refactor: move from io/ioutil to io and os packages (#1546)

The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

controllers/admin/config.go

@@ -4,9 +4,9 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"net"
 	"net/http"
+	"os"
 	"path/filepath"
 	"reflect"
 	"strings"
@@ -223,7 +223,7 @@ func SetLogo(w http.ResponseWriter, r *http.Request) {
 	}
 
 	imgPath := filepath.Join("data", "logo"+extension)
-	if err := ioutil.WriteFile(imgPath, bytes, 0600); err != nil {
+	if err := os.WriteFile(imgPath, bytes, 0600); err != nil {
 		controllers.WriteSimpleResponse(w, false, err.Error())
 		return
 	}

controllers/emoji.go

@@ -2,7 +2,6 @@ package controllers
 
 import (
 	"encoding/json"
-	"io/ioutil"
 	"net/http"
 	"os"
 	"path"
@@ -31,7 +30,7 @@ func getCustomEmojiList() []models.CustomEmoji {
 	}
 
 	if len(emojiCache) == 0 {
-		files, err := ioutil.ReadDir(fullPath)
+		files, err := os.ReadDir(fullPath)
 		if err != nil {
 			log.Errorln(err)
 			return emojiCache

controllers/logo.go

@@ -1,8 +1,8 @@
 package controllers
 
 import (
-	"io/ioutil"
 	"net/http"
+	"os"
 	"path/filepath"
 	"strconv"
 
@@ -94,5 +94,5 @@ func writeBytesAsImage(data []byte, contentType string, w http.ResponseWriter, c
 }
 
 func getImage(path string) ([]byte, error) {
-	return ioutil.ReadFile(path) // nolint
+	return os.ReadFile(path) // nolint
 }