https://github.com/python/cpython/commit/34393cbdd46fd965de86f1e7bc89ab111f506723
commit: 34393cbdd46fd965de86f1e7bc89ab111f506723
branch: main
author: Russell Keith-Magee <[email protected]>
committer: freakboy3742 <[email protected]>
date: 2025-06-24T08:55:50+08:00
summary:
gh-135648: Document that `shutil.copyfileobj` doesn't flush (#135737)
Adds a note about flush/close on copyfileobj, and updates
the Emscripten build script to follow documented advice.
files:
M Doc/library/shutil.rst
M Tools/wasm/emscripten/__main__.py
diff --git a/Doc/library/shutil.rst b/Doc/library/shutil.rst
index e7c4c4f46bd011..2dde40c9d92f45 100644
--- a/Doc/library/shutil.rst
+++ b/Doc/library/shutil.rst
@@ -47,6 +47,13 @@ Directory and files operations
0, only the contents from the current file position to the end of the file
will
be copied.
+ :func:`copyfileobj` will *not* guarantee that the destination stream has
+ been flushed on completion of the copy. If you want to read from the
+ destination at the completion of the copy operation (for example, reading
+ the contents of a temporary file that has been copied from a HTTP stream),
+ you must ensure that you have called :func:`~io.IOBase.flush` or
+ :func:`~io.IOBase.close` on the file-like object before attempting to read
+ the destination file.
.. function:: copyfile(src, dst, *, follow_symlinks=True)
diff --git a/Tools/wasm/emscripten/__main__.py
b/Tools/wasm/emscripten/__main__.py
index 849bd5de44eb7b..c0d58aeaadd2cf 100644
--- a/Tools/wasm/emscripten/__main__.py
+++ b/Tools/wasm/emscripten/__main__.py
@@ -167,11 +167,12 @@ def make_build_python(context, working_dir):
@subdir(HOST_BUILD_DIR, clean_ok=True)
def make_emscripten_libffi(context, working_dir):
shutil.rmtree(working_dir / "libffi-3.4.6", ignore_errors=True)
- with tempfile.NamedTemporaryFile(suffix=".tar.gz") as tmp_file:
+ with tempfile.NamedTemporaryFile(suffix=".tar.gz", delete_on_close=False)
as tmp_file:
with urlopen(
"https://github.com/libffi/libffi/releases/download/v3.4.6/libffi-3.4.6.tar.gz";
) as response:
shutil.copyfileobj(response, tmp_file)
+ tmp_file.close()
shutil.unpack_archive(tmp_file.name, working_dir)
call(
[EMSCRIPTEN_DIR / "make_libffi.sh"],
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