select: use poll() if existing, avoid poll() with no sockets #15096
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poll() on macOS 10.12 was deemed broken in 2016 when we discovered that it misbehaves when provided with no sockets to wait for. The HAVE_POLL_FINE is used to mark a poll() implementation that behaves correctly: it *should* still wait the timeout time. curl has therefore opted to use select() on Apple operating systems ever since. To avoid the risk that this or other breakage cause problems. However, using select() internally is also bad because it suffers from problems when using file descriptors beyond 1024. This change makes poll() used if it is present, but if there is no sockets to wait for it avoids using poll() and instead falls back to select() - but without any sockets to wait for there is no 1024 problem. This removes all previous special-handling involving HAVE_POLL_FINE. ref: https://daniel.haxx.se/blog/2016/10/11/poll-on-mac-10-12-is-broken/ Closes #15096
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This build-time flag no longer exists. curl/curl#15096 curl/curl@c72cefe
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poll() on macOS 10.12 was deemed broken in 2016 when we discovered that it misbehaves when provided with no sockets to wait for. The HAVE_POLL_FINE is used to mark a poll() implementation that behaves correctly: it should still wait the timeout time.
curl has therefore opted to use select() on Apple operating systems ever since. To avoid the risk that this or other breakage cause problems.
However, using select() internally is also bad because it suffers from problems when using file descriptors beyond 1024.
This change makes curl use poll() if there is one present, but if there is no sockets to wait for it avoids using poll() and instead falls back to select() - but without any sockets to wait for there is no 1024 problem. This removes all previous special-handling involving
HAVE_POLL_FINE.ref: https://daniel.haxx.se/blog/2016/10/11/poll-on-mac-10-12-is-broken/