/
listen.go
130 lines (116 loc) · 2.18 KB
/
listen.go
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package gotrig
import (
"fmt"
"io"
"math/rand"
"os"
"path/filepath"
"strconv"
"syscall"
"time"
)
/*
#include "skarnet.h"
*/
import "C"
type Listener struct {
B <-chan byte
Err error
f *os.File
fd, fdw uintptr
path string
shouldQuit chan struct{}
}
// Close stops consuming events, may only be invoked once per *Listener
func (x *Listener) Close() {
close(x.shouldQuit)
}
func (x *Listener) close() {
os.Remove(x.path)
C.fd_close(C.int(x.fdw))
x.f.Close()
}
func randomName() string {
return strconv.FormatInt(time.Now().Unix(), 16) + "-" + strconv.FormatInt(rand.Int63(), 16)
}
func subscribe(name string, fifo, fifow uintptr) (*Listener, error) {
f := os.NewFile(fifo, name)
ch := make(chan byte)
ch2 := make(chan byte)
x := &Listener{
B: ch2,
fd: fifo,
fdw: fifow,
path: name,
shouldQuit: make(chan struct{}),
}
go func() {
buf := make([]byte, 1)
for {
n, err := f.Read(buf)
if n > 0 {
ch <- buf[0]
}
if err != nil {
if err != io.EOF {
x.Err = err
}
return
}
}
}()
go func() {
defer func() {
close(ch2)
x.close()
}()
for {
select {
case <-x.shouldQuit:
return
case b := <-ch:
select {
case <-x.shouldQuit:
return
case ch2 <- b:
}
}
}
}()
return x, nil
}
func Listen(path string) (*Listener, error) {
rname := ".ftrig-" + randomName()
tmpfifo := filepath.Join(path, rname)
err := syscall.Mkfifo(tmpfifo, syscall.S_IRUSR|syscall.S_IWUSR|syscall.S_IWGRP|syscall.S_IWOTH)
if err != nil {
return nil, err
}
fd, fdw, name := C.int(0), C.int(0), filepath.Join(path, rname[1:])
fd, err = C.open_read(C.CString(tmpfifo))
if fd == -1 {
goto err1
}
fdw, err = C.open_write(C.CString(tmpfifo))
if fd == -1 {
C.fd_close(fd)
goto err1
}
err = os.Rename(tmpfifo, name)
if err != nil {
C.fd_close(fdw)
C.fd_close(fd)
goto err1
}
err = syscall.SetNonblock(int(fd), false)
if err != nil {
goto err1
}
return subscribe(name, uintptr(fd), uintptr(fdw))
err1:
os.Remove(tmpfifo)
if errno, ok := err.(syscall.Errno); ok {
return nil, errno
}
return nil, fmt.Errorf("unknown error opening fifo at %q", tmpfifo)
}