perf(size): Compute zip metadata size without building a zip

src/launchpad/artifacts/apple/zipped_xcarchive.py

@@ -234,7 +234,7 @@ def generate_ipa(self, output_path: Path):
 
             # Zip the Payload directory, preserving symlinks and permissions
             try:
-                zip_directory(payload_dir, output_path, preserve_symlinks=True)
+                zip_directory(payload_dir, output_path)
             except OSError as e:
                 raise RuntimeError("Failed to generate IPA file") from e
 

src/launchpad/size/utils/apple_bundle_size.py

@@ -1,8 +1,5 @@
 import os
 import plistlib
-import tempfile
-import uuid
-import zipfile
 
 from pathlib import Path
 from typing import List, NamedTuple
@@ -13,7 +10,6 @@
 from launchpad.size.models.common import AppComponent, ComponentType
 from launchpad.utils.file_utils import get_file_size, to_nearest_block_size
 from launchpad.utils.logging import get_logger
-from launchpad.utils.zip_utils import zip_directory
 
 logger = get_logger(__name__)
 
@@ -366,42 +362,18 @@ def _calculate_install_size(path: Path) -> int:
     return total_size
 
 
-# We used to build this zip with Info-ZIP's `zip`, which quietly adds a UT (timestamps) and a ux
-# (uid/gid) extra field to every entry: 28 bytes in the local header, 24 in the central directory.
-# Python's zipfile writes neither, so add them back and the sizes we report stay where they were.
-_INFOZIP_EXTRA_FIELD_BYTES_PER_ENTRY = 52
+# Per-entry bytes Info-ZIP's `zip -r` writes besides the name: local header (30), central header (46)
+# and its UT/ux extra fields (52). The name appears in both headers; the end record adds 22.
+_ZIP_ENTRY_OVERHEAD_BYTES = 30 + 46 + 52
+_ZIP_END_RECORD_BYTES = 22
 
 
 def _zip_metadata_size_for_bundle(bundle_url: Path) -> int:
-    zip_file_path = Path(tempfile.gettempdir()) / f"{uuid.uuid4()}.zip"
-
-    try:
-        logger.debug(f"Creating ZIP file: {zip_file_path} from {bundle_url.name}")
-        zip_directory(bundle_url, zip_file_path, preserve_symlinks=False)
-
-        with zipfile.ZipFile(zip_file_path) as zf:
-            infos = zf.infolist()
-        total_compressed = sum(info.compress_size for info in infos)
-
-        # Get actual ZIP file size
-        total_zip_size = os.path.getsize(zip_file_path)
-
-        # Metadata is everything that isn't payload: headers, names, central directory, EOCD.
-        # Compressed bytes sit in both terms and cancel, so the compression level can't skew this.
-        metadata_size = total_zip_size - total_compressed + _INFOZIP_EXTRA_FIELD_BYTES_PER_ENTRY * len(infos)
-
-        if metadata_size < 0:
-            logger.warning(
-                f"Negative metadata size calculated: {metadata_size}. ZIP size: {total_zip_size}, Compressed content: {total_compressed}"
-            )
-            return 0
-
-        return metadata_size
-
-    except Exception:
-        logger.exception("Error calculating ZIP metadata size")
-        return 0
-
-    finally:
-        if zip_file_path.exists():
-            zip_file_path.unlink()
+    names = []
+    for dirpath, dirnames, filenames in os.walk(bundle_url, followlinks=True):
+        real = Path(dirpath).resolve()
+        dirnames[:] = [d for d in dirnames if not real.is_relative_to(Path(dirpath, d).resolve())]
+        rel = Path(dirpath).relative_to(bundle_url.parent).as_posix()
+        names.append(f"{rel}/")
+        names.extend(f"{rel}/{f}" for f in filenames if os.path.exists(os.path.join(dirpath, f)))
+    return _ZIP_END_RECORD_BYTES + sum(_ZIP_ENTRY_OVERHEAD_BYTES + 2 * len(os.fsencode(n)) for n in names)

src/launchpad/utils/zip_utils.py

@@ -23,34 +23,20 @@ def _zip_info_for(arcname: str, st: os.stat_result) -> zipfile.ZipInfo:
     return info
 
 
-def zip_directory(source_dir: Path, output_path: Path, *, preserve_symlinks: bool = True) -> None:
-    """Recursively zip ``source_dir`` into ``output_path``.
-
-    Mirrors ``zip -r`` (or ``zip -r -y`` when ``preserve_symlinks`` is set): entries are
-    named relative to the parent of ``source_dir`` so the archive root is ``source_dir.name``,
-    directory entries are included, and unix permissions are preserved.
-
-    Args:
-        source_dir: Directory to archive
-        output_path: Destination ``.zip`` path (overwritten if it exists)
-        preserve_symlinks: Store symlinks as symlink entries instead of following them
-    """
+def zip_directory(source_dir: Path, output_path: Path) -> None:
+    """Zip ``source_dir`` like ``zip -r -y``: symlinks kept as links, archive root is ``source_dir.name``."""
     source_dir = Path(source_dir)
     base = source_dir.parent
 
     with zipfile.ZipFile(output_path, "w", zipfile.ZIP_DEFLATED) as zf:
-        _add_path(zf, source_dir, base, preserve_symlinks)
+        _add_path(zf, source_dir, base)
 
 
-def _add_path(zf: zipfile.ZipFile, path: Path, base: Path, preserve_symlinks: bool) -> None:
-    try:
-        st = path.lstat() if preserve_symlinks else path.stat()
-    except FileNotFoundError:
-        # Dangling symlink while following links; Info-ZIP skips these too
-        return
+def _add_path(zf: zipfile.ZipFile, path: Path, base: Path) -> None:
+    st = path.lstat()
     arcname = path.relative_to(base).as_posix()
 
-    if preserve_symlinks and stat.S_ISLNK(st.st_mode):
+    if stat.S_ISLNK(st.st_mode):
         info = _zip_info_for(arcname, st)
         zf.writestr(info, os.readlink(path))
         return
@@ -60,7 +46,7 @@ def _add_path(zf: zipfile.ZipFile, path: Path, base: Path, preserve_symlinks: bo
         info.external_attr |= 0x10  # MS-DOS directory flag, as Info-ZIP sets it
         zf.writestr(info, b"")
         for child in sorted(path.iterdir()):
-            _add_path(zf, child, base, preserve_symlinks)
+            _add_path(zf, child, base)
         return
 
     info = _zip_info_for(arcname, st)

tests/unit/utils/test_zip_utils.py

@@ -23,7 +23,7 @@ def test_zip_directory_preserves_symlinks_and_permissions(tmp_path: Path) -> Non
     bundle = _make_bundle(tmp_path)
     out = tmp_path / "out.zip"
 
-    zip_directory(bundle, out, preserve_symlinks=True)
+    zip_directory(bundle, out)
 
     with zipfile.ZipFile(out) as zf:
         assert zf.testzip() is None
@@ -39,18 +39,3 @@ def test_zip_directory_preserves_symlinks_and_permissions(tmp_path: Path) -> Non
         assert zf.read(link) == b"Versions/A/Foo"
 
         assert stat.S_IMODE(infos["Test.app/Test"].external_attr >> 16) == 0o755
-
-
-def test_zip_directory_follows_symlinks_when_requested(tmp_path: Path) -> None:
-    bundle = _make_bundle(tmp_path)
-    os.symlink("does-not-exist", bundle / "dangling")
-    out = tmp_path / "out.zip"
-
-    zip_directory(bundle, out, preserve_symlinks=False)
-
-    with zipfile.ZipFile(out) as zf:
-        infos = {i.filename: i for i in zf.infolist()}
-        link = infos["Test.app/Frameworks/Foo.framework/Foo"]
-        assert stat.S_ISREG(link.external_attr >> 16)
-        assert zf.read(link) == b"binary" * 100
-        assert "Test.app/dangling" not in infos