Synnefo » snf-ganeti

def _GetProcStatusPath(pid):

  """Returns the path for a PID's proc status file.

  @type pid: int

  @param pid: Process ID

  @rtype: string

  """

  return "/proc/%d/status" % pid

    return Retry(_TryStat, (0.01, 1.5, 0.1), 0.5,

                 args=[_GetProcStatusPath(pid)])

def _ParseSigsetT(sigset):

  """Parse a rendered sigset_t value.

  This is the opposite of the Linux kernel's fs/proc/array.c:render_sigset_t

  function.

  @type sigset: string

  @param sigset: Rendered signal set from /proc/$pid/status

  @rtype: set

  @return: Set of all enabled signal numbers

  """

  result = set()

  signum = 0

  for ch in reversed(sigset):

    chv = int(ch, 16)

    # The following could be done in a loop, but it's easier to read and

    # understand in the unrolled form

    if chv & 1:

      result.add(signum + 1)

    if chv & 2:

      result.add(signum + 2)

    if chv & 4:

      result.add(signum + 3)

    if chv & 8:

      result.add(signum + 4)

    signum += 4

  return result

def _GetProcStatusField(pstatus, field):

  """Retrieves a field from the contents of a proc status file.

  @type pstatus: string

  @param pstatus: Contents of /proc/$pid/status

  @type field: string

  @param field: Name of field whose value should be returned

  @rtype: string

  """

  for line in pstatus.splitlines():

    parts = line.split(":", 1)

    if len(parts) < 2 or parts[0] != field:

      continue

    return parts[1].strip()

  return None

def IsProcessHandlingSignal(pid, signum, status_path=None):

  """Checks whether a process is handling a signal.

  @type pid: int

  @param pid: Process ID

  @type signum: int

  @param signum: Signal number

  @rtype: bool

  """

  if status_path is None:

    status_path = _GetProcStatusPath(pid)

  try:

    proc_status = ReadFile(status_path)

  except EnvironmentError, err:

    # In at least one case, reading /proc/$pid/status failed with ESRCH.

    if err.errno in (errno.ENOENT, errno.ENOTDIR, errno.EINVAL, errno.ESRCH):

      return False

    raise

  sigcgt = _GetProcStatusField(proc_status, "SigCgt")

  if sigcgt is None:

    raise RuntimeError("%s is missing 'SigCgt' field" % status_path)

  # Now check whether signal is handled

  return signum in _ParseSigsetT(sigcgt)