pkg/fsutils: deprecate in favor of containerd/continuity/fs

The pkg/fsutils package was forked in containerd, and later moved to
containerd/continuity/fs. As we're moving more bits to containerd, let's also
use the same implementation to reduce code-duplication and to prevent them from
diverging.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 5b6b42162bf0511ac717ae1b57a43350b8e5f75e)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

daemon/graphdriver/overlay/overlay.go

@@ -12,12 +12,12 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/containerd/continuity/fs"
 	"github.com/docker/docker/daemon/graphdriver"
 	"github.com/docker/docker/daemon/graphdriver/copy"
 	"github.com/docker/docker/daemon/graphdriver/overlayutils"
 	"github.com/docker/docker/pkg/archive"
 	"github.com/docker/docker/pkg/containerfs"
-	"github.com/docker/docker/pkg/fsutils"
 	"github.com/docker/docker/pkg/idtools"
 	"github.com/docker/docker/pkg/parsers"
 	"github.com/moby/locker"
@@ -142,7 +142,7 @@ func Init(home string, options []string, idMap idtools.IdentityMapping) (graphdr
 		backingFs = fsName
 	}
 
-	supportsDType, err := fsutils.SupportsDType(testdir)
+	supportsDType, err := fs.SupportsDType(testdir)
 	if err != nil {
 		return nil, err
 	}

daemon/graphdriver/overlay2/overlay.go

@@ -15,13 +15,13 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/containerd/continuity/fs"
 	"github.com/docker/docker/daemon/graphdriver"
 	"github.com/docker/docker/daemon/graphdriver/overlayutils"
 	"github.com/docker/docker/pkg/archive"
 	"github.com/docker/docker/pkg/chrootarchive"
 	"github.com/docker/docker/pkg/containerfs"
 	"github.com/docker/docker/pkg/directory"
-	"github.com/docker/docker/pkg/fsutils"
 	"github.com/docker/docker/pkg/idtools"
 	"github.com/docker/docker/pkg/parsers"
 	"github.com/docker/docker/quota"
@@ -152,7 +152,7 @@ func Init(home string, options []string, idMap idtools.IdentityMapping) (graphdr
 		backingFs = fsName
 	}
 
-	supportsDType, err := fsutils.SupportsDType(testdir)
+	supportsDType, err := fs.SupportsDType(testdir)
 	if err != nil {
 		return nil, err
 	}

pkg/fsutils/fsutils_linux.go

@@ -1,85 +1,8 @@
 package fsutils // import "github.com/docker/docker/pkg/fsutils"
 
-import (
-	"fmt"
-	"os"
-	"unsafe"
+import "github.com/containerd/continuity/fs"
 
-	"golang.org/x/sys/unix"
-)
-
-func locateDummyIfEmpty(path string) (string, error) {
-	children, err := os.ReadDir(path)
-	if err != nil {
-		return "", err
-	}
-	if len(children) != 0 {
-		return "", nil
-	}
-	dummyFile, err := os.CreateTemp(path, "fsutils-dummy")
-	if err != nil {
-		return "", err
-	}
-	name := dummyFile.Name()
-	err = dummyFile.Close()
-	return name, err
-}
-
-// SupportsDType returns whether the filesystem mounted on path supports d_type
-func SupportsDType(path string) (bool, error) {
-	// locate dummy so that we have at least one dirent
-	dummy, err := locateDummyIfEmpty(path)
-	if err != nil {
-		return false, err
-	}
-	if dummy != "" {
-		defer os.Remove(dummy)
-	}
-
-	visited := 0
-	supportsDType := true
-	fn := func(ent *unix.Dirent) bool {
-		visited++
-		if ent.Type == unix.DT_UNKNOWN {
-			supportsDType = false
-			// stop iteration
-			return true
-		}
-		// continue iteration
-		return false
-	}
-	if err = iterateReadDir(path, fn); err != nil {
-		return false, err
-	}
-	if visited == 0 {
-		return false, fmt.Errorf("did not hit any dirent during iteration %s", path)
-	}
-	return supportsDType, nil
-}
-
-func iterateReadDir(path string, fn func(*unix.Dirent) bool) error {
-	d, err := os.Open(path)
-	if err != nil {
-		return err
-	}
-	defer d.Close()
-	fd := int(d.Fd())
-	buf := make([]byte, 4096)
-	for {
-		nbytes, err := unix.ReadDirent(fd, buf)
-		if err != nil {
-			return err
-		}
-		if nbytes == 0 {
-			break
-		}
-		for off := 0; off < nbytes; {
-			ent := (*unix.Dirent)(unsafe.Pointer(&buf[off]))
-			if stop := fn(ent); stop {
-				return nil
-			}
-			off += int(ent.Reclen)
-		}
-	}
-	return nil
-}
+// SupportsDType returns whether the filesystem mounted on path supports d_type.
+//
+// Deprecated: use github.com/containerd/continuity/fs.SupportsDType
+var SupportsDType = fs.SupportsDType

pkg/fsutils/fsutils_linux_test.go

@@ -1,92 +0,0 @@
-//go:build linux
-// +build linux
-
-package fsutils // import "github.com/docker/docker/pkg/fsutils"
-
-import (
-	"os"
-	"os/exec"
-	"testing"
-
-	"golang.org/x/sys/unix"
-)
-
-func testSupportsDType(t *testing.T, expected bool, mkfsCommand string, mkfsArg ...string) {
-	// check whether mkfs is installed
-	if _, err := exec.LookPath(mkfsCommand); err != nil {
-		t.Skipf("%s not installed: %v", mkfsCommand, err)
-	}
-
-	// create a sparse image
-	imageSize := int64(32 * 1024 * 1024)
-	imageFile, err := os.CreateTemp("", "fsutils-image")
-	if err != nil {
-		t.Fatal(err)
-	}
-	imageFileName := imageFile.Name()
-	defer os.Remove(imageFileName)
-	if _, err = imageFile.Seek(imageSize-1, 0); err != nil {
-		t.Fatal(err)
-	}
-	if _, err = imageFile.Write([]byte{0}); err != nil {
-		t.Fatal(err)
-	}
-	if err = imageFile.Close(); err != nil {
-		t.Fatal(err)
-	}
-
-	// create a mountpoint
-	mountpoint, err := os.MkdirTemp("", "fsutils-mountpoint")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer os.RemoveAll(mountpoint)
-
-	// format the image
-	args := append(mkfsArg, imageFileName)
-	t.Logf("Executing `%s %v`", mkfsCommand, args)
-	out, err := exec.Command(mkfsCommand, args...).CombinedOutput()
-	if len(out) > 0 {
-		t.Log(string(out))
-	}
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	// loopback-mount the image.
-	// for ease of setting up loopback device, we use os/exec rather than unix.Mount
-	out, err = exec.Command("mount", "-o", "loop", imageFileName, mountpoint).CombinedOutput()
-	if len(out) > 0 {
-		t.Log(string(out))
-	}
-	if err != nil {
-		t.Skip("skipping the test because mount failed")
-	}
-	defer func() {
-		if err := unix.Unmount(mountpoint, 0); err != nil {
-			t.Fatal(err)
-		}
-	}()
-
-	// check whether it supports d_type
-	result, err := SupportsDType(mountpoint)
-	if err != nil {
-		t.Fatal(err)
-	}
-	t.Logf("Supports d_type: %v", result)
-	if result != expected {
-		t.Fatalf("expected %v, got %v", expected, result)
-	}
-}
-
-func TestSupportsDTypeWithFType0XFS(t *testing.T) {
-	testSupportsDType(t, false, "mkfs.xfs", "-m", "crc=0", "-n", "ftype=0")
-}
-
-func TestSupportsDTypeWithFType1XFS(t *testing.T) {
-	testSupportsDType(t, true, "mkfs.xfs", "-m", "crc=0", "-n", "ftype=1")
-}
-
-func TestSupportsDTypeWithExt4(t *testing.T) {
-	testSupportsDType(t, true, "mkfs.ext4")
-}