return
	}

	if r.ContentLength <= 0 {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrEmptyRequestBody), r.URL)
		return
	}

	// Take read lock on object, here so subsequent lower-level
	// calls do not need to.
	lock := objectAPI.NewNSLock(bucket, object)
	lkctx, err := lock.GetRLock(ctx, globalOperationTimeout)
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)

            <ul>
            <li>{@code length(string)}: Returns the length of the given string.</li>
            <li>{@code upper(string)}: Converts the string to uppercase.</li>
            <li>{@code lower(string)}: Converts the string to lowercase.</li>
            <li>{@code substring(string, start, [end])}: Returns a substring of the given string.</li>