lib/versioner: Restore for all versioners, cross-device support (#5514)

* lib/versioner: Restore for all versioners, cross-device support

Fixes #4631
Fixes #4586
Fixes #1634
Fixes #5338
Fixes #5419

lib/osutil/osutil_test.go

@@ -7,6 +7,7 @@
 package osutil_test
 
 import (
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -192,7 +193,7 @@ func TestInWritableDirWindowsRename(t *testing.T) {
 	}
 
 	rename := func(path string) error {
-		return osutil.Rename(fs, path, path+"new")
+		return osutil.RenameOrCopy(fs, fs, path, path+"new")
 	}
 
 	for _, path := range []string{"testdata/windows/ro/readonly", "testdata/windows/ro", "testdata/windows"} {
@@ -268,3 +269,79 @@ func TestIsDeleted(t *testing.T) {
 	testFs.Chmod("inacc", 0777)
 	os.RemoveAll("testdata")
 }
+
+func TestRenameOrCopy(t *testing.T) {
+	mustTempDir := func() string {
+		t.Helper()
+		tmpDir, err := ioutil.TempDir("", "")
+		if err != nil {
+			t.Fatal(err)
+		}
+		return tmpDir
+	}
+	sameFs := fs.NewFilesystem(fs.FilesystemTypeBasic, mustTempDir())
+	tests := []struct {
+		src  fs.Filesystem
+		dst  fs.Filesystem
+		file string
+	}{
+		{
+			src:  sameFs,
+			dst:  sameFs,
+			file: "file",
+		},
+		{
+			src:  fs.NewFilesystem(fs.FilesystemTypeBasic, mustTempDir()),
+			dst:  fs.NewFilesystem(fs.FilesystemTypeBasic, mustTempDir()),
+			file: "file",
+		},
+		{
+			src:  fs.NewFilesystem(fs.FilesystemTypeFake, `fake://fake/?files=1&seed=42`),
+			dst:  fs.NewFilesystem(fs.FilesystemTypeBasic, mustTempDir()),
+			file: osutil.NativeFilename(`05/7a/4d52f284145b9fe8`),
+		},
+	}
+
+	for _, test := range tests {
+		content := test.src.URI()
+		if _, err := test.src.Lstat(test.file); err != nil {
+			if !fs.IsNotExist(err) {
+				t.Fatal(err)
+			}
+			if fd, err := test.src.Create(test.file); err != nil {
+				t.Fatal(err)
+			} else {
+				if _, err := fd.Write([]byte(test.src.URI())); err != nil {
+					t.Fatal(err)
+				}
+				_ = fd.Close()
+			}
+		} else {
+			fd, err := test.src.Open(test.file)
+			if err != nil {
+				t.Fatal(err)
+			}
+			buf, err := ioutil.ReadAll(fd)
+			if err != nil {
+				t.Fatal(err)
+			}
+			_ = fd.Close()
+			content = string(buf)
+		}
+
+		err := osutil.RenameOrCopy(test.src, test.dst, test.file, "new")
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if fd, err := test.dst.Open("new"); err != nil {
+			t.Fatal(err)
+		} else {
+			if buf, err := ioutil.ReadAll(fd); err != nil {
+				t.Fatal(err)
+			} else if string(buf) != content {
+				t.Fatalf("expected %s got %s", content, string(buf))
+			}
+		}
+	}
+}