ea336061c2
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The PR introduces the `platform.Select()` API, wrapping `select(2)` on POSIX and emulated in some cases on Windows. RATIONALE.md contains a full explanation of the approach followed in `poll_oneoff` to handle Stdin and the other types of file descriptors, and the clock subscriptions. It also introduces an abstraction (`StdioFilePoller`) to allow the simulation of different scenarios (waiting for input, input ready, timeout expired, etc.) when unit-testing interactive input. This closes #1317. Signed-off-by: Edoardo Vacchi <evacchi@users.noreply.github.com>
32 lines
899 B
Go
32 lines
899 B
Go
package platform
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import (
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"syscall"
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"time"
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)
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// wasiFdStdin is the constant value for stdin on Wasi.
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// We need this constant because on Windows os.Stdin.Fd() != 0.
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const wasiFdStdin = 0
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// syscall_select emulates the select syscall on Windows for two, well-known cases, returns syscall.ENOSYS for all others.
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// If r contains fd 0, then it immediately returns 1 (data ready on stdin) and r will have the fd 0 bit set.
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// If n==0 it will wait for the given timeout duration, but it will return syscall.ENOSYS if timeout is nil,
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// i.e. it won't block indefinitely.
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func syscall_select(n int, r, w, e *FdSet, timeout *time.Duration) (int, error) {
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if n == 0 {
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// don't block indefinitely
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if timeout == nil {
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return -1, syscall.ENOSYS
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}
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time.Sleep(*timeout)
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return 0, nil
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}
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if r.IsSet(wasiFdStdin) {
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r.Zero()
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r.Set(wasiFdStdin)
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return 1, nil
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}
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return -1, syscall.ENOSYS
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}
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