tests/get-with-headers.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

"""This does HTTP GET requests given a host:port and path and returns
a subset of the headers plus the body of the result."""

import httplib, sys

try:
    import msvcrt, os
    msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
    pass

twice = False
if '--twice' in sys.argv:
    sys.argv.remove('--twice')
    twice = True

reasons = {'Not modified': 'Not Modified'} # python 2.4

tag = None
def request(host, path, show):

    global tag
    headers = {}
    if tag:
        headers['If-None-Match'] = tag

    conn = httplib.HTTPConnection(host)
    conn.request("GET", path, None, headers)
    response = conn.getresponse()
    print response.status, reasons.get(response.reason, response.reason)
    for h in [h.lower() for h in show]:
        if response.getheader(h, None) is not None:
            print "%s: %s" % (h, response.getheader(h))

    print
    data = response.read()
    sys.stdout.write(data)

    if twice and response.getheader('ETag', None):
        tag = response.getheader('ETag')

    return response.status

status = request(sys.argv[1], sys.argv[2], sys.argv[3:])
if twice:
    status = request(sys.argv[1], sys.argv[2], sys.argv[3:])

if 200 <= status <= 305:
    sys.exit(0)
sys.exit(1)