Support F_GETFL and F_SETFL for fcntl #4212
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src/shims/unix/fd.rs
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| if flag == this.eval_libc_i32("O_NONBLOCK") { | ||
| anonsocket_fd.set_nonblock(); | ||
| } else { | ||
| throw_unsup_format!("fcntl: only O_NONBLOCK are supported for F_GETFL") | ||
| } |
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This should also support un-setting the O_NONBLOCK flag, right? I assume that's what happens on flag == 0.
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Good call!
I just realised this is indeed how tokio set their fd from non-blocking to blocking. https://github.com/tokio-rs/tokio/blob/817fa605ee6a2549fe8e6057ec23a8309d42d2e9/tokio/src/net/unix/pipe.rs#L1432
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Reminder, once the PR becomes ready for a review, use |
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Co-authored-by: Ralf Jung <[email protected]>
Co-authored-by: Ralf Jung <[email protected]>
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On the latest commit b22019d, I made all the tests in this PR to use isolation mode. |
| err_unsup_format!("fcntl: only socketpair / pipe are supported for F_GETFL") | ||
| })?; | ||
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| if anonsocket_fd.is_nonblock() { |
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Does this match real implementations -- only returning O_NONBLOCK and no other flag?
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I overlooked something, we need to return O_RDWR for socketpair, O_RDONLY and O_WRONLY for pipe. So we need to add something to differentiate between socketpair and pipe's reading / writing end here.
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Probably we should have get_flags and set_flags methods on the FD trait so this logic can live with the FD implementation.
When a socketpair's peer FD has been closed, does it become RDONLY?
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When a socketpair's peer FD has been closed, does it become RDONLY?
fcntl(F_GETFL) will still return O_RDWR even though the subsequent write will error with EPIPE.
Same thing happened to pipe too. So both socketpair and pipe fds have fixed O_RDONLY / O_WRONLY / O_RDWR value.
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Okay, then please implement that and add a comment explaining why.
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Just a heads up, this PR will stall for a while due to exam prep, but I will be back on it after rust week. |
This PR supports
F_SETFLandF_GETFLflags forfcntl. In this implementation,F_SETFLcan only setO_NONBLOCKflag.The interaction between these
fcntloperations and blocking fd is summarised here.Fixes #4119