bpo-33671: allow setting shutil.copyfile() bufsize globally (GH-12016)

diff --git a/Lib/shutil.py b/Lib/shutil.py
index 065e08bc5c343e805d00fa7fd85b6dd4122d9f71..29e7564622e1f26b7881ebd5018886828c51bc03 100644 (file)
--- a/Lib/shutil.py
+++ b/Lib/shutil.py
@@ -187,9 +187,11 @@ def _copyfileobj_readinto(fsrc, fdst, length=COPY_BUFSIZE):
             else:
                 fdst_write(mv)
 
-def copyfileobj(fsrc, fdst, length=COPY_BUFSIZE):
+def copyfileobj(fsrc, fdst, length=0):
     """copy data from file-like object fsrc to file-like object fdst"""
     # Localize variable access to minimize overhead.
+    if not length:
+        length = COPY_BUFSIZE
     fsrc_read = fsrc.read
     fdst_write = fdst.write
     while True: