Stop using deprecated package io/ioutil

Since Go 1.16 (which recently became the minimum supported Go version
for this project), the package io/ioutil is deprecated in favor of
equivalent functionality in the io and os packages.  staticcheck warns
about this.  Address all the warnings by switching to the non-deprecated
replacement functions.

5 files changed, 17 insertions, 18 deletions

diff --git a/filesystem/filesystem.go b/filesystem/filesystem.go
index 7852abb..0e1f0c8 100644
--- a/filesystem/filesystem.go
+++ b/filesystem/filesystem.go
@@ -35,7 +35,6 @@ package filesystem
 import (
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/user"
@@ -335,7 +334,7 @@ func (m *Mount) PolicyPath(descriptor string) string {
 // directory and returns a temporary Mount which represents this temporary
 // directory. The caller is responsible for removing this temporary directory.
 func (m *Mount) tempMount() (*Mount, error) {
-	tempDir, err := ioutil.TempDir(filepath.Dir(m.BaseDir()), tempPrefix)
+	tempDir, err := os.MkdirTemp(filepath.Dir(m.BaseDir()), tempPrefix)
 	return &Mount{Path: tempDir}, err
 }
 
@@ -635,7 +634,7 @@ func (m *Mount) writeData(path string, data []byte, owner *user.User, mode os.Fi
 	// Write the data to a temporary file, sync it, then rename into place
 	// so that the operation will be atomic.
 	dirPath := filepath.Dir(path)
-	tempFile, err := ioutil.TempFile(dirPath, tempPrefix)
+	tempFile, err := os.CreateTemp(dirPath, tempPrefix)
 	if err != nil {
 		log.Print(err)
 		if os.IsPermission(err) {
@@ -767,7 +766,7 @@ func readMetadataFileSafe(path string, trustedUser *user.User) ([]byte, int64, e
 	}
 	// Read the file contents, allowing at most maxMetadataFileSize bytes.
 	reader := &io.LimitedReader{R: file, N: maxMetadataFileSize + 1}
-	data, err := ioutil.ReadAll(reader)
+	data, err := io.ReadAll(reader)
 	if err != nil {
 		return nil, -1, err
 	}
diff --git a/filesystem/filesystem_test.go b/filesystem/filesystem_test.go
index 79fb133..f9c34ae 100644
--- a/filesystem/filesystem_test.go
+++ b/filesystem/filesystem_test.go
@@ -20,7 +20,6 @@
 package filesystem
 
 import (
-	"io/ioutil"
 	"os"
 	"os/user"
 	"path/filepath"
@@ -172,7 +171,7 @@ func TestSetupWithAbsoluteSymlink(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	tempDir, err := ioutil.TempDir("", "fscrypt")
+	tempDir, err := os.MkdirTemp("", "fscrypt")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -519,7 +518,7 @@ func TestLinkedProtector(t *testing.T) {
 }
 
 func createFile(path string, size int64) error {
-	if err := ioutil.WriteFile(path, []byte{}, 0600); err != nil {
+	if err := os.WriteFile(path, []byte{}, 0600); err != nil {
 		return err
 	}
 	return os.Truncate(path, size)
@@ -532,7 +531,7 @@ func TestReadMetadataFileSafe(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	tempDir, err := ioutil.TempDir("", "fscrypt")
+	tempDir, err := os.MkdirTemp("", "fscrypt")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/filesystem/mountpoint.go b/filesystem/mountpoint.go
index 0b0693b..0abae06 100644
--- a/filesystem/mountpoint.go
+++ b/filesystem/mountpoint.go
@@ -25,7 +25,6 @@ import (
 	"bufio"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -537,11 +536,15 @@ func getMountFromLink(link string) (*Mount, error) {
 }
 
 func (mnt *Mount) getFilesystemUUID() (string, error) {
-	dirContents, err := ioutil.ReadDir(uuidDirectory)
+	dirEntries, err := os.ReadDir(uuidDirectory)
 	if err != nil {
 		return "", err
 	}
-	for _, fileInfo := range dirContents {
+	for _, dirEntry := range dirEntries {
+		fileInfo, err := dirEntry.Info()
+		if err != nil {
+			continue
+		}
 		if fileInfo.Mode()&os.ModeSymlink == 0 {
 			continue // Only interested in UUID symlinks
 		}
diff --git a/filesystem/mountpoint_test.go b/filesystem/mountpoint_test.go
index 99d4b55..43b5a0d 100644
--- a/filesystem/mountpoint_test.go
+++ b/filesystem/mountpoint_test.go
@@ -26,7 +26,6 @@ package filesystem
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -122,7 +121,7 @@ func TestLoadSourceDevice(t *testing.T) {
 func TestNondirectoryMountsIgnored(t *testing.T) {
 	beginLoadMountInfoTest()
 	defer endLoadMountInfoTest()
-	file, err := ioutil.TempFile("", "fscrypt_regfile")
+	file, err := os.CreateTemp("", "fscrypt_regfile")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -155,7 +154,7 @@ func TestNonLatestMountsIgnored(t *testing.T) {
 
 // Test that escape sequences in the mountinfo file are unescaped correctly.
 func TestLoadMountWithSpecialCharacters(t *testing.T) {
-	tempDir, err := ioutil.TempDir("", "fscrypt")
+	tempDir, err := os.MkdirTemp("", "fscrypt")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -296,7 +295,7 @@ func TestRootMountpointIsPreferred(t *testing.T) {
 // Test that a mountpoint that is not "/" but still contains all other
 // mountpoints is preferred, given independent subtrees.
 func TestHighestMountpointIsPreferred(t *testing.T) {
-	tempDir, err := ioutil.TempDir("", "fscrypt")
+	tempDir, err := os.MkdirTemp("", "fscrypt")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -331,7 +330,7 @@ func TestHighestMountpointIsPreferred(t *testing.T) {
 // mountpoints are contained in other mountpoints, the chosen Mount is the root
 // of a tree of mountpoints whose mounted subtrees contain all mounted subtrees.
 func TestLoadContainedSubtreesAndMountpoints(t *testing.T) {
-	tempDir, err := ioutil.TempDir("", "fscrypt")
+	tempDir, err := os.MkdirTemp("", "fscrypt")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/filesystem/path_test.go b/filesystem/path_test.go
index 1c59dd5..d325054 100644
--- a/filesystem/path_test.go
+++ b/filesystem/path_test.go
@@ -20,7 +20,6 @@ package filesystem
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"testing"
 
@@ -61,7 +60,7 @@ func TestHaveReadAccessTo(t *testing.T) {
 	if util.IsUserRoot() {
 		t.Skip("This test cannot be run as root")
 	}
-	file, err := ioutil.TempFile("", "fscrypt_test")
+	file, err := os.CreateTemp("", "fscrypt_test")
 	if err != nil {
 		t.Fatal(err)
 	}