Add bitbake-dev to allow ease of testing and development of bitbake trunk

git-svn-id: https://svn.o-hand.com/repos/poky/trunk@5337 311d38ba-8fff-0310-9ca6-ca027cbcb966
author: Richard Purdie <richard@openedhand.com> 2008-09-30 15:08:33 +0000
committer: Richard Purdie <richard@openedhand.com> 2008-09-30 15:08:33 +0000
commit: c30eddb243e7e65f67f656e62848a033cf6f2e5c (patch)
tree: 110dd95788b76f55d31cb8d30aac2de8400b6f4a /bitbake-dev/lib/bb/daemonize.py
parent: 5ef0510474004eeb2ae8a99b64e2febb1920e077 (diff)
download: poky-c30eddb243e7e65f67f656e62848a033cf6f2e5c.tar.gz
1 files changed, 189 insertions, 0 deletions
diff --git a/bitbake-dev/lib/bb/daemonize.py b/bitbake-dev/lib/bb/daemonize.py
new file mode 100644
index 0000000000..6023c9ccd2
--- /dev/null
+++ b/bitbake-dev/lib/bb/daemonize.py
@@ -0,0 +1,189 @@
+"""
+Python Deamonizing helper
+Configurable daemon behaviors:
+   1.) The current working directory set to the "/" directory.
+   2.) The current file creation mode mask set to 0.
+   3.) Close all open files (1024). 
+   4.) Redirect standard I/O streams to "/dev/null".
+A failed call to fork() now raises an exception.
+References:
+   1) Advanced Programming in the Unix Environment: W. Richard Stevens
+   2) Unix Programming Frequently Asked Questions:
+         http://www.erlenstar.demon.co.uk/unix/faq_toc.html
+Modified to allow a function to be daemonized and return for 
+bitbake use by Richard Purdie
+"""
+__author__ = "Chad J. Schroeder"
+__copyright__ = "Copyright (C) 2005 Chad J. Schroeder"
+__version__ = "0.2"
+# Standard Python modules.
+import os               # Miscellaneous OS interfaces.
+import sys              # System-specific parameters and functions.
+# Default daemon parameters.
+# File mode creation mask of the daemon.
+UMASK = 0
+# Default maximum for the number of available file descriptors.
+MAXFD = 1024
+# The standard I/O file descriptors are redirected to /dev/null by default.
+if (hasattr(os, "devnull")):
+   REDIRECT_TO = os.devnull
+else:
+   REDIRECT_TO = "/dev/null"
+def createDaemon(function, logfile):
+   """
+   Detach a process from the controlling terminal and run it in the
+   background as a daemon, returning control to the caller.
+   """
+   try:
+      # Fork a child process so the parent can exit.  This returns control to
+      # the command-line or shell.  It also guarantees that the child will not
+      # be a process group leader, since the child receives a new process ID
+      # and inherits the parent's process group ID.  This step is required
+      # to insure that the next call to os.setsid is successful.
+      pid = os.fork()
+   except OSError, e:
+      raise Exception, "%s [%d]" % (e.strerror, e.errno)
+   if (pid == 0):       # The first child.
+      # To become the session leader of this new session and the process group
+      # leader of the new process group, we call os.setsid().  The process is
+      # also guaranteed not to have a controlling terminal.
+      os.setsid()
+      # Is ignoring SIGHUP necessary?
+      #
+      # It's often suggested that the SIGHUP signal should be ignored before
+      # the second fork to avoid premature termination of the process.  The
+      # reason is that when the first child terminates, all processes, e.g.
+      # the second child, in the orphaned group will be sent a SIGHUP.
+      #
+      # "However, as part of the session management system, there are exactly
+      # two cases where SIGHUP is sent on the death of a process:
+      #
+      #   1) When the process that dies is the session leader of a session that
+      #      is attached to a terminal device, SIGHUP is sent to all processes
+      #      in the foreground process group of that terminal device.
+      #   2) When the death of a process causes a process group to become
+      #      orphaned, and one or more processes in the orphaned group are
+      #      stopped, then SIGHUP and SIGCONT are sent to all members of the
+      #      orphaned group." [2]
+      #
+      # The first case can be ignored since the child is guaranteed not to have
+      # a controlling terminal.  The second case isn't so easy to dismiss.
+      # The process group is orphaned when the first child terminates and
+      # POSIX.1 requires that every STOPPED process in an orphaned process
+      # group be sent a SIGHUP signal followed by a SIGCONT signal.  Since the
+      # second child is not STOPPED though, we can safely forego ignoring the
+      # SIGHUP signal.  In any case, there are no ill-effects if it is ignored.
+      #
+      # import signal           # Set handlers for asynchronous events.
+      # signal.signal(signal.SIGHUP, signal.SIG_IGN)
+      try:
+         # Fork a second child and exit immediately to prevent zombies.  This
+         # causes the second child process to be orphaned, making the init
+         # process responsible for its cleanup.  And, since the first child is
+         # a session leader without a controlling terminal, it's possible for
+         # it to acquire one by opening a terminal in the future (System V-
+         # based systems).  This second fork guarantees that the child is no
+         # longer a session leader, preventing the daemon from ever acquiring
+         # a controlling terminal.
+         pid = os.fork()        # Fork a second child.
+      except OSError, e:
+         raise Exception, "%s [%d]" % (e.strerror, e.errno)
+      if (pid == 0):    # The second child.
+         # We probably don't want the file mode creation mask inherited from
+         # the parent, so we give the child complete control over permissions.
+         os.umask(UMASK)
+      else:
+         # Parent (the first child) of the second child.
+         os._exit(0)
+   else:
+      # exit() or _exit()?
+      # _exit is like exit(), but it doesn't call any functions registered
+      # with atexit (and on_exit) or any registered signal handlers.  It also
+      # closes any open file descriptors.  Using exit() may cause all stdio
+      # streams to be flushed twice and any temporary files may be unexpectedly
+      # removed.  It's therefore recommended that child branches of a fork()
+      # and the parent branch(es) of a daemon use _exit().
+      return
+   # Close all open file descriptors.  This prevents the child from keeping
+   # open any file descriptors inherited from the parent.  There is a variety
+   # of methods to accomplish this task.  Three are listed below.
+   #
+   # Try the system configuration variable, SC_OPEN_MAX, to obtain the maximum
+   # number of open file descriptors to close.  If it doesn't exists, use
+   # the default value (configurable).
+   #
+   # try:
+   #    maxfd = os.sysconf("SC_OPEN_MAX")
+   # except (AttributeError, ValueError):
+   #    maxfd = MAXFD
+   #
+   # OR
+   #
+   # if (os.sysconf_names.has_key("SC_OPEN_MAX")):
+   #    maxfd = os.sysconf("SC_OPEN_MAX")
+   # else:
+   #    maxfd = MAXFD
+   #
+   # OR
+   #
+   # Use the getrlimit method to retrieve the maximum file descriptor number
+   # that can be opened by this process.  If there is not limit on the
+   # resource, use the default value.
+   #
+   import resource              # Resource usage information.
+   maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
+   if (maxfd == resource.RLIM_INFINITY):
+      maxfd = MAXFD
+  
+   # Iterate through and close all file descriptors.
+#   for fd in range(0, maxfd):
+#      try:
+#         os.close(fd)
+#      except OSError:  # ERROR, fd wasn't open to begin with (ignored)
+#         pass
+   # Redirect the standard I/O file descriptors to the specified file.  Since
+   # the daemon has no controlling terminal, most daemons redirect stdin,
+   # stdout, and stderr to /dev/null.  This is done to prevent side-effects
+   # from reads and writes to the standard I/O file descriptors.
+   # This call to open is guaranteed to return the lowest file descriptor,
+   # which will be 0 (stdin), since it was closed above.
+#   os.open(REDIRECT_TO, os.O_RDWR)     # standard input (0)
+   # Duplicate standard input to standard output and standard error.
+#   os.dup2(0, 1)                       # standard output (1)
+#   os.dup2(0, 2)                       # standard error (2)
+   si = file('/dev/null', 'r')
+   so = file(logfile, 'w')
+   se = so
+   # Replace those fds with our own
+   os.dup2(si.fileno(), sys.stdin.fileno())
+   os.dup2(so.fileno(), sys.stdout.fileno())
+   os.dup2(se.fileno(), sys.stderr.fileno())
+   function()
+   os._exit(0)
author	Richard Purdie <richard@openedhand.com>	2008-09-30 15:08:33 +0000
committer	Richard Purdie <richard@openedhand.com>	2008-09-30 15:08:33 +0000
commit	c30eddb243e7e65f67f656e62848a033cf6f2e5c (patch)
tree	110dd95788b76f55d31cb8d30aac2de8400b6f4a /bitbake-dev/lib/bb/daemonize.py
parent	5ef0510474004eeb2ae8a99b64e2febb1920e077 (diff)
download	poky-c30eddb243e7e65f67f656e62848a033cf6f2e5c.tar.gz

diff --git a/bitbake-dev/lib/bb/daemonize.py b/bitbake-dev/lib/bb/daemonize.py new file mode 100644 index 0000000000..6023c9ccd2 --- /dev/null +++ b/bitbake-dev/lib/bb/daemonize.py
@@ -0,0 +1,189 @@
	1	"""
	2	Python Deamonizing helper
	3
	4	Configurable daemon behaviors:
	5
	6	1.) The current working directory set to the "/" directory.
	7	2.) The current file creation mode mask set to 0.
	8	3.) Close all open files (1024).
	9	4.) Redirect standard I/O streams to "/dev/null".
	10
	11	A failed call to fork() now raises an exception.
	12
	13	References:
	14	1) Advanced Programming in the Unix Environment: W. Richard Stevens
	15	2) Unix Programming Frequently Asked Questions:
	16	http://www.erlenstar.demon.co.uk/unix/faq_toc.html
	17
	18	Modified to allow a function to be daemonized and return for
	19	bitbake use by Richard Purdie
	20	"""
	21
	22	__author__ = "Chad J. Schroeder"
	23	__copyright__ = "Copyright (C) 2005 Chad J. Schroeder"
	24	__version__ = "0.2"
	25
	26	# Standard Python modules.
	27	import os # Miscellaneous OS interfaces.
	28	import sys # System-specific parameters and functions.
	29
	30	# Default daemon parameters.
	31	# File mode creation mask of the daemon.
	32	UMASK = 0
	33
	34	# Default maximum for the number of available file descriptors.
	35	MAXFD = 1024
	36
	37	# The standard I/O file descriptors are redirected to /dev/null by default.
	38	if (hasattr(os, "devnull")):
	39	REDIRECT_TO = os.devnull
	40	else:
	41	REDIRECT_TO = "/dev/null"
	42
	43	def createDaemon(function, logfile):
	44	"""
	45	Detach a process from the controlling terminal and run it in the
	46	background as a daemon, returning control to the caller.
	47	"""
	48
	49	try:
	50	# Fork a child process so the parent can exit. This returns control to
	51	# the command-line or shell. It also guarantees that the child will not
	52	# be a process group leader, since the child receives a new process ID
	53	# and inherits the parent's process group ID. This step is required
	54	# to insure that the next call to os.setsid is successful.
	55	pid = os.fork()
	56	except OSError, e:
	57	raise Exception, "%s [%d]" % (e.strerror, e.errno)
	58
	59	if (pid == 0): # The first child.
	60	# To become the session leader of this new session and the process group
	61	# leader of the new process group, we call os.setsid(). The process is
	62	# also guaranteed not to have a controlling terminal.
	63	os.setsid()
	64
	65	# Is ignoring SIGHUP necessary?
	66	#
	67	# It's often suggested that the SIGHUP signal should be ignored before
	68	# the second fork to avoid premature termination of the process. The
	69	# reason is that when the first child terminates, all processes, e.g.
	70	# the second child, in the orphaned group will be sent a SIGHUP.
	71	#
	72	# "However, as part of the session management system, there are exactly
	73	# two cases where SIGHUP is sent on the death of a process:
	74	#
	75	# 1) When the process that dies is the session leader of a session that
	76	# is attached to a terminal device, SIGHUP is sent to all processes
	77	# in the foreground process group of that terminal device.
	78	# 2) When the death of a process causes a process group to become
	79	# orphaned, and one or more processes in the orphaned group are
	80	# stopped, then SIGHUP and SIGCONT are sent to all members of the
	81	# orphaned group." [2]
	82	#
	83	# The first case can be ignored since the child is guaranteed not to have
	84	# a controlling terminal. The second case isn't so easy to dismiss.
	85	# The process group is orphaned when the first child terminates and
	86	# POSIX.1 requires that every STOPPED process in an orphaned process
	87	# group be sent a SIGHUP signal followed by a SIGCONT signal. Since the
	88	# second child is not STOPPED though, we can safely forego ignoring the
	89	# SIGHUP signal. In any case, there are no ill-effects if it is ignored.
	90	#
	91	# import signal # Set handlers for asynchronous events.
	92	# signal.signal(signal.SIGHUP, signal.SIG_IGN)
	93
	94	try:
	95	# Fork a second child and exit immediately to prevent zombies. This
	96	# causes the second child process to be orphaned, making the init
	97	# process responsible for its cleanup. And, since the first child is
	98	# a session leader without a controlling terminal, it's possible for
	99	# it to acquire one by opening a terminal in the future (System V-
	100	# based systems). This second fork guarantees that the child is no
	101	# longer a session leader, preventing the daemon from ever acquiring
	102	# a controlling terminal.
	103	pid = os.fork() # Fork a second child.
	104	except OSError, e:
	105	raise Exception, "%s [%d]" % (e.strerror, e.errno)
	106
	107	if (pid == 0): # The second child.
	108	# We probably don't want the file mode creation mask inherited from
	109	# the parent, so we give the child complete control over permissions.
	110	os.umask(UMASK)
	111	else:
	112	# Parent (the first child) of the second child.
	113	os._exit(0)
	114	else:
	115	# exit() or _exit()?
	116	# _exit is like exit(), but it doesn't call any functions registered
	117	# with atexit (and on_exit) or any registered signal handlers. It also
	118	# closes any open file descriptors. Using exit() may cause all stdio
	119	# streams to be flushed twice and any temporary files may be unexpectedly
	120	# removed. It's therefore recommended that child branches of a fork()
	121	# and the parent branch(es) of a daemon use _exit().
	122	return
	123
	124	# Close all open file descriptors. This prevents the child from keeping
	125	# open any file descriptors inherited from the parent. There is a variety
	126	# of methods to accomplish this task. Three are listed below.
	127	#
	128	# Try the system configuration variable, SC_OPEN_MAX, to obtain the maximum
	129	# number of open file descriptors to close. If it doesn't exists, use
	130	# the default value (configurable).
	131	#
	132	# try:
	133	# maxfd = os.sysconf("SC_OPEN_MAX")
	134	# except (AttributeError, ValueError):
	135	# maxfd = MAXFD
	136	#
	137	# OR
	138	#
	139	# if (os.sysconf_names.has_key("SC_OPEN_MAX")):
	140	# maxfd = os.sysconf("SC_OPEN_MAX")
	141	# else:
	142	# maxfd = MAXFD
	143	#
	144	# OR
	145	#
	146	# Use the getrlimit method to retrieve the maximum file descriptor number
	147	# that can be opened by this process. If there is not limit on the
	148	# resource, use the default value.
	149	#
	150	import resource # Resource usage information.
	151	maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
	152	if (maxfd == resource.RLIM_INFINITY):
	153	maxfd = MAXFD
	154
	155	# Iterate through and close all file descriptors.
	156	# for fd in range(0, maxfd):
	157	# try:
	158	# os.close(fd)
	159	# except OSError: # ERROR, fd wasn't open to begin with (ignored)
	160	# pass
	161
	162	# Redirect the standard I/O file descriptors to the specified file. Since
	163	# the daemon has no controlling terminal, most daemons redirect stdin,
	164	# stdout, and stderr to /dev/null. This is done to prevent side-effects
	165	# from reads and writes to the standard I/O file descriptors.
	166
	167	# This call to open is guaranteed to return the lowest file descriptor,
	168	# which will be 0 (stdin), since it was closed above.
	169	# os.open(REDIRECT_TO, os.O_RDWR) # standard input (0)
	170
	171	# Duplicate standard input to standard output and standard error.
	172	# os.dup2(0, 1) # standard output (1)
	173	# os.dup2(0, 2) # standard error (2)
	174
	175
	176	si = file('/dev/null', 'r')
	177	so = file(logfile, 'w')
	178	se = so
	179
	180
	181	# Replace those fds with our own
	182	os.dup2(si.fileno(), sys.stdin.fileno())
	183	os.dup2(so.fileno(), sys.stdout.fileno())
	184	os.dup2(se.fileno(), sys.stderr.fileno())
	185
	186	function()
	187
	188	os._exit(0)
	189