path: root/bin/just-mr.py

#!/usr/bin/env python3
# Copyright 2022 Huawei Cloud Computing Technology Co., Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


import hashlib
from importlib.resources import path
import json
import os
import shutil
import subprocess
import sys
import tempfile
import time

from argparse import ArgumentParser
from pathlib import Path

JUST = "just"
ROOT = "/justroot"
DISTDIR = []

ALWAYS_FILE = False

GIT_CHECKOUT_LOCATIONS = {}

TAKE_OVER = [
    "bindings",
    "target_file_name",
    "index_file_name",
    "rule_file_name",
    "expression_file_name",
]
ALT_DIRS = [
    "target_root",
    "rule_root",
    "expression_root",
    "index_root",
]

GIT_NOBODY_ENV = {
    "GIT_AUTHOR_DATE": "1970-01-01T00:00Z",
    "GIT_AUTHOR_NAME": "Nobody",
    "GIT_AUTHOR_EMAIL": "nobody@example.org",
    "GIT_COMMITTER_DATE": "1970-01-01T00:00Z",
    "GIT_COMMITTER_NAME": "Nobody",
    "GIT_COMMITTER_EMAIL": "nobody@example.org",
    "GIT_CONFIG_GLOBAL": "/dev/null",
    "GIT_CONFIG_SYSTEM": "/dev/null",
}


def log(*args, **kwargs):
    print(*args, file=sys.stderr, **kwargs)


def fail(s):
    log(s)
    sys.exit(1)


def try_rmtree(tree):
    for _ in range(10):
        try:
            shutil.rmtree(tree)
            return
        except:
            time.sleep(1.0)
    fail("Failed to remove %s" % (tree, ))


def move_to_place(src, dst):
    os.makedirs(os.path.dirname(dst), exist_ok=True)
    try:
        os.rename(src, dst)
    except Exception as e:
        if not os.path.exists(dst):
            fail("Failed to move %s to %s: %s" % (src, dst, e))
    if not os.path.exists(dst):
        fail("%s not present after move" % (dst, ))


def run_cmd(cmd,
            *,
            env=None,
            stdout=subprocess.DEVNULL,
            stdin=None,
            cwd,
            attempts=1):
    for _ in range(attempts):
        result = subprocess.run(cmd,
                                cwd=cwd,
                                env=env,
                                stdout=stdout,
                                stdin=stdin)
        if result.returncode == 0:
            return
        time.sleep(1.0)
    if result.returncode != 0:
        fail("Command %s in %s failed" % (cmd, cwd))


def read_config(configfile):
    if configfile:
        with open(configfile) as f:
            return json.load(f)
    default_config = os.path.join(Path.home(), ".just-repos.json")

    if os.path.isfile(default_config):
        with open(default_config) as f:
            return json.load(f)

    return {}


def git_root(*, upstream):
    if upstream in GIT_CHECKOUT_LOCATIONS:
        return GIT_CHECKOUT_LOCATIONS[upstream]
    elif upstream and os.path.isabs(upstream) and os.path.isdir(upstream):
        return upstream
    else:
        return os.path.join(ROOT, "git")


def is_cache_git_root(upstream):
    """return true if upstream is the default git root in the cache directory"""
    return git_root(upstream=upstream) == git_root(upstream=None)


def git_keep(commit, *, upstream):
    if not is_cache_git_root(upstream):
        # for those, we assume the referenced commit is kept by
        # some branch anyway
        return
    run_cmd([
        "git", "tag", "-f", "-m", "Keep referenced tree alive",
        "keep-%s" % (commit, ), commit
    ],
            cwd=git_root(upstream=upstream),
            env=dict(os.environ, **GIT_NOBODY_ENV),
            attempts=3)


def git_init_options(*, upstream):
    if upstream in GIT_CHECKOUT_LOCATIONS:
        return []
    else:
        return ["--bare"]


def ensure_git(*, upstream):
    root = git_root(upstream=upstream)
    if os.path.exists(root):
        return
    os.makedirs(root)
    run_cmd(["git", "init"] + git_init_options(upstream=upstream), cwd=root)


def git_commit_present(commit, *, upstream):
    result = subprocess.run(["git", "show", "--oneline", commit],
                            stdout=subprocess.DEVNULL,
                            stderr=subprocess.DEVNULL,
                            cwd=git_root(upstream=upstream))
    return result.returncode == 0


def git_url_is_path(url):
    for prefix in ["ssh://", "http://", "https://"]:
        if url.startswith(prefix):
            return False
    return True


def git_fetch(*, repo, branch):
    if git_url_is_path(repo):
        repo = os.path.abspath(repo)
    run_cmd(["git", "fetch", repo, branch], cwd=git_root(upstream=repo))


def subdir_path(checkout, desc):
    return os.path.normpath(os.path.join(checkout, desc.get("subdir", ".")))


def git_tree(*, commit, subdir, upstream):
    tree = subprocess.run(
        ["git", "log", "-n", "1", "--format=%T", commit],
        stdout=subprocess.PIPE,
        cwd=git_root(upstream=upstream)).stdout.decode('utf-8').strip()
    return git_subtree(tree=tree, subdir=subdir, upstream=upstream)


def git_subtree(*, tree, subdir, upstream):
    if subdir == ".":
        return tree
    return subprocess.Popen(
        ["git", "cat-file", "--batch-check=%(objectname)"],
        stdout=subprocess.PIPE,
        stdin=subprocess.PIPE,
        cwd=git_root(upstream=upstream)).communicate(
            input=("%s:%s" %
                   (tree, subdir)).encode())[0].decode('utf-8').strip()


def git_checkout_dir(commit):
    return os.path.join(ROOT, "workspaces", "git", commit)


def git_checkout(desc):
    commit = desc["commit"]
    target = git_checkout_dir(commit)
    if ALWAYS_FILE and os.path.exists(target):
        return ["file", subdir_path(target, desc)]
    repo = desc["repository"]
    if git_url_is_path(repo):
        repo = os.path.abspath(repo)
    root = git_root(upstream=repo)
    ensure_git(upstream=repo)
    if not git_commit_present(commit, upstream=repo):
        branch = desc["branch"]
        log("Fetching %s from %s (in %s)" % (branch, repo, root))
        git_fetch(repo=repo, branch=branch)
        if not git_commit_present(commit, upstream=repo):
            fail("Fetching %s from %s failed to fetch %s" %
                 (branch, repo, commit))
        git_keep(commit, upstream=repo)
    if ALWAYS_FILE:
        if os.path.exists(target):
            try_rmtree(target)
        os.makedirs(target)
        with tempfile.TemporaryFile() as f:
            run_cmd(["git", "archive", commit], cwd=root, stdout=f)
            f.seek(0)
            run_cmd(["tar", "x"], cwd=target, stdin=f)
            return ["file", subdir_path(target, desc)]
    tree = git_tree(commit=commit,
                    subdir=desc.get("subdir", "."),
                    upstream=repo)
    return ["git tree", tree, root]


def update_git(desc):
    repo = desc["repository"]
    branch = desc["branch"]
    lsremote = subprocess.run(["git", "ls-remote", repo, branch],
                              stdout=subprocess.PIPE).stdout
    desc["commit"] = lsremote.decode('utf-8').split('\t')[0]


def git_hash(content):
    header = "blob {}\0".format(len(content)).encode('utf-8')
    h = hashlib.sha1()
    h.update(header)
    h.update(content)
    return h.hexdigest()


def add_to_cas(data):
    if isinstance(data, str):
        data = data.encode('utf-8')
    cas_root = os.path.join(ROOT, "protocol-dependent/git-sha1/casf")
    basename = git_hash(data)
    target = os.path.join(cas_root, basename)
    tempname = os.path.join(cas_root, "%s.%d" % (basename, os.getpid()))

    if os.path.exists(target):
        return target

    os.makedirs(cas_root, exist_ok=True)
    with open(tempname, "wb") as f:
        f.write(data)
        f.flush()
        os.chmod(f.fileno(), 0o444)
        os.fsync(f.fileno())
    os.utime(tempname, (0, 0))
    os.rename(tempname, target)
    return target


def cas_path(h):
    return os.path.join(ROOT, "protocol-dependent/git-sha1/casf", h)


def is_in_cas(h):
    return os.path.exists(cas_path(h))


def add_file_to_cas(filename):
    # TODO: avoid going through memory
    with open(filename, "rb") as f:
        data = f.read()
    add_to_cas(data)


def add_distfile_to_cas(distfile):
    for d in DISTDIR:
        candidate = os.path.join(d, distfile)
        if os.path.exists(candidate):
            add_file_to_cas(candidate)


def archive_checkout_dir(content, repo_type):
    return os.path.join(ROOT, "workspaces", repo_type, content)


def archive_tmp_checkout_dir(content, repo_type):
    return os.path.join(ROOT, "tmp-workspaces", repo_type,
                        "%d-%s" % (os.getpid(), content))


def archive_tree_id_file(content, repo_type):
    return os.path.join(ROOT, "tree-map", repo_type, content)


def get_distfile(desc):
    distfile = desc.get("distfile")
    if not distfile:
        distfile = os.path.basename(desc.get("fetch"))
    return distfile


def archive_fetch(desc, content):
    """ Makes sure archive is available and accounted for in cas
    """
    if not is_in_cas(content):
        distfile = get_distfile(desc)
        if distfile:
            add_distfile_to_cas(distfile)
    if not is_in_cas(content):
        url = desc["fetch"]
        data = subprocess.run(["wget", "-O", "-", url],
                              stdout=subprocess.PIPE).stdout
        if "sha256" in desc:
            actual_hash = hashlib.sha256(data).hexdigest()
            if desc["sha256"] != actual_hash:
                fail("SHA256 mismatch for %s, expected %s, found %s" %
                     (url, desc["sha256"], actual_hash))
        if "sha512" in desc:
            actual_hash = hashlib.sha512(data).hexdigest()
            if desc["sha512"] != actual_hash:
                fail("SHA512 mismatch for %s, expected %s, found %s" %
                     (url, desc["sha512"], actual_hash))
        add_to_cas(data)
        if not is_in_cas(content):
            fail("Failed to fetch a file with id %s from %s" % (content, url))


def archive_checkout(desc, repo_type="archive"):
    content_id = desc["content"]
    target = archive_checkout_dir(content_id, repo_type=repo_type)
    if ALWAYS_FILE and os.path.exists(target):
        return ["file", subdir_path(target, desc)]
    tree_id_file = archive_tree_id_file(content_id, repo_type=repo_type)
    if (not ALWAYS_FILE) and os.path.exists(tree_id_file):
        with open(tree_id_file) as f:
            archive_tree_id = f.read()
        # ensure git cache exists
        ensure_git(upstream=None)
        return [
            "git tree",
            git_subtree(tree=archive_tree_id,
                        subdir=desc.get("subdir", "."),
                        upstream=None),
            git_root(upstream=None),
        ]
    archive_fetch(desc, content=content_id)
    target_tmp = archive_tmp_checkout_dir(content_id, repo_type=repo_type)
    if os.path.exists(target_tmp):
        try_rmtree(target_tmp)
    os.makedirs(target_tmp)
    if repo_type == "zip":
        run_cmd(["unzip", "-d", ".", cas_path(content_id)], cwd=target_tmp)
    else:
        run_cmd(["tar", "xf", cas_path(content_id)], cwd=target_tmp)
    if ALWAYS_FILE:
        move_to_place(target_tmp, target)
        return ["file", subdir_path(target, desc)]
    tree = import_to_git(target_tmp, repo_type, content_id)
    try_rmtree(target_tmp)
    os.makedirs(os.path.dirname(tree_id_file), exist_ok=True)
    with open(tree_id_file, "w") as f:
        f.write(tree)
    return [
        "git tree",
        git_subtree(tree=tree, subdir=desc.get("subdir", "."), upstream=None),
        git_root(upstream=None)
    ]


def import_to_git(target, repo_type, content_id):
    run_cmd(
        ["git", "init"],
        cwd=target,
        env=dict(os.environ, **GIT_NOBODY_ENV),
    )
    run_cmd(
        ["git", "add", "."],
        cwd=target,
        env=dict(os.environ, **GIT_NOBODY_ENV),
    )
    run_cmd(
        ["git", "commit", "-m",
         "Content of %s %r" % (repo_type, content_id)],
        cwd=target,
        env=dict(os.environ, **GIT_NOBODY_ENV),
    )

    ensure_git(upstream=None)
    run_cmd(["git", "fetch", target], cwd=git_root(upstream=None))
    commit = subprocess.run(["git", "log", "-n", "1", "--format=%H"],
                            stdout=subprocess.PIPE,
                            cwd=target).stdout.decode('utf-8').strip()
    git_keep(commit, upstream=None)
    return subprocess.run(["git", "log", "-n", "1", "--format=%T"],
                          stdout=subprocess.PIPE,
                          cwd=target).stdout.decode('utf-8').strip()


def file_as_git(fpath):
    root_result = subprocess.run(["git", "rev-parse", "--show-toplevel"],
                                 cwd=fpath,
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.DEVNULL)
    if not root_result.returncode == 0:
        # TODO: consider also doing this for pending changes
        # copy non-git paths to tmp-workspace and import to git
        fpath = os.path.realpath(fpath)
        target = archive_tmp_checkout_dir(os.path.relpath(fpath, "/"),
                                          repo_type="file")
        os.makedirs(os.path.dirname(target), exist_ok=True)
        shutil.copytree(fpath, target)
        tree = import_to_git(target, "file", fpath)
        try_rmtree(target)
        return ["git tree", tree, git_root(upstream=None)]
    root = root_result.stdout.decode('utf-8').rstrip()
    subdir = os.path.relpath(fpath, root)
    root_tree = subprocess.run(
        ["git", "log", "-n", "1", "--format=%T"],
        cwd=root,
        stdout=subprocess.PIPE).stdout.decode('utf-8').strip()
    return [
        "git tree",
        git_subtree(tree=root_tree, subdir=subdir, upstream=root), root
    ]


def file_checkout(desc):
    fpath = os.path.abspath(desc["path"])
    if desc.get("pragma", {}).get("to_git") and not ALWAYS_FILE:
        return file_as_git(fpath)
    return ["file", os.path.abspath(fpath)]


def resolve_repo(desc, *, seen=None, repos):
    seen = seen or []
    if not isinstance(desc, str):
        return desc
    if desc in seen:
        fail("Cyclic reference in repository source definition: %r" % (seen, ))
    return resolve_repo(repos[desc]["repository"],
                        seen=seen + [desc],
                        repos=repos)


def distdir_repo_dir(content):
    return os.path.join(ROOT, "distdir", content)


def distdir_tmp_dir(content):
    return os.path.join(ROOT, "tmp-workspaces", "distdir",
                        "%d-%s" % (os.getpid(), content))


def distdir_tree_id_file(content):
    return os.path.join(ROOT, "distfiles-tree-map", content)


def distdir_checkout(desc, repos):
    """ Logic for processing the distdir repo type.
    """
    content = {}

    # All repos in distdir list are considered, irrespective of reachability
    distdir_repos = desc.get("repositories", [])
    for repo in distdir_repos:
        # If repo does not exist, fail
        if repo not in repos:
            print("No configuration for repository %s found" % ())
            sys.exit(1)
        repo_desc = repos[repo].get("repository", {})
        repo_desc_type = repo_desc.get("type")
        # Only do work for archived types
        if repo_desc_type in ["archive", "zip"]:
            # fetch repo
            content_id = repo_desc["content"]
            archive_fetch(repo_desc, content=content_id)
            # Store the relevant info in the map
            content[get_distfile(repo_desc)] = content_id

    # Hash the map as unique id for the distdir repo entry
    distdir_content_id = git_hash(json.dumps(content).encode('utf-8'))
    target_distdir_dir = distdir_repo_dir(distdir_content_id)

    # Check if content already exists
    if ALWAYS_FILE and os.path.exists(target_distdir_dir):
        return ["file", target_distdir_dir]
    tree_id_file = distdir_tree_id_file(distdir_content_id)
    if (not ALWAYS_FILE) and os.path.exists(tree_id_file):
        with open(tree_id_file) as f:
            distdir_tree_id = f.read()
        # ensure git cache exists
        ensure_git(upstream=None)
        return [
            "git tree",
            git_subtree(tree=distdir_tree_id, subdir=".", upstream=None),
            git_root(upstream=None)
        ]

    # Create the dirstdir repo folder content
    target_tmp_dir = distdir_tmp_dir(distdir_content_id)
    if os.path.exists(target_tmp_dir):
        try_rmtree(target_tmp_dir)
    os.makedirs(target_tmp_dir)
    for name, content_id in content.items():
        target = os.path.join(target_tmp_dir, name)
        os.link(cas_path(content_id), target)

    if (ALWAYS_FILE):
        # Return with path to distdir repo
        move_to_place(target_tmp_dir, target_distdir_dir)
        return ["file", target_distdir_dir]

    # Gitify the distdir repo folder
    tree = import_to_git(target_tmp_dir, "distdir", distdir_content_id)
    try_rmtree(target_tmp_dir)

    # Cache git info to tree id file
    os.makedirs(os.path.dirname(tree_id_file), exist_ok=True)
    with open(tree_id_file, "w") as f:
        f.write(tree)

    # Return git tree info
    return [
        "git tree",
        git_subtree(tree=tree, subdir=".", upstream=None),
        git_root(upstream=None)
    ]


def checkout(desc, *, name, repos):
    repo_desc = resolve_repo(desc, repos=repos)
    repo_type = repo_desc.get("type")
    if repo_type == "git":
        return git_checkout(repo_desc)
    if repo_type in ["archive", "zip"]:
        return archive_checkout(repo_desc, repo_type=repo_type)
    if repo_type == "file":
        return file_checkout(repo_desc)
    if repo_type == "distdir":
        return distdir_checkout(repo_desc, repos=repos)
    fail("Unknown repository type %s for %s" % (repo_type, name))


def reachable_repositories(repo, *, repos):
    # First compute the set of repositories transitively reachable via bindings
    reachable = set()

    def traverse(x):
        nonlocal reachable
        if x in reachable:
            return
        reachable.add(x)
        bindings = repos[x].get("bindings", {})
        for bound in bindings.values():
            traverse(bound)

    traverse(repo)

    # Now add the repositories that serve as overlay directories for
    # targets, rules, etc. Those repositories have to be fetched as well, but
    # we do not have to consider their bindings.
    to_fetch = reachable.copy()
    for x in reachable:
        for layer in ALT_DIRS:
            if layer in repos[x]:
                to_fetch.add(repos[x][layer])

    return reachable, to_fetch


def setup(*, config, args, interactive=False):
    repos = config.get("repositories", {})
    repos_to_setup = repos.keys()
    repos_to_include = repos.keys()
    mr_config = {}
    main = None

    if args:
        if len(args) > 1:
            fail("Usage: %s setup [<main repo>]" % (sys.argv[0], ))
        main = args[0]
        repos_to_include, repos_to_setup = reachable_repositories(main,
                                                                  repos=repos)
        mr_config["main"] = main

    mr_repos = {}
    for repo in repos_to_setup:
        desc = repos[repo]
        if repo == main and interactive:
            config = {}
        else:
            workspace = checkout(desc.get("repository", {}),
                                 name=repo,
                                 repos=repos)
            config = {"workspace_root": workspace}
        for key in TAKE_OVER:
            val = desc.get(key, {})
            if val:
                config[key] = val
        mr_repos[repo] = config
    # Alternate directories are specifies as the workspace of
    # some other repository. So we have to iterate over all repositories again
    # to add those directories. We do this only for the repositories we include
    # in the final configuration.
    for repo in repos_to_include:
        desc = repos[repo]
        if repo == main and interactive:
            continue
        for key in ALT_DIRS:
            val = desc.get(key, {})
            if val:
                if val == main and interactive:
                    continue
                mr_repos[repo][key] = mr_repos[val]["workspace_root"]
    mr_repos_actual = {}
    for repo in repos_to_include:
        mr_repos_actual[repo] = mr_repos[repo]
    mr_config["repositories"] = mr_repos_actual

    return add_to_cas(json.dumps(mr_config, indent=2, sort_keys=True))


def build(*, config, args):
    if len(args) != 3:
        fail("Usage: %s build <repo> <moudle> <target>" % (sys.argv[0], ))
    config = setup(config=config, args=[args[0]])
    cmd = [
        JUST, "build", "-C", config, "--local-build-root", ROOT, args[1],
        args[2]
    ]
    log("Setup finished, exec %s" % (cmd, ))
    os.execvp(JUST, cmd)


def install(*, config, args):
    if len(args) != 4:
        fail("Usage: %s install <repo> <moudle> <target> <install-path>" %
             (sys.argv[0], ))
    config = setup(config=config, args=[args[0]])
    cmd = [
        JUST, "install", "-C", config, "--local-build-root", ROOT, "-o",
        args[3], args[1], args[2]
    ]
    log("Setup finished, exec %s" % (cmd, ))
    os.execvp(JUST, cmd)


def update(*, config, args):
    for repo in args:
        desc = config["repositories"][repo]["repository"]
        desc = resolve_repo(desc, repos=config["repositories"])
        repo_type = desc.get("type")
        if repo_type == "git":
            update_git(desc)
        else:
            fail("Don't know how to update %s repositories" % (repo_type, ))
    print(json.dumps(config, indent=2))
    sys.exit(0)


def fetch(*, config, args):
    if args:
        print("Warning: ignoring arguments %r" % (args, ))
    fetch_dir = None
    for d in DISTDIR:
        if os.path.isdir(d):
            fetch_dir = os.path.abspath(d)
            break
    if not fetch_dir:
        print("No directory found to fetch to, considered %r" % (DISTDIR, ))
        sys.exit(1)
    print("Fetching to %r" % (fetch_dir, ))

    repos = config["repositories"]
    for repo, desc in repos.items():
        if ("repository" in desc and isinstance(desc["repository"], dict)
                and desc["repository"]["type"] in ["zip", "archive"]):
            repo_desc = desc["repository"]
            distfile = repo_desc.get("distfile") or os.path.basename(
                repo_desc["fetch"])
            content = repo_desc["content"]
            print("%r --> %r (content: %s)" % (repo, distfile, content))
            archive_fetch(repo_desc, content)
            shutil.copyfile(cas_path(content),
                            os.path.join(fetch_dir, distfile))

    sys.exit(0)


def main():
    parser = ArgumentParser()
    parser.add_argument("-C",
                        dest="repository_config",
                        help="Repository-description file to use",
                        metavar="FILE")
    parser.add_argument("-L",
                        dest="checkout_location",
                        help="Specification file for checkout locations")
    parser.add_argument("--local-build-root",
                        dest="local_build_root",
                        help="Root for CAS, repository space, etc",
                        metavar="PATH")
    parser.add_argument("--distdir",
                        dest="distdir",
                        action="append",
                        help="Directory to look for distfiles before fetching",
                        metavar="PATH")
    parser.add_argument("--just",
                        dest="just",
                        help="Path to the just binary",
                        metavar="PATH")
    parser.add_argument("--always-file",
                        dest="always_file",
                        action="store_true",
                        default=False,
                        help="Always create file roots")

    (options, args) = parser.parse_known_args()
    config = read_config(options.repository_config)
    global ROOT
    ROOT = options.local_build_root or os.path.join(Path.home(), ".cache/just")
    ROOT = ROOT if os.path.isabs(ROOT) else os.path.abspath(ROOT)
    global GIT_CHECKOUT_LOCATIONS
    if options.checkout_location:
        with open(options.checkout_location) as f:
            GIT_CHECKOUT_LOCATIONS = json.load(f).get("checkouts",
                                                      {}).get("git", {})
    elif os.path.isfile(os.path.join(Path().home(), ".just-local.json")):
        with open(os.path.join(Path().home(), ".just-local.json")) as f:
            GIT_CHECKOUT_LOCATIONS = json.load(f).get("checkouts",
                                                      {}).get("git", {})
    global DISTDIR
    if options.distdir:
        DISTDIR = options.distdir

    DISTDIR.append(os.path.join(Path.home(), ".distfiles"))

    global JUST
    if options.just:
        JUST = os.path.abspath(options.just)

    global ALWAYS_FILE
    ALWAYS_FILE = options.always_file

    if not args:
        fail("Usage: %s <cmd> [<args>]" % (sys.argv[0], ))
    if args[0] == "setup-env":
        # Setup for interactive use, i.e., fetch the required repositories
        # and generate an appropriate multi-repository configuration file.
        # Store it in the CAS and print its path on stdout.
        #
        # For the main repository (if specified), leave out the workspace
        # so that in the usage of just the workspace is determined from
        # the working directory; in this way, working on a checkout of that
        # repository is possible, while having all dependencies set up
        # correctly.
        print(setup(config=config, args=args[1:], interactive=True))
        return
    if args[0] == "setup":
        # Setup such that the main repository keeps its workspace given in
        # the input config.
        print(setup(config=config, args=args[1:]))
        return
    if args[0] == "build":
        build(config=config, args=args[1:])
    if args[0] == "install":
        install(config=config, args=args[1:])
    if args[0] == "update":
        update(config=config, args=args[1:])
    if args[0] == "fetch":
        fetch(config=config, args=args[1:])
    fail("Unknown subcommand %s" % (args[0], ))


if __name__ == "__main__":
    main()