bpo-20849: add dirs_exist_ok arg to shutil.copytree (patch by Josh Bronson)

1 files changed, 13 insertions, 9 deletions

diff --git a/Lib/shutil.py b/Lib/shutil.py
index 74348ba..8d0de72 100644
--- a/Lib/shutil.py
+++ b/Lib/shutil.py
@@ -432,13 +432,13 @@ def ignore_patterns(*patterns):
     return _ignore_patterns
 
 def _copytree(entries, src, dst, symlinks, ignore, copy_function,
-              ignore_dangling_symlinks):
+              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)
+    os.makedirs(dst, exist_ok=dirs_exist_ok)
     errors = []
     use_srcentry = copy_function is copy2 or copy_function is copy
 
@@ -461,14 +461,15 @@ def _copytree(entries, src, dst, symlinks, ignore, copy_function,
                     # ignore dangling symlink if the flag is on
                     if not os.path.exists(linkto) and ignore_dangling_symlinks:
                         continue
-                    # otherwise let the copy occurs. copy2 will raise an error
+                    # otherwise let the copy occur. copy2 will raise an error
                     if srcentry.is_dir():
                         copytree(srcobj, dstname, symlinks, ignore,
-                                 copy_function)
+                                 copy_function, dirs_exist_ok=dirs_exist_ok)
                     else:
                         copy_function(srcobj, dstname)
             elif srcentry.is_dir():
-                copytree(srcobj, dstname, symlinks, ignore, copy_function)
+                copytree(srcobj, dstname, symlinks, ignore, copy_function,
+                         dirs_exist_ok=dirs_exist_ok)
             else:
                 # Will raise a SpecialFileError for unsupported file types
                 copy_function(srcentry, dstname)
@@ -489,10 +490,12 @@ def _copytree(entries, src, dst, symlinks, ignore, copy_function,
     return dst
 
 def copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2,
-             ignore_dangling_symlinks=False):
-    """Recursively copy a directory tree.
+             ignore_dangling_symlinks=False, dirs_exist_ok=False):
+    """Recursively copy a directory tree and return the destination directory.
+
+    dirs_exist_ok dictates whether to raise an exception in case dst or any
+    missing parent directory already exists.
 
-    The destination directory must not already exist.
     If exception(s) occur, an Error is raised with a list of reasons.
 
     If the optional symlinks flag is true, symbolic links in the
@@ -527,7 +530,8 @@ def copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2,
     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)
+                         ignore_dangling_symlinks=ignore_dangling_symlinks,
+                         dirs_exist_ok=dirs_exist_ok)
 
 # version vulnerable to race conditions
 def _rmtree_unsafe(path, onerror):