Take Daemon stdin/stdout/stderr args as file objects

Previously Daemon constructor took stdin/stdout/stderr as
paths (defaulting to '/dev/null') and opened them as regular files.
This greatly limits the type of filehandles supported (no pipes, for
example), and doesn't allow simple things like reusing existing fds.

This change switches to accepting file objects rather than strings,
and uses a sentinal value to represent the previous "open /dev/null"
default behaviour.

Change-Id: I51b36ce912194abd89ed46fad9943802f271444a

diff --git a/neutron/agent/linux/daemon.py b/neutron/agent/linux/daemon.py
index f9866445fedcae1fb8c03ff5f03beea1e92e447e..f180f5432287eae93b6898d40acdf58508adbefd 100644 (file)
--- a/neutron/agent/linux/daemon.py
+++ b/neutron/agent/linux/daemon.py
@@ -29,6 +29,8 @@ from neutron.i18n import _LE, _LI
 
 LOG = logging.getLogger(__name__)
 
+DEVNULL = object()
+
 
 def setuid(user_id_or_name):
     try:
@@ -155,8 +157,8 @@ class Daemon(object):
 
     Usage: subclass the Daemon class and override the run() method
     """
-    def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null',
-                 stderr='/dev/null', procname='python', uuid=None,
+    def __init__(self, pidfile, stdin=DEVNULL, stdout=DEVNULL,
+                 stderr=DEVNULL, procname='python', uuid=None,
                  user=None, group=None, watch_log=True):
         self.stdin = stdin
         self.stdout = stdout
@@ -192,9 +194,10 @@ class Daemon(object):
         # redirect standard file descriptors
         sys.stdout.flush()
         sys.stderr.flush()
-        stdin = open(self.stdin, 'r')
-        stdout = open(self.stdout, 'a+')
-        stderr = open(self.stderr, 'a+', 0)
+        devnull = open(os.devnull, 'w+')
+        stdin = devnull if self.stdin is DEVNULL else self.stdin
+        stdout = devnull if self.stdout is DEVNULL else self.stdout
+        stderr = devnull if self.stderr is DEVNULL else self.stderr
         os.dup2(stdin.fileno(), sys.stdin.fileno())
         os.dup2(stdout.fileno(), sys.stdout.fileno())
         os.dup2(stderr.fileno(), sys.stderr.fileno())

diff --git a/neutron/tests/unit/agent/linux/test_daemon.py b/neutron/tests/unit/agent/linux/test_daemon.py
index 7293ae4b3a4895524f24ec0aa0f38c6389abef6a..b4bb355e1a9fba8ec4975a48975de47d9a6c95bb 100644 (file)
--- a/neutron/tests/unit/agent/linux/test_daemon.py
+++ b/neutron/tests/unit/agent/linux/test_daemon.py
@@ -242,6 +242,8 @@ class TestDaemon(base.BaseTestCase):
                 d._fork()
 
     def test_daemonize(self):
+        self.os.devnull = '/dev/null'
+
         d = daemon.Daemon('pidfile')
         with mock.patch.object(d, '_fork') as fork:
             with mock.patch.object(daemon, 'atexit') as atexit: