package filesystem import ( "fmt" "os" "path/filepath" "emperror.dev/errors" "github.com/apex/log" ) type ErrorCode string const ( ErrCodeIsDirectory ErrorCode = "E_ISDIR" ErrCodeDiskSpace ErrorCode = "E_NODISK" ErrCodeUnknownArchive ErrorCode = "E_UNKNFMT" ErrCodePathResolution ErrorCode = "E_BADPATH" ErrCodeDenylistFile ErrorCode = "E_DENYLIST" ErrCodeUnknownError ErrorCode = "E_UNKNOWN" ) type Error struct { code ErrorCode // Contains the underlying error leading to this. This value may or may not be // present, it is entirely dependent on how this error was triggered. err error // This contains the value of the final destination that triggered this specific // error event. resolved string // This value is generally only present on errors stemming from a path resolution // error. For everything else you should be setting and reading the resolved path // value which will be far more useful. path string } // newFilesystemError returns a new error instance with a stack trace associated. func newFilesystemError(code ErrorCode, err error) error { if err != nil { return errors.WithStackDepth(&Error{code: code, err: err}, 1) } return errors.WithStackDepth(&Error{code: code}, 1) } // Code returns the ErrorCode for this specific error instance. func (e *Error) Code() ErrorCode { return e.code } // Returns a human-readable error string to identify the Error by. func (e *Error) Error() string { switch e.code { case ErrCodeIsDirectory: return fmt.Sprintf("filesystem: cannot perform action: [%s] is a directory", e.resolved) case ErrCodeDiskSpace: return "filesystem: not enough disk space" case ErrCodeUnknownArchive: return "filesystem: unknown archive format" case ErrCodeDenylistFile: r := e.resolved if r == "" { r = "" } return fmt.Sprintf("filesystem: file access prohibited: [%s] is on the denylist", r) case ErrCodePathResolution: r := e.resolved if r == "" { r = "" } return fmt.Sprintf("filesystem: server path [%s] resolves to a location outside the server root: %s", e.path, r) case ErrCodeUnknownError: fallthrough default: return fmt.Sprintf("filesystem: an error occurred: %s", e.Unwrap()) } } // Unwrap returns the underlying cause of this filesystem error. In some causes // there may not be a cause present, in which case nil will be returned. func (e *Error) Unwrap() error { return e.err } // Generates an error logger instance with some basic information. func (fs *Filesystem) error(err error) *log.Entry { return log.WithField("subsystem", "filesystem").WithField("root", fs.root).WithField("error", err) } // Handle errors encountered when walking through directories. // // If there is a path resolution error just skip the item entirely. Only return this for a // directory, otherwise return nil. Returning this error for a file will stop the walking // for the remainder of the directory. This is assuming an os.FileInfo struct was even returned. func (fs *Filesystem) handleWalkerError(err error, f os.FileInfo) error { if !IsErrorCode(err, ErrCodePathResolution) { return err } if f != nil && f.IsDir() { return filepath.SkipDir } return nil } // IsFilesystemError checks if the given error is one of the Filesystem errors. func IsFilesystemError(err error) bool { var fserr *Error if err != nil && errors.As(err, &fserr) { return true } return false } // IsErrorCode checks if "err" is a filesystem Error type. If so, it will then // drop in and check that the error code is the same as the provided ErrorCode // passed in "code". func IsErrorCode(err error, code ErrorCode) bool { var fserr *Error if err != nil && errors.As(err, &fserr) { return fserr.code == code } return false } // NewBadPathResolution returns a new BadPathResolution error. func NewBadPathResolution(path string, resolved string) error { return errors.WithStackDepth(&Error{code: ErrCodePathResolution, path: path, resolved: resolved}, 1) } // wrapError wraps the provided error as a Filesystem error and attaches the // provided resolved source to it. If the error is already a Filesystem error // no action is taken. func wrapError(err error, resolved string) error { if err == nil || IsFilesystemError(err) { return err } return errors.WithStackDepth(&Error{code: ErrCodeUnknownError, err: err, resolved: resolved}, 1) }