Fix Pex isolation losing perm bits.

Now that PEXes only run in unzipped mode and venv mode, they always
will be isolating from loose sources and the resources copy mechanism
is no longer needed.

pex/third_party/__init__.py

@@ -7,11 +7,9 @@
 import importlib
 import os
 import re
-import shutil
 import sys
 import zipfile
 from collections import OrderedDict, namedtuple
-from contextlib import closing
 
 
 # NB: All pex imports are performed lazily to play well with the un-imports performed by both the
@@ -346,8 +344,13 @@ def isolated():
     global _ISOLATED
     if _ISOLATED is None:
         from pex import vendor
-        from pex.common import atomic_directory, is_pyc_temporary_file
-        from pex.third_party.pkg_resources import resource_isdir, resource_listdir, resource_stream
+        from pex.common import (
+            atomic_directory,
+            filter_pyc_dirs,
+            filter_pyc_files,
+            is_pyc_temporary_file,
+            safe_copy,
+        )
         from pex.util import CacheHelper
         from pex.variables import ENV
 
@@ -360,32 +363,6 @@ def isolated():
             for vendor_spec in vendor.iter_vendor_specs()
         )
 
-        # TODO(John Sirois): Unify with `pex.util.DistributionHelper.access_zipped_assets`.
-        def recursive_copy(srcdir, dstdir):
-            os.mkdir(dstdir)
-            for entry_name in resource_listdir(module, srcdir):
-                if not entry_name:
-                    # The `resource_listdir` function returns a '' entry name for the directory
-                    # entry itself if it is either present on the filesystem or present as an
-                    # explicit zip entry. Since we only care about files and subdirectories at this
-                    # point, skip these entries.
-                    continue
-                # NB: Resource path components are always separated by /, on all systems.
-                src_entry = "{}/{}".format(srcdir, entry_name) if srcdir else entry_name
-                dst_entry = os.path.join(dstdir, entry_name)
-                if resource_isdir(module, src_entry):
-                    if os.path.basename(src_entry) == "__pycache__":
-                        continue
-                    recursive_copy(src_entry, dst_entry)
-                elif (
-                    not entry_name.endswith(".pyc")
-                    and not is_pyc_temporary_file(entry_name)
-                    and src_entry not in vendor_lockfiles
-                ):
-                    with open(dst_entry, "wb") as fp:
-                        with closing(resource_stream(module, src_entry)) as resource:
-                            shutil.copyfileobj(resource, fp)
-
         pex_path = os.path.join(vendor.VendorSpec.ROOT, "pex")
         with _tracer().timed("Hashing pex"):
             assert os.path.isdir(pex_path), (
@@ -400,7 +377,21 @@ def recursive_copy(srcdir, dstdir):
             with atomic_directory(isolated_dir, exclusive=True) as chroot:
                 if not chroot.is_finalized():
                     with _tracer().timed("Extracting pex to {}".format(isolated_dir)):
-                        recursive_copy("", os.path.join(chroot.work_dir, "pex"))
+                        pex_path = os.path.join(vendor.VendorSpec.ROOT, "pex")
+                        for root, dirs, files in os.walk(pex_path):
+                            relroot = os.path.relpath(root, pex_path)
+                            for d in filter_pyc_dirs(dirs):
+                                os.makedirs(os.path.join(chroot.work_dir, "pex", relroot, d))
+                            for f in filter_pyc_files(files):
+                                rel_f = os.path.join(relroot, f)
+                                if (
+                                    not is_pyc_temporary_file(rel_f)
+                                    and rel_f not in vendor_lockfiles
+                                ):
+                                    safe_copy(
+                                        os.path.join(root, f),
+                                        os.path.join(chroot.work_dir, "pex", rel_f),
+                                    )
 
         _ISOLATED = IsolationResult(pex_hash=dir_hash, chroot_path=isolated_dir)
     return _ISOLATED