[1/3] bitbake-setup: add the initial implementation

diff --git a/bin/bitbake-setup b/bin/bitbake-setup
new file mode 100755
index 000000000..ef7ce35b4
--- /dev/null
+++ b/bin/bitbake-setup
@@ -0,0 +1,791 @@ 
+#!/usr/bin/env python3
+
+#
+# SPDX-License-Identifier: GPL-2.0-only
+#
+
+import logging
+import os
+import sys
+import argparse
+import warnings
+import json
+import shutil
+import time
+import stat
+import tempfile
+import configparser
+import datetime
+
+default_registry = 'git://github.com/kanavin/bitbake-setup-configurations.git;protocol=https;branch=main;rev=main'
+
+bindir = os.path.abspath(os.path.dirname(__file__))
+sys.path[0:0] = [os.path.join(os.path.dirname(bindir), 'lib')]
+
+import bb.msg
+import bb.process
+
+logger = bb.msg.logger_create('bitbake-setup', sys.stdout)
+
+def cache_dir(top_dir):
+    return os.path.join(top_dir, '.bitbake-setup-cache')
+
+def init_bb_cache(settings, args):
+    dldir = settings["default"]["dl-dir"]
+    bb_cachedir = os.path.join(cache_dir(args.top_dir), 'bitbake-cache')
+
+    d = bb.data.init()
+    d.setVar("DL_DIR", dldir)
+    d.setVar("BB_CACHEDIR", bb_cachedir)
+    d.setVar("__BBSRCREV_SEEN", "1")
+    if args.no_network:
+        d.setVar("BB_SRCREV_POLICY", "cache")
+    bb.fetch.fetcher_init(d)
+    return d
+
+def save_bb_cache():
+    bb.fetch2.fetcher_parse_save()
+    bb.fetch2.fetcher_parse_done()
+
+def get_config_name(config):
+    return os.path.basename(config).split('.')[0]
+
+def write_config(config, config_dir):
+    with open(os.path.join(config_dir, "config-upstream.json"),'w') as s:
+        json.dump(config, s, sort_keys=True, indent=4)
+
+def commit_config(config_dir):
+    bb.process.run("git -C {} add .".format(config_dir))
+    bb.process.run("git -C {} commit --no-verify -a -m 'Configuration at {}'".format(config_dir, time.asctime()))
+
+def _write_layer_list(dest, repodirs):
+    layers = []
+    for r in repodirs:
+        for root, dirs, files in os.walk(os.path.join(dest,r)):
+            if os.path.basename(root) == 'conf' and 'layer.conf' in files:
+                layers.append(os.path.relpath(os.path.dirname(root), dest))
+    layers_f = os.path.join(dest, ".oe-layers.json")
+    with open(layers_f, 'w') as f:
+        json.dump({"version":"1.0","layers":layers}, f, sort_keys=True, indent=4)
+
+def checkout_layers(layers, layerdir, d):
+    repodirs = []
+    oesetupbuild = None
+    print("Fetching layer/tool repositories into {}".format(layerdir))
+    for r_name in layers:
+        r_data = layers[r_name]
+        repodir = r_data["path"]
+        repodirs.append(repodir)
+
+        r_remote = r_data['git-remote']
+        rev = r_remote['rev']
+        remotes = r_remote['remotes']
+
+        for remote in remotes:
+            type,host,path,user,pswd,params = bb.fetch.decodeurl(remotes[remote]["uri"])
+            fetchuri = bb.fetch.encodeurl(('git',host,path,user,pswd,params))
+            print("    {}".format(r_name))
+            fetcher = bb.fetch.Fetch(["{};protocol={};rev={};nobranch=1;destsuffix={}".format(fetchuri,type,rev,repodir)], d)
+            do_fetch(fetcher, layerdir)
+
+        if os.path.exists(os.path.join(layerdir, repodir, 'scripts/oe-setup-build')):
+            oesetupbuild = os.path.join(layerdir, repodir, 'scripts/oe-setup-build')
+            oeinitbuildenv = os.path.join(layerdir, repodir, 'oe-init-build-env')
+
+    print("        ")
+    _write_layer_list(layerdir, repodirs)
+
+    if oesetupbuild:
+        links = {'setup-build': oesetupbuild, 'oe-scripts': os.path.dirname(oesetupbuild), 'init-build-env': oeinitbuildenv}
+        for l,t in links.items():
+            symlink = os.path.join(layerdir, l)
+            if os.path.lexists(symlink):
+                os.remove(symlink)
+            os.symlink(os.path.relpath(t,layerdir),symlink)
+
+def setup_bitbake_build(bitbake_config, layerdir, builddir):
+    def _setup_build_conf(layers, build_conf_dir):
+        os.makedirs(build_conf_dir)
+        layers_s = "\n".join(["  {} \\".format(os.path.join(layerdir,l)) for l in layers])
+        bblayers_conf = """BBLAYERS ?= " \
+{}
+  "
+""".format(layers_s)
+        with open(os.path.join(build_conf_dir, "bblayers.conf"), 'w') as f:
+            f.write(bblayers_conf)
+
+        local_conf = """#
+# This file is intended for local configuration tweaks.
+#
+# If you would like to publish and share changes made to this file,
+# it is recommended to put them into a distro config, or to create
+# layer fragments from changes made here.
+#
+"""
+        with open(os.path.join(build_conf_dir, "local.conf"), 'w') as f:
+            f.write(local_conf)
+
+        with open(os.path.join(build_conf_dir, "templateconf.cfg"), 'w') as f:
+            f.write("")
+
+        with open(os.path.join(build_conf_dir, "conf-summary.txt"), 'w') as f:
+            f.write(bitbake_config["description"] + "\n")
+
+        with open(os.path.join(build_conf_dir, "conf-notes.txt"), 'w') as f:
+            f.write("")
+
+    def _make_init_build_env(builddir, initbuildenv):
+        cmd = ". {} {}".format(initbuildenv, builddir)
+        initbuild_in_builddir = os.path.join(builddir, 'init-build-env')
+        with open(initbuild_in_builddir, 'w') as f:
+            f.write(cmd)
+
+    bitbake_builddir = os.path.join(builddir, "build")
+    print("Setting up bitbake configuration in\n    {}\n".format(bitbake_builddir))
+
+    template = bitbake_config.get("oe-template")
+    layers = bitbake_config.get("bb-layers")
+    if not template and not layers:
+        print("Bitbake configuration does not contain a reference to an OpenEmbedded build template via 'oe-template' or a list of layers via 'bb-layers'; please use oe-setup-build, oe-init-build-env or another mechanism manually to complete the setup.")
+        return
+    oesetupbuild = os.path.join(layerdir, 'setup-build')
+    if template and not os.path.exists(oesetupbuild):
+        raise Exception("Cannot complete setting up a bitbake build directory from OpenEmbedded template '{}' as oe-setup-build was not found in any layers; please use oe-init-build-env manually.".format(template))
+
+    bitbake_confdir = os.path.join(bitbake_builddir, 'conf')
+    backup_bitbake_confdir = bitbake_confdir + "-backup.{}".format(time.strftime("%Y%m%d%H%M%S"))
+    if os.path.exists(bitbake_confdir):
+        os.rename(bitbake_confdir, backup_bitbake_confdir)
+
+    if layers:
+        _setup_build_conf(layers, bitbake_confdir)
+
+    if template:
+        bb.process.run("{} setup -c {} -b {} --no-shell".format(oesetupbuild, template, bitbake_builddir))
+    else:
+        initbuildenv = os.path.join(layerdir, 'init-build-env')
+        if not os.path.exists(initbuildenv):
+            print("Could not find oe-init-build-env in any of the layers; please use another mechanism to initialize the bitbake environment")
+            return
+        _make_init_build_env(bitbake_builddir, os.path.realpath(initbuildenv))
+
+    siteconf_symlink = os.path.join(bitbake_confdir, "site.conf")
+    siteconf = os.path.normpath(os.path.join(builddir, '..', "site.conf"))
+    if os.path.lexists(siteconf_symlink):
+        os.remove(symlink)
+    os.symlink(os.path.relpath(siteconf, bitbake_confdir) ,siteconf_symlink)
+
+
+    init_script = os.path.join(bitbake_builddir, "init-build-env")
+    shell = os.path.basename(os.environ.get("SHELL","bash"))
+    fragments = bitbake_config.get("oe-fragments", []) + sorted(bitbake_config.get("oe-fragment-choices",{}).values())
+    if fragments:
+        bb.process.run("{} -c '. {} && bitbake-config-build enable-fragment {}'".format(shell, init_script, " ".join(fragments)))
+
+    if os.path.exists(backup_bitbake_confdir):
+        bitbake_config_diff = get_diff(backup_bitbake_confdir, bitbake_confdir)
+        if bitbake_config_diff:
+            print("Existing bitbake configuration directory renamed to {}".format(backup_bitbake_confdir))
+            print("The bitbake configuration has changed:")
+            print(bitbake_config_diff)
+        else:
+            shutil.rmtree(backup_bitbake_confdir)
+
+    print("This bitbake configuration provides:\n    {}\n".format(bitbake_config["description"]))
+
+    readme = """{}\n\nAdditional information is in {} and {}\n
+Source the environment using '. {}' to run builds from the command line.
+The bitbake configuration files (local.conf, bblayers.conf and more) can be found in {}/conf
+""".format(
+        bitbake_config["description"],
+        os.path.join(bitbake_builddir,'conf/conf-summary.txt'),
+        os.path.join(bitbake_builddir,'conf/conf-notes.txt'),
+        init_script,
+        bitbake_builddir
+        )
+    readme_file = os.path.join(bitbake_builddir, "README")
+    with open(readme_file, 'w') as f:
+        f.write(readme)
+    print("Usage instructions and additional information are in\n     {}\n".format(readme_file))
+    print("The bitbake configuration files (local.conf, bblayers.conf and more) can be found in\n    {}/conf\n".format(bitbake_builddir))
+    print("To run builds, source the environment using\n    source {}".format(init_script))
+
+def get_registry_config(registry_path, id):
+    for root, dirs, files in os.walk(registry_path):
+        for f in files:
+            if f.endswith('.conf.json') and id == get_config_name(f):
+                return os.path.join(root, f)
+    raise Exception("Unable to find {} in available configurations; use 'list' sub-command to see what is available".format(id))
+
+def update_build(config, confdir, builddir, layerdir, d):
+    layer_config = config["data"]["sources"]
+    layer_overrides = config["source-overrides"]["sources"]
+    for k,v in layer_overrides.items():
+        if k in layer_config:
+            layer_config[k]["git-remote"] = v["git-remote"]
+    checkout_layers(layer_config, layerdir, d)
+    bitbake_config = config["bitbake-config"]
+    setup_bitbake_build(bitbake_config, layerdir, builddir)
+
+def flatten_bitbake_configs(configs):
+    def merge_configs(c1,c2):
+        c_merged = {}
+        for k,v in c2.items():
+            if k not in c1.keys():
+                c_merged[k] = v
+        for k,v in c1.items():
+            if k not in c2.keys():
+                c_merged[k] = v
+            else:
+               c_merged[k] = c1[k] + c2[k]
+        del c_merged['configurations']
+        return c_merged
+
+    flattened_configs = []
+    for c in configs:
+        if 'configurations' not in c:
+            flattened_configs.append(c)
+        else:
+            for sub_c in flatten_bitbake_configs(c['configurations']):
+                flattened_configs.append(merge_configs(c, sub_c))
+    return flattened_configs
+
+def choose_bitbake_config(configs, parameters, non_interactive):
+    flattened_configs = flatten_bitbake_configs(configs)
+    configs_dict = {i["name"]:i for i in flattened_configs}
+
+    if parameters:
+        config_id = parameters[0]
+        if config_id not in configs_dict:
+            raise Exception("Bitbake configuration {} not found; replace with one of {}".format(config_id, configs_dict))
+        return configs_dict[config_id]
+
+    enumerated_configs = list(enumerate(flattened_configs))
+    if len(enumerated_configs) == 1:
+        only_config = flattened_configs[0]
+        print("\nSelecting the only available bitbake configuration {}".format(only_config["name"]))
+        return only_config
+
+    if non_interactive:
+        raise Exception("Unable to choose from bitbake configurations in non-interactive mode: {}".format(configs_dict))
+
+    print("\nAvailable bitbake configurations:")
+    for n, config_data in enumerated_configs:
+        print("{}. {}\t{}".format(n, config_data["name"], config_data["description"]))
+    print("\nPlease select one of the above bitbake configurations by its number:")
+    config_n = int(input())
+    return flattened_configs[config_n]
+
+def choose_config(configs, non_interactive):
+    not_expired_configs = [k for k in configs.keys() if not has_expired(configs[k].get("expires", None))]
+    config_list = list(enumerate(not_expired_configs))
+    if len(config_list) == 1:
+        only_config = config_list[0][1]
+        print("\nSelecting the only available configuration {}\n".format(only_config))
+        return only_config
+
+    if non_interactive:
+        raise Exception("Unable to choose from configurations in non-interactive mode: {}".format(not_expired_configs))
+
+    print("\nAvailable configurations:")
+    for n, config_name in config_list:
+        config_data = configs[config_name]
+        expiry_date = config_data.get("expires", None)
+        config_desc = config_data["description"]
+        if expiry_date:
+           print("{}. {}\t{} (supported until {})".format(n, config_name, config_desc, expiry_date))
+        else:
+           print("{}. {}\t{}".format(n, config_name, config_desc))
+    print("\nPlease select one of the above configurations by its number:")
+    config_n = int(input())
+    return config_list[config_n][1]
+
+def choose_fragments(possibilities, parameters, non_interactive):
+    choices = {}
+    for k,v in possibilities.items():
+        choice = [o for o in v["options"] if o in parameters]
+        if len(choice) > 1:
+            raise Exception("Options specified on command line do not allow a single selection from possibilities {}, please remove one or more from {}".format(v["options"], parameters))
+        if len(choice) == 1:
+            choices[k] = choice[0]
+            continue
+
+        if non_interactive:
+            raise Exception("Unable to choose from options in non-interactive mode: {}".format(v["options"]))
+
+        print("\n" + v["description"] + ":")
+        options_enumerated = list(enumerate(v["options"]))
+        for n,o in options_enumerated:
+            print("{}. {}".format(n, o))
+        print("\nPlease select one of the above options by its number:")
+        option_n = int(input())
+        choices[k] = options_enumerated[option_n][1]
+    return choices
+
+def obtain_config(settings, args, source_overrides, d):
+    if args.config:
+        config_id = args.config[0]
+        config_parameters = args.config[1:]
+        if os.path.exists(config_id):
+            print("Reading configuration from local file\n    {}".format(config_id))
+            upstream_config = {'type':'local',
+                               'path':os.path.abspath(config_id),
+                               'name':get_config_name(config_id),
+                               'data':json.load(open(config_id))
+                               }
+        elif config_id.startswith("http://") or config_id.startswith("https://"):
+            print("Reading configuration from network URI\n    {}".format(config_id))
+            import urllib.request
+            with urllib.request.urlopen(config_id) as f:
+              upstream_config = {'type':'network','uri':config_id,'name':get_config_name(config_id),'data':json.load(f)}
+        else:
+            print("Looking up config {} in configuration registry".format(config_id))
+            registry_path = update_registry(settings["default"]["registry"], cache_dir(args.top_dir), d)
+            registry_configs = list_registry(registry_path, with_expired=True)
+            if config_id not in registry_configs:
+                raise Exception("Config {} not found in configuration registry, re-run 'init' without parameters to choose from available configurations.".format(config_id))
+            upstream_config = {'type':'registry','registry':settings["default"]["registry"],'name':config_id,'data':json.load(open(get_registry_config(registry_path,config_id)))}
+        expiry_date = upstream_config['data'].get("expires", None)
+        if has_expired(expiry_date):
+            print("This configuration is no longer supported after {}. Please consider changing to a supported configuration.".format(expiry_date))
+    else:
+        registry_path = update_registry(settings["default"]["registry"], cache_dir(args.top_dir), d)
+        registry_configs = list_registry(registry_path, with_expired=True)
+        config_id = choose_config(registry_configs, args.non_interactive)
+        config_parameters = []
+        upstream_config = {'type':'registry','registry':settings["default"]["registry"],'name':config_id,'data':json.load(open(get_registry_config(registry_path,config_id)))}
+
+    upstream_config['bitbake-config'] = choose_bitbake_config(upstream_config['data']['bitbake-setup']['configurations'], config_parameters, args.non_interactive)
+    upstream_config['bitbake-config']['oe-fragment-choices'] = choose_fragments(upstream_config['bitbake-config'].get('oe-fragments-one-of',{}), config_parameters[1:], args.non_interactive)
+    upstream_config['non-interactive-cmdline-options'] = [config_id, upstream_config['bitbake-config']['name']] + sorted(upstream_config['bitbake-config']['oe-fragment-choices'].values())
+    upstream_config['source-overrides'] = source_overrides
+    return upstream_config
+
+def init_config(settings, args, d):
+    stdout = sys.stdout
+    def handle_task_progress(event, d):
+        rate = event.rate if event.rate else ''
+        progress = event.progress if event.progress > 0 else 0
+        print("{}% {}                ".format(progress, rate), file=stdout, end='\r')
+
+    source_overrides = json.load(open(args.source_overrides)) if args.source_overrides else {'sources':{}}
+    upstream_config = obtain_config(settings, args, source_overrides, d)
+    print("\nRun 'bitbake-setup init --non-interactive {}' to select this configuration non-interactively.\n".format(" ".join(upstream_config['non-interactive-cmdline-options'])))
+
+    builddir = os.path.join(os.path.abspath(args.top_dir), "{}-{}".format(upstream_config['name']," ".join(upstream_config['non-interactive-cmdline-options'][1:]).replace(" ","-").replace("/","_")))
+    if os.path.exists(builddir):
+        print("Build already initialized in {}\nUse 'bitbake-setup status' to check if it needs to be updated or 'bitbake-setup update' to perform the update.".format(builddir))
+        return
+
+    print("Initializing a build in\n    {}".format(builddir))
+    if not args.non_interactive:
+        y_or_n = input('Continue? y/n: ')
+        if y_or_n != 'y':
+            exit()
+        print()
+
+
+    os.makedirs(builddir)
+
+    confdir = os.path.join(builddir, "config")
+    layerdir = os.path.join(builddir, "layers")
+
+    os.makedirs(confdir)
+    os.makedirs(layerdir)
+
+    bb.process.run("git -C {} init -b main".format(confdir))
+    # Make sure commiting doesn't fail if no default git user is configured on the machine
+    bb.process.run("git -C {} config user.name bitbake-setup".format(confdir))
+    bb.process.run("git -C {} config user.email bitbake-setup@not.set".format(confdir))
+    bb.process.run("git -C {} commit --no-verify --allow-empty -m 'Initial commit'".format(confdir))
+
+    bb.event.register("bb.build.TaskProgress", handle_task_progress, data=d)
+
+    write_config(upstream_config, confdir)
+    commit_config(confdir)
+    update_build(upstream_config, confdir, builddir, layerdir, d)
+
+    bb.event.remove("bb.build.TaskProgress", None)
+
+def get_diff(file1, file2):
+    try:
+        bb.process.run('diff -uNr {} {}'.format(file1, file2))
+    except bb.process.ExecutionError as e:
+        if e.exitcode == 1:
+            return e.stdout
+        else:
+            raise e
+    return None
+
+def are_layers_changed(layers, layerdir, d):
+    changed = False
+    for r_name in layers:
+        r_data = layers[r_name]
+        repodir = r_data["path"]
+
+        r_remote = r_data['git-remote']
+        rev = r_remote['rev']
+        remotes = r_remote['remotes']
+
+        for remote in remotes:
+            type,host,path,user,pswd,params = bb.fetch.decodeurl(remotes[remote]["uri"])
+            fetchuri = bb.fetch.encodeurl(('git',host,path,user,pswd,params))
+            fetcher = bb.fetch.FetchData("{};protocol={};rev={};nobranch=1;destsuffix={}".format(fetchuri,type,rev,repodir), d)
+            upstream_revision = fetcher.method.latest_revision(fetcher, d, 'default')
+            rev_parse_result = bb.process.run('git -C {} rev-parse HEAD'.format(os.path.join(layerdir, repodir)))
+            local_revision = rev_parse_result[0].strip()
+            if upstream_revision != local_revision:
+                changed = True
+                print('Layer repository {} checked out into {} updated revision {} from {} to {}'.format(remotes[remote]["uri"], os.path.join(layerdir, repodir), rev, local_revision, upstream_revision))
+
+    return changed
+
+def build_status(settings, args, d, update=False):
+    builddir = args.build_dir
+
+    confdir = os.path.join(builddir, "config")
+    layerdir = os.path.join(builddir, "layers")
+
+    current_upstream_config = json.load(open(os.path.join(confdir, "config-upstream.json")))
+
+    args.config = current_upstream_config['non-interactive-cmdline-options']
+    args.non_interactive = True
+    source_overrides = current_upstream_config["source-overrides"]
+    new_upstream_config = obtain_config(settings, args, source_overrides, d)
+
+    write_config(new_upstream_config, confdir)
+    config_diff = bb.process.run('git -C {} diff'.format(confdir))[0]
+
+    if config_diff:
+        print('\nConfiguration in {} has changed:\n{}'.format(builddir, config_diff))
+        if update:
+            commit_config(confdir)
+            update_build(new_upstream_config, confdir, builddir, layerdir, d)
+        else:
+            bb.process.run('git -C {} restore config-upstream.json'.format(confdir))
+        return
+
+    if are_layers_changed(current_upstream_config["data"]["sources"], layerdir, d):
+        if update:
+            update_build(current_upstream_config, confdir, builddir, layerdir, d)
+        return
+
+    print("\nConfiguration in {} has not changed.".format(builddir))
+
+def build_update(settings, args, d):
+    build_status(settings, args, d, update=True)
+
+def do_fetch(fetcher, dir):
+    # git fetcher simply dumps git output to stdout; in bitbake context that is redirected to temp/log.do_fetch
+    # and we need to set up smth similar here
+    fetchlogdir = os.path.join(dir, 'logs')
+    os.makedirs(fetchlogdir, exist_ok=True)
+    fetchlog = os.path.join(fetchlogdir, 'fetch_log.{}'.format(datetime.datetime.now().strftime("%Y%m%d%H%M%S")))
+    with open(fetchlog, 'a') as f:
+        oldstdout = sys.stdout
+        sys.stdout = f
+        fetcher.download()
+        fetcher.unpack(dir)
+        sys.stdout = oldstdout
+
+def update_registry(registry, cachedir, d):
+    registrydir = 'configurations'
+    full_registrydir = os.path.join(cachedir, registrydir)
+    print("Fetching configuration registry\n    {}\ninto\n    {}".format(registry, full_registrydir))
+    fetcher = bb.fetch.Fetch(["{};destsuffix={}".format(registry, registrydir)], d)
+    do_fetch(fetcher, cachedir)
+    return full_registrydir
+
+def has_expired(expiry_date):
+    if expiry_date:
+        return datetime.datetime.now() > datetime.datetime.fromisoformat(expiry_date)
+    return False
+
+def list_registry(registry_path, with_expired):
+    json_data = {}
+
+    for root, dirs, files in os.walk(registry_path):
+        for f in files:
+            if f.endswith('.conf.json'):
+                config_name = get_config_name(f)
+                config_data = json.load(open(os.path.join(root, f)))
+                config_desc = config_data["description"]
+                expiry_date = config_data.get("expires", None)
+                if expiry_date:
+                    if with_expired or not has_expired(expiry_date):
+                        json_data[config_name] = {"description": config_desc, "expires": expiry_date}
+                else:
+                    json_data[config_name] = {"description": config_desc}
+    return json_data
+
+def list_configs(settings, args, d):
+    registry_path = update_registry(settings["default"]["registry"], cache_dir(args.top_dir), d)
+    json_data = list_registry(registry_path, args.with_expired)
+    print("\nAvailable configurations:")
+    for config_name, config_data in json_data.items():
+        expiry_date = config_data.get("expires", None)
+        config_desc = config_data["description"]
+        if expiry_date:
+           if args.with_expired or not has_expired(expiry_date):
+               print("{}\t{} (supported until {})".format(config_name, config_desc, expiry_date))
+        else:
+           print("{}\t{}".format(config_name, config_desc))
+    print("\nRun 'init' with one of the above configuration identifiers to set up a build.")
+
+    if args.write_json:
+        with open(args.write_json, 'w') as f:
+            json.dump(json_data, f, sort_keys=True, indent=4)
+        print("Available configurations written into {}".format(args.write_json))
+
+def default_settings_path(top_dir):
+    return os.path.join(top_dir, 'bitbake-setup.conf')
+
+def write_settings(top_dir, force_replace, non_interactive=True):
+    settings_path = default_settings_path(top_dir)
+    if not os.path.exists(settings_path) or force_replace:
+
+        settings = configparser.ConfigParser()
+        settings['default'] = {
+                             'registry':default_registry,
+                             'dl-dir':os.path.join(top_dir, '.bitbake-setup-downloads'),
+                            }
+        os.makedirs(os.path.dirname(settings_path), exist_ok=True)
+
+        siteconfpath = os.path.join(top_dir, 'site.conf')
+        print('Configuration registry set to\n    {}\n'.format(settings['default']['registry']))
+        print('Bitbake-setup download cache (DL_DIR) set to\n    {}\n'.format(settings['default']['dl-dir']))
+        print('A new settings file will be created in\n    {}\n'.format(settings_path))
+        print('A common site.conf file will be created, please edit or replace before running builds\n    {}\n'.format(siteconfpath))
+        if not non_interactive:
+            y_or_n = input('Bitbake-setup will be configured with the above settings in {}, y/n: '.format(top_dir))
+            if y_or_n != 'y':
+                print("\nYou can run 'bitbake-setup install-settings' to edit them before setting up builds")
+                exit()
+            print()
+
+        if os.path.exists(settings_path):
+            backup_conf = settings_path + "-backup.{}".format(time.strftime("%Y%m%d%H%M%S"))
+            os.rename(settings_path, backup_conf)
+            print("Previous settings are in {}".format(backup_conf))
+        with open(settings_path, 'w') as settingsfile:
+            settings.write(settingsfile)
+
+        if os.path.exists(siteconfpath):
+            backup_siteconf = siteconfpath + "-backup.{}".format(time.strftime("%Y%m%d%H%M%S"))
+            os.rename(siteconfpath, backup_siteconf)
+            print("Previous settings are in {}".format(backup_siteconf))
+        with open(siteconfpath, 'w') as siteconffile:
+            siteconffile.write('# This file is intended for build host-specific bitbake settings\n')
+
+def load_settings(top_dir, non_interactive):
+    # This creates a new settings file if it does not yet exist
+    write_settings(top_dir, force_replace=False, non_interactive=non_interactive)
+
+    settings_path = default_settings_path(top_dir)
+    settings = configparser.ConfigParser()
+    print('Loading settings from\n    {}\n'.format(settings_path))
+    settings.read([settings_path])
+    return settings
+
+def global_settings_path(args):
+    return args.global_settings if args.global_settings else os.path.join(os.path.expanduser('~'), '.config', 'bitbake-setup', 'config')
+
+def write_global_settings(settings_path, force_replace, non_interactive=True):
+    if not os.path.exists(settings_path) or force_replace:
+
+        settings = configparser.ConfigParser()
+        settings['default'] = {
+                             'top-dir-prefix':os.path.expanduser('~'),
+                             'top-dir-name':'bitbake-builds'
+                            }
+        os.makedirs(os.path.dirname(settings_path), exist_ok=True)
+        print('Configuring global settings in\n    {}\n'.format(settings_path))
+        print('Top directory prefix (where all top level directories are created) set to\n    {}\n'.format(settings['default']['top-dir-prefix']))
+        print('Top directory name (this is added to the top directory prefix to form a top directory where builds are set up) set to\n    {}\n'.format(settings['default']['top-dir-name']))
+        if not non_interactive:
+            y_or_n = input('Write out the global settings as specified above (y/n)? ')
+            if y_or_n != 'y':
+                print("\nYou can run 'bitbake-setup install-global-settings' to edit them before setting up builds")
+                exit()
+            print()
+
+        if os.path.exists(settings_path):
+            backup_conf = settings_path + "-backup.{}".format(time.strftime("%Y%m%d%H%M%S"))
+            os.rename(settings_path, backup_conf)
+            print("Previous global settings are in {}".format(backup_conf))
+        with open(settings_path, 'w') as settingsfile:
+            settings.write(settingsfile)
+
+def load_global_settings(settings_path, non_interactive):
+    # This creates a new settings file if it does not yet exist
+    write_global_settings(settings_path, force_replace=False, non_interactive=non_interactive)
+
+    settings = configparser.ConfigParser()
+    print('Loading global settings from\n    {}\n'.format(settings_path))
+    settings.read([settings_path])
+    return settings
+
+def change_settings(top_dir, new_settings):
+    settings = load_settings(top_dir, non_interactive=True)
+    for section, section_settings in new_settings.items():
+        for setting, value in section_settings.items():
+            settings[section][setting] = value
+            print("Setting '{}' in section '{}' is changed to '{}'".format(setting, section, value))
+
+    settings_path = default_settings_path(top_dir)
+    with open(settings_path, 'w') as settingsfile:
+        settings.write(settingsfile)
+    print("New settings written to {}".format(settings_path))
+    return settings
+
+def change_global_settings(settings_path, new_settings):
+    settings = load_global_settings(settings_path, non_interactive=True)
+    for section, section_settings in new_settings.items():
+        for setting, value in section_settings.items():
+            settings[section][setting] = value
+            print("Setting '{}' in section '{}' is changed to '{}'".format(setting, section, value))
+
+    with open(settings_path, 'w') as settingsfile:
+        settings.write(settingsfile)
+    print("New global settings written to {}".format(settings_path))
+    return settings
+
+def get_build_dir_via_bbpath():
+    bbpath = os.environ.get('BBPATH')
+    if bbpath:
+        bitbake_dir = os.path.normpath(bbpath.split(':')[0])
+        if os.path.exists(os.path.join(bitbake_dir,'init-build-env')):
+            build_dir = os.path.dirname(bitbake_dir)
+            return build_dir
+    return None
+
+def get_top_dir(args, global_settings):
+    build_dir_via_bbpath = get_build_dir_via_bbpath()
+    if build_dir_via_bbpath:
+        top_dir = os.path.dirname(build_dir_via_bbpath)
+        if os.path.exists(default_settings_path(top_dir)):
+            return top_dir
+
+    if hasattr(args, 'build_dir'):
+        # commands without --top-dir-prefix/name arguments (status, update) still need to know where
+        # the top dir is, but it should be auto-deduced as parent of args.build_dir
+        top_dir = os.path.dirname(os.path.normpath(args.build_dir))
+        return top_dir
+
+    top_dir_prefix = args.top_dir_prefix if args.top_dir_prefix else global_settings['default']['top-dir-prefix']
+    top_dir_name = args.top_dir_name if args.top_dir_name else global_settings['default']['top-dir-name']
+    return os.path.join(top_dir_prefix, top_dir_name)
+
+def main():
+    def add_top_dir_arg(parser):
+        parser.add_argument('--top-dir-prefix', help='Top level directory prefix. This is where all top level directories are created.')
+        parser.add_argument('--top-dir-name', help='Top level directory name. Together with the top directory prefix this forms a top directory where builds are set up and downloaded configurations and layers are cached for reproducibility and offline builds.')
+
+    def add_build_dir_arg(parser):
+        build_dir = get_build_dir_via_bbpath()
+        if build_dir:
+            parser.add_argument('--build-dir', default=build_dir, help="Path to the build, default is %(default)s via BBPATH")
+        else:
+            parser.add_argument('--build-dir', required=True, help="Path to the build")
+
+    parser = argparse.ArgumentParser(
+        description="BitBake setup utility. Run with 'init' argument to get started.",
+        epilog="Use %(prog)s <subcommand> --help to get help on a specific command"
+        )
+    parser.add_argument('-d', '--debug', help='Enable debug output', action='store_true')
+    parser.add_argument('-q', '--quiet', help='Print only errors', action='store_true')
+    parser.add_argument('--color', choices=['auto', 'always', 'never'], default='auto', help='Colorize output (where %(metavar)s is %(choices)s)', metavar='COLOR')
+    parser.add_argument('--no-network', action='store_true', help='Do not check whether configuration repositories and layer repositories have been updated; use only the local cache.')
+    parser.add_argument('--global-settings', action='store', help='Path to the global settings file where defaults for top directory prefix and name can be specified')
+
+    subparsers = parser.add_subparsers()
+
+    parser_list = subparsers.add_parser('list', help='List available configurations')
+    add_top_dir_arg(parser_list)
+    parser_list.add_argument('--with-expired', action='store_true', help='List also configurations that are no longer supported due to reaching their end-of-life dates.')
+    parser_list.add_argument('--write-json', action='store', help='Write available configurations into a json file so they can be programmatically processed.')
+    parser_list.set_defaults(func=list_configs)
+
+    parser_init = subparsers.add_parser('init', help='Select a configuration and initialize a build from it')
+    add_top_dir_arg(parser_init)
+    parser_init.add_argument('config', nargs='*', help="path/URL/id to a configuration file (use 'list' command to get available ids), followed by configuration options. Bitbake-setup will ask to choose from available choices if command line doesn't completely specify them.")
+    parser_init.add_argument('--non-interactive', action='store_true', help='Do not ask to interactively choose from available options; if bitbake-setup cannot make a decision it will stop with a failure.')
+    parser_init.add_argument('--source-overrides', action='store', help='Override sources information (repositories/revisions) with values from a local json file.')
+    parser_init.set_defaults(func=init_config)
+
+    parser_status = subparsers.add_parser('status', help='Check if the build needs to be synchronized with configuration')
+    add_build_dir_arg(parser_status)
+    parser_status.set_defaults(func=build_status)
+
+    parser_update = subparsers.add_parser('update', help='Update a build to be in sync with configuration')
+    add_build_dir_arg(parser_update)
+    parser_update.set_defaults(func=build_update)
+
+    parser_install_settings = subparsers.add_parser('install-settings', help='Write a settings file with default values into the top level directory (contains the location of build configuration registry, downloads directory and other settings specific to a top directory)')
+    add_top_dir_arg(parser_install_settings)
+    parser_install_settings.set_defaults(func=write_settings)
+
+    parser_install_global_settings = subparsers.add_parser('install-global-settings', help='Write a global settings file with default values (contains the default prefix and name of the top directory)')
+    parser_install_global_settings.set_defaults(func=write_global_settings)
+
+    parser_change_setting = subparsers.add_parser('change-setting', help='Change a setting in the settings file')
+    add_top_dir_arg(parser_change_setting)
+    parser_change_setting.add_argument('section', help="Section in a settings file, typically 'default'")
+    parser_change_setting.add_argument('key', help="Name of the setting")
+    parser_change_setting.add_argument('value', help="Value of the setting")
+    parser_change_setting.set_defaults(func=change_settings)
+
+    parser_change_global_setting = subparsers.add_parser('change-global-setting', help='Change a setting in the global settings file')
+    parser_change_global_setting.add_argument('section', help="Section in a global settings file, typically 'default'")
+    parser_change_global_setting.add_argument('key', help="Name of the setting")
+    parser_change_global_setting.add_argument('value', help="Value of the setting")
+    parser_change_global_setting.set_defaults(func=change_global_settings)
+
+    args = parser.parse_args()
+
+    logging.basicConfig(stream=sys.stdout)
+    if args.debug:
+        logger.setLevel(logging.DEBUG)
+    elif args.quiet:
+        logger.setLevel(logging.ERROR)
+
+    # Need to re-run logger_create with color argument
+    # (will be the same logger since it has the same name)
+    bb.msg.logger_create('bitbake-setup', output=sys.stdout,
+                         color=args.color,
+                         level=logger.getEffectiveLevel())
+
+    if 'func' in args:
+        if args.func == write_global_settings:
+            write_global_settings(global_settings_path(args), force_replace=True)
+            return
+        elif args.func == change_global_settings:
+            change_global_settings(global_settings_path(args), {args.section:{args.key:args.value}})
+            return
+
+        if hasattr(args, 'build_dir'):
+            if not os.path.exists(os.path.join(args.build_dir,'build', 'init-build-env')):
+                print("Not a valid build directory: build/init-build-env does not exist in {}".format(args.build_dir))
+                return
+
+        if not hasattr(args, 'non_interactive'):
+            args.non_interactive = True
+
+        global_settings = load_global_settings(global_settings_path(args), args.non_interactive)
+        args.top_dir = get_top_dir(args, global_settings)
+
+        print('Bitbake-setup is using {} as top directory (can be changed with --top-dir-prefix/name arguments or by setting them in {}).\n'.format(args.top_dir, global_settings_path(args)))
+        if args.func == write_settings:
+            write_settings(args.top_dir, force_replace=True)
+        elif args.func == change_settings:
+            change_settings(args.top_dir, {args.section:{args.key:args.value}})
+        else:
+            settings = load_settings(args.top_dir, args.non_interactive)
+            d = init_bb_cache(settings, args)
+            args.func(settings, args, d)
+            save_bb_cache()
+    else:
+        from argparse import Namespace
+        parser.print_help()
+
+main()