102 lines
2.5 KiB
Go
102 lines
2.5 KiB
Go
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//
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// Copyright 2014-2023 Cristian Maglie. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//
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//go:build linux || darwin || freebsd || openbsd
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package unixutils
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import (
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"time"
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"github.com/creack/goselect"
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)
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// FDSet is a set of file descriptors suitable for a select call
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type FDSet struct {
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set goselect.FDSet
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max uintptr
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}
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// NewFDSet creates a set of file descriptors suitable for a Select call.
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func NewFDSet(fds ...int) *FDSet {
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s := &FDSet{}
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s.Add(fds...)
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return s
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}
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// Add adds the file descriptors passed as parameter to the FDSet.
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func (s *FDSet) Add(fds ...int) {
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for _, fd := range fds {
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f := uintptr(fd)
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s.set.Set(f)
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if f > s.max {
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s.max = f
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}
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}
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}
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// FDResultSets contains the result of a Select operation.
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type FDResultSets struct {
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readable *goselect.FDSet
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writeable *goselect.FDSet
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errors *goselect.FDSet
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}
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// IsReadable test if a file descriptor is ready to be read.
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func (r *FDResultSets) IsReadable(fd int) bool {
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return r.readable.IsSet(uintptr(fd))
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}
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// IsWritable test if a file descriptor is ready to be written.
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func (r *FDResultSets) IsWritable(fd int) bool {
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return r.writeable.IsSet(uintptr(fd))
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}
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// IsError test if a file descriptor is in error state.
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func (r *FDResultSets) IsError(fd int) bool {
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return r.errors.IsSet(uintptr(fd))
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}
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// Select performs a select system call,
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// file descriptors in the rd set are tested for read-events,
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// file descriptors in the wd set are tested for write-events and
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// file descriptors in the er set are tested for error-events.
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// The function will block until an event happens or the timeout expires.
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// The function return an FDResultSets that contains all the file descriptor
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// that have a pending read/write/error event.
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func Select(rd, wr, er *FDSet, timeout time.Duration) (*FDResultSets, error) {
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max := uintptr(0)
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res := &FDResultSets{}
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if rd != nil {
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// fdsets are copied so the parameters are left untouched
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copyOfRd := rd.set
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res.readable = ©OfRd
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// Determine max fd.
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max = rd.max
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}
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if wr != nil {
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// fdsets are copied so the parameters are left untouched
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copyOfWr := wr.set
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res.writeable = ©OfWr
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// Determine max fd.
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if wr.max > max {
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max = wr.max
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}
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}
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if er != nil {
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// fdsets are copied so the parameters are left untouched
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copyOfEr := er.set
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res.errors = ©OfEr
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// Determine max fd.
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if er.max > max {
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max = er.max
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}
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}
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err := goselect.Select(int(max+1), res.readable, res.writeable, res.errors, timeout)
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return res, err
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}
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