simplifying if-else chains to switches (#6208)

cmd/admin-handlers.go

@@ -478,9 +478,10 @@ func toAdminAPIErrCode(err error) APIErrorCode {
 	switch err {
 	case errXLWriteQuorum:
 		return ErrAdminConfigNoQuorum
-	}
+	default:
 		return toAPIErrorCode(err)
 	}
+}
 
 // SetConfigResult - represents detailed results of a set-config
 // operation.

cmd/admin-rpc-client.go

@@ -398,14 +398,16 @@ func getValidServerConfig(serverConfigs []serverConfig, errs []error) (scv serve
 				// seen. See example above for
 				// clarity.
 				continue
-			} else if j < i && serverConfigs[i].ConfigDiff(&serverConfigs[j]) == "" {
+			}
+			if j < i && serverConfigs[i].ConfigDiff(&serverConfigs[j]) == "" {
 				// serverConfigs[i] is equal to
 				// serverConfigs[j], update
 				// serverConfigs[j]'s counter since it
 				// is the lower index.
 				configCounter[j]++
 				break
-			} else if j == i {
+			}
+			if j == i {
 				// serverConfigs[i] is equal to no
 				// other value seen before. It is
 				// unique so far.

cmd/bool-flag.go

@@ -56,11 +56,12 @@ func (bf *BoolFlag) UnmarshalJSON(data []byte) (err error) {
 
 // ParseBoolFlag - parses string into BoolFlag.
 func ParseBoolFlag(s string) (bf BoolFlag, err error) {
-	if s == "on" {
+	switch s {
+	case "on":
 		bf = true
-	} else if s == "off" {
+	case "off":
 		bf = false
-	} else {
+	default:
 		err = fmt.Errorf("invalid value ‘%s’ for BoolFlag", s)
 	}
 

cmd/common-main.go

@@ -99,9 +99,10 @@ func handleCommonCmdArgs(ctx *cli.Context) {
 
 	var configDir string
 
-	if ctx.IsSet("config-dir") {
+	switch {
+	case ctx.IsSet("config-dir"):
 		configDir = ctx.String("config-dir")
-	} else if ctx.GlobalIsSet("config-dir") {
+	case ctx.GlobalIsSet("config-dir"):
 		configDir = ctx.GlobalString("config-dir")
 		// cli package does not expose parent's "config-dir" option.  Below code is workaround.
 		if configDir == "" || configDir == getConfigDir() {
@@ -109,7 +110,7 @@ func handleCommonCmdArgs(ctx *cli.Context) {
 				configDir = ctx.Parent().GlobalString("config-dir")
 			}
 		}
-	} else {
+	default:
 		// Neither local nor global config-dir option is provided.  In this case, try to use
 		// default config directory.
 		configDir = getConfigDir()

cmd/fs-v1-helpers.go

@@ -121,24 +121,26 @@ func fsMkdir(ctx context.Context, dirPath string) (err error) {
 	}
 
 	if err = os.Mkdir((dirPath), 0777); err != nil {
-		if os.IsExist(err) {
+		switch {
+		case os.IsExist(err):
 			return errVolumeExists
-		} else if os.IsPermission(err) {
+		case os.IsPermission(err):
 			logger.LogIf(ctx, errDiskAccessDenied)
 			return errDiskAccessDenied
-		} else if isSysErrNotDir(err) {
+		case isSysErrNotDir(err):
 			// File path cannot be verified since
 			// one of the parents is a file.
 			logger.LogIf(ctx, errDiskAccessDenied)
 			return errDiskAccessDenied
-		} else if isSysErrPathNotFound(err) {
+		case isSysErrPathNotFound(err):
 			// Add specific case for windows.
 			logger.LogIf(ctx, errDiskAccessDenied)
 			return errDiskAccessDenied
-		}
+		default:
 			logger.LogIf(ctx, err)
 			return err
 		}
+	}
 
 	return nil
 }

cmd/fs-v1-rwpool.go

@@ -93,19 +93,21 @@ func (fsi *fsIOPool) Open(path string) (*lock.RLockedFile, error) {
 		// Open file for reading with read lock.
 		newRlkFile, err := lock.RLockedOpenFile(path)
 		if err != nil {
-			if os.IsNotExist(err) {
+			switch {
+			case os.IsNotExist(err):
 				return nil, errFileNotFound
-			} else if os.IsPermission(err) {
+			case os.IsPermission(err):
 				return nil, errFileAccessDenied
-			} else if isSysErrIsDir(err) {
+			case isSysErrIsDir(err):
 				return nil, errIsNotRegular
-			} else if isSysErrNotDir(err) {
+			case isSysErrNotDir(err):
 				return nil, errFileAccessDenied
-			} else if isSysErrPathNotFound(err) {
+			case isSysErrPathNotFound(err):
 				return nil, errFileNotFound
-			}
+			default:
 				return nil, err
 			}
+		}
 
 		/// Save new reader on the map.
 
@@ -148,15 +150,17 @@ func (fsi *fsIOPool) Write(path string) (wlk *lock.LockedFile, err error) {
 
 	wlk, err = lock.LockedOpenFile(path, os.O_RDWR, 0666)
 	if err != nil {
-		if os.IsNotExist(err) {
+		switch {
+		case os.IsNotExist(err):
 			return nil, errFileNotFound
-		} else if os.IsPermission(err) {
+		case os.IsPermission(err):
 			return nil, errFileAccessDenied
-		} else if isSysErrIsDir(err) {
+		case isSysErrIsDir(err):
 			return nil, errIsNotRegular
-		}
+		default:
 			return nil, err
 		}
+	}
 	return wlk, nil
 }
 
@@ -175,15 +179,17 @@ func (fsi *fsIOPool) Create(path string) (wlk *lock.LockedFile, err error) {
 	// Attempt to create the file.
 	wlk, err = lock.LockedOpenFile(path, os.O_RDWR|os.O_CREATE, 0666)
 	if err != nil {
-		if os.IsPermission(err) {
+		switch {
+		case os.IsPermission(err):
 			return nil, errFileAccessDenied
-		} else if isSysErrIsDir(err) {
+		case isSysErrIsDir(err):
 			return nil, errIsNotRegular
-		} else if isSysErrPathNotFound(err) {
+		case isSysErrPathNotFound(err):
 			return nil, errFileAccessDenied
-		}
+		default:
 			return nil, err
 		}
+	}
 
 	// Success.
 	return wlk, nil

cmd/httprange.go

@@ -89,7 +89,8 @@ func parseRequestRange(rangeString string, resourceSize int64) (hrange *httpRang
 	}
 
 	// rangeString contains first and last byte positions. eg. "bytes=2-5"
-	if offsetBegin > -1 && offsetEnd > -1 {
+	switch {
+	case offsetBegin > -1 && offsetEnd > -1:
 		if offsetBegin > offsetEnd {
 			// Last byte position is not greater than first byte position. eg. "bytes=5-2"
 			return nil, fmt.Errorf("'%s' does not have valid range value", rangeString)
@@ -103,7 +104,7 @@ func parseRequestRange(rangeString string, resourceSize int64) (hrange *httpRang
 		if offsetEnd >= resourceSize {
 			offsetEnd = resourceSize - 1
 		}
-	} else if offsetBegin > -1 {
+	case offsetBegin > -1:
 		// rangeString contains only first byte position. eg. "bytes=8-"
 		if offsetBegin >= resourceSize {
 			// First byte position should not be >= resourceSize.
@@ -111,7 +112,7 @@ func parseRequestRange(rangeString string, resourceSize int64) (hrange *httpRang
 		}
 
 		offsetEnd = resourceSize - 1
-	} else if offsetEnd > -1 {
+	case offsetEnd > -1:
 		// rangeString contains only last byte position. eg. "bytes=-3"
 		if offsetEnd == 0 {
 			// Last byte position should not be zero eg. "bytes=-0"
@@ -125,7 +126,7 @@ func parseRequestRange(rangeString string, resourceSize int64) (hrange *httpRang
 		}
 
 		offsetEnd = resourceSize - 1
-	} else {
+	default:
 		// rangeString contains first and last byte positions missing. eg. "bytes=-"
 		return nil, fmt.Errorf("'%s' does not have valid range value", rangeString)
 	}

cmd/logger/logger.go

@@ -94,13 +94,14 @@ type Console interface {
 }
 
 func consoleLog(console Console, msg string, args ...interface{}) {
-	if jsonFlag {
+	switch {
+	case jsonFlag:
 		// Strip escape control characters from json message
 		msg = ansiRE.ReplaceAllLiteralString(msg, "")
 		console.json(msg, args...)
-	} else if quiet {
+	case quiet:
 		console.quiet(msg, args...)
-	} else {
+	default:
 		console.pretty(msg, args...)
 	}
 }

cmd/object-api-errors.go

@@ -375,20 +375,14 @@ func (e BackendDown) Error() string {
 
 // isErrIncompleteBody - Check if error type is IncompleteBody.
 func isErrIncompleteBody(err error) bool {
-	switch err.(type) {
-	case IncompleteBody:
-		return true
-	}
-	return false
+	_, ok := err.(IncompleteBody)
+	return ok
 }
 
 // isErrObjectNotFound - Check if error type is ObjectNotFound.
 func isErrObjectNotFound(err error) bool {
-	switch err.(type) {
-	case ObjectNotFound:
-		return true
-	}
-	return false
+	_, ok := err.(ObjectNotFound)
+	return ok
 }
 
 // isInsufficientReadQuorum - Check if error type is InsufficientReadQuorum.

cmd/os-reliable.go

@@ -130,20 +130,23 @@ func renameAll(srcFilePath, dstFilePath string) (err error) {
 	}
 
 	if err = reliableRename(srcFilePath, dstFilePath); err != nil {
-		if isSysErrNotDir(err) {
+		switch {
+		case isSysErrNotDir(err):
 			return errFileAccessDenied
-		} else if isSysErrPathNotFound(err) {
+		case isSysErrPathNotFound(err):
 			// This is a special case should be handled only for
 			// windows, because windows API does not return "not a
 			// directory" error message. Handle this specifically here.
 			return errFileAccessDenied
-		} else if isSysErrCrossDevice(err) {
+		case isSysErrCrossDevice(err):
 			return fmt.Errorf("%s (%s)->(%s)", errCrossDeviceLink, srcFilePath, dstFilePath)
-		} else if os.IsNotExist(err) {
+		case os.IsNotExist(err):
 			return errFileNotFound
+		default:
+			return err
 		}
 	}
-	return err
+	return nil
 }
 
 // Reliably retries os.RenameAll if for some reason os.RenameAll returns

cmd/posix-errors.go

@@ -27,13 +27,9 @@ func isSysErrNoSys(err error) bool {
 	if err == syscall.ENOSYS {
 		return true
 	}
-	if pathErr, ok := err.(*os.PathError); ok {
-		switch pathErr.Err {
-		case syscall.ENOSYS:
-			return true
-		}
-	}
-	return false
+	pathErr, ok := err.(*os.PathError)
+	return ok && pathErr.Err == syscall.ENOSYS
+
 }
 
 // Not supported error
@@ -41,13 +37,9 @@ func isSysErrOpNotSupported(err error) bool {
 	if err == syscall.EOPNOTSUPP {
 		return true
 	}
-	if pathErr, ok := err.(*os.PathError); ok {
-		switch pathErr.Err {
-		case syscall.EOPNOTSUPP:
-			return true
-		}
-	}
-	return false
+	pathErr, ok := err.(*os.PathError)
+	return ok && pathErr.Err == syscall.EOPNOTSUPP
+
 }
 
 // No space left on device error
@@ -55,13 +47,8 @@ func isSysErrNoSpace(err error) bool {
 	if err == syscall.ENOSPC {
 		return true
 	}
-	if pathErr, ok := err.(*os.PathError); ok {
-		switch pathErr.Err {
-		case syscall.ENOSPC:
-			return true
-		}
-	}
-	return false
+	pathErr, ok := err.(*os.PathError)
+	return ok && pathErr.Err == syscall.ENOSPC
 }
 
 // Input/output error
@@ -69,13 +56,8 @@ func isSysErrIO(err error) bool {
 	if err == syscall.EIO {
 		return true
 	}
-	if pathErr, ok := err.(*os.PathError); ok {
-		switch pathErr.Err {
-		case syscall.EIO:
-			return true
-		}
-	}
-	return false
+	pathErr, ok := err.(*os.PathError)
+	return ok && pathErr.Err == syscall.EIO
 }
 
 // Check if the given error corresponds to EISDIR (is a directory).
@@ -83,13 +65,9 @@ func isSysErrIsDir(err error) bool {
 	if err == syscall.EISDIR {
 		return true
 	}
-	if pathErr, ok := err.(*os.PathError); ok {
-		switch pathErr.Err {
-		case syscall.EISDIR:
-			return true
-		}
-	}
-	return false
+	pathErr, ok := err.(*os.PathError)
+	return ok && pathErr.Err == syscall.EISDIR
+
 }
 
 // Check if the given error corresponds to ENOTDIR (is not a directory).
@@ -97,13 +75,8 @@ func isSysErrNotDir(err error) bool {
 	if err == syscall.ENOTDIR {
 		return true
 	}
-	if pathErr, ok := err.(*os.PathError); ok {
-		switch pathErr.Err {
-		case syscall.ENOTDIR:
-			return true
-		}
-	}
-	return false
+	pathErr, ok := err.(*os.PathError)
+	return ok && pathErr.Err == syscall.ENOTDIR
 }
 
 // Check if the given error corresponds to the ENAMETOOLONG (name too long).
@@ -111,13 +84,8 @@ func isSysErrTooLong(err error) bool {
 	if err == syscall.ENAMETOOLONG {
 		return true
 	}
-	if pathErr, ok := err.(*os.PathError); ok {
-		switch pathErr.Err {
-		case syscall.ENAMETOOLONG:
-			return true
-		}
-	}
-	return false
+	pathErr, ok := err.(*os.PathError)
+	return ok && pathErr.Err == syscall.ENAMETOOLONG
 }
 
 // Check if the given error corresponds to ENOTEMPTY for unix
@@ -133,8 +101,7 @@ func isSysErrNotEmpty(err error) bool {
 				return true
 			}
 		}
-		switch pathErr.Err {
-		case syscall.ENOTEMPTY:
+		if pathErr.Err == syscall.ENOTEMPTY {
 			return true
 		}
 	}
@@ -161,15 +128,11 @@ func isSysErrHandleInvalid(err error) bool {
 		return false
 	}
 	// Check if err contains ERROR_INVALID_HANDLE errno
-	if errno, ok := err.(syscall.Errno); ok && errno == 0x6 {
-		return true
-	}
-	return false
+	errno, ok := err.(syscall.Errno)
+	return ok && errno == 0x6
 }
 
 func isSysErrCrossDevice(err error) bool {
-	if e, ok := err.(*os.LinkError); ok {
-		return e.Err == syscall.EXDEV
-	}
-	return false
+	e, ok := err.(*os.LinkError)
+	return ok && e.Err == syscall.EXDEV
 }

cmd/posix.go

@@ -329,15 +329,17 @@ func (s *posix) checkDiskFound() (err error) {
 	}
 	_, err = os.Stat(s.diskPath)
 	if err != nil {
-		if os.IsNotExist(err) {
+		switch {
+		case os.IsNotExist(err):
 			return errDiskNotFound
-		} else if isSysErrTooLong(err) {
+		case isSysErrTooLong(err):
 			return errFileNameTooLong
-		} else if isSysErrIO(err) {
+		case isSysErrIO(err):
 			return errFaultyDisk
-		}
+		default:
 			return err
 		}
+	}
 	return nil
 }
 
@@ -597,17 +599,19 @@ func (s *posix) DeleteVol(volume string) (err error) {
 	}
 	err = os.Remove((volumeDir))
 	if err != nil {
-		if os.IsNotExist(err) {
+		switch {
+		case os.IsNotExist(err):
 			return errVolumeNotFound
-		} else if isSysErrNotEmpty(err) {
+		case isSysErrNotEmpty(err):
 			return errVolumeNotEmpty
-		} else if os.IsPermission(err) {
+		case os.IsPermission(err):
 			return errDiskAccessDenied
-		} else if isSysErrIO(err) {
+		case isSysErrIO(err):
 			return errFaultyDisk
-		}
+		default:
 			return err
 		}
+	}
 	return nil
 }
 
@@ -771,17 +775,19 @@ func (s *posix) ReadFile(volume, path string, offset int64, buffer []byte, verif
 	// Open the file for reading.
 	file, err := os.Open((filePath))
 	if err != nil {
-		if os.IsNotExist(err) {
+		switch {
+		case os.IsNotExist(err):
 			return 0, errFileNotFound
-		} else if os.IsPermission(err) {
+		case os.IsPermission(err):
 			return 0, errFileAccessDenied
-		} else if isSysErrNotDir(err) {
+		case isSysErrNotDir(err):
 			return 0, errFileAccessDenied
-		} else if isSysErrIO(err) {
+		case isSysErrIO(err):
 			return 0, errFaultyDisk
-		}
+		default:
 			return 0, err
 		}
+	}
 
 	// Close the file descriptor.
 	defer file.Close()
@@ -880,15 +886,17 @@ func (s *posix) createFile(volume, path string) (f *os.File, err error) {
 	w, err := os.OpenFile(filePath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0666)
 	if err != nil {
 		// File path cannot be verified since one of the parents is a file.
-		if isSysErrNotDir(err) {
+		switch {
+		case isSysErrNotDir(err):
 			return nil, errFileAccessDenied
-		} else if os.IsPermission(err) {
+		case os.IsPermission(err):
 			return nil, errFileAccessDenied
-		} else if isSysErrIO(err) {
+		case isSysErrIO(err):
 			return nil, errFaultyDisk
-		}
+		default:
 			return nil, err
 		}
+	}
 
 	return w, nil
 }

cmd/postpolicyform.go

@@ -57,9 +57,10 @@ func toString(val interface{}) string {
 	switch v := val.(type) {
 	case string:
 		return v
-	}
+	default:
 		return ""
 	}
+}
 
 // toLowerString - safely convert interface to lower string
 func toLowerString(val interface{}) string {
@@ -78,18 +79,15 @@ func toInteger(val interface{}) (int64, error) {
 	case string:
 		i, err := strconv.Atoi(v)
 		return int64(i), err
-	}
-
+	default:
 		return 0, errors.New("Invalid number format")
 	}
+}
 
 // isString - Safely check if val is of type string without causing panic.
 func isString(val interface{}) bool {
-	switch val.(type) {
-	case string:
-		return true
-	}
-	return false
+	_, ok := val.(string)
+	return ok
 }
 
 // ContentLengthRange - policy content-length-range field.

cmd/xl-sets.go

@@ -427,10 +427,11 @@ func hashKey(algo string, key string, cardinality int) int {
 	switch algo {
 	case formatXLVersionV2DistributionAlgo:
 		return crcHashMod(key, cardinality)
-	}
+	default:
 		// Unknown algorithm returns -1, also if cardinality is lesser than 0.
 		return -1
 	}
+}
 
 // Returns always a same erasure coded set for a given input.
 func (s *xlSets) getHashedSet(input string) (set *xlObjects) {