Allow identically-broken symlinks

[pinch] / pinch.py

diff --git a/pinch.py b/pinch.py
index e3c7ca0d4aab71b2c2984a0220129efe106fd023..9e80c01436aa2071501be22e3048f70473ef4aad 100644 (file)
--- a/pinch.py
+++ b/pinch.py
@@ -1,3 +1,10 @@
+# pinch: PIN CHannels - a replacement for `nix-channel --update`
+#
+# This program is free software: you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the
+# Free Software Foundation, version 3.
+
+
 import argparse
 import configparser
 import filecmp
@@ -141,7 +148,6 @@ def symlink_archive(v: Verification, path: str) -> str:
 class AliasSearchPath(NamedTuple):
     alias_of: str
 
-    # pylint: disable=no-self-use
     def pin(self, _: Verification, __: Optional[Pin]) -> AliasPin:
         return AliasPin()
 
@@ -149,7 +155,6 @@ class AliasSearchPath(NamedTuple):
 class SymlinkSearchPath(NamedTuple):
     path: str
 
-    # pylint: disable=no-self-use
     def pin(self, _: Verification, __: Optional[Pin]) -> SymlinkPin:
         return SymlinkPin()
 
@@ -202,7 +207,6 @@ class ChannelSearchPath(NamedTuple):
             tarball_sha256=table['nixexprs.tar.xz'].digest,
             git_revision=new_gitpin.git_revision)
 
-    # pylint: disable=no-self-use
     def fetch(self, v: Verification, pin: Pin) -> str:
         assert isinstance(pin, ChannelPin)
 
@@ -262,15 +266,29 @@ def parse_channel(v: Verification, channel_html: str) \
     d = xml.dom.minidom.parseString(channel_html)
     v.ok()
 
-    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)
-
-    v.status('Extracting git commit:')
+    v.status('Finding release name (1)')
+    title = d.getElementsByTagName('title')[0].firstChild
+    v.result(isinstance(title, xml.dom.minidom.CharacterData))
+    assert isinstance(title, xml.dom.minidom.CharacterData)
+    release_name = title.nodeValue.split()[2]
+    v.status('Finding release name (2)')
+    h1 = d.getElementsByTagName('h1')[0].firstChild
+    v.result(isinstance(h1, xml.dom.minidom.CharacterData))
+    assert isinstance(h1, xml.dom.minidom.CharacterData)
+    v.status('Verifying release name:')
+    v.status(release_name)
+    v.result(release_name == h1.nodeValue.split()[2])
+
+    v.status('Finding git commit')
     git_commit_node = d.getElementsByTagName('tt')[0]
+    v.result(
+        isinstance(
+            git_commit_node.firstChild,
+            xml.dom.minidom.CharacterData))
+    assert isinstance(
+        git_commit_node.firstChild,
+        xml.dom.minidom.CharacterData)
+    v.status('Extracting git commit:')
     git_revision = git_commit_node.firstChild.nodeValue
     v.status(git_revision)
     v.ok()
@@ -286,7 +304,7 @@ def parse_channel(v: Verification, channel_html: str) \
         digest = Digest16(row.childNodes[2].firstChild.firstChild.nodeValue)
         table[name] = ChannelTableEntry(url=url, digest=digest, size=size)
     v.ok()
-    return table, GitPin(release_name=title_name, git_revision=git_revision)
+    return table, GitPin(release_name=release_name, git_revision=git_revision)
 
 
 def digest_string(s: bytes) -> Digest16:
@@ -396,14 +414,24 @@ def verify_git_ancestry(
     v.result(process.returncode == 0)
 
 
+def broken_symlinks_are_identical(root1: str, root2: str, path: str) -> bool:
+    a = os.path.join(root1, path)
+    b = os.path.join(root2, path)
+    return (os.path.islink(a)
+            and os.path.islink(b)
+            and not os.path.exists(a)
+            and not os.path.exists(b)
+            and os.readlink(a) == os.readlink(b))
+
+
 def compare_tarball_and_git(
         v: Verification,
         pin: GitPin,
         channel_contents: str,
         git_contents: str) -> None:
     v.status('Comparing channel tarball with git checkout')
-    match, mismatch, errors = compare(os.path.join(
-        channel_contents, pin.release_name), git_contents)
+    tarball_contents = os.path.join(channel_contents, pin.release_name)
+    match, mismatch, errors = compare(tarball_contents, git_contents)
     v.ok()
     v.check(f'{len(match)} files match', len(match) > 0)
     v.check(f'{len(mismatch)} files differ', len(mismatch) == 0)
@@ -413,15 +441,21 @@ def compare_tarball_and_git(
         'nixpkgs',
         'programs.sqlite',
         'svn-revision']
-    benign_errors = []
+    benign_expected_errors = []
     for ee in expected_errors:
         if ee in errors:
             errors.remove(ee)
-            benign_errors.append(ee)
-    v.check(f'{len(errors)} unexpected incomparable files', len(errors) == 0)
+            benign_expected_errors.append(ee)
+    errors = [
+        e for e in errors
+        if not broken_symlinks_are_identical(tarball_contents, git_contents, e)
+    ]
+    v.check(
+        f'{len(errors)} unexpected incomparable files: {errors}',
+        len(errors) == 0)
     v.check(
-        f'({len(benign_errors)} of {len(expected_errors)} expected incomparable files)',
-        len(benign_errors) == len(expected_errors))
+        f'({len(benign_expected_errors)} of {len(expected_errors)} expected incomparable files)',
+        len(benign_expected_errors) == len(expected_errors))
 
 
 def extract_tarball(
@@ -572,7 +606,7 @@ def read_config_section(
     _, all_fields = filter_dict(dict(conf.items()), set(['type']))
     pin_fields, remaining_fields = filter_dict(all_fields, set(P._fields))
     # Error suppression works around https://github.com/python/mypy/issues/9007
-    pin_present = pin_fields != {} or P._fields == ()
+    pin_present = pin_fields or P._fields == ()
     pin = P(**pin_fields) if pin_present else None  # type: ignore
     return SP(**remaining_fields), pin
 
@@ -581,7 +615,7 @@ def read_pinned_config_section(
         section: str, conf: configparser.SectionProxy) -> Tuple[SearchPath, Pin]:
     sp, pin = read_config_section(conf)
     if pin is None:
-        raise Exception(
+        raise RuntimeError(
             f'Cannot update unpinned channel "{section}" (Run "pin" before "update")')
     return sp, pin
 
@@ -600,7 +634,7 @@ def read_config_files(
         config = read_config(file)
         for section in config.sections():
             if section in merged_config:
-                raise Exception('Duplicate channel "{section}"')
+                raise RuntimeError('Duplicate channel "{section}"')
             merged_config[section] = config[section]
     return merged_config