#!/usr/bin/python

'Launch a Git Daemon on an ephemeral port, and report which port was used.'

import argparse
import contextlib
import pipes
import socket
import subprocess
import sys

# Parse arguments with bare argparse, since cliapp hates unknown options
class UnsupportedArgument(argparse.Action):
    def __call__(self, parser, namespace, values, option_string=None):
        sys.stderr.write('%s not supported\n' % option_string)
        sys.exit(1)

parser = argparse.ArgumentParser(description=__doc__)
for arg in ('user', 'group', 'detach', 'port', 'syslog', 'pid-file'):
    parser.add_argument('--' + arg, action=UnsupportedArgument)
parser.add_argument('--listen', default='127.0.0.1')
parser.add_argument('--port-file', required=True,
                    help='Report which port the git daemon was bound to.')
options, args = parser.parse_known_args()

with contextlib.closing(socket.socket()) as sock:
    sock.bind((options.listen, 0))
    host, port = sock.getsockname()
    with open(options.port_file, 'w') as f:
        f.write('%s\n' % port)
    sock.listen(1)
    while True:
        conn, addr = sock.accept()
        with contextlib.closing(conn):
            gitcmd = ['git', 'daemon', '--inetd']
            gitcmd.extend(args)
            cmdstr = (' '.join(map(pipes.quote, gitcmd)))
            sys.stderr.write('Running %s' % cmdstr)
            ret = subprocess.call(args=gitcmd, stdin=conn, stdout=conn,
                                  stderr=conn, close_fds=True)
            if ret != 0:
                sys.stderr.write('%s exited %d\n' % (cmdstr, ret))
            # git-daemon returns 255 when the repo doesn't exist
            if ret not in (0, 255):
                break
sys.exit(ret)