tests/get-with-headers.py

global: use python3 in shebangs

Python 3 is the future. We want Python scripts to be using Python 3
by default.

This change updates all `#!/usr/bin/env python` shebangs to use
`python3`.

Does this mean all scripts use or require Python 3: no.

In the test environment, the `PATH` environment variable in tests is
updated to guarantee that the Python executable used to run
run-tests.py is used. Since test scripts all now use
`#!/usr/bin/env python3`, we had to update this code to install
a `python3` symlink instead of `python`.

It is possible there are some random scripts now executed with the
incorrect Python interpreter in some contexts. However, I would argue
that this was a pre-existing bug: we should almost always be executing
new Python processes using the `sys.executable` from the originating
Python script, as `python` or `python3` won't guarantee we'll use the
same interpreter.

Differential Revision: https://phab.mercurial-scm.org/D9273

#!/usr/bin/env python3

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

from __future__ import absolute_import

import argparse
import json
import os
import sys

from mercurial import (
    pycompat,
    util,
)

httplib = util.httplib

try:
    import msvcrt

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

stdout = getattr(sys.stdout, 'buffer', sys.stdout)

parser = argparse.ArgumentParser()
parser.add_argument('--twice', action='store_true')
parser.add_argument('--headeronly', action='store_true')
parser.add_argument('--json', action='store_true')
parser.add_argument('--hgproto')
parser.add_argument(
    '--requestheader',
    nargs='*',
    default=[],
    help='Send an additional HTTP request header. Argument '
    'value is <header>=<value>',
)
parser.add_argument('--bodyfile', help='Write HTTP response body to a file')
parser.add_argument('host')
parser.add_argument('path')
parser.add_argument('show', nargs='*')

args = parser.parse_args()

twice = args.twice
headeronly = args.headeronly
formatjson = args.json
hgproto = args.hgproto
requestheaders = args.requestheader

tag = None


def request(host, path, show):
    assert not path.startswith('/'), path
    global tag
    headers = {}
    if tag:
        headers['If-None-Match'] = tag
    if hgproto:
        headers['X-HgProto-1'] = hgproto

    for header in requestheaders:
        key, value = header.split('=', 1)
        headers[key] = value

    conn = httplib.HTTPConnection(host)
    conn.request("GET", '/' + path, None, headers)
    response = conn.getresponse()
    stdout.write(
        b'%d %s\n' % (response.status, response.reason.encode('ascii'))
    )
    if show[:1] == ['-']:
        show = sorted(
            h for h, v in response.getheaders() if h.lower() not in show
        )
    for h in [h.lower() for h in show]:
        if response.getheader(h, None) is not None:
            stdout.write(
                b"%s: %s\n"
                % (h.encode('ascii'), response.getheader(h).encode('ascii'))
            )
    if not headeronly:
        stdout.write(b'\n')
        data = response.read()

        if args.bodyfile:
            bodyfh = open(args.bodyfile, 'wb')
        else:
            bodyfh = stdout

        # Pretty print JSON. This also has the beneficial side-effect
        # of verifying emitted JSON is well-formed.
        if formatjson:
            # json.dumps() will print trailing newlines. Eliminate them
            # to make tests easier to write.
            data = pycompat.json_loads(data)
            lines = json.dumps(data, sort_keys=True, indent=2).splitlines()
            for line in lines:
                bodyfh.write(pycompat.sysbytes(line.rstrip()))
                bodyfh.write(b'\n')
        else:
            bodyfh.write(data)

        if args.bodyfile:
            bodyfh.close()

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

    return response.status


status = request(args.host, args.path, args.show)
if twice:
    status = request(args.host, args.path, args.show)

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