refactor: move from io/ioutil to io and os package

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>

content/helpers.go

@@ -19,7 +19,6 @@ package content
 import (
 	"context"
 	"io"
-	"io/ioutil"
 	"math/rand"
 	"sync"
 	"time"
@@ -230,7 +229,7 @@ func seekReader(r io.Reader, offset, size int64) (io.Reader, error) {
 	}
 
 	// well then, let's just discard up to the offset
-	n, err := copyWithBuffer(ioutil.Discard, io.LimitReader(r, offset))
+	n, err := copyWithBuffer(io.Discard, io.LimitReader(r, offset))
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to discard to offset")
 	}

content/local/store.go

@@ -20,7 +20,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"math/rand"
 	"os"
 	"path/filepath"
@@ -568,7 +567,7 @@ func (s *store) writer(ctx context.Context, ref string, total int64, expected di
 
 		// the ingest is new, we need to setup the target location.
 		// write the ref to a file for later use
-		if err := ioutil.WriteFile(refp, []byte(ref), 0666); err != nil {
+		if err := os.WriteFile(refp, []byte(ref), 0666); err != nil {
 			return nil, err
 		}
 
@@ -581,7 +580,7 @@ func (s *store) writer(ctx context.Context, ref string, total int64, expected di
 		}
 
 		if total > 0 {
-			if err := ioutil.WriteFile(filepath.Join(path, "total"), []byte(fmt.Sprint(total)), 0666); err != nil {
+			if err := os.WriteFile(filepath.Join(path, "total"), []byte(fmt.Sprint(total)), 0666); err != nil {
 				return nil, err
 			}
 		}
@@ -656,13 +655,13 @@ func (s *store) ingestPaths(ref string) (string, string, string) {
 }
 
 func readFileString(path string) (string, error) {
-	p, err := ioutil.ReadFile(path)
+	p, err := os.ReadFile(path)
 	return string(p), err
 }
 
 // readFileTimestamp reads a file with just a timestamp present.
 func readFileTimestamp(p string) (time.Time, error) {
-	b, err := ioutil.ReadFile(p)
+	b, err := os.ReadFile(p)
 	if err != nil {
 		if os.IsNotExist(err) {
 			err = errors.Wrap(errdefs.ErrNotFound, err.Error())

content/local/store_test.go

@@ -23,7 +23,6 @@ import (
 	_ "crypto/sha256" // required for digest package
 	"fmt"
 	"io"
-	"io/ioutil"
 	"math/rand"
 	"os"
 	"path/filepath"
@@ -158,7 +157,7 @@ func TestContentWriter(t *testing.T) {
 	}
 	expected := digest.FromBytes(p)
 
-	checkCopy(t, int64(len(p)), cw, bufio.NewReader(ioutil.NopCloser(bytes.NewReader(p))))
+	checkCopy(t, int64(len(p)), cw, bufio.NewReader(io.NopCloser(bytes.NewReader(p))))
 
 	if err := cw.Commit(ctx, int64(len(p)), expected); err != nil {
 		t.Fatal(err)
@@ -174,7 +173,7 @@ func TestContentWriter(t *testing.T) {
 	}
 
 	// now, attempt to write the same data again
-	checkCopy(t, int64(len(p)), cw, bufio.NewReader(ioutil.NopCloser(bytes.NewReader(p))))
+	checkCopy(t, int64(len(p)), cw, bufio.NewReader(io.NopCloser(bytes.NewReader(p))))
 	if err := cw.Commit(ctx, int64(len(p)), expected); err == nil {
 		t.Fatal("expected already exists error")
 	} else if !errdefs.IsAlreadyExists(err) {
@@ -184,7 +183,7 @@ func TestContentWriter(t *testing.T) {
 	path := checkBlobPath(t, cs, expected)
 
 	// read the data back, make sure its the same
-	pp, err := ioutil.ReadFile(path)
+	pp, err := os.ReadFile(path)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -299,7 +298,7 @@ func contentStoreEnv(t checker) (context.Context, string, content.Store, func())
 	}
 	fn := runtime.FuncForPC(pc)
 
-	tmpdir, err := ioutil.TempDir("", filepath.Base(fn.Name())+"-")
+	tmpdir, err := os.MkdirTemp("", filepath.Base(fn.Name())+"-")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -362,7 +361,7 @@ func checkWrite(ctx context.Context, t checker, cs content.Store, dgst digest.Di
 }
 
 func TestWriterTruncateRecoversFromIncompleteWrite(t *testing.T) {
-	tmpdir, err := ioutil.TempDir("", "test-local-content-store-recover")
+	tmpdir, err := os.MkdirTemp("", "test-local-content-store-recover")
 	assert.NilError(t, err)
 	defer os.RemoveAll(tmpdir)
 
@@ -401,7 +400,7 @@ func setupIncompleteWrite(ctx context.Context, t *testing.T, cs content.Store, r
 }
 
 func TestWriteReadEmptyFileTimestamp(t *testing.T) {
-	root, err := ioutil.TempDir("", "test-write-read-file-timestamp")
+	root, err := os.MkdirTemp("", "test-write-read-file-timestamp")
 	if err != nil {
 		t.Errorf("failed to create a tmp dir: %v", err)
 	}

content/testsuite/testsuite.go

@@ -21,7 +21,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"math/rand"
 	"os"
 	"runtime"
@@ -104,7 +103,7 @@ func makeTest(t *testing.T, name string, storeFn func(ctx context.Context, root
 		ctx := context.WithValue(context.Background(), nameKey{}, name)
 		ctx = logtest.WithT(ctx, t)
 
-		tmpDir, err := ioutil.TempDir("", "content-suite-"+name+"-")
+		tmpDir, err := os.MkdirTemp("", "content-suite-"+name+"-")
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -782,7 +781,7 @@ func checkSmallBlob(ctx context.Context, t *testing.T, store content.Store) {
 	}
 	defer ra.Close()
 	r := io.NewSectionReader(ra, 0, readSize)
-	b, err := ioutil.ReadAll(r)
+	b, err := io.ReadAll(r)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1080,7 +1079,7 @@ func createContent(size int64) ([]byte, digest.Digest) {
 	// test runs. An atomic integer works just good enough for this.
 	seed := atomic.AddInt64(&contentSeed, 1)
 
-	b, err := ioutil.ReadAll(io.LimitReader(rand.New(rand.NewSource(seed)), size))
+	b, err := io.ReadAll(io.LimitReader(rand.New(rand.NewSource(seed)), size))
 	if err != nil {
 		panic(err)
 	}