rclone/fs/fspath/path.go
Nick Craig-Wood eb6e9b194a fspath: Stop empty strings being a valid path - fixes #4239
Before this change you could use "" as a valid remote, so `rclone lsf
""` would work. This was treated as the current directory.

This is unexpected and creates a footgun for scripting when an empty
variable is passed to rclone by accident.

This fix returns the error "can't use empty string as a path" instead
of allowing it.
2020-05-19 12:34:23 +01:00

115 lines
3.4 KiB
Go

// Package fspath contains routines for fspath manipulation
package fspath
import (
"errors"
"path"
"path/filepath"
"regexp"
"strings"
"github.com/rclone/rclone/fs/driveletter"
)
const (
configNameRe = `[\w_ -]+`
remoteNameRe = `^(:?` + configNameRe + `):`
)
var (
errInvalidCharacters = errors.New("config name contains invalid characters - may only contain 0-9, A-Z ,a-z ,_ , - and space ")
errCantBeEmpty = errors.New("can't use empty string as a path")
// urlMatcher is a pattern to match an rclone URL
// note that this matches invalid remoteNames
urlMatcher = regexp.MustCompile(`^(:?[^\\/:]*):(.*)$`)
// configNameMatcher is a pattern to match an rclone config name
configNameMatcher = regexp.MustCompile(`^` + configNameRe + `$`)
// remoteNameMatcher is a pattern to match an rclone remote name
remoteNameMatcher = regexp.MustCompile(remoteNameRe + `$`)
)
// CheckConfigName returns an error if configName is invalid
func CheckConfigName(configName string) error {
if !configNameMatcher.MatchString(configName) {
return errInvalidCharacters
}
return nil
}
// CheckRemoteName returns an error if remoteName is invalid
func CheckRemoteName(remoteName string) error {
if !remoteNameMatcher.MatchString(remoteName) {
return errInvalidCharacters
}
return nil
}
// Parse deconstructs a remote path into configName and fsPath
//
// If the path is a local path then configName will be returned as "".
//
// So "remote:path/to/dir" will return "remote", "path/to/dir"
// and "/path/to/local" will return ("", "/path/to/local")
//
// Note that this will turn \ into / in the fsPath on Windows
//
// An error may be returned if the remote name has invalid characters
// in it or if the path is empty.
func Parse(path string) (configName, fsPath string, err error) {
if path == "" {
return "", "", errCantBeEmpty
}
parts := urlMatcher.FindStringSubmatch(path)
configName, fsPath = "", path
if parts != nil && !driveletter.IsDriveLetter(parts[1]) {
configName, fsPath = parts[1], parts[2]
err = CheckRemoteName(configName + ":")
if err != nil {
return configName, fsPath, errInvalidCharacters
}
}
// change native directory separators to / if there are any
fsPath = filepath.ToSlash(fsPath)
return configName, fsPath, nil
}
// Split splits a remote into a parent and a leaf
//
// if it returns leaf as an empty string then remote is a directory
//
// if it returns parent as an empty string then that means the current directory
//
// The returned values have the property that parent + leaf == remote
// (except under Windows where \ will be translated into /)
func Split(remote string) (parent string, leaf string, err error) {
remoteName, remotePath, err := Parse(remote)
if err != nil {
return "", "", err
}
if remoteName != "" {
remoteName += ":"
}
// Construct new remote name without last segment
parent, leaf = path.Split(remotePath)
return remoteName + parent, leaf, nil
}
// JoinRootPath joins any number of path elements into a single path, adding a
// separating slash if necessary. The result is Cleaned; in particular,
// all empty strings are ignored.
// If the first non empty element has a leading "//" this is preserved.
func JoinRootPath(elem ...string) string {
for i, e := range elem {
if e != "" {
if strings.HasPrefix(e, "//") {
return "/" + path.Clean(strings.Join(elem[i:], "/"))
}
return path.Clean(strings.Join(elem[i:], "/"))
}
}
return ""
}