git.scottworley.com Git - pinch/blob - pinch.py

   1 import filecmp
   2 import functools
   3 import hashlib
   4 import operator
   5 import os
   6 import os.path
   7 import shutil
   8 import subprocess
   9 import tempfile
  10 import types
  11 import urllib.parse
  12 import urllib.request
  13 import xml.dom.minidom
  14
  15 from typing import (
  16     Dict,
  17     Iterable,
  18     List,
  19     NewType,
  20     Sequence,
  21     Tuple,
  22 )
  23
  24 Digest16 = NewType('Digest16', str)
  25 Digest32 = NewType('Digest32', str)
  26
  27
  28 class InfoTableEntry(types.SimpleNamespace):
  29     digest: Digest16
  30     file: str
  31     size: int
  32     url: str
  33
  34
  35 class Info(types.SimpleNamespace):
  36     channel_html: bytes
  37     forwarded_url: str
  38     git_revision: str
  39     release_name: str
  40     table: Dict[str, InfoTableEntry]
  41     url: str
  42
  43
  44 class VerificationError(Exception):
  45     pass
  46
  47
  48 class Verification:
  49
  50     def __init__(self) -> None:
  51         self.line_length = 0
  52
  53     def status(self, s: str) -> None:
  54         print(s, end=' ', flush=True)
  55         self.line_length += 1 + len(s)  # Unicode??
  56
  57     @staticmethod
  58     def _color(s: str, c: int) -> str:
  59         return '\033[%2dm%s\033[00m' % (c, s)
  60
  61     def result(self, r: bool) -> None:
  62         message, color = {True: ('OK ', 92), False: ('FAIL', 91)}[r]
  63         length = len(message)
  64         cols = shutil.get_terminal_size().columns
  65         pad = (cols - (self.line_length + length)) % cols
  66         print(' ' * pad + self._color(message, color))
  67         self.line_length = 0
  68         if not r:
  69             raise VerificationError()
  70
  71     def check(self, s: str, r: bool) -> None:
  72         self.status(s)
  73         self.result(r)
  74
  75     def ok(self) -> None:
  76         self.result(True)
  77
  78
  79 def compare(a: str,
  80             b: str) -> Tuple[Sequence[str],
  81                              Sequence[str],
  82                              Sequence[str]]:
  83
  84     def throw(error: OSError) -> None:
  85         raise error
  86
  87     def join(x: str, y: str) -> str:
  88         return y if x == '.' else os.path.join(x, y)
  89
  90     def recursive_files(d: str) -> Iterable[str]:
  91         all_files: List[str] = []
  92         for path, dirs, files in os.walk(d, onerror=throw):
  93             rel = os.path.relpath(path, start=d)
  94             all_files.extend(join(rel, f) for f in files)
  95             for dir_or_link in dirs:
  96                 if os.path.islink(join(path, dir_or_link)):
  97                     all_files.append(join(rel, dir_or_link))
  98         return all_files
  99
 100     def exclude_dot_git(files: Iterable[str]) -> Iterable[str]:
 101         return (f for f in files if not f.startswith('.git/'))
 102
 103     files = functools.reduce(
 104         operator.or_, (set(
 105             exclude_dot_git(
 106                 recursive_files(x))) for x in [a, b]))
 107     return filecmp.cmpfiles(a, b, files, shallow=False)
 108
 109
 110 def fetch(v: Verification, channel_url: str) -> Info:
 111     info = Info()
 112     info.url = channel_url
 113     v.status('Fetching channel')
 114     request = urllib.request.urlopen(
 115         'https://channels.nixos.org/nixos-20.03', timeout=10)
 116     info.channel_html = request.read()
 117     info.forwarded_url = request.geturl()
 118     v.result(request.status == 200)
 119     v.check('Got forwarded', info.url != info.forwarded_url)
 120     return info
 121
 122
 123 def parse_table(v: Verification, info: Info) -> None:
 124     v.status('Parsing channel description as XML')
 125     d = xml.dom.minidom.parseString(info.channel_html)
 126     v.ok()
 127
 128     v.status('Extracting release name:')
 129     title_name = d.getElementsByTagName(
 130         'title')[0].firstChild.nodeValue.split()[2]
 131     h1_name = d.getElementsByTagName('h1')[0].firstChild.nodeValue.split()[2]
 132     v.status(title_name)
 133     v.result(title_name == h1_name)
 134     info.release_name = title_name
 135
 136     v.status('Extracting git commit:')
 137     git_commit_node = d.getElementsByTagName('tt')[0]
 138     info.git_commit = git_commit_node.firstChild.nodeValue
 139     v.status(info.git_commit)
 140     v.ok()
 141     v.status('Verifying git commit label')
 142     v.result(git_commit_node.previousSibling.nodeValue == 'Git commit ')
 143
 144     v.status('Parsing table')
 145     info.table = {}
 146     for row in d.getElementsByTagName('tr')[1:]:
 147         name = row.childNodes[0].firstChild.firstChild.nodeValue
 148         url = row.childNodes[0].firstChild.getAttribute('href')
 149         size = int(row.childNodes[1].firstChild.nodeValue)
 150         digest = Digest16(row.childNodes[2].firstChild.firstChild.nodeValue)
 151         info.table[name] = InfoTableEntry(url=url, digest=digest, size=size)
 152     v.ok()
 153
 154
 155 def digest_file(filename: str) -> Digest16:
 156     hasher = hashlib.sha256()
 157     with open(filename, 'rb') as f:
 158         # pylint: disable=cell-var-from-loop
 159         for block in iter(lambda: f.read(4096), b''):
 160             hasher.update(block)
 161     return Digest16(hasher.hexdigest())
 162
 163
 164 def to_Digest16(v: Verification, digest32: Digest32) -> Digest16:
 165     v.status('Converting digest to base16')
 166     process = subprocess.run(
 167         ['nix', 'to-base16', '--type', 'sha256', digest32], capture_output=True)
 168     v.result(process.returncode == 0)
 169     return Digest16(process.stdout.decode().strip())
 170
 171
 172 def to_Digest32(v: Verification, digest16: Digest16) -> Digest32:
 173     v.status('Converting digest to base32')
 174     process = subprocess.run(
 175         ['nix', 'to-base32', '--type', 'sha256', digest16], capture_output=True)
 176     v.result(process.returncode == 0)
 177     return Digest32(process.stdout.decode().strip())
 178
 179
 180 def fetch_with_nix_prefetch_url(
 181         v: Verification,
 182         url: str,
 183         digest: Digest16) -> str:
 184     v.status('Fetching %s' % url)
 185     process = subprocess.run(
 186         ['nix-prefetch-url', '--print-path', url, digest], capture_output=True)
 187     v.result(process.returncode == 0)
 188     prefetch_digest, path, empty = process.stdout.decode().split('\n')
 189     assert empty == ''
 190     v.check("Verifying nix-prefetch-url's digest",
 191             to_Digest16(v, Digest32(prefetch_digest)) == digest)
 192     v.status("Verifying file digest")
 193     file_digest = digest_file(path)
 194     v.result(file_digest == digest)
 195     return path
 196
 197
 198 def fetch_resources(v: Verification, info: Info) -> None:
 199     for resource in ['git-revision', 'nixexprs.tar.xz']:
 200         fields = info.table[resource]
 201         url = urllib.parse.urljoin(info.forwarded_url, fields.url)
 202         fields.file = fetch_with_nix_prefetch_url(v, url, fields.digest)
 203     v.status('Verifying git commit on main page matches git commit in table')
 204     v.result(
 205         open(
 206             info.table['git-revision'].file).read(999) == info.git_commit)
 207
 208
 209 def extract_channel(v: Verification, info: Info) -> None:
 210     with tempfile.TemporaryDirectory() as d:
 211         v.status('Extracting %s' % info.table['nixexprs.tar.xz'].file)
 212         shutil.unpack_archive(info.table['nixexprs.tar.xz'].file, d)
 213         v.ok()
 214         v.status('Removing temporary directory')
 215     v.ok()
 216
 217
 218 def main() -> None:
 219     v = Verification()
 220     info = fetch(v, 'https://channels.nixos.org/nixos-20.03')
 221     parse_table(v, info)
 222     fetch_resources(v, info)
 223     extract_channel(v, info)
 224     print(info)
 225
 226
 227 main()