store: make state (de)serialization internal

This hides the state hanlding in the store package. As before, it
can be disabled by passing `nil` instead of the path to the state
file.

Signed-off-by: Tom Gundersen <teg@jklm.no>

cmd/osbuild-composer/main.go

@@ -2,10 +2,8 @@ package main
 
 import (
 	"flag"
-	"io/ioutil"
 	"log"
 	"os"
-	"path/filepath"
 
 	"osbuild-composer/internal/jobqueue"
 	"osbuild-composer/internal/rpmmd"
@@ -15,13 +13,13 @@ import (
 	"github.com/coreos/go-systemd/activation"
 )
 
-const StateFile = "/var/lib/osbuild-composer/state.json"
-
 func main() {
 	var verbose bool
 	flag.BoolVar(&verbose, "v", false, "Print access log")
 	flag.Parse()
 
+	stateFile := "/var/lib/osbuild-composer/state.json"
+
 	listeners, err := activation.Listeners()
 	if err != nil {
 		panic(err)
@@ -55,60 +53,11 @@ func main() {
 		panic(err)
 	}
 
-	state, err := ioutil.ReadFile(StateFile)
-	if err != nil && !os.IsNotExist(err) {
-		log.Fatalf("cannot read state: %v", err)
-	}
-
-	stateChannel := make(chan []byte, 10)
-
-	store := store.New(state, stateChannel)
+	store := store.New(&stateFile)
 
 	jobAPI := jobqueue.New(logger, store)
 	weldrAPI := weldr.New(repo, packages, logger, store)
-	go func() {
-		for {
-			err := writeFileAtomically(StateFile, <-stateChannel, 0755)
-			if err != nil {
-				log.Fatalf("cannot write state: %v", err)
-			}
-		}
-	}()
 
 	go jobAPI.Serve(jobListener)
 	weldrAPI.Serve(weldrListener)
 }
-
-func writeFileAtomically(filename string, data []byte, mode os.FileMode) error {
-	dir, name := filepath.Dir(filename), filepath.Base(filename)
-
-	tmpfile, err := ioutil.TempFile(dir, name+"-*.tmp")
-	if err != nil {
-		return err
-	}
-
-	_, err = tmpfile.Write(data)
-	if err != nil {
-		os.Remove(tmpfile.Name())
-		return err
-	}
-
-	err = tmpfile.Chmod(mode)
-	if err != nil {
-		return err
-	}
-
-	err = tmpfile.Close()
-	if err != nil {
-		os.Remove(tmpfile.Name())
-		return err
-	}
-
-	err = os.Rename(tmpfile.Name(), filename)
-	if err != nil {
-		os.Remove(tmpfile.Name())
-		return err
-	}
-
-	return nil
-}