Backport of Python 3.8 shutil.copytree, refs #744

datasette/utils/__init__.py

@@ -15,6 +15,7 @@
 import urllib
 import numbers
 import yaml
+from .shutil_backport import copytree
 
 try:
     import pysqlite3 as sqlite3
@@ -602,9 +603,9 @@ def link_or_copy(src, dst):
 
 def link_or_copy_directory(src, dst):
     try:
-        shutil.copytree(src, dst, copy_function=os.link, dirs_exist_ok=True)
+        copytree(src, dst, copy_function=os.link, dirs_exist_ok=True)
     except OSError:
-        shutil.copytree(src, dst, dirs_exist_ok=True)
+        copytree(src, dst, dirs_exist_ok=True)
 
 
 def module_from_path(path, name):

datasette/utils/shutil_backport.py

@@ -0,0 +1,101 @@
+"""
+Backported from Python 3.8.
+
+This code is licensed under the Python License:
+https://github.com/python/cpython/blob/v3.8.3/LICENSE
+"""
+import os
+from shutil import copy, copy2, copystat, Error
+
+
+def _copytree(
+    entries,
+    src,
+    dst,
+    symlinks,
+    ignore,
+    copy_function,
+    ignore_dangling_symlinks,
+    dirs_exist_ok=False,
+):
+    if ignore is not None:
+        ignored_names = ignore(src, set(os.listdir(src)))
+    else:
+        ignored_names = set()
+
+    os.makedirs(dst, exist_ok=dirs_exist_ok)
+    errors = []
+    use_srcentry = copy_function is copy2 or copy_function is copy
+
+    for srcentry in entries:
+        if srcentry.name in ignored_names:
+            continue
+        srcname = os.path.join(src, srcentry.name)
+        dstname = os.path.join(dst, srcentry.name)
+        srcobj = srcentry if use_srcentry else srcname
+        try:
+            if srcentry.is_symlink():
+                linkto = os.readlink(srcname)
+                if symlinks:
+                    os.symlink(linkto, dstname)
+                    copystat(srcobj, dstname, follow_symlinks=not symlinks)
+                else:
+                    if not os.path.exists(linkto) and ignore_dangling_symlinks:
+                        continue
+                    if srcentry.is_dir():
+                        copytree(
+                            srcobj,
+                            dstname,
+                            symlinks,
+                            ignore,
+                            copy_function,
+                            dirs_exist_ok=dirs_exist_ok,
+                        )
+                    else:
+                        copy_function(srcobj, dstname)
+            elif srcentry.is_dir():
+                copytree(
+                    srcobj,
+                    dstname,
+                    symlinks,
+                    ignore,
+                    copy_function,
+                    dirs_exist_ok=dirs_exist_ok,
+                )
+            else:
+                copy_function(srcentry, dstname)
+        except Error as err:
+            errors.extend(err.args[0])
+        except OSError as why:
+            errors.append((srcname, dstname, str(why)))
+    try:
+        copystat(src, dst)
+    except OSError as why:
+        # Copying file access times may fail on Windows
+        if getattr(why, "winerror", None) is None:
+            errors.append((src, dst, str(why)))
+    if errors:
+        raise Error(errors)
+    return dst
+
+
+def copytree(
+    src,
+    dst,
+    symlinks=False,
+    ignore=None,
+    copy_function=copy2,
+    ignore_dangling_symlinks=False,
+    dirs_exist_ok=False,
+):
+    with os.scandir(src) as entries:
+        return _copytree(
+            entries=entries,
+            src=src,
+            dst=dst,
+            symlinks=symlinks,
+            ignore=ignore,
+            copy_function=copy_function,
+            ignore_dangling_symlinks=ignore_dangling_symlinks,
+            dirs_exist_ok=dirs_exist_ok,
+        )