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>
44 lines
1.2 KiB
Go
44 lines
1.2 KiB
Go
package platform
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import (
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"syscall"
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"time"
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"unsafe"
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)
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// syscall_select invokes select on Darwin, with the given timeout Duration.
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// We implement our own version instead of relying on syscall.Select because the latter
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// only returns the error and discards the result.
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func syscall_select(n int, r, w, e *FdSet, timeout *time.Duration) (int, error) {
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var t *syscall.Timeval
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if timeout != nil {
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tv := syscall.NsecToTimeval(timeout.Nanoseconds())
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t = &tv
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}
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result, _, errno := syscall_syscall6(
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libc_select_trampoline_addr,
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uintptr(n),
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uintptr(unsafe.Pointer(r)),
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uintptr(unsafe.Pointer(w)),
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uintptr(unsafe.Pointer(e)),
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uintptr(unsafe.Pointer(t)),
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0)
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res := int(result)
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if errno == 0 {
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return res, nil
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}
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return res, errno
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}
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// libc_select_trampoline_addr is the address of the
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// `libc_select_trampoline` symbol, defined in `select_darwin.s`.
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//
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// We use this to invoke the syscall through syscall_syscall6 imported below.
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var libc_select_trampoline_addr uintptr
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// Imports the select symbol from libc as `libc_select`.
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//
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// Note: CGO mechanisms are used in darwin regardless of the CGO_ENABLED value
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// or the "cgo" build flag. See /RATIONALE.md for why.
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//go:cgo_import_dynamic libc_select select "/usr/lib/libSystem.B.dylib"
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