package testsuites import ( "bytes" "crypto/sha1" "io" "io/ioutil" "math/rand" "os" "path" "sort" "sync" "testing" "time" "github.com/docker/docker-registry/storagedriver" "gopkg.in/check.v1" ) // Test hooks up gocheck into the "go test" runner. func Test(t *testing.T) { check.TestingT(t) } // RegisterInProcessSuite registers an in-process storage driver test suite with // the go test runner. func RegisterInProcessSuite(driverConstructor DriverConstructor, skipCheck SkipCheck) { check.Suite(&DriverSuite{ Constructor: driverConstructor, SkipCheck: skipCheck, }) } // RegisterIPCSuite registers a storage driver test suite which runs the named // driver as a child process with the given parameters. func RegisterIPCSuite(driverName string, ipcParams map[string]string, skipCheck SkipCheck) { panic("ipc testing is disabled for now") // NOTE(stevvooe): IPC testing is disabled for now. Uncomment the code // block before and remove the panic when we phase it back in. // suite := &DriverSuite{ // Constructor: func() (storagedriver.StorageDriver, error) { // d, err := ipc.NewDriverClient(driverName, ipcParams) // if err != nil { // return nil, err // } // err = d.Start() // if err != nil { // return nil, err // } // return d, nil // }, // SkipCheck: skipCheck, // } // suite.Teardown = func() error { // if suite.StorageDriver == nil { // return nil // } // driverClient := suite.StorageDriver.(*ipc.StorageDriverClient) // return driverClient.Stop() // } // check.Suite(suite) } // SkipCheck is a function used to determine if a test suite should be skipped. // If a SkipCheck returns a non-empty skip reason, the suite is skipped with // the given reason. type SkipCheck func() (reason string) // NeverSkip is a default SkipCheck which never skips the suite. var NeverSkip SkipCheck = func() string { return "" } // DriverConstructor is a function which returns a new // storagedriver.StorageDriver. type DriverConstructor func() (storagedriver.StorageDriver, error) // DriverTeardown is a function which cleans up a suite's // storagedriver.StorageDriver. type DriverTeardown func() error // DriverSuite is a gocheck test suite designed to test a // storagedriver.StorageDriver. // The intended way to create a DriverSuite is with RegisterInProcessSuite or // RegisterIPCSuite. type DriverSuite struct { Constructor DriverConstructor Teardown DriverTeardown SkipCheck storagedriver.StorageDriver } // SetUpSuite sets up the gocheck test suite. func (suite *DriverSuite) SetUpSuite(c *check.C) { if reason := suite.SkipCheck(); reason != "" { c.Skip(reason) } d, err := suite.Constructor() c.Assert(err, check.IsNil) suite.StorageDriver = d } // TearDownSuite tears down the gocheck test suite. func (suite *DriverSuite) TearDownSuite(c *check.C) { if suite.Teardown != nil { err := suite.Teardown() c.Assert(err, check.IsNil) } } // TestWriteRead1 tests a simple write-read workflow. func (suite *DriverSuite) TestWriteRead1(c *check.C) { filename := randomPath(32) contents := []byte("a") suite.writeReadCompare(c, filename, contents) } // TestWriteRead2 tests a simple write-read workflow with unicode data. func (suite *DriverSuite) TestWriteRead2(c *check.C) { filename := randomPath(32) contents := []byte("\xc3\x9f") suite.writeReadCompare(c, filename, contents) } // TestWriteRead3 tests a simple write-read workflow with a small string. func (suite *DriverSuite) TestWriteRead3(c *check.C) { filename := randomPath(32) contents := randomContents(32) suite.writeReadCompare(c, filename, contents) } // TestWriteRead4 tests a simple write-read workflow with 1MB of data. func (suite *DriverSuite) TestWriteRead4(c *check.C) { filename := randomPath(32) contents := randomContents(1024 * 1024) suite.writeReadCompare(c, filename, contents) } // TestWriteReadNonUTF8 tests that non-utf8 data may be written to the storage // driver safely. func (suite *DriverSuite) TestWriteReadNonUTF8(c *check.C) { filename := randomPath(32) contents := []byte{0x80, 0x80, 0x80, 0x80} suite.writeReadCompare(c, filename, contents) } // TestTruncate tests that putting smaller contents than an original file does // remove the excess contents. func (suite *DriverSuite) TestTruncate(c *check.C) { filename := randomPath(32) contents := randomContents(1024 * 1024) suite.writeReadCompare(c, filename, contents) contents = randomContents(1024) suite.writeReadCompare(c, filename, contents) } // TestReadNonexistent tests reading content from an empty path. func (suite *DriverSuite) TestReadNonexistent(c *check.C) { filename := randomPath(32) _, err := suite.StorageDriver.GetContent(filename) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{}) } // TestWriteReadStreams1 tests a simple write-read streaming workflow. func (suite *DriverSuite) TestWriteReadStreams1(c *check.C) { filename := randomPath(32) contents := []byte("a") suite.writeReadCompareStreams(c, filename, contents) } // TestWriteReadStreams2 tests a simple write-read streaming workflow with // unicode data. func (suite *DriverSuite) TestWriteReadStreams2(c *check.C) { filename := randomPath(32) contents := []byte("\xc3\x9f") suite.writeReadCompareStreams(c, filename, contents) } // TestWriteReadStreams3 tests a simple write-read streaming workflow with a // small amount of data. func (suite *DriverSuite) TestWriteReadStreams3(c *check.C) { filename := randomPath(32) contents := randomContents(32) suite.writeReadCompareStreams(c, filename, contents) } // TestWriteReadStreams4 tests a simple write-read streaming workflow with 1MB // of data. func (suite *DriverSuite) TestWriteReadStreams4(c *check.C) { filename := randomPath(32) contents := randomContents(1024 * 1024) suite.writeReadCompareStreams(c, filename, contents) } // TestWriteReadStreamsNonUTF8 tests that non-utf8 data may be written to the // storage driver safely. func (suite *DriverSuite) TestWriteReadStreamsNonUTF8(c *check.C) { filename := randomPath(32) contents := []byte{0x80, 0x80, 0x80, 0x80} suite.writeReadCompareStreams(c, filename, contents) } // TestWriteReadLargeStreams tests that a 5GB file may be written to the storage // driver safely. func (suite *DriverSuite) TestWriteReadLargeStreams(c *check.C) { if testing.Short() { c.Skip("Skipping test in short mode") } filename := randomPath(32) defer suite.StorageDriver.Delete(firstPart(filename)) checksum := sha1.New() var offset int64 var chunkSize int64 = 1024 * 1024 for i := 0; i < 5*1024; i++ { contents := randomContents(chunkSize) written, err := suite.StorageDriver.WriteStream(filename, offset, io.TeeReader(bytes.NewReader(contents), checksum)) c.Assert(err, check.IsNil) c.Assert(written, check.Equals, chunkSize) offset += chunkSize } reader, err := suite.StorageDriver.ReadStream(filename, 0) c.Assert(err, check.IsNil) writtenChecksum := sha1.New() io.Copy(writtenChecksum, reader) c.Assert(writtenChecksum.Sum(nil), check.DeepEquals, checksum.Sum(nil)) } // TestReadStreamWithOffset tests that the appropriate data is streamed when // reading with a given offset. func (suite *DriverSuite) TestReadStreamWithOffset(c *check.C) { filename := randomPath(32) defer suite.StorageDriver.Delete(firstPart(filename)) chunkSize := int64(32) contentsChunk1 := randomContents(chunkSize) contentsChunk2 := randomContents(chunkSize) contentsChunk3 := randomContents(chunkSize) err := suite.StorageDriver.PutContent(filename, append(append(contentsChunk1, contentsChunk2...), contentsChunk3...)) c.Assert(err, check.IsNil) reader, err := suite.StorageDriver.ReadStream(filename, 0) c.Assert(err, check.IsNil) defer reader.Close() readContents, err := ioutil.ReadAll(reader) c.Assert(err, check.IsNil) c.Assert(readContents, check.DeepEquals, append(append(contentsChunk1, contentsChunk2...), contentsChunk3...)) reader, err = suite.StorageDriver.ReadStream(filename, chunkSize) c.Assert(err, check.IsNil) defer reader.Close() readContents, err = ioutil.ReadAll(reader) c.Assert(err, check.IsNil) c.Assert(readContents, check.DeepEquals, append(contentsChunk2, contentsChunk3...)) reader, err = suite.StorageDriver.ReadStream(filename, chunkSize*2) c.Assert(err, check.IsNil) defer reader.Close() readContents, err = ioutil.ReadAll(reader) c.Assert(err, check.IsNil) c.Assert(readContents, check.DeepEquals, contentsChunk3) // Ensure we get invalid offest for negative offsets. reader, err = suite.StorageDriver.ReadStream(filename, -1) c.Assert(err, check.FitsTypeOf, storagedriver.InvalidOffsetError{}) c.Assert(err.(storagedriver.InvalidOffsetError).Offset, check.Equals, int64(-1)) c.Assert(err.(storagedriver.InvalidOffsetError).Path, check.Equals, filename) c.Assert(reader, check.IsNil) // Read past the end of the content and make sure we get a reader that // returns 0 bytes and io.EOF reader, err = suite.StorageDriver.ReadStream(filename, chunkSize*3) c.Assert(err, check.IsNil) defer reader.Close() buf := make([]byte, chunkSize) n, err := reader.Read(buf) c.Assert(err, check.Equals, io.EOF) c.Assert(n, check.Equals, 0) // Check the N-1 boundary condition, ensuring we get 1 byte then io.EOF. reader, err = suite.StorageDriver.ReadStream(filename, chunkSize*3-1) c.Assert(err, check.IsNil) defer reader.Close() n, err = reader.Read(buf) c.Assert(n, check.Equals, 1) // We don't care whether the io.EOF comes on the this read or the first // zero read, but the only error acceptable here is io.EOF. if err != nil { c.Assert(err, check.Equals, io.EOF) } // Any more reads should result in zero bytes and io.EOF n, err = reader.Read(buf) c.Assert(n, check.Equals, 0) c.Assert(err, check.Equals, io.EOF) } // TestContinueStreamAppend tests that a stream write can be appended to without // corrupting the data. func (suite *DriverSuite) TestContinueStreamAppend(c *check.C) { filename := randomPath(32) defer suite.StorageDriver.Delete(firstPart(filename)) chunkSize := int64(10 * 1024 * 1024) contentsChunk1 := randomContents(chunkSize) contentsChunk2 := randomContents(chunkSize) contentsChunk3 := randomContents(chunkSize) contentsChunk4 := randomContents(chunkSize) zeroChunk := make([]byte, int64(chunkSize)) fullContents := append(append(contentsChunk1, contentsChunk2...), contentsChunk3...) nn, err := suite.StorageDriver.WriteStream(filename, 0, bytes.NewReader(contentsChunk1)) c.Assert(err, check.IsNil) c.Assert(nn, check.Equals, int64(len(contentsChunk1))) fi, err := suite.StorageDriver.Stat(filename) c.Assert(err, check.IsNil) c.Assert(fi, check.NotNil) c.Assert(fi.Size(), check.Equals, int64(len(contentsChunk1))) if fi.Size() > chunkSize { c.Fatalf("Offset too large, %d > %d", fi.Size(), chunkSize) } nn, err = suite.StorageDriver.WriteStream(filename, fi.Size(), bytes.NewReader(contentsChunk2)) c.Assert(err, check.IsNil) c.Assert(nn, check.Equals, int64(len(contentsChunk2))) fi, err = suite.StorageDriver.Stat(filename) c.Assert(err, check.IsNil) c.Assert(fi, check.NotNil) c.Assert(fi.Size(), check.Equals, 2*chunkSize) if fi.Size() > 2*chunkSize { c.Fatalf("Offset too large, %d > %d", fi.Size(), 2*chunkSize) } nn, err = suite.StorageDriver.WriteStream(filename, fi.Size(), bytes.NewReader(fullContents[fi.Size():])) c.Assert(err, check.IsNil) c.Assert(nn, check.Equals, int64(len(fullContents[fi.Size():]))) received, err := suite.StorageDriver.GetContent(filename) c.Assert(err, check.IsNil) c.Assert(received, check.DeepEquals, fullContents) // Writing past size of file extends file (no offest error). We would like // to write chunk 4 one chunk length past chunk 3. It should be successful // and the resulting file will be 5 chunks long, with a chunk of all // zeros. fullContents = append(fullContents, zeroChunk...) fullContents = append(fullContents, contentsChunk4...) nn, err = suite.StorageDriver.WriteStream(filename, int64(len(fullContents))-chunkSize, bytes.NewReader(contentsChunk4)) c.Assert(err, check.IsNil) c.Assert(nn, check.Equals, chunkSize) fi, err = suite.StorageDriver.Stat(filename) c.Assert(err, check.IsNil) c.Assert(fi, check.NotNil) c.Assert(fi.Size(), check.Equals, int64(len(fullContents))) received, err = suite.StorageDriver.GetContent(filename) c.Assert(err, check.IsNil) c.Assert(len(received), check.Equals, len(fullContents)) c.Assert(received[chunkSize*3:chunkSize*4], check.DeepEquals, zeroChunk) c.Assert(received[chunkSize*4:chunkSize*5], check.DeepEquals, contentsChunk4) c.Assert(received, check.DeepEquals, fullContents) // Ensure that negative offsets return correct error. nn, err = suite.StorageDriver.WriteStream(filename, -1, bytes.NewReader(zeroChunk)) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.InvalidOffsetError{}) c.Assert(err.(storagedriver.InvalidOffsetError).Path, check.Equals, filename) c.Assert(err.(storagedriver.InvalidOffsetError).Offset, check.Equals, int64(-1)) } // TestReadNonexistentStream tests that reading a stream for a nonexistent path // fails. func (suite *DriverSuite) TestReadNonexistentStream(c *check.C) { filename := randomPath(32) _, err := suite.StorageDriver.ReadStream(filename, 0) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{}) } // TestList checks the returned list of keys after populating a directory tree. func (suite *DriverSuite) TestList(c *check.C) { rootDirectory := "/" + randomFilename(int64(8+rand.Intn(8))) defer suite.StorageDriver.Delete("/") parentDirectory := rootDirectory + "/" + randomFilename(int64(8+rand.Intn(8))) childFiles := make([]string, 50) for i := 0; i < len(childFiles); i++ { childFile := parentDirectory + "/" + randomFilename(int64(8+rand.Intn(8))) childFiles[i] = childFile err := suite.StorageDriver.PutContent(childFile, randomContents(32)) c.Assert(err, check.IsNil) } sort.Strings(childFiles) keys, err := suite.StorageDriver.List("/") c.Assert(err, check.IsNil) c.Assert(keys, check.DeepEquals, []string{rootDirectory}) keys, err = suite.StorageDriver.List(rootDirectory) c.Assert(err, check.IsNil) c.Assert(keys, check.DeepEquals, []string{parentDirectory}) keys, err = suite.StorageDriver.List(parentDirectory) c.Assert(err, check.IsNil) sort.Strings(keys) c.Assert(keys, check.DeepEquals, childFiles) // A few checks to add here (check out #819 for more discussion on this): // 1. Ensure that all paths are absolute. // 2. Ensure that listings only include direct children. // 3. Ensure that we only respond to directory listings that end with a slash (maybe?). } // TestMove checks that a moved object no longer exists at the source path and // does exist at the destination. func (suite *DriverSuite) TestMove(c *check.C) { contents := randomContents(32) sourcePath := randomPath(32) destPath := randomPath(32) defer suite.StorageDriver.Delete(firstPart(sourcePath)) defer suite.StorageDriver.Delete(firstPart(destPath)) err := suite.StorageDriver.PutContent(sourcePath, contents) c.Assert(err, check.IsNil) err = suite.StorageDriver.Move(sourcePath, destPath) c.Assert(err, check.IsNil) received, err := suite.StorageDriver.GetContent(destPath) c.Assert(err, check.IsNil) c.Assert(received, check.DeepEquals, contents) _, err = suite.StorageDriver.GetContent(sourcePath) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{}) } // TestMoveNonexistent checks that moving a nonexistent key fails func (suite *DriverSuite) TestMoveNonexistent(c *check.C) { sourcePath := randomPath(32) destPath := randomPath(32) err := suite.StorageDriver.Move(sourcePath, destPath) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{}) } // TestDelete checks that the delete operation removes data from the storage // driver func (suite *DriverSuite) TestDelete(c *check.C) { filename := randomPath(32) contents := randomContents(32) defer suite.StorageDriver.Delete(firstPart(filename)) err := suite.StorageDriver.PutContent(filename, contents) c.Assert(err, check.IsNil) err = suite.StorageDriver.Delete(filename) c.Assert(err, check.IsNil) _, err = suite.StorageDriver.GetContent(filename) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{}) } // TestDeleteNonexistent checks that removing a nonexistent key fails. func (suite *DriverSuite) TestDeleteNonexistent(c *check.C) { filename := randomPath(32) err := suite.StorageDriver.Delete(filename) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{}) } // TestDeleteFolder checks that deleting a folder removes all child elements. func (suite *DriverSuite) TestDeleteFolder(c *check.C) { dirname := randomPath(32) filename1 := randomPath(32) filename2 := randomPath(32) filename3 := randomPath(32) contents := randomContents(32) defer suite.StorageDriver.Delete(firstPart(dirname)) err := suite.StorageDriver.PutContent(path.Join(dirname, filename1), contents) c.Assert(err, check.IsNil) err = suite.StorageDriver.PutContent(path.Join(dirname, filename2), contents) c.Assert(err, check.IsNil) err = suite.StorageDriver.PutContent(path.Join(dirname, filename3), contents) c.Assert(err, check.IsNil) err = suite.StorageDriver.Delete(path.Join(dirname, filename1)) c.Assert(err, check.IsNil) _, err = suite.StorageDriver.GetContent(path.Join(dirname, filename1)) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{}) _, err = suite.StorageDriver.GetContent(path.Join(dirname, filename2)) c.Assert(err, check.IsNil) _, err = suite.StorageDriver.GetContent(path.Join(dirname, filename3)) c.Assert(err, check.IsNil) err = suite.StorageDriver.Delete(dirname) c.Assert(err, check.IsNil) _, err = suite.StorageDriver.GetContent(path.Join(dirname, filename1)) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{}) _, err = suite.StorageDriver.GetContent(path.Join(dirname, filename2)) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{}) _, err = suite.StorageDriver.GetContent(path.Join(dirname, filename3)) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{}) } // TestStatCall runs verifies the implementation of the storagedriver's Stat call. func (suite *DriverSuite) TestStatCall(c *check.C) { content := randomContents(4096) dirPath := randomPath(32) fileName := randomFilename(32) filePath := path.Join(dirPath, fileName) defer suite.StorageDriver.Delete(dirPath) // Call on non-existent file/dir, check error. fi, err := suite.StorageDriver.Stat(filePath) c.Assert(err, check.NotNil) c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{}) c.Assert(fi, check.IsNil) err = suite.StorageDriver.PutContent(filePath, content) c.Assert(err, check.IsNil) // Call on regular file, check results start := time.Now().Truncate(time.Second) // truncated for filesystem fi, err = suite.StorageDriver.Stat(filePath) c.Assert(err, check.IsNil) expectedModTime := time.Now() c.Assert(fi, check.NotNil) c.Assert(fi.Path(), check.Equals, filePath) c.Assert(fi.Size(), check.Equals, int64(len(content))) c.Assert(fi.IsDir(), check.Equals, false) if start.After(fi.ModTime()) { c.Fatalf("modtime %s before file created (%v)", fi.ModTime(), start) } if fi.ModTime().After(expectedModTime) { c.Fatalf("modtime %s after file created (%v)", fi.ModTime(), expectedModTime) } // Call on directory start = time.Now().Truncate(time.Second) fi, err = suite.StorageDriver.Stat(dirPath) c.Assert(err, check.IsNil) expectedModTime = time.Now() c.Assert(fi, check.NotNil) c.Assert(fi.Path(), check.Equals, dirPath) c.Assert(fi.Size(), check.Equals, int64(0)) c.Assert(fi.IsDir(), check.Equals, true) if start.After(fi.ModTime()) { c.Fatalf("modtime %s before file created (%v)", fi.ModTime(), start) } if fi.ModTime().After(expectedModTime) { c.Fatalf("modtime %s after file created (%v)", fi.ModTime(), expectedModTime) } } // TestConcurrentFileStreams checks that multiple *os.File objects can be passed // in to WriteStream concurrently without hanging. // TODO(bbland): fix this test... func (suite *DriverSuite) TestConcurrentFileStreams(c *check.C) { // if _, isIPC := suite.StorageDriver.(*ipc.StorageDriverClient); isIPC { // c.Skip("Need to fix out-of-process concurrency") // } var wg sync.WaitGroup testStream := func(size int64) { defer wg.Done() suite.testFileStreams(c, size) } wg.Add(6) go testStream(8 * 1024 * 1024) go testStream(4 * 1024 * 1024) go testStream(2 * 1024 * 1024) go testStream(1024 * 1024) go testStream(1024) go testStream(64) wg.Wait() } func (suite *DriverSuite) testFileStreams(c *check.C, size int64) { tf, err := ioutil.TempFile("", "tf") c.Assert(err, check.IsNil) defer os.Remove(tf.Name()) tfName := path.Base(tf.Name()) defer suite.StorageDriver.Delete(tfName) contents := randomContents(size) _, err = tf.Write(contents) c.Assert(err, check.IsNil) tf.Sync() tf.Seek(0, os.SEEK_SET) nn, err := suite.StorageDriver.WriteStream(tfName, 0, tf) c.Assert(err, check.IsNil) c.Assert(nn, check.Equals, size) reader, err := suite.StorageDriver.ReadStream(tfName, 0) c.Assert(err, check.IsNil) defer reader.Close() readContents, err := ioutil.ReadAll(reader) c.Assert(err, check.IsNil) c.Assert(readContents, check.DeepEquals, contents) } func (suite *DriverSuite) writeReadCompare(c *check.C, filename string, contents []byte) { defer suite.StorageDriver.Delete(firstPart(filename)) err := suite.StorageDriver.PutContent(filename, contents) c.Assert(err, check.IsNil) readContents, err := suite.StorageDriver.GetContent(filename) c.Assert(err, check.IsNil) c.Assert(readContents, check.DeepEquals, contents) } func (suite *DriverSuite) writeReadCompareStreams(c *check.C, filename string, contents []byte) { defer suite.StorageDriver.Delete(firstPart(filename)) nn, err := suite.StorageDriver.WriteStream(filename, 0, bytes.NewReader(contents)) c.Assert(err, check.IsNil) c.Assert(nn, check.Equals, int64(len(contents))) reader, err := suite.StorageDriver.ReadStream(filename, 0) c.Assert(err, check.IsNil) defer reader.Close() readContents, err := ioutil.ReadAll(reader) c.Assert(err, check.IsNil) c.Assert(readContents, check.DeepEquals, contents) } var filenameChars = []byte("abcdefghijklmnopqrstuvwxyz0123456789") func randomPath(length int64) string { path := "" for int64(len(path)) < length { chunkLength := rand.Int63n(length-int64(len(path))) + 1 chunk := randomFilename(chunkLength) path += chunk if length-int64(len(path)) == 1 { path += randomFilename(1) } else if length-int64(len(path)) > 1 { path += "/" } } return path } func randomFilename(length int64) string { b := make([]byte, length) for i := range b { b[i] = filenameChars[rand.Intn(len(filenameChars))] } return string(b) } func randomContents(length int64) []byte { b := make([]byte, length) for i := range b { b[i] = byte(rand.Intn(2 << 8)) } return b } func firstPart(filePath string) string { for { if filePath[len(filePath)-1] == '/' { filePath = filePath[:len(filePath)-1] } dir, file := path.Split(filePath) if dir == "" && file == "" { return "/" } if dir == "" { return file } if file == "" { return dir } filePath = dir } }