initial commit for Enea Linux 4.0-140929daisy-140929

Migrated from the internal git server on the daisy-enea-point-release branch

Signed-off-by: Tudor Florea <tudor.florea@enea.com>

1 files changed, 190 insertions, 0 deletions

diff --git a/bitbake/lib/bb/daemonize.py b/bitbake/lib/bb/daemonize.py
new file mode 100644
index 0000000000..f0714b3af6
--- /dev/null
+++ b/bitbake/lib/bb/daemonize.py
@@ -0,0 +1,190 @@
+"""
+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.
+# For BitBake's children, we do want to inherit the parent umask.
+UMASK = None
+
+# 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 as 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 as 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.
+            if UMASK is not None:
+                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)