> library(survival)
> time = c(10, 15, 23, 30, 35, 52, 100)
> dead = c(1, 1, 1, 1, 1, 1, 0)
> fit = survfit(Surv(time, dead) ~ 1)
> print(fit, print.rmean=TRUE)
Call: survfit(formula = Surv(time, dead) ~ 1)

records      n.max    n.start     events     *rmean *se(rmean)     median    0.95LCL    0.95UCL
7.0        7.0        7.0        6.0       37.9       10.7       30.0       15.0         NA
* restricted mean with upper limit =  100

|    no. of  restricted
|  subjects        mean      Std. Err.    [95% Conf. Interval]
-------------+-------------------------------------------------------------
  total |         7    37.85714(*)   10.73888      16.8093     58.905

(*) largest observed analysis time is censored, mean is underestimated

fit.table = summary(fit, rmean=TRUE)$table # or, preferably, rmean=100
rmean = fit.table[["*rmean"]]                               # Estimate restricted mean
rmean.se = fit.table[["*se(rmean)"]]                        # Estimated standard error
rmean + c(-1,1) * qnorm(.05/2, lower.tail=FALSE) * rmean.se # 95% CI
[1] 16.80932 58.90497