René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"inaccurate block size in socket._sendfile_use_sendfile","articleBody":"# Bug report\r\n\r\n### Bug description:\r\n\r\n`socket._sendfile_use_sendfile(self, file, offset=0, count=None)` intent to use the file size reamains from current position as block size, to a underlying `sendfile` syscall, when count is not specified.\r\n\r\nBut as the codes below shows, it will always use the whole file size as block size even if offset is non zero, so the blocksize is larger than actuall file bytes remains from offset:\r\n\r\nhttps://github.com/python/cpython/blob/89ddea4886942b0c27a778a0ad3f0d5ac5f518f0/Lib/socket.py#L363\r\n\r\nOn modern platforms, if someone specified the count which is larger than the actual file size, `sendfile` will accept it, and only sending the remaining data and returns the bytes which have been sent.\r\n\r\nSo the bug (if it is a bug) have no effect for now, and it's so minor, but I think we should fix it however. And if we want using `TransmitFile` as a `sendfile` implenentation on Windows, the inaccurate block size will leads to an error, which is mentioned in https://github.com/python/cpython/issues/102898#issuecomment-1824554063, and the fix will be a must have.\r\n\r\n### CPython versions tested on:\r\n\r\n3.8, 3.9, 3.10, 3.11, 3.12, 3.13, CPython main branch\r\n\r\n### Operating systems tested on:\r\n\r\nmacOS\r\n\r\n\u003c!-- gh-linked-prs --\u003e\r\n### Linked PRs\r\n* gh-112342\r\n\u003c!-- /gh-linked-prs --\u003e\r\n","author":{"url":"https://github.com/aisk","@type":"Person","name":"aisk"},"datePublished":"2023-11-23T16:20:07.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/112341/cpython/issues/112341"}