bpo-38319: Fix shutil._fastcopy_sendfile(): set sendfile() max block size (GH-16491)

1 files changed, 2 insertions, 2 deletions

diff --git a/Lib/socket.py b/Lib/socket.py
index e5989d9dfd..84a5dcb0da 100755
--- a/Lib/socket.py
+++ b/Lib/socket.py
@@ -356,8 +356,8 @@ class socket(_socket.socket):
                 raise _GiveupOnSendfile(err)  # not a regular file
             if not fsize:
                 return 0  # empty file
-            blocksize = fsize if not count else count
-
+            # Truncate to 1GiB to avoid OverflowError, see bpo-38319.
+            blocksize = min(count or fsize, 2 ** 30)
             timeout = self.gettimeout()
             if timeout == 0:
                 raise ValueError("non-blocking sockets are not supported")