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     Tuple,
  21 )
  22
  23 Digest16 = NewType('Digest16', str)
  24 Digest32 = NewType('Digest32', str)
  25
  26
  27 class ChannelTableEntry(types.SimpleNamespace):
  28     digest: Digest16
  29     file: str
  30     size: int
  31     url: str
  32
  33
  34 class Channel(types.SimpleNamespace):
  35     channel_html: bytes
  36     forwarded_url: str
  37     git_cachedir: str
  38     git_ref: str
  39     git_repo: str
  40     git_revision: str
  41     release_name: str
  42     table: Dict[str, ChannelTableEntry]
  43     url: str
  44
  45
  46 class VerificationError(Exception):
  47     pass
  48
  49
  50 class Verification:
  51
  52     def __init__(self) -> None:
  53         self.line_length = 0
  54
  55     def status(self, s: str) -> None:
  56         print(s, end=' ', flush=True)
  57         self.line_length += 1 + len(s)  # Unicode??
  58
  59     @staticmethod
  60     def _color(s: str, c: int) -> str:
  61         return '\033[%2dm%s\033[00m' % (c, s)
  62
  63     def result(self, r: bool) -> None:
  64         message, color = {True: ('OK ', 92), False: ('FAIL', 91)}[r]
  65         length = len(message)
  66         cols = shutil.get_terminal_size().columns
  67         pad = (cols - (self.line_length + length)) % cols
  68         print(' ' * pad + self._color(message, color))
  69         self.line_length = 0
  70         if not r:
  71             raise VerificationError()
  72
  73     def check(self, s: str, r: bool) -> None:
  74         self.status(s)
  75         self.result(r)
  76
  77     def ok(self) -> None:
  78         self.result(True)
  79
  80
  81 def compare(a: str, b: str) -> Tuple[List[str], List[str], List[str]]:
  82
  83     def throw(error: OSError) -> None:
  84         raise error
  85
  86     def join(x: str, y: str) -> str:
  87         return y if x == '.' else os.path.join(x, y)
  88
  89     def recursive_files(d: str) -> Iterable[str]:
  90         all_files: List[str] = []
  91         for path, dirs, files in os.walk(d, onerror=throw):
  92             rel = os.path.relpath(path, start=d)
  93             all_files.extend(join(rel, f) for f in files)
  94             for dir_or_link in dirs:
  95                 if os.path.islink(join(path, dir_or_link)):
  96                     all_files.append(join(rel, dir_or_link))
  97         return all_files
  98
  99     def exclude_dot_git(files: Iterable[str]) -> Iterable[str]:
 100         return (f for f in files if not f.startswith('.git/'))
 101
 102     files = functools.reduce(
 103         operator.or_, (set(
 104             exclude_dot_git(
 105                 recursive_files(x))) for x in [a, b]))
 106     return filecmp.cmpfiles(a, b, files, shallow=False)
 107
 108
 109 def fetch(v: Verification, channel: Channel) -> None:
 110     v.status('Fetching channel')
 111     request = urllib.request.urlopen(channel.url, timeout=10)
 112     channel.channel_html = request.read()
 113     channel.forwarded_url = request.geturl()
 114     v.result(request.status == 200)
 115     v.check('Got forwarded', channel.url != channel.forwarded_url)
 116
 117
 118 def parse_channel(v: Verification, channel: Channel) -> None:
 119     v.status('Parsing channel description as XML')
 120     d = xml.dom.minidom.parseString(channel.channel_html)
 121     v.ok()
 122
 123     v.status('Extracting release name:')
 124     title_name = d.getElementsByTagName(
 125         'title')[0].firstChild.nodeValue.split()[2]
 126     h1_name = d.getElementsByTagName('h1')[0].firstChild.nodeValue.split()[2]
 127     v.status(title_name)
 128     v.result(title_name == h1_name)
 129     channel.release_name = title_name
 130
 131     v.status('Extracting git commit:')
 132     git_commit_node = d.getElementsByTagName('tt')[0]
 133     channel.git_commit = git_commit_node.firstChild.nodeValue
 134     v.status(channel.git_commit)
 135     v.ok()
 136     v.status('Verifying git commit label')
 137     v.result(git_commit_node.previousSibling.nodeValue == 'Git commit ')
 138
 139     v.status('Parsing table')
 140     channel.table = {}
 141     for row in d.getElementsByTagName('tr')[1:]:
 142         name = row.childNodes[0].firstChild.firstChild.nodeValue
 143         url = row.childNodes[0].firstChild.getAttribute('href')
 144         size = int(row.childNodes[1].firstChild.nodeValue)
 145         digest = Digest16(row.childNodes[2].firstChild.firstChild.nodeValue)
 146         channel.table[name] = ChannelTableEntry(
 147             url=url, digest=digest, size=size)
 148     v.ok()
 149
 150
 151 def digest_string(s: bytes) -> Digest16:
 152     return Digest16(hashlib.sha256(s).hexdigest())
 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, channel: Channel) -> None:
 199     for resource in ['git-revision', 'nixexprs.tar.xz']:
 200         fields = channel.table[resource]
 201         url = urllib.parse.urljoin(channel.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             channel.table['git-revision'].file).read(999) == channel.git_commit)
 207
 208
 209 def git_fetch(v: Verification, channel: Channel) -> None:
 210     # It would be nice if we could share the nix git cache, but as of the time
 211     # of writing it is transitioning from gitv2 (deprecated) to gitv3 (not ready
 212     # yet), and trying to straddle them both is too far into nix implementation
 213     # details for my comfort.  So we re-implement here half of nix.fetchGit.
 214     # :(
 215
 216     # TODO: Consider using pyxdg to find this path.
 217     channel.git_cachedir = os.path.expanduser(
 218         '~/.cache/nix-pin-channel/git/%s' %
 219         digest_string(
 220             channel.url.encode()))
 221     if not os.path.exists(channel.git_cachedir):
 222         v.status("Initializing git repo")
 223         process = subprocess.run(
 224             ['git', 'init', '--bare', channel.git_cachedir])
 225         v.result(process.returncode == 0)
 226
 227     v.status('Checking if we already have this rev:')
 228     process = subprocess.run(
 229         ['git', '-C', channel.git_cachedir, 'cat-file', '-e', channel.git_commit])
 230     if process.returncode == 0:
 231         v.status('yes')
 232     if process.returncode == 1:
 233         v.status('no')
 234     v.result(process.returncode == 0 or process.returncode == 1)
 235     if process.returncode == 1:
 236         v.status('Fetching ref "%s"' % channel.git_ref)
 237         # We don't use --force here because we want to abort and freak out if forced
 238         # updates are happening.
 239         process = subprocess.run(['git',
 240                                   '-C',
 241                                   channel.git_cachedir,
 242                                   'fetch',
 243                                   channel.git_repo,
 244                                   '%s:%s' % (channel.git_ref,
 245                                              channel.git_ref)])
 246         v.result(process.returncode == 0)
 247         v.status('Verifying that fetch retrieved this rev')
 248         process = subprocess.run(
 249             ['git', '-C', channel.git_cachedir, 'cat-file', '-e', channel.git_commit])
 250         v.result(process.returncode == 0)
 251
 252     v.status('Verifying rev is an ancestor of ref')
 253     process = subprocess.run(['git',
 254                               '-C',
 255                               channel.git_cachedir,
 256                               'merge-base',
 257                               '--is-ancestor',
 258                               channel.git_commit,
 259                               channel.git_ref])
 260     v.result(process.returncode == 0)
 261
 262
 263 def check_channel_contents(v: Verification, channel: Channel) -> None:
 264     with tempfile.TemporaryDirectory() as channel_contents, \
 265             tempfile.TemporaryDirectory() as git_contents:
 266         v.status('Extracting tarball %s' %
 267                  channel.table['nixexprs.tar.xz'].file)
 268         shutil.unpack_archive(
 269             channel.table['nixexprs.tar.xz'].file,
 270             channel_contents)
 271         v.ok()
 272         v.status('Checking out corresponding git revision')
 273         git = subprocess.Popen(['git',
 274                                 '-C',
 275                                 channel.git_cachedir,
 276                                 'archive',
 277                                 channel.git_commit],
 278                                stdout=subprocess.PIPE)
 279         tar = subprocess.Popen(
 280             ['tar', 'x', '-C', git_contents, '-f', '-'], stdin=git.stdout)
 281         git.stdout.close()
 282         tar.wait()
 283         git.wait()
 284         v.result(git.returncode == 0 and tar.returncode == 0)
 285         v.status('Comparing channel tarball with git checkout')
 286         match, mismatch, errors = compare(os.path.join(
 287             channel_contents, channel.release_name), git_contents)
 288         v.ok()
 289         v.check('%d files match' % len(match), len(match) > 0)
 290         v.check('%d files differ' % len(mismatch), len(mismatch) == 0)
 291         expected_errors = [
 292             '.git-revision',
 293             '.version-suffix',
 294             'nixpkgs',
 295             'programs.sqlite',
 296             'svn-revision']
 297         benign_errors = []
 298         for ee in expected_errors:
 299             if ee in errors:
 300                 errors.remove(ee)
 301                 benign_errors.append(ee)
 302         v.check(
 303             '%d unexpected incomparable files' %
 304             len(errors),
 305             len(errors) == 0)
 306         v.check(
 307             '(%d of %d expected incomparable files)' %
 308             (len(benign_errors),
 309              len(expected_errors)),
 310             len(benign_errors) == len(expected_errors))
 311         v.status('Removing temporary directories')
 312     v.ok()
 313
 314
 315 def main() -> None:
 316     v = Verification()
 317     channel = Channel(url='https://channels.nixos.org/nixos-20.03',
 318                       git_repo='https://github.com/NixOS/nixpkgs.git',
 319                       git_ref='nixos-20.03')
 320     fetch(v, channel)
 321     parse_channel(v, channel)
 322     fetch_resources(v, channel)
 323     git_fetch(v, channel)
 324     check_channel_contents(v, channel)
 325     print(channel)
 326
 327
 328 main()