depfixer: silence fix_jar() and make it do something

fix_jar() tries to remove an existing Class-Path entry from the jar
manifest by postprocessing the manifest and passing it to `jar -um`.
However, `jar -um` can only add/replace manifest entries, not remove
them, and it also complains loudly when replacing an entry:

    Dec 13, 2022 7:11:19 PM java.util.jar.Attributes read
    WARNING: Duplicate name in Manifest: Manifest-Version.
    Ensure that the manifest does not have duplicate entries, and
    that blank lines separate individual sections in both your
    manifest and in the META-INF/MANIFEST.MF entry in the jar file.

Thus fix_jar() produces one such warning for each entry in the manifest
and accomplishes nothing else.

Use jar -uM instead.  This completely removes the manifest from the jar
and allows adding it back as a normal zip member, fixing fix_jar() and
avoiding the warnings.

Fixes: https://github.com/mesonbuild/meson/issues/10491
Fixes: c70a051e93 ("java: remove manifest classpath from installed jar")

1 files changed, 17 insertions, 0 deletions

diff --git a/unittests/helpers.py b/unittests/helpers.py
index ac9d980..d3d1560 100644
--- a/unittests/helpers.py
+++ b/unittests/helpers.py
@@ -5,6 +5,7 @@ import unittest
 import functools
 import re
 import typing as T
+import zipfile
 from pathlib import Path
 from contextlib import contextmanager
 
@@ -176,6 +177,22 @@ def get_rpath(fname: str) -> T.Optional[str]:
         return None
     return final
 
+def get_classpath(fname: str) -> T.Optional[str]:
+    with zipfile.ZipFile(fname) as zip:
+        with zip.open('META-INF/MANIFEST.MF') as member:
+            contents = member.read().decode().strip()
+    lines = []
+    for line in contents.splitlines():
+        if line.startswith(' '):
+            # continuation line
+            lines[-1] += line[1:]
+        else:
+            lines.append(line)
+    manifest = {
+        k.lower(): v.strip() for k, v in [l.split(':', 1) for l in lines]
+    }
+    return manifest.get('class-path')
+
 def get_path_without_cmd(cmd: str, path: str) -> str:
     pathsep = os.pathsep
     paths = OrderedSet([Path(p).resolve() for p in path.split(pathsep)])