Stop using deprecated ioutil functions

kyaml/filesys/confirmeddir.go

@@ -4,7 +4,7 @@
 package filesys
 
 import (
-	"io/ioutil"
+	"os"
 	"path/filepath"
 	"strings"
 )
@@ -17,12 +17,12 @@ type ConfirmedDir string
 // The directory is cleaned, no symlinks, etc. so it's
 // returned as a ConfirmedDir.
 func NewTmpConfirmedDir() (ConfirmedDir, error) {
-	n, err := ioutil.TempDir("", "kustomize-")
+	n, err := os.MkdirTemp("", "kustomize-")
 	if err != nil {
 		return "", err
 	}
 
-	// In MacOs `ioutil.TempDir` creates a directory
+	// In MacOs `os.MkdirTemp` creates a directory
 	// with root in the `/var` folder, which is in turn
 	// a symlinked path to `/private/var`.
 	// Function `filepath.EvalSymlinks`is used to

kyaml/filesys/fsnode_test.go

@@ -9,7 +9,6 @@ package filesys
 import (
 	"fmt"
 	"io"
-	"io/ioutil"
 	"math/rand"
 	"os"
 	"path/filepath"
@@ -141,7 +140,7 @@ func runBasicOperations(
 		if fi.Name() != c.name {
 			t.Fatalf("%s; expected name '%s', got '%s'", c.what, c.name, fi.Name())
 		}
-		buff, err := ioutil.ReadAll(f)
+		buff, err := io.ReadAll(f)
 		if err != nil {
 			t.Fatalf("%s; unexpected error: %v", c.what, err)
 		}

kyaml/filesys/fsondisk.go

@@ -5,7 +5,6 @@ package filesys
 
 import (
 	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -125,12 +124,12 @@ func (fsOnDisk) ReadDir(name string) ([]string, error) {
 	return result, nil
 }
 
-// ReadFile delegates to ioutil.ReadFile.
-func (fsOnDisk) ReadFile(name string) ([]byte, error) { return ioutil.ReadFile(name) }
+// ReadFile delegates to os.ReadFile.
+func (fsOnDisk) ReadFile(name string) ([]byte, error) { return os.ReadFile(name) }
 
-// WriteFile delegates to ioutil.WriteFile with read/write permissions.
+// WriteFile delegates to os.WriteFile with read/write permissions.
 func (fsOnDisk) WriteFile(name string, c []byte) error {
-	return errors.Wrap(ioutil.WriteFile(name, c, 0666)) //nolint:gosec
+	return errors.Wrap(os.WriteFile(name, c, 0666)) //nolint:gosec
 }
 
 // Walk delegates to filepath.Walk.