1 files changed, 77 insertions, 0 deletions
diff --git a/debputy/disabled-plugins/lua.py b/debputy/disabled-plugins/lua.py
new file mode 100644
index 0000000..7d49c6e
--- /dev/null
+++ b/debputy/disabled-plugins/lua.py
@@ -0,0 +1,77 @@
+import itertools
+from typing import Any, Optional, Tuple, IO, Iterable
+
+from debputy.plugin.api import DebputyPluginInitializer, VirtualPath
+
+_BUF_SIZE = 8096
+
+
+def initialize(api: DebputyPluginInitializer) -> None:
+    register_processing_steps_via_non_public_api(api)
+
+
+def register_processing_steps_via_non_public_api(api: Any) -> None:
+    api.package_processor(
+        "deduplicate-lua-files",
+        deduplicate_lua_files,
+    )
+
+
+def find_lowest_lua5_version_dir(fs_root: VirtualPath) -> Optional[Tuple[int, VirtualPath]]:
+    for lua5_minor_version in range(1, 9):
+        lua_dir = fs_root.lookup(f"/usr/share/lua/5.{lua5_minor_version}/")
+        if not lua_dir:
+            continue
+        return lua5_minor_version, lua_dir
+    return None
+
+
+def _compute_rel_path(reference_point: VirtualPath, target_file: VirtualPath) -> str:
+    assert target_file.path.startswith(reference_point.path + "/")
+    return target_file.path[len(reference_point.path) + 1:]
+
+
+def _chunk(fd: IO[bytes]) -> Iterable[bytes]:
+    c = fd.read(_BUF_SIZE)
+    while c:
+        yield c
+        c = fd.read(_BUF_SIZE)
+
+
+def _same_content(a: VirtualPath, b: VirtualPath) -> bool:
+    if a.size != b.size:
+        return False
+    # It might be tempting to use `cmp {a.fs_path} {b.fs_path}`, but this method makes it easier to test
+    # as the test will not have to create physical files.
+    #
+    # We could also replace this with a checksum check, then we could store them in a table and deduplicate
+    # between multiple versions (not just against the lowest version). Decided against it because this is
+    # are more faithful translation of the original code.
+    with a.open(byte_io=True, buffering=_BUF_SIZE) as afd, b.open(byte_io=True, buffering=_BUF_SIZE) as bfd:
+        for a_chunk, b_chunk in itertools.zip_longest(afd, bfd, fillvalue=None):
+            if a_chunk is None or b_chunk is None or a_chunk != b_chunk:
+                return False
+    return True
+
+
+def deduplicate_lua_files(fs_root: VirtualPath, _unused1: Any, _unused2: Any) -> None:
+    res_tuple = find_lowest_lua5_version_dir(fs_root)
+    if res_tuple is None:
+        return
+    lua5_minor_version, lua5_reference_dir = res_tuple
+    all_lua5_ref_files = [
+        lua_file
+        for lua_file in lua5_reference_dir.all_paths()
+        if lua_file.is_file and lua_file.name.endswith(".lua")
+    ]
+    for lua_file in all_lua5_ref_files:
+        rel_path = _compute_rel_path(lua5_reference_dir, lua_file)
+        for newer_lua_minor_version in range(lua5_minor_version + 1, 9):
+            alt_lua_file = fs_root.lookup(f"/usr/share/lua/5.{newer_lua_minor_version}/{rel_path}")
+            if alt_lua_file is None or not alt_lua_file.is_file or not _same_content(lua_file, alt_lua_file):
+                continue
+            parent_dir = alt_lua_file.parent_dir
+            assert parent_dir is not None
+            alt_lua_file.unlink()
+            # We do not have to normalize the link; debputy will handle that later.
+            parent_dir.add_symlink(alt_lua_file.name, lua_file.absolute)