mercurial/hgweb/wsgicgi.py

packaging: add support for PyOxidizer

I've successfully built Mercurial on the development tip of
PyOxidizer on Linux and Windows. It mostly "just works" on Linux.
Windows is a bit more finicky.

In-memory resource files are probably not all working correctly
due to bugs in PyOxidizer's naming of modules. PyOxidizer now
now supports installing files next to the produced binary. (We
do this for templates in the added file.) So a workaround
should be available.

Also, since the last time I submitted support for PyOxidizer,
PyOxidizer gained the ability to auto-generate Rust projects
to build executables. So we don't need to worry about vendoring
any Rust code to initially support PyOxidizer. However, at some
point we will likely want to write our own command line driver
that embeds a Python interpreter via PyOxidizer so we can run
Rust code outside the confines of a Python interpreter. But that
will be a follow-up.

I would also like to add packaging.py CLI commands to build
PyOxidizer distributions. This can come later, if ever.
PyOxidizer's new "targets" feature makes it really easy to define
packaging tasks in its Starlark configuration file. While not
much is implemented yet, eventually we should be able to produce
MSIs, etc using a `pyoxidizer build` one-liner. We'll get there...

Differential Revision: https://phab.mercurial-scm.org/D7450

# hgweb/wsgicgi.py - CGI->WSGI translator
#
# Copyright 2006 Eric Hopper <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
#
# This was originally copied from the public domain code at
# http://www.python.org/dev/peps/pep-0333/#the-server-gateway-side

from __future__ import absolute_import

import os

from ..pycompat import getattr
from .. import pycompat

from ..utils import procutil

from . import common


def launch(application):
    procutil.setbinary(procutil.stdin)
    procutil.setbinary(procutil.stdout)

    environ = dict(pycompat.iteritems(os.environ))  # re-exports
    environ.setdefault('PATH_INFO', b'')
    if environ.get('SERVER_SOFTWARE', '').startswith('Microsoft-IIS'):
        # IIS includes script_name in PATH_INFO
        scriptname = environ['SCRIPT_NAME']
        if environ['PATH_INFO'].startswith(scriptname):
            environ['PATH_INFO'] = environ['PATH_INFO'][len(scriptname) :]

    stdin = procutil.stdin
    if environ.get('HTTP_EXPECT', '').lower() == '100-continue':
        stdin = common.continuereader(stdin, procutil.stdout.write)

    environ['wsgi.input'] = stdin
    environ['wsgi.errors'] = procutil.stderr
    environ['wsgi.version'] = (1, 0)
    environ['wsgi.multithread'] = False
    environ['wsgi.multiprocess'] = True
    environ['wsgi.run_once'] = True

    if environ.get('HTTPS', 'off').lower() in ('on', '1', 'yes'):
        environ['wsgi.url_scheme'] = 'https'
    else:
        environ['wsgi.url_scheme'] = 'http'

    headers_set = []
    headers_sent = []
    out = procutil.stdout

    def write(data):
        if not headers_set:
            raise AssertionError(b"write() before start_response()")

        elif not headers_sent:
            # Before the first output, send the stored headers
            status, response_headers = headers_sent[:] = headers_set
            out.write(b'Status: %s\r\n' % pycompat.bytesurl(status))
            for hk, hv in response_headers:
                out.write(
                    b'%s: %s\r\n'
                    % (pycompat.bytesurl(hk), pycompat.bytesurl(hv))
                )
            out.write(b'\r\n')

        out.write(data)
        out.flush()

    def start_response(status, response_headers, exc_info=None):
        if exc_info:
            try:
                if headers_sent:
                    # Re-raise original exception if headers sent
                    raise exc_info[0](exc_info[1], exc_info[2])
            finally:
                del exc_info  # avoid dangling circular ref
        elif headers_set:
            raise AssertionError(b"Headers already set!")

        headers_set[:] = [status, response_headers]
        return write

    content = application(environ, start_response)
    try:
        for chunk in content:
            write(chunk)
        if not headers_sent:
            write(b'')  # send headers now if body was empty
    finally:
        getattr(content, 'close', lambda: None)()