https://github.com/python/cpython/commit/8d050f98f58617c99a09e1a75a6502bcd0ad6bba commit: 8d050f98f58617c99a09e1a75a6502bcd0ad6bba branch: 3.14 author: Miss Islington (bot) <[email protected]> committer: kumaraditya303 <[email protected]> date: 2026-05-29T18:56:00+05:30 summary:
[3.14] gh-150107: Fix asyncio sendfile fallback ignoring non-zero offset (GH-150270) (#150569) gh-150107: Fix asyncio sendfile fallback ignoring non-zero offset (GH-150270) (cherry picked from commit c72d5ea638731ec29723ded2d26ec7f997f06f17) Co-authored-by: Grant Herman <[email protected]> Co-authored-by: Victor Stinner <[email protected]> files: A Misc/NEWS.d/next/Core_and_Builtins/2026-05-22-17-09-28.gh-issue-150107.GD72-D.rst M Lib/asyncio/base_events.py M Lib/asyncio/proactor_events.py M Lib/asyncio/unix_events.py M Lib/asyncio/windows_events.py M Lib/test/test_asyncio/test_sendfile.py diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py index b83b84181fd24dc..d22996f562e20d2 100644 --- a/Lib/asyncio/base_events.py +++ b/Lib/asyncio/base_events.py @@ -963,7 +963,7 @@ async def _sock_sendfile_native(self, sock, file, offset, count): f"and file {file!r} combination") async def _sock_sendfile_fallback(self, sock, file, offset, count): - if offset: + if hasattr(file, 'seek'): file.seek(offset) blocksize = ( min(count, constants.SENDFILE_FALLBACK_READBUFFER_SIZE) @@ -1278,7 +1278,6 @@ async def sendfile(self, transport, file, offset=0, count=None, raise RuntimeError( f"fallback is disabled and native sendfile is not " f"supported for transport {transport!r}") - return await self._sendfile_fallback(transport, file, offset, count) @@ -1287,7 +1286,7 @@ async def _sendfile_native(self, transp, file, offset, count): "sendfile syscall is not supported") async def _sendfile_fallback(self, transp, file, offset, count): - if offset: + if hasattr(file, 'seek'): file.seek(offset) blocksize = min(count, 16384) if count else 16384 buf = bytearray(blocksize) diff --git a/Lib/asyncio/proactor_events.py b/Lib/asyncio/proactor_events.py index f404273c3ae5c1d..6b94975d0046ea3 100644 --- a/Lib/asyncio/proactor_events.py +++ b/Lib/asyncio/proactor_events.py @@ -756,8 +756,7 @@ async def _sock_sendfile_native(self, sock, file, offset, count): offset += blocksize total_sent += blocksize finally: - if total_sent > 0: - file.seek(offset) + file.seek(offset) async def _sendfile_native(self, transp, file, offset, count): resume_reading = transp.is_reading() diff --git a/Lib/asyncio/unix_events.py b/Lib/asyncio/unix_events.py index 1c1458127db5ac1..f667c9647c6407c 100644 --- a/Lib/asyncio/unix_events.py +++ b/Lib/asyncio/unix_events.py @@ -384,12 +384,12 @@ def _sock_sendfile_native_impl(self, fut, registered_fd, sock, fileno, # order to simplify the common case. self.remove_writer(registered_fd) if fut.cancelled(): - self._sock_sendfile_update_filepos(fileno, offset, total_sent) + self._sock_sendfile_update_filepos(fileno, offset) return if count: blocksize = count - total_sent if blocksize <= 0: - self._sock_sendfile_update_filepos(fileno, offset, total_sent) + self._sock_sendfile_update_filepos(fileno, offset) fut.set_result(total_sent) return @@ -423,20 +423,20 @@ def _sock_sendfile_native_impl(self, fut, registered_fd, sock, fileno, # plain send(). err = exceptions.SendfileNotAvailableError( "os.sendfile call failed") - self._sock_sendfile_update_filepos(fileno, offset, total_sent) + self._sock_sendfile_update_filepos(fileno, offset) fut.set_exception(err) else: - self._sock_sendfile_update_filepos(fileno, offset, total_sent) + self._sock_sendfile_update_filepos(fileno, offset) fut.set_exception(exc) except (SystemExit, KeyboardInterrupt): raise except BaseException as exc: - self._sock_sendfile_update_filepos(fileno, offset, total_sent) + self._sock_sendfile_update_filepos(fileno, offset) fut.set_exception(exc) else: if sent == 0: # EOF - self._sock_sendfile_update_filepos(fileno, offset, total_sent) + self._sock_sendfile_update_filepos(fileno, offset) fut.set_result(total_sent) else: offset += sent @@ -447,9 +447,9 @@ def _sock_sendfile_native_impl(self, fut, registered_fd, sock, fileno, fd, sock, fileno, offset, count, blocksize, total_sent) - def _sock_sendfile_update_filepos(self, fileno, offset, total_sent): - if total_sent > 0: - os.lseek(fileno, offset, os.SEEK_SET) + def _sock_sendfile_update_filepos(self, fileno, offset): + # After this helper runs, the source fd's lseek pointer is at offset." + os.lseek(fileno, offset, os.SEEK_SET) def _sock_add_cancellation_callback(self, fut, sock): def cb(fut): diff --git a/Lib/asyncio/windows_events.py b/Lib/asyncio/windows_events.py index 5f75b17d8ca649b..0bf7732136f1f8e 100644 --- a/Lib/asyncio/windows_events.py +++ b/Lib/asyncio/windows_events.py @@ -610,6 +610,9 @@ def sendfile(self, sock, file, offset, count): ov = _overlapped.Overlapped(NULL) offset_low = offset & 0xffff_ffff offset_high = (offset >> 32) & 0xffff_ffff + # TransmitFile ignores OVERLAPPED.Offset for handles not opened with + # FILE_FLAG_OVERLAPPED, so seek the CRT file pointer to match. + file.seek(offset) ov.TransmitFile(sock.fileno(), msvcrt.get_osfhandle(file.fileno()), offset_low, offset_high, diff --git a/Lib/test/test_asyncio/test_sendfile.py b/Lib/test/test_asyncio/test_sendfile.py index dcd963b3355ef86..7afd7de3bb936e6 100644 --- a/Lib/test/test_asyncio/test_sendfile.py +++ b/Lib/test/test_asyncio/test_sendfile.py @@ -228,6 +228,61 @@ def test_sock_sendfile_zero_size(self): self.assertEqual(ret, 0) self.assertEqual(self.file.tell(), 0) + def check_sock_sendfile_offset(self, data, offset, force_fallback=False): + sock, proto = self.prepare_socksendfile() + with tempfile.TemporaryFile() as f: + f.write(data) + f.flush() + self.assertEqual(f.tell(), len(data)) + + if force_fallback: + async def _sock_sendfile_fail(sock, file, offset, count): + raise asyncio.exceptions.SendfileNotAvailableError() + with support.swap_attr(self.loop, '_sock_sendfile_native', _sock_sendfile_fail): + ret = self.run_loop(self.loop.sock_sendfile(sock, f, offset, None)) + else: + ret = self.run_loop(self.loop.sock_sendfile(sock, f, offset, None)) + + self.assertEqual(f.tell(), len(data)) + + sock.close() + self.run_loop(proto.wait_closed()) + + self.assertEqual(ret, len(data) - offset) + + + def test_sock_sendfile_offset(self): + data = b'abcdef' + for offset in (0, len(data) // 2, len(data)): + for force_fallback in (False, True): + with self.subTest(offset=offset, force_fallback=force_fallback): + self.check_sock_sendfile_offset(data, offset, force_fallback) + + def check_sendfile_offset(self, offset, fallback): + srv_proto, cli_proto = self.prepare_sendfile() + self.file.seek(123) + coro = self.loop.sendfile(cli_proto.transport, self.file, offset, fallback=fallback) + try: + ret = self.run_loop(coro) + except asyncio.SendfileNotAvailableError: + if fallback: + raise + cli_proto.transport.close() + self.run_loop(srv_proto.done) + return + cli_proto.transport.close() + self.run_loop(srv_proto.done) + self.assertEqual(ret, len(self.DATA) - offset) + self.assertEqual(srv_proto.nbytes, len(self.DATA) - offset) + self.assertEqual(srv_proto.data, self.DATA[offset:]) + self.assertEqual(self.file.tell(), len(self.DATA)) + + def test_sendfile_offset(self): + for offset in (0, len(self.DATA) // 2, len(self.DATA)): + for fallback in (False, True): + with self.subTest(offset=offset, fallback=fallback): + self.check_sendfile_offset(offset, fallback) + def test_sock_sendfile_mix_with_regular_send(self): buf = b"mix_regular_send" * (4 * 1024) # 64 KiB sock, proto = self.prepare_socksendfile() diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-05-22-17-09-28.gh-issue-150107.GD72-D.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-05-22-17-09-28.gh-issue-150107.GD72-D.rst new file mode 100644 index 000000000000000..a13f249e48cc021 --- /dev/null +++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-05-22-17-09-28.gh-issue-150107.GD72-D.rst @@ -0,0 +1,3 @@ +:mod:`asyncio`: ``sendfile()`` and ``sock_sendfile()`` event loop methods +now call ``file.seek(offset)`` if *file* has a ``seek()`` method, +even if *offset* is ``0`` (default value). _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
