112 lines
2.1 KiB
Go
112 lines
2.1 KiB
Go
// SPDX-License-Identifier: MIT
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//
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// Copyright © 2020 Kent Gibson <warthog618@gmail.com>.
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package gpiod
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import (
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"fmt"
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"time"
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"github.com/warthog618/gpiod/uapi"
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"golang.org/x/sys/unix"
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)
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type infoWatcher struct {
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epfd int
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// the handler for detected events
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ch InfoChangeHandler
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// pipe to signal watcher to shutdown
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donefds []int
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// closed once watcher exits
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doneCh chan struct{}
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}
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func newInfoWatcher(fd int, ch InfoChangeHandler) (iw *infoWatcher, err error) {
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var epfd int
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epfd, err = unix.EpollCreate1(unix.EPOLL_CLOEXEC)
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if err != nil {
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return
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}
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defer func() {
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if err != nil {
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unix.Close(epfd)
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}
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}()
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p := []int{0, 0}
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err = unix.Pipe2(p, unix.O_CLOEXEC)
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if err != nil {
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return
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}
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defer func() {
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if err != nil {
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unix.Close(p[0])
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unix.Close(p[1])
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}
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}()
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epv := unix.EpollEvent{Events: unix.EPOLLIN, Fd: int32(p[0])}
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err = unix.EpollCtl(epfd, unix.EPOLL_CTL_ADD, int(p[0]), &epv)
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if err != nil {
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return
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}
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epv.Fd = int32(fd)
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err = unix.EpollCtl(epfd, unix.EPOLL_CTL_ADD, fd, &epv)
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if err != nil {
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return
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}
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iw = &infoWatcher{
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epfd: epfd,
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ch: ch,
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donefds: p,
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doneCh: make(chan struct{}),
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}
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go iw.watch()
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return
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}
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func (iw *infoWatcher) close() {
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unix.Write(iw.donefds[1], []byte("bye"))
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<-iw.doneCh
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unix.Close(iw.donefds[0])
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unix.Close(iw.donefds[1])
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}
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func (iw *infoWatcher) watch() {
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epollEvents := make([]unix.EpollEvent, 2)
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defer close(iw.doneCh)
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for {
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n, err := unix.EpollWait(iw.epfd, epollEvents[:], -1)
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if err != nil {
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if err == unix.EBADF || err == unix.EINVAL {
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// fd closed so exit
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return
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}
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if err == unix.EINTR {
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continue
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}
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panic(fmt.Sprintf("EpollWait unexpected error: %v", err))
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}
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for i := 0; i < n; i++ {
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ev := epollEvents[i]
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fd := ev.Fd
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if fd == int32(iw.donefds[0]) {
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unix.Close(iw.epfd)
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return
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}
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lic, err := uapi.ReadLineInfoChanged(uintptr(fd))
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if err != nil {
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continue
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}
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lice := LineInfoChangeEvent{
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Info: newLineInfo(lic.Info),
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Timestamp: time.Duration(lic.Timestamp),
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Type: LineInfoChangeType(lic.Type),
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}
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iw.ch(lice)
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}
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}
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}
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