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 ChannelTableEntry(types.SimpleNamespace):
  29     digest: Digest16
  30     file: str
  31     size: int
  32     url: str
  33
  34
  35 class Channel(types.SimpleNamespace):
  36     channel_html: bytes
  37     forwarded_url: str
  38     git_revision: str
  39     release_name: str
  40     table: Dict[str, ChannelTableEntry]
  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: Channel) -> None:
 111     v.status('Fetching channel')
 112     request = urllib.request.urlopen(channel.url, timeout=10)
 113     channel.channel_html = request.read()
 114     channel.forwarded_url = request.geturl()
 115     v.result(request.status == 200)
 116     v.check('Got forwarded', channel.url != channel.forwarded_url)
 117
 118
 119 def parse_channel(v: Verification, channel: Channel) -> None:
 120     v.status('Parsing channel description as XML')
 121     d = xml.dom.minidom.parseString(channel.channel_html)
 122     v.ok()
 123
 124     v.status('Extracting release name:')
 125     title_name = d.getElementsByTagName(
 126         'title')[0].firstChild.nodeValue.split()[2]
 127     h1_name = d.getElementsByTagName('h1')[0].firstChild.nodeValue.split()[2]
 128     v.status(title_name)
 129     v.result(title_name == h1_name)
 130     channel.release_name = title_name
 131
 132     v.status('Extracting git commit:')
 133     git_commit_node = d.getElementsByTagName('tt')[0]
 134     channel.git_commit = git_commit_node.firstChild.nodeValue
 135     v.status(channel.git_commit)
 136     v.ok()
 137     v.status('Verifying git commit label')
 138     v.result(git_commit_node.previousSibling.nodeValue == 'Git commit ')
 139
 140     v.status('Parsing table')
 141     channel.table = {}
 142     for row in d.getElementsByTagName('tr')[1:]:
 143         name = row.childNodes[0].firstChild.firstChild.nodeValue
 144         url = row.childNodes[0].firstChild.getAttribute('href')
 145         size = int(row.childNodes[1].firstChild.nodeValue)
 146         digest = Digest16(row.childNodes[2].firstChild.firstChild.nodeValue)
 147         channel.table[name] = ChannelTableEntry(url=url, digest=digest, size=size)
 148     v.ok()
 149
 150
 151 def digest_file(filename: str) -> Digest16:
 152     hasher = hashlib.sha256()
 153     with open(filename, 'rb') as f:
 154         # pylint: disable=cell-var-from-loop
 155         for block in iter(lambda: f.read(4096), b''):
 156             hasher.update(block)
 157     return Digest16(hasher.hexdigest())
 158
 159
 160 def to_Digest16(v: Verification, digest32: Digest32) -> Digest16:
 161     v.status('Converting digest to base16')
 162     process = subprocess.run(
 163         ['nix', 'to-base16', '--type', 'sha256', digest32], capture_output=True)
 164     v.result(process.returncode == 0)
 165     return Digest16(process.stdout.decode().strip())
 166
 167
 168 def to_Digest32(v: Verification, digest16: Digest16) -> Digest32:
 169     v.status('Converting digest to base32')
 170     process = subprocess.run(
 171         ['nix', 'to-base32', '--type', 'sha256', digest16], capture_output=True)
 172     v.result(process.returncode == 0)
 173     return Digest32(process.stdout.decode().strip())
 174
 175
 176 def fetch_with_nix_prefetch_url(
 177         v: Verification,
 178         url: str,
 179         digest: Digest16) -> str:
 180     v.status('Fetching %s' % url)
 181     process = subprocess.run(
 182         ['nix-prefetch-url', '--print-path', url, digest], capture_output=True)
 183     v.result(process.returncode == 0)
 184     prefetch_digest, path, empty = process.stdout.decode().split('\n')
 185     assert empty == ''
 186     v.check("Verifying nix-prefetch-url's digest",
 187             to_Digest16(v, Digest32(prefetch_digest)) == digest)
 188     v.status("Verifying file digest")
 189     file_digest = digest_file(path)
 190     v.result(file_digest == digest)
 191     return path
 192
 193
 194 def fetch_resources(v: Verification, channel: Channel) -> None:
 195     for resource in ['git-revision', 'nixexprs.tar.xz']:
 196         fields = channel.table[resource]
 197         url = urllib.parse.urljoin(channel.forwarded_url, fields.url)
 198         fields.file = fetch_with_nix_prefetch_url(v, url, fields.digest)
 199     v.status('Verifying git commit on main page matches git commit in table')
 200     v.result(
 201         open(
 202             channel.table['git-revision'].file).read(999) == channel.git_commit)
 203
 204
 205 def check_channel_contents(v: Verification, channel: Channel) -> None:
 206     with tempfile.TemporaryDirectory() as d:
 207         v.status('Extracting %s' % channel.table['nixexprs.tar.xz'].file)
 208         shutil.unpack_archive(channel.table['nixexprs.tar.xz'].file, d)
 209         v.ok()
 210         v.status('Removing temporary directory')
 211     v.ok()
 212
 213
 214 def main() -> None:
 215     v = Verification()
 216     channel = Channel(url='https://channels.nixos.org/nixos-20.03')
 217     fetch(v, channel)
 218     parse_channel(v, channel)
 219     fetch_resources(v, channel)
 220     check_channel_contents(v, channel)
 221     print(channel)
 222
 223
 224 main()