Home Assistant wrapper

hasswrap.go

package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"syscall"
	"time"
)

const remSerialPath = "/remserial/remotezstick"

func main() {
	log.Printf("hasswrap starting.")
	flag.Parse()

	errc := make(chan error, 1)

	go func() {
		errc <- fmt.Errorf("remserial ended: %v", runRemoteSerial())
	}()
	go func() {
		if err := waitRemSerial(); err != nil {
			errc <- err
		}
		log.Printf("remote serial up. starting home assistant.")
		errc <- fmt.Errorf("home assistant ended: %v", runHomeAssistant())
	}()
	go cleanLoop()

	log.Fatal(<-errc)
}

func cleanLoop() {
	const ozwLog = "/config/OZW_Log.txt"
	for {
		var st syscall.Stat_t
		if err := syscall.Stat(ozwLog, &st); err != nil {
			log.Printf("stat %s: %v", ozwLog, err)
		} else {
			size := st.Blocks * 512 // not Size; want un-sparse space only
			log.Printf("stat %s: %d blocks, %d bytes (%d size)", ozwLog, st.Blocks, size, st.Size)
			if size > 10<<20 {
				err := syscall.Truncate(ozwLog, 0)
				log.Printf("truncate %s: err=%v", err)
			}
		}
		time.Sleep(time.Minute)
	}
}

func waitRemSerial() error {
	t0 := time.Now()
	for i := 0; i < 20; i++ {
		if _, err := os.Lstat(remSerialPath); err == nil {
			return nil
		}
		time.Sleep(100 * time.Millisecond)
	}
	return fmt.Errorf("remote serial device %s didn't appear in %v", remSerialPath, time.Since(t0).Round(100*time.Millisecond))
}

func runRemoteSerial() error {
	dir := filepath.Dir(remSerialPath)
	if fi, err := os.Stat(dir); err != nil {
		return fmt.Errorf("statting serial device dir: %v", err)
	} else if !fi.IsDir() {
		return fmt.Errorf("dir %v is: %v", dir, fi.Mode())
	}
	cmd := exec.Command("/usr/local/bin/remserial", "-r", "zpi.ward.fitzpat.com", "-p", "23000",
		"-l", remSerialPath, "/dev/ptmx")
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	return cmd.Run()
}

func runHomeAssistant() error {
	cmd := exec.Command("python", "-m", "homeassistant", "--config", "/config")
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	return cmd.Run()
}