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 tempfile
   9 import urllib.parse
  10 import urllib.request
  11 import xml.dom.minidom
  12
  13 from typing import (
  14     Any,
  15     Dict,
  16     Iterable,
  17     List,
  18     Sequence,
  19     Tuple,
  20 )
  21
  22
  23 class VerificationError(Exception):
  24     pass
  25
  26
  27 class Verification:
  28
  29     def __init__(self) -> None:
  30         self.line_length = 0
  31
  32     def status(self, s: str) -> None:
  33         print(s, end=' ', flush=True)
  34         self.line_length += 1 + len(s)  # Unicode??
  35
  36     @staticmethod
  37     def _color(s: str, c: int) -> str:
  38         return '\033[%2dm%s\033[00m' % (c, s)
  39
  40     def result(self, r: bool) -> None:
  41         message, color = {True: ('OK ', 92), False: ('FAIL', 91)}[r]
  42         length = len(message)
  43         cols = shutil.get_terminal_size().columns
  44         pad = (cols - (self.line_length + length)) % cols
  45         print(' ' * pad + self._color(message, color))
  46         self.line_length = 0
  47         if not r:
  48             raise VerificationError()
  49
  50     def check(self, s: str, r: bool) -> None:
  51         self.status(s)
  52         self.result(r)
  53
  54     def ok(self) -> None:
  55         self.result(True)
  56
  57
  58 def compare(a: str,
  59             b: str) -> Tuple[Sequence[str],
  60                              Sequence[str],
  61                              Sequence[str]]:
  62
  63     def throw(error: OSError) -> None:
  64         raise error
  65
  66     def join(x: str, y: str) -> str:
  67         return y if x == '.' else os.path.join(x, y)
  68
  69     def recursive_files(d: str) -> Iterable[str]:
  70         all_files: List[str] = []
  71         for path, dirs, files in os.walk(d, onerror=throw):
  72             rel = os.path.relpath(path, start=d)
  73             all_files.extend(join(rel, f) for f in files)
  74             for dir_or_link in dirs:
  75                 if os.path.islink(join(path, dir_or_link)):
  76                     all_files.append(join(rel, dir_or_link))
  77         return all_files
  78
  79     def exclude_dot_git(files: Iterable[str]) -> Iterable[str]:
  80         return (f for f in files if not f.startswith('.git/'))
  81
  82     files = functools.reduce(
  83         operator.or_, (set(
  84             exclude_dot_git(
  85                 recursive_files(x))) for x in [a, b]))
  86     return filecmp.cmpfiles(a, b, files, shallow=False)
  87
  88
  89 def fetch(v: Verification, channel_url: str) -> Dict[str, Any]:
  90     info: Dict[str, Any] = {'url': channel_url}
  91     v.status('Fetching channel')
  92     request = urllib.request.urlopen(
  93         'https://channels.nixos.org/nixos-20.03', timeout=10)
  94     info['channel_html'] = request.read()
  95     info['forwarded_url'] = request.geturl()
  96     v.result(request.status == 200)
  97     v.check('Got forwarded', info['url'] != info['forwarded_url'])
  98     return info
  99
 100
 101 def parse(v: Verification, info: Dict[str, Any]) -> None:
 102     v.status('Parsing channel description as XML')
 103     d = xml.dom.minidom.parseString(info['channel_html'])
 104     v.ok()
 105
 106     v.status('Extracting git commit')
 107     git_commit_node = d.getElementsByTagName('tt')[0]
 108     info['git_commit'] = git_commit_node.firstChild.nodeValue
 109     v.ok()
 110     v.status('Verifying git commit label')
 111     v.result(git_commit_node.previousSibling.nodeValue == 'Git commit ')
 112
 113     v.status('Parsing table')
 114     info['table'] = {}
 115     for row in d.getElementsByTagName('tr')[1:]:
 116         name = row.childNodes[0].firstChild.firstChild.nodeValue
 117         url = row.childNodes[0].firstChild.getAttribute('href')
 118         size = int(row.childNodes[1].firstChild.nodeValue)
 119         digest = row.childNodes[2].firstChild.firstChild.nodeValue
 120         info['table'][name] = {'url': url, 'digest': digest, 'size': size}
 121     v.ok()
 122
 123
 124 def fetch_resources(v: Verification, info: Dict[str, Any]) -> None:
 125
 126     for resource in ['git-revision', 'nixexprs.tar.xz']:
 127         fields = info['table'][resource]
 128         v.status('Fetching resource "%s"' % resource)
 129         url = urllib.parse.urljoin(info['forwarded_url'], fields['url'])
 130         request = urllib.request.urlopen(url, timeout=10)
 131         if fields['size'] < 4096:
 132             fields['content'] = request.read()
 133         else:
 134             with tempfile.NamedTemporaryFile(suffix='.nixexprs.tar.xz', delete=False) as tmp_file:
 135                 shutil.copyfileobj(request, tmp_file)
 136                 fields['file'] = tmp_file.name
 137         v.result(request.status == 200)
 138         v.status('Verifying digest for "%s"' % resource)
 139         if fields['size'] < 4096:
 140             actual_hash = hashlib.sha256(fields['content']).hexdigest()
 141         else:
 142             hasher = hashlib.sha256()
 143             with open(fields['file'], 'rb') as f:
 144                 # pylint: disable=cell-var-from-loop
 145                 for block in iter(lambda: f.read(4096), b''):
 146                     hasher.update(block)
 147             actual_hash = hasher.hexdigest()
 148         v.result(actual_hash == fields['digest'])
 149     v.check('Verifying git commit on main page matches git commit in table',
 150             info['table']['git-revision']['content'].decode() == info['git_commit'])
 151
 152
 153 def extract_channel(v: Verification, info: Dict[str, Any]) -> None:
 154     with tempfile.TemporaryDirectory() as d:
 155         v.status('Extracting nixexprs.tar.xz')
 156         shutil.unpack_archive(info['table']['nixexprs.tar.xz']['file'], d)
 157         v.ok()
 158         v.status('Removing temporary directory')
 159     v.ok()
 160
 161
 162 def main() -> None:
 163     v = Verification()
 164     info = fetch(v, 'https://channels.nixos.org/nixos-20.03')
 165     parse(v, info)
 166     fetch_resources(v, info)
 167     extract_channel(v, info)
 168     print(info)
 169
 170
 171 main()