X-Git-Url: https://code.grnet.gr/git/ganeti-local/blobdiff_plain/339be5a8385dcdb58e85cd1385102a80f4829a11..95f84636f431ffaf777de917dabbb12bc548a678:/lib/utils.py

diff --git a/lib/utils.py b/lib/utils.py
index d0d07bc..1d0750e 100644
--- a/lib/utils.py
+++ b/lib/utils.py
@@ -46,6 +46,8 @@ import signal
 import datetime
 import calendar
 import collections
+import struct
+import IN
 
 from cStringIO import StringIO
 
@@ -69,6 +71,18 @@ no_fork = False
 
 _RANDOM_UUID_FILE = "/proc/sys/kernel/random/uuid"
 
+# Structure definition for getsockopt(SOL_SOCKET, SO_PEERCRED, ...):
+# struct ucred { pid_t pid; uid_t uid; gid_t gid; };
+#
+# The GNU C Library defines gid_t and uid_t to be "unsigned int" and
+# pid_t to "int".
+#
+# IEEE Std 1003.1-2008:
+# "nlink_t, uid_t, gid_t, and id_t shall be integer types"
+# "blksize_t, pid_t, and ssize_t shall be signed integer types"
+_STRUCT_UCRED = "iII"
+_STRUCT_UCRED_SIZE = struct.calcsize(_STRUCT_UCRED)
+
 
 class RunResult(object):
   """Holds the result of running external programs.
@@ -328,6 +342,19 @@ def RunParts(dir_name, env=None, reset_env=False):
   return rr
 
 
+def GetSocketCredentials(sock):
+  """Returns the credentials of the foreign process connected to a socket.
+
+  @param sock: Unix socket
+  @rtype: tuple; (number, number, number)
+  @return: The PID, UID and GID of the connected foreign process.
+
+  """
+  peercred = sock.getsockopt(socket.SOL_SOCKET, IN.SO_PEERCRED,
+                             _STRUCT_UCRED_SIZE)
+  return struct.unpack(_STRUCT_UCRED, peercred)
+
+
 def RemoveFile(filename):
   """Remove a file ignoring some errors.
 
@@ -539,16 +566,28 @@ def IsProcessAlive(pid):
   @return: True if the process exists
 
   """
+  def _TryStat(name):
+    try:
+      os.stat(name)
+      return True
+    except EnvironmentError, err:
+      if err.errno in (errno.ENOENT, errno.ENOTDIR):
+        return False
+      elif err.errno == errno.EINVAL:
+        raise RetryAgain(err)
+      raise
+
+  assert isinstance(pid, int), "pid must be an integer"
   if pid <= 0:
     return False
 
+  proc_entry = "/proc/%d/status" % pid
+  # /proc in a multiprocessor environment can have strange behaviors.
+  # Retry the os.stat a few times until we get a good result.
   try:
-    os.stat("/proc/%d/status" % pid)
-    return True
-  except EnvironmentError, err:
-    if err.errno in (errno.ENOENT, errno.ENOTDIR):
-      return False
-    raise
+    return Retry(_TryStat, (0.01, 1.5, 0.1), 0.5, args=[proc_entry])
+  except RetryTimeout, err:
+    err.RaiseInner()
 
 
 def ReadPidFile(pidfile):
@@ -1487,20 +1526,6 @@ def FirstFree(seq, base=0):
   return None
 
 
-def all(seq, pred=bool): # pylint: disable-msg=W0622
-  "Returns True if pred(x) is True for every element in the iterable"
-  for _ in itertools.ifilterfalse(pred, seq):
-    return False
-  return True
-
-
-def any(seq, pred=bool): # pylint: disable-msg=W0622
-  "Returns True if pred(x) is True for at least one element in the iterable"
-  for _ in itertools.ifilter(pred, seq):
-    return True
-  return False
-
-
 def SingleWaitForFdCondition(fdobj, event, timeout):
   """Waits for a condition to occur on the socket.
 
@@ -1592,12 +1617,6 @@ def WaitForFdCondition(fdobj, event, timeout):
   return result
 
 
-def partition(seq, pred=bool): # # pylint: disable-msg=W0622
-  "Partition a list in two, based on the given predicate"
-  return (list(itertools.ifilter(pred, seq)),
-          list(itertools.ifilterfalse(pred, seq)))
-
-
 def UniqueSequence(seq):
   """Returns a list with unique elements.
 
@@ -2491,12 +2510,25 @@ def ReadWatcherPauseFile(filename, now=None, remove_after=3600):
 class RetryTimeout(Exception):
   """Retry loop timed out.
 
+  Any arguments which was passed by the retried function to RetryAgain will be
+  preserved in RetryTimeout, if it is raised. If such argument was an exception
+  the RaiseInner helper method will reraise it.
+
   """
+  def RaiseInner(self):
+    if self.args and isinstance(self.args[0], Exception):
+      raise self.args[0]
+    else:
+      raise RetryTimeout(*self.args)
 
 
 class RetryAgain(Exception):
   """Retry again.
 
+  Any arguments passed to RetryAgain will be preserved, if a timeout occurs, as
+  arguments to RetryTimeout. If an exception is passed, the RaiseInner() method
+  of the RetryTimeout() method can be used to reraise it.
+
   """
 
 
@@ -2605,11 +2637,12 @@ def Retry(fn, delay, timeout, args=None, wait_fn=time.sleep,
   assert calc_delay is None or callable(calc_delay)
 
   while True:
+    retry_args = []
     try:
       # pylint: disable-msg=W0142
       return fn(*args)
-    except RetryAgain:
-      pass
+    except RetryAgain, err:
+      retry_args = err.args
     except RetryTimeout:
       raise errors.ProgrammerError("Nested retry loop detected that didn't"
                                    " handle RetryTimeout")
@@ -2617,7 +2650,8 @@ def Retry(fn, delay, timeout, args=None, wait_fn=time.sleep,
     remaining_time = end_time - _time_fn()
 
     if remaining_time < 0.0:
-      raise RetryTimeout()
+      # pylint: disable-msg=W0142
+      raise RetryTimeout(*retry_args)
 
     assert remaining_time >= 0.0