X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=python%2Fovs%2Fdaemon.py;h=4e54e697fabe6f7c923cbcddadccd70e037533e0;hb=595cf43e0127565e54c0f033f0f907a007ac2cae;hp=a8373cfd0168c42e7ea6c9e0eb8559eb8089afc6;hpb=991559357f6a03c3a5b70c053c8c2554aa8d5ee4;p=openvswitch

diff --git a/python/ovs/daemon.py b/python/ovs/daemon.py
index a8373cfd..4e54e697 100644
--- a/python/ovs/daemon.py
+++ b/python/ovs/daemon.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2010 Nicira Networks
+# Copyright (c) 2010, 2011 Nicira Networks
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -35,6 +35,10 @@ _detach = False
 # --pidfile: Name of pidfile (null if none).
 _pidfile = None
 
+# Our pidfile's inode and device, if we have created one.
+_pidfile_dev = None
+_pidfile_ino = None
+
 # --overwrite-pidfile: Create pidfile even if one already exists and is locked?
 _overwrite_pidfile = False
 
@@ -48,6 +52,8 @@ _monitor = False
 # File descriptor used by daemonize_start() and daemonize_complete().
 _daemonize_fd = None
 
+RESTART_EXIT_CODE = 5
+
 def make_pidfile_name(name):
     """Returns the file name that would be used for a pidfile if 'name' were
     provided to set_pidfile()."""
@@ -105,37 +111,17 @@ def set_monitor():
     global _monitor
     _monitor = True
 
-def _already_running():
-    """If a pidfile has been configured and that pidfile already exists and is
-    locked by a running process, returns True.  Otherwise, returns False."""
-    if _pidfile is not None:
-        try:
-            file = open(_pidfile, "r+")
-            try:
-                try:
-                    fcntl.lockf(file, fcntl.LOCK_EX | fcntl.LOCK_NB)
-                except IOError, e:
-                    if e.errno in [errno.EACCES, errno.EAGAIN]:
-                        return True
-                    logging.error("error locking %s (%s)"
-                                  % (_pidfile, os.strerror(e.errno)))
-                    return False
-            finally:
-                # This releases the lock, which we don't really want.
-                file.close()
-        except IOError, e:
-            if e.errno == errno.ENOENT:
-                return False
-            logging.error("error opening %s (%s)"
-                          % (_pidfile, os.strerror(e.errno)))
-    return False
-
 def die_if_already_running():
     """If a locked pidfile exists, issue a warning message and, unless
     ignore_existing_pidfile() has been called, terminate the program."""
-    if _already_running():
+    if _pidfile is None:
+        return
+    pid = read_pidfile_if_exists(_pidfile)
+    if pid > 0:
         if not _overwrite_pidfile:
-            sys.stderr.write("%s: already running\n" % get_pidfile())
+            msg = "%s: already running as pid %d" % (_pidfile, pid)
+            logging.error("%s, aborting" % msg)
+            sys.stderr.write("%s\n" % msg)
             sys.exit(1)
         else:
             logging.warn("%s: %s already running"
@@ -163,7 +149,7 @@ def _make_pidfile():
             logging.error("%s: create failed: %s"
                           % (tmpfile, os.strerror(e.errno)))
             return
-            
+
         try:
             fcntl.lockf(file, fcntl.LOCK_EX | fcntl.LOCK_NB)
         except IOError, e:
@@ -191,6 +177,10 @@ def _make_pidfile():
             file.close()
             return
 
+        s = os.fstat(file.fileno())
+        _pidfile_dev = s.st_dev
+        _pidfile_ino = s.st_ino
+
 def daemonize():
     """If configured with set_pidfile() or set_detach(), creates the pid file
     and detaches from the foreground session."""
@@ -258,6 +248,11 @@ def _fork_notify_startup(fd):
         os.close(fd)
 
 def _should_restart(status):
+    global RESTART_EXIT_CODE
+
+    if os.WIFEXITED(status) and os.WEXITSTATUS(status) == RESTART_EXIT_CODE:
+        return True
+
     if os.WIFSIGNALED(status):
         for signame in ("SIGABRT", "SIGALRM", "SIGBUS", "SIGFPE", "SIGILL",
                         "SIGPIPE", "SIGSEGV", "SIGXCPU", "SIGXFSZ"):
@@ -365,12 +360,25 @@ Daemon options:
    --overwrite-pidfile     with --pidfile, start even if already running
 """ % (ovs.dirs.RUNDIR, ovs.util.PROGRAM_NAME))
 
-def read_pidfile(pidfile):
-    """Opens and reads a PID from 'pidfile'.  Returns the nonnegative PID if
-    successful, otherwise a negative errno value."""
+def __read_pidfile(pidfile, must_exist):
+    if _pidfile_dev is not None:
+        try:
+            s = os.stat(pidfile)
+            if s.st_ino == _pidfile_ino and s.st_dev == _pidfile_dev:
+                # It's our own pidfile.  We can't afford to open it,
+                # because closing *any* fd for a file that a process
+                # has locked also releases all the locks on that file.
+                #
+                # Fortunately, we know the associated pid anyhow.
+                return os.getpid()
+        except OSError:
+            pass
+
     try:
         file = open(pidfile, "r")
     except IOError, e:
+        if e.errno == errno.ENOENT and not must_exist:
+            return 0
         logging.warning("%s: open: %s" % (pidfile, os.strerror(e.errno)))
         return -e.errno
 
@@ -407,6 +415,16 @@ def read_pidfile(pidfile):
         except IOError:
             pass
 
+def read_pidfile(pidfile):
+    """Opens and reads a PID from 'pidfile'.  Returns the positive PID if
+    successful, otherwise a negative errno value."""
+    return __read_pidfile(pidfile, True)
+
+def read_pidfile_if_exists(pidfile):
+    """Opens and reads a PID from 'pidfile'.  Returns 0 if 'pidfile' does not
+    exist, the positive PID if successful, otherwise a negative errno value."""
+    return __read_pidfile(pidfile, False)
+
 # XXX Python's getopt does not support options with optional arguments, so we
 # have to separate --pidfile (with no argument) from --pidfile-name (with an
 # argument).  Need to write our own getopt I guess.