(self, args):
+        self.mood = -1 # Suicidal
+        self.backoff = 0
+        self.delay = 0
+        self.killing = 0
+        if self.proc.pid:
+            self.proc.kill(signal.SIGTERM)
+            self.sendreply("Sent SIGTERM; will exit later")
+            self.killing = 1
+            self.delay = time.time() + self.options.backofflimit
+        else:
+            self.sendreply("Exiting now")
+            self.logger.info("Exiting")
+            sys.exit(0)
+
+    def cmd_kill(self, args):
+        if args[1:]:
+            try:
+                sig = int(args[1])
+            except:
+                self.sendreply("Bad signal %r" % args[1])
+                return
+        else:
+            sig = signal.SIGTERM
+        if not self.proc.pid:
+            self.sendreply("Application not running")
+        else:
+            msg = self.proc.kill(sig)
+            if msg:
+                self.sendreply("Kill %d failed: %s" % (sig, msg))
+            else:
+                self.sendreply("Signal %d sent" % sig)
+
+    def cmd_status(self, args):
+        if not self.proc.pid:
+            status = "stopped"
+        else:
+            status = "running"
+        self.sendreply("status=%s\n" % status +
+                       "now=%r\n" % time.time() +
+                       "mood=%d\n" % self.mood +
+                       "delay=%r\n" % self.delay +
+                       "backoff=%r\n" % self.backoff +
+                       "lasttime=%r\n" % self.proc.lasttime +
+                       "application=%r\n" % self.proc.pid +
+                       "manager=%r\n" % os.getpid() +
+                       "backofflimit=%r\n" % self.options.backofflimit +
+                       "filename=%r\n" % self.proc.filename +
+                       "args=%r\n" % self.proc.args)
+
+    def cmd_help(self, args):
+        self.sendreply(
+            "Available commands:\n"
+            "  help -- return command help\n"
+            "  status -- report application status (default command)\n"
+            "  kill [signal] -- send a signal to the application\n"
+            "                   (default signal is SIGTERM)\n"
+            "  start -- start the application if not already running\n"
+            "  stop -- stop the application if running\n"
+            "          (the daemon manager keeps running)\n"
+            "  restart -- stop followed by start\n"
+            "  exit -- stop the application and exit\n"
+            )
+
+    def sendreply(self, msg):
+        try:
+            if not msg.endswith("\n"):
+                msg = msg + "\n"
+            if hasattr(self.commandsocket, "sendall"):
+                self.commandsocket.sendall(msg)
+            else:
+                # This is quadratic, but msg is rarely more than 100 bytes :-)
+                while msg:
+                    sent = self.commandsocket.send(msg)
+                    msg = msg[sent:]
+        except socket.error, msg:
+            self.logger.warn("Error sending reply: %s" % str(msg))
+
+
+# Helpers for dealing with signals and exit status
+
+def decode_wait_status(sts):
+    """Decode the status returned by wait() or waitpid().
+
+    Return a tuple (exitstatus, message) where exitstatus is the exit
+    status, or -1 if the process was killed by a signal; and message
+    is a message telling what happened.  It is the caller's
+    responsibility to display the message.
+    """
+    if os.WIFEXITED(sts):
+        es = os.WEXITSTATUS(sts) & 0xffff
+        msg = "exit status %s" % es
+        return es, msg
+    elif os.WIFSIGNALED(sts):
+        sig = os.WTERMSIG(sts)
+        msg = "terminated by %s" % signame(sig)
+        if hasattr(os, "WCOREDUMP"):
+            iscore = os.WCOREDUMP(sts)
+        else:
+            iscore = sts & 0x80
+        if iscore:
+            msg += " (core dumped)"
+        return -1, msg
+    else:
+        msg = "unknown termination cause 0x%04x" % sts
+        return -1, msg
+
+_signames = None
+
+def signame(sig):
+    """Return a symbolic name for a signal.
+
+    Return "signal NNN" if there is no corresponding SIG name in the
+    signal module.
+    """
+
+    if _signames is None:
+        _init_signames()
+    return _signames.get(sig) or "signal %d" % sig
+
+def _init_signames():
+    global _signames
+    d = {}
+    for k, v in signal.__dict__.items():
+        k_startswith = getattr(k, "startswith", None)
+        if k_startswith is None:
+            continue
+        if k_startswith("SIG") and not k_startswith("SIG_"):
+            d[v] = k
+    _signames = d
+
+def get_path():
+    """Return a list corresponding to $PATH, or a default."""
+    path = ["/bin", "/usr/bin", "/usr/local/bin"]
+    if os.environ.has_key("PATH"):
+        p = os.environ["PATH"]
+        if p:
+            path = p.split(os.pathsep)
+    return path
+
+# Main program
+def main(args=None):
+    assert os.name == "posix", "This code makes many Unix-specific assumptions"
+
+    d = Daemonizer()
+    d.main(args)
+
+if __name__ == "__main__":
+    main()