archiver: use ExtendedStat from FS interface

With this change, NodeFromFileInfo is the last function that bypasses
the FS interface in the archiver.

internal/archiver/archiver.go

@@ -459,7 +459,7 @@ func (arch *Archiver) save(ctx context.Context, snPath, target string, previous
 
 		// check if the file has not changed before performing a fopen operation (more expensive, specially
 		// in network filesystems)
-		if previous != nil && !fileChanged(fi, previous, arch.ChangeIgnoreFlags) {
+		if previous != nil && !fileChanged(arch.FS, fi, previous, arch.ChangeIgnoreFlags) {
 			if arch.allBlobsPresent(previous) {
 				debug.Log("%v hasn't changed, using old list of blobs", target)
 				arch.trackItem(snPath, previous, previous, ItemStats{}, time.Since(start))
@@ -579,7 +579,7 @@ func (arch *Archiver) save(ctx context.Context, snPath, target string, previous
 // fileChanged tries to detect whether a file's content has changed compared
 // to the contents of node, which describes the same path in the parent backup.
 // It should only be run for regular files.
-func fileChanged(fi os.FileInfo, node *restic.Node, ignoreFlags uint) bool {
+func fileChanged(fs fs.FS, fi os.FileInfo, node *restic.Node, ignoreFlags uint) bool {
 	switch {
 	case node == nil:
 		return true

internal/archiver/archiver_test.go

@@ -686,10 +686,11 @@ func TestFileChanged(t *testing.T) {
 			}
 			save(t, filename, content)
 
+			fs := &fs.Local{}
 			fiBefore := lstat(t, filename)
 			node := nodeFromFI(t, filename, fiBefore)
 
-			if fileChanged(fiBefore, node, 0) {
+			if fileChanged(fs, fiBefore, node, 0) {
 				t.Fatalf("unchanged file detected as changed")
 			}
 
@@ -699,12 +700,12 @@ func TestFileChanged(t *testing.T) {
 
 			if test.SameFile {
 				// file should be detected as unchanged
-				if fileChanged(fiAfter, node, test.ChangeIgnore) {
+				if fileChanged(fs, fiAfter, node, test.ChangeIgnore) {
 					t.Fatalf("unmodified file detected as changed")
 				}
 			} else {
 				// file should be detected as changed
-				if !fileChanged(fiAfter, node, test.ChangeIgnore) && !test.SameFile {
+				if !fileChanged(fs, fiAfter, node, test.ChangeIgnore) && !test.SameFile {
 					t.Fatalf("modified file detected as unchanged")
 				}
 			}
@@ -721,7 +722,7 @@ func TestFilChangedSpecialCases(t *testing.T) {
 
 	t.Run("nil-node", func(t *testing.T) {
 		fi := lstat(t, filename)
-		if !fileChanged(fi, nil, 0) {
+		if !fileChanged(&fs.Local{}, fi, nil, 0) {
 			t.Fatal("nil node detected as unchanged")
 		}
 	})
@@ -730,7 +731,7 @@ func TestFilChangedSpecialCases(t *testing.T) {
 		fi := lstat(t, filename)
 		node := nodeFromFI(t, filename, fi)
 		node.Type = "symlink"
-		if !fileChanged(fi, node, 0) {
+		if !fileChanged(&fs.Local{}, fi, node, 0) {
 			t.Fatal("node with changed type detected as unchanged")
 		}
 	})

internal/fs/fs_local.go

@@ -52,6 +52,11 @@ func (fs Local) DeviceID(fi os.FileInfo) (id uint64, err error) {
 	return deviceID(fi)
 }
 
+// ExtendedStat converts the give FileInfo into ExtendedFileInfo.
+func (fs Local) ExtendedStat(fi os.FileInfo) ExtendedFileInfo {
+	return ExtendedStat(fi)
+}
+
 // Join joins any number of path elements into a single path, adding a
 // Separator if necessary. Join calls Clean on the result; in particular, all
 // empty strings are ignored. On Windows, the result is a UNC path if and only

internal/fs/fs_reader.go

@@ -126,6 +126,12 @@ func (fs *Reader) DeviceID(_ os.FileInfo) (deviceID uint64, err error) {
 	return 0, errors.New("Device IDs are not supported")
 }
 
+func (fs *Reader) ExtendedStat(fi os.FileInfo) ExtendedFileInfo {
+	return ExtendedFileInfo{
+		FileInfo: fi,
+	}
+}
+
 // Join joins any number of path elements into a single path, adding a
 // Separator if necessary. Join calls Clean on the result; in particular, all
 // empty strings are ignored. On Windows, the result is a UNC path if and only

internal/fs/interface.go

@@ -11,6 +11,7 @@ type FS interface {
 	Stat(name string) (os.FileInfo, error)
 	Lstat(name string) (os.FileInfo, error)
 	DeviceID(fi os.FileInfo) (deviceID uint64, err error)
+	ExtendedStat(fi os.FileInfo) ExtendedFileInfo
 
 	Join(elem ...string) string
 	Separator() string