virtualbox: Add an update script

Just a small updater which should fetch the latest sha256sums from the
upstream site and check whether the current version is the latest one.

The output is in a JSON file in the same directory, which then will be
used by the Nix expressions to fetch the upstream files.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

pkgs/applications/virtualization/virtualbox/update.py

@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+import os
+import re
+import json
+import urllib.request
+
+from distutils.version import LooseVersion
+
+UPSTREAM_INFO_FILE = os.path.join(
+    os.path.dirname(os.path.abspath(__file__)),
+    "upstream-info.json"
+)
+
+
+def fetch_latest_version():
+    url = "http://download.virtualbox.org/virtualbox/LATEST.TXT"
+    return urllib.request.urlopen(url).read().strip().decode()
+
+
+def load_upstream_info():
+    try:
+        with open(UPSTREAM_INFO_FILE, 'r') as fp:
+            return json.load(fp)
+    except FileNotFoundError:
+        return {'version': "0"}
+
+
+def save_upstream_info(contents):
+    remark = "Generated using update.py from the same directory."
+    contents['__NOTE'] = remark
+    data = json.dumps(contents, indent=2, sort_keys=True)
+    with open(UPSTREAM_INFO_FILE, 'w') as fp:
+        fp.write(data + "\n")
+
+
+def fetch_file_table(version):
+    url = "http://download.virtualbox.org/virtualbox/{}/SHA256SUMS"
+    url = url.format(version)
+    result = {}
+    for line in urllib.request.urlopen(url):
+        sha, name = line.rstrip().split()
+        result[name.lstrip(b'*').decode()] = sha.decode()
+    return result
+
+
+def update_to_version(version):
+    extpack_start = 'Oracle_VM_VirtualBox_Extension_Pack-'
+    version_re = version.replace('.', '\\.')
+    attribute_map = {
+        'extpack': r'^' + extpack_start + r'[^-]+-[^.]+.vbox-extpack$',
+        'extpackRev': r'^' + extpack_start + r'[^-]+-([^.]+).vbox-extpack$',
+        'main': r'^VirtualBox-' + version_re + r'.tar.bz2$',
+        'guest': r'^VBoxGuestAdditions_' + version_re + r'.iso$',
+    }
+    table = fetch_file_table(version)
+    new_attrs = {'version': version}
+    for attr, searchexpr in attribute_map.items():
+        result = [re.search(searchexpr, key) for key in table.keys()]
+        filtered = filter(lambda m: m is not None, result)
+        found = [m.groups()[0] if len(m.groups()) > 0 else table[m.group(0)]
+                 for m in filtered if m is not None]
+
+        if len(found) == 0:
+            msg = "No package found for attribute {}".format(attr)
+            raise AssertionError(msg)
+        elif len(found) != 1:
+            msg = "More than one package found for attribute {}: ".format(attr)
+            msg += ', '.join(found)
+            raise AssertionError(msg)
+        else:
+            new_attrs[attr] = found[0]
+    return new_attrs
+
+
+info = load_upstream_info()
+latest = fetch_latest_version()
+if LooseVersion(info['version']) < LooseVersion(latest):
+    print("Updating to version {}...".format(latest), end="", flush=True)
+    new_attrs = update_to_version(latest)
+    save_upstream_info(new_attrs)
+    print(" done.")
+else:
+    print("Version {} is already the latest one.".format(info['version']))