rpcfetch: config: add config mutex

The GUI will need to update configuration, so now conf is thread safe.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

fetch/apply.go

@@ -1,12 +1,10 @@
 package main
 
 import (
-	"encoding/gob"
 	"errors"
 	"fmt"
 	"log"
 	"os"
-	"path"
 	"strconv"
 	"strings"
 	"time"
@@ -63,6 +61,7 @@ func (s *applyState) replace(t string) string {
 }
 
 func apply() {
+	confLock.RLock()
 	act := *conf.Activity
 	s := &applyState{}
 
@@ -74,6 +73,7 @@ func apply() {
 		SmallImage: act.Assets.SmallImage,
 		SmallText:  s.replace(act.Assets.SmallText),
 	}
+	confLock.RUnlock()
 
 	if nonce, err := retry(&act); err != nil {
 		log.Fatalf("error setting activity: %s", err)
@@ -82,27 +82,6 @@ func apply() {
 	}
 }
 
-func save() {
-	nf, err := os.CreateTemp(path.Dir(confPath), ".rpcfetch.conf.*")
-	if err != nil {
-		log.Fatalf("error creating temporary configuration file: %s", err)
-	}
-
-	if err = gob.NewEncoder(nf).Encode(defaultConfig); err != nil {
-		fmt.Printf("error writing configuration file: %s\n", err)
-		os.Exit(1)
-	}
-
-	if err = nf.Close(); err != nil {
-		log.Fatalf("error closing temporary configuration file: %s", err)
-	}
-
-	if err = os.Rename(nf.Name(), confPath); err != nil {
-		log.Fatalf("error renaming configuration file: %s", err)
-	}
-	log.Printf("saved configuration to %s", confPath)
-}
-
 func retry(act *rpcfetch.Activity) (string, error) {
 try:
 	nonce, err := d.SetActivity(act)

fetch/config.go

@@ -1,14 +1,55 @@
 package main
 
 import (
+	"encoding/gob"
+	"fmt"
+	"log"
+	"os"
+	"path"
+	"sync"
+
 	"git.ophivana.moe/cat/rpcfetch"
 )
 
+var (
+	conf     *config
+	confLock = &sync.RWMutex{}
+)
+
 type config struct {
 	ID       string
 	Activity *rpcfetch.Activity
 }
 
+func (c *config) write(v config) {
+	confLock.Lock()
+	*c = v
+	confLock.Unlock()
+}
+
+func save() {
+	nf, err := os.CreateTemp(path.Dir(confPath), ".rpcfetch.conf.*")
+	if err != nil {
+		log.Fatalf("error creating temporary configuration file: %s", err)
+	}
+
+	confLock.RLock()
+	if err = gob.NewEncoder(nf).Encode(defaultConfig); err != nil {
+		fmt.Printf("error writing configuration file: %s\n", err)
+		os.Exit(1)
+	}
+	confLock.RUnlock()
+
+	if err = nf.Close(); err != nil {
+		log.Fatalf("error closing temporary configuration file: %s", err)
+	}
+
+	if err = os.Rename(nf.Name(), confPath); err != nil {
+		log.Fatalf("error renaming configuration file: %s", err)
+	}
+	log.Printf("saved configuration to %s", confPath)
+}
+
 // sample config so the program works out of the box
 var defaultConfig = config{
 	ID: "1252927154480611351",

fetch/main.go

@@ -14,7 +14,6 @@ import (
 var (
 	d *rpcfetch.Client
 
-	conf     config
 	confPath string
 )
 
@@ -33,7 +32,7 @@ func main() {
 
 		// use defaults
 		log.Print("configuration file does not exist, using defaults")
-		conf = defaultConfig
+		conf = &defaultConfig
 	} else {
 		// decode from existing file
 		if err = gob.NewDecoder(cf).Decode(&conf); err != nil {