tests/killdaemons.py

check-code: catch Python 'is' comparing number or string literals

The Python 'is' operator compares object identity, so it should
definitely not be applied to string or number literals, which Python
implementations are free to represent with a temporary object.

This should catch the following kinds of bogus expressions (examples):

  x is 'foo'     x is not 'foo'
  x is "bar"     x is not "bar"
  x is 42        x is not 42
  x is -36       x is not -36

As originally proposed by Martin Geisler, amended with catching
negative numbers.

#!/usr/bin/env python

import os, time, errno, signal

# Kill off any leftover daemon processes
try:
    fp = open(os.environ['DAEMON_PIDS'])
    for line in fp:
        try:
            pid = int(line)
        except ValueError:
            continue
        try:
            os.kill(pid, 0)
            os.kill(pid, signal.SIGTERM)
            for i in range(10):
                time.sleep(0.05)
                os.kill(pid, 0)
            os.kill(pid, signal.SIGKILL)
        except OSError, err:
            if err.errno != errno.ESRCH:
                raise
    fp.close()
except IOError:
    pass