Sub-command

[pinch] / pinch.py

diff --git a/pinch.py b/pinch.py
index f974d1c0adc3982dbc08e469ed0eed4c4f1b682b..71496a317a48366ca119cf7dba7da86ba2987931 100644 (file)
--- a/pinch.py
+++ b/pinch.py
@@ -1,3 +1,5 @@
+import argparse
+import configparser

 import filecmp
 import functools
 import hashlib
 import filecmp
 import functools
 import hashlib


@@ -5,20 +7,45 @@ import operator
 import os
 import os.path
 import shutil
 import os
 import os.path
 import shutil

+import subprocess

 import tempfile
 import tempfile

+import types

 import urllib.parse
 import urllib.request
 import xml.dom.minidom
 
 from typing import (
 import urllib.parse
 import urllib.request
 import xml.dom.minidom
 
 from typing import (

-    Any,

     Dict,
     Iterable,
     List,
     Dict,
     Iterable,
     List,

-    Sequence,
+    NewType,

     Tuple,
 )
 
     Tuple,
 )
 

+Digest16 = NewType('Digest16', str)
+Digest32 = NewType('Digest32', str)
+
+
+class ChannelTableEntry(types.SimpleNamespace):
+    absolute_url: str
+    digest: Digest16
+    file: str
+    size: int
+    url: str
+
+
+class Channel(types.SimpleNamespace):
+    channel_html: bytes
+    channel_url: str
+    forwarded_url: str
+    git_cachedir: str
+    git_ref: str
+    git_repo: str
+    git_revision: str
+    old_git_revision: str
+    release_name: str
+    table: Dict[str, ChannelTableEntry]
+

 
 class VerificationError(Exception):
     pass
 
 class VerificationError(Exception):
     pass


@@ -55,10 +82,7 @@ class Verification:
         self.result(True)
 
 
         self.result(True)
 
 

-def compare(a: str,
-            b: str) -> Tuple[Sequence[str],
-                             Sequence[str],
-                             Sequence[str]]:
+def compare(a: str, b: str) -> Tuple[List[str], List[str], List[str]]:

 
     def throw(error: OSError) -> None:
         raise error
 
     def throw(error: OSError) -> None:
         raise error


@@ -86,86 +110,329 @@ def compare(a: str,
     return filecmp.cmpfiles(a, b, files, shallow=False)
 
 
     return filecmp.cmpfiles(a, b, files, shallow=False)
 
 

-def fetch(v: Verification, channel_url: str) -> Dict[str, Any]:
-    info: Dict[str, Any] = {'url': channel_url}
+def fetch(v: Verification, channel: Channel) -> None:

     v.status('Fetching channel')
     v.status('Fetching channel')

-    request = urllib.request.urlopen(
-        'https://channels.nixos.org/nixos-20.03', timeout=10)
-    info['channel_html'] = request.read()
-    info['forwarded_url'] = request.geturl()
+    request = urllib.request.urlopen(channel.channel_url, timeout=10)
+    channel.channel_html = request.read()
+    channel.forwarded_url = request.geturl()

     v.result(request.status == 200)
     v.result(request.status == 200)

-    v.check('Got forwarded', info['url'] != info['forwarded_url'])
-    return info
+    v.check('Got forwarded', channel.channel_url != channel.forwarded_url)

 
 
 
 

-def parse(v: Verification, info: Dict[str, Any]) -> None:
+def parse_channel(v: Verification, channel: Channel) -> None:

     v.status('Parsing channel description as XML')
     v.status('Parsing channel description as XML')

-    d = xml.dom.minidom.parseString(info['channel_html'])
+    d = xml.dom.minidom.parseString(channel.channel_html)

     v.ok()
 
     v.ok()
 

-    v.status('Extracting git commit')
+    v.status('Extracting release name:')
+    title_name = d.getElementsByTagName(
+        'title')[0].firstChild.nodeValue.split()[2]
+    h1_name = d.getElementsByTagName('h1')[0].firstChild.nodeValue.split()[2]
+    v.status(title_name)
+    v.result(title_name == h1_name)
+    channel.release_name = title_name
+
+    v.status('Extracting git commit:')

     git_commit_node = d.getElementsByTagName('tt')[0]
     git_commit_node = d.getElementsByTagName('tt')[0]

-    info['git_commit'] = git_commit_node.firstChild.nodeValue
+    channel.git_revision = git_commit_node.firstChild.nodeValue
+    v.status(channel.git_revision)

     v.ok()
     v.status('Verifying git commit label')
     v.result(git_commit_node.previousSibling.nodeValue == 'Git commit ')
 
     v.status('Parsing table')
     v.ok()
     v.status('Verifying git commit label')
     v.result(git_commit_node.previousSibling.nodeValue == 'Git commit ')
 
     v.status('Parsing table')

-    info['table'] = {}
+    channel.table = {}

     for row in d.getElementsByTagName('tr')[1:]:
         name = row.childNodes[0].firstChild.firstChild.nodeValue
         url = row.childNodes[0].firstChild.getAttribute('href')
         size = int(row.childNodes[1].firstChild.nodeValue)
     for row in d.getElementsByTagName('tr')[1:]:
         name = row.childNodes[0].firstChild.firstChild.nodeValue
         url = row.childNodes[0].firstChild.getAttribute('href')
         size = int(row.childNodes[1].firstChild.nodeValue)

-        digest = row.childNodes[2].firstChild.firstChild.nodeValue
-        info['table'][name] = {'url': url, 'digest': digest, 'size': size}
+        digest = Digest16(row.childNodes[2].firstChild.firstChild.nodeValue)
+        channel.table[name] = ChannelTableEntry(
+            url=url, digest=digest, size=size)

     v.ok()
 
 
     v.ok()
 
 

-def fetch_resources(v: Verification, info: Dict[str, Any]) -> None:
+def digest_string(s: bytes) -> Digest16:
+    return Digest16(hashlib.sha256(s).hexdigest())
+
+
+def digest_file(filename: str) -> Digest16:
+    hasher = hashlib.sha256()
+    with open(filename, 'rb') as f:
+        # pylint: disable=cell-var-from-loop
+        for block in iter(lambda: f.read(4096), b''):
+            hasher.update(block)
+    return Digest16(hasher.hexdigest())

 
 

+
+def to_Digest16(v: Verification, digest32: Digest32) -> Digest16:
+    v.status('Converting digest to base16')
+    process = subprocess.run(
+        ['nix', 'to-base16', '--type', 'sha256', digest32], capture_output=True)
+    v.result(process.returncode == 0)
+    return Digest16(process.stdout.decode().strip())
+
+
+def to_Digest32(v: Verification, digest16: Digest16) -> Digest32:
+    v.status('Converting digest to base32')
+    process = subprocess.run(
+        ['nix', 'to-base32', '--type', 'sha256', digest16], capture_output=True)
+    v.result(process.returncode == 0)
+    return Digest32(process.stdout.decode().strip())
+
+
+def fetch_with_nix_prefetch_url(
+        v: Verification,
+        url: str,
+        digest: Digest16) -> str:
+    v.status('Fetching %s' % url)
+    process = subprocess.run(
+        ['nix-prefetch-url', '--print-path', url, digest], capture_output=True)
+    v.result(process.returncode == 0)
+    prefetch_digest, path, empty = process.stdout.decode().split('\n')
+    assert empty == ''
+    v.check("Verifying nix-prefetch-url's digest",
+            to_Digest16(v, Digest32(prefetch_digest)) == digest)
+    v.status("Verifying file digest")
+    file_digest = digest_file(path)
+    v.result(file_digest == digest)
+    return path
+
+
+def fetch_resources(v: Verification, channel: Channel) -> None:

     for resource in ['git-revision', 'nixexprs.tar.xz']:
     for resource in ['git-revision', 'nixexprs.tar.xz']:

-        fields = info['table'][resource]
-        v.status('Fetching resource "%s"' % resource)
-        url = urllib.parse.urljoin(info['forwarded_url'], fields['url'])
-        request = urllib.request.urlopen(url, timeout=10)
-        if fields['size'] < 4096:
-            fields['content'] = request.read()
-        else:
-            with tempfile.NamedTemporaryFile(suffix='.nixexprs.tar.xz', delete=False) as tmp_file:
-                shutil.copyfileobj(request, tmp_file)
-                fields['file'] = tmp_file.name
-        v.result(request.status == 200)
-        v.status('Verifying digest for "%s"' % resource)
-        if fields['size'] < 4096:
-            actual_hash = hashlib.sha256(fields['content']).hexdigest()
-        else:
-            hasher = hashlib.sha256()
-            with open(fields['file'], 'rb') as f:
-                # pylint: disable=cell-var-from-loop
-                for block in iter(lambda: f.read(4096), b''):
-                    hasher.update(block)
-            actual_hash = hasher.hexdigest()
-        v.result(actual_hash == fields['digest'])
-    v.check('Verifying git commit on main page matches git commit in table',
-            info['table']['git-revision']['content'].decode() == info['git_commit'])
-
-
-def extract_channel(v: Verification, info: Dict[str, Any]) -> None:
-    with tempfile.TemporaryDirectory() as d:
-        v.status('Extracting nixexprs.tar.xz')
-        shutil.unpack_archive(info['table']['nixexprs.tar.xz']['file'], d)
-        v.ok()
-        v.status('Removing temporary directory')
+        fields = channel.table[resource]
+        fields.absolute_url = urllib.parse.urljoin(
+            channel.forwarded_url, fields.url)
+        fields.file = fetch_with_nix_prefetch_url(
+            v, fields.absolute_url, fields.digest)
+    v.status('Verifying git commit on main page matches git commit in table')
+    v.result(
+        open(
+            channel.table['git-revision'].file).read(999) == channel.git_revision)
+
+
+def git_fetch(v: Verification, channel: Channel) -> None:
+    # It would be nice if we could share the nix git cache, but as of the time
+    # of writing it is transitioning from gitv2 (deprecated) to gitv3 (not ready
+    # yet), and trying to straddle them both is too far into nix implementation
+    # details for my comfort.  So we re-implement here half of nix.fetchGit.
+    # :(
+
+    # TODO: Consider using pyxdg to find this path.
+    channel.git_cachedir = os.path.expanduser(
+        '~/.cache/nix-pin-channel/git/%s' %
+        digest_string(
+            channel.git_repo.encode()))
+    if not os.path.exists(channel.git_cachedir):
+        v.status("Initializing git repo")
+        process = subprocess.run(
+            ['git', 'init', '--bare', channel.git_cachedir])
+        v.result(process.returncode == 0)
+
+    have_rev = False
+    if hasattr(channel, 'git_revision'):
+        v.status('Checking if we already have this rev:')
+        process = subprocess.run(
+            ['git', '-C', channel.git_cachedir, 'cat-file', '-e', channel.git_revision])
+        if process.returncode == 0:
+            v.status('yes')
+        if process.returncode == 1:
+            v.status('no')
+        v.result(process.returncode == 0 or process.returncode == 1)
+        have_rev = process.returncode == 0
+
+    if not have_rev:
+        v.status(
+            'Fetching ref "%s" from %s' %
+            (channel.git_ref, channel.git_repo))
+        # We don't use --force here because we want to abort and freak out if forced
+        # updates are happening.
+        process = subprocess.run(['git',
+                                  '-C',
+                                  channel.git_cachedir,
+                                  'fetch',
+                                  channel.git_repo,
+                                  '%s:%s' % (channel.git_ref,
+                                             channel.git_ref)])
+        v.result(process.returncode == 0)
+        if hasattr(channel, 'git_revision'):
+            v.status('Verifying that fetch retrieved this rev')
+            process = subprocess.run(
+                ['git', '-C', channel.git_cachedir, 'cat-file', '-e', channel.git_revision])
+            v.result(process.returncode == 0)
+
+    if not hasattr(channel, 'git_revision'):
+        channel.git_revision = open(
+            os.path.join(
+                channel.git_cachedir,
+                'refs',
+                'heads',
+                channel.git_ref)).read(999).strip()
+
+    v.status('Verifying rev is an ancestor of ref')
+    process = subprocess.run(['git',
+                              '-C',
+                              channel.git_cachedir,
+                              'merge-base',
+                              '--is-ancestor',
+                              channel.git_revision,
+                              channel.git_ref])
+    v.result(process.returncode == 0)
+
+    if hasattr(channel, 'old_git_revision'):
+        v.status(
+            'Verifying rev is an ancestor of previous rev %s' %
+            channel.old_git_revision)
+        process = subprocess.run(['git',
+                                  '-C',
+                                  channel.git_cachedir,
+                                  'merge-base',
+                                  '--is-ancestor',
+                                  channel.old_git_revision,
+                                  channel.git_revision])
+        v.result(process.returncode == 0)
+
+
+def compare_tarball_and_git(
+        v: Verification,
+        channel: Channel,
+        channel_contents: str,
+        git_contents: str) -> None:
+    v.status('Comparing channel tarball with git checkout')
+    match, mismatch, errors = compare(os.path.join(
+        channel_contents, channel.release_name), git_contents)
+    v.ok()
+    v.check('%d files match' % len(match), len(match) > 0)
+    v.check('%d files differ' % len(mismatch), len(mismatch) == 0)
+    expected_errors = [
+        '.git-revision',
+        '.version-suffix',
+        'nixpkgs',
+        'programs.sqlite',
+        'svn-revision']
+    benign_errors = []
+    for ee in expected_errors:
+        if ee in errors:
+            errors.remove(ee)
+            benign_errors.append(ee)
+    v.check(
+        '%d unexpected incomparable files' %
+        len(errors),
+        len(errors) == 0)
+    v.check(
+        '(%d of %d expected incomparable files)' %
+        (len(benign_errors),
+         len(expected_errors)),
+        len(benign_errors) == len(expected_errors))
+
+
+def extract_tarball(v: Verification, channel: Channel, dest: str) -> None:
+    v.status('Extracting tarball %s' %
+             channel.table['nixexprs.tar.xz'].file)
+    shutil.unpack_archive(
+        channel.table['nixexprs.tar.xz'].file,
+        dest)

     v.ok()
 
 
     v.ok()
 
 

-def main() -> None:
+def git_checkout(v: Verification, channel: Channel, dest: str) -> None:
+    v.status('Checking out corresponding git revision')
+    git = subprocess.Popen(['git',
+                            '-C',
+                            channel.git_cachedir,
+                            'archive',
+                            channel.git_revision],
+                           stdout=subprocess.PIPE)
+    tar = subprocess.Popen(
+        ['tar', 'x', '-C', dest, '-f', '-'], stdin=git.stdout)
+    git.stdout.close()
+    tar.wait()
+    git.wait()
+    v.result(git.returncode == 0 and tar.returncode == 0)
+
+
+def check_channel_metadata(
+        v: Verification,
+        channel: Channel,
+        channel_contents: str) -> None:
+    v.status('Verifying git commit in channel tarball')
+    v.result(
+        open(
+            os.path.join(
+                channel_contents,
+                channel.release_name,
+                '.git-revision')).read(999) == channel.git_revision)
+
+    v.status(
+        'Verifying version-suffix is a suffix of release name %s:' %
+        channel.release_name)
+    version_suffix = open(
+        os.path.join(
+            channel_contents,
+            channel.release_name,
+            '.version-suffix')).read(999)
+    v.status(version_suffix)
+    v.result(channel.release_name.endswith(version_suffix))
+
+
+def check_channel_contents(v: Verification, channel: Channel) -> None:
+    with tempfile.TemporaryDirectory() as channel_contents, \
+            tempfile.TemporaryDirectory() as git_contents:
+
+        extract_tarball(v, channel, channel_contents)
+        check_channel_metadata(v, channel, channel_contents)
+
+        git_checkout(v, channel, git_contents)
+
+        compare_tarball_and_git(v, channel, channel_contents, git_contents)
+
+        v.status('Removing temporary directories')
+    v.ok()
+
+
+def pin_channel(v: Verification, channel: Channel) -> None:
+    fetch(v, channel)
+    parse_channel(v, channel)
+    fetch_resources(v, channel)
+    git_fetch(v, channel)
+    check_channel_contents(v, channel)
+
+
+def make_channel(conf: configparser.SectionProxy) -> Channel:
+    channel = Channel(**dict(conf.items()))
+    if hasattr(channel, 'git_revision'):
+        channel.old_git_revision = channel.git_revision
+        del channel.git_revision
+    return channel
+
+
+def pin(args: argparse.Namespace) -> None:

     v = Verification()
     v = Verification()

-    info = fetch(v, 'https://channels.nixos.org/nixos-20.03')
-    parse(v, info)
-    fetch_resources(v, info)
-    extract_channel(v, info)
-    print(info)
+    config = configparser.ConfigParser()
+    config.read_file(open(args.channels_file), args.channels_file)
+    for section in config.sections():
+        channel = make_channel(config[section])
+        if 'channel_url' in config[section]:
+            pin_channel(v, channel)
+            config[section]['tarball_url'] = channel.table['nixexprs.tar.xz'].absolute_url
+            config[section]['tarball_sha256'] = channel.table['nixexprs.tar.xz'].digest
+        else:
+            git_fetch(v, channel)
+        config[section]['git_revision'] = channel.git_revision
+
+    with open(args.channels_file, 'w') as configfile:
+        config.write(configfile)
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(prog='pinch')
+    subparsers = parser.add_subparsers(dest='mode', required=True)
+    parser_pin = subparsers.add_parser('pin')
+    parser_pin.add_argument('channels_file', type=str)
+    parser_pin.set_defaults(func=pin)
+    args = parser.parse_args()
+    args.func(args)

 
 
 main()
 
 
 main()