South African President P.W. Botha on Friday was recovering from a stroke, his office said, but a newspaper reported the South African leader will need at least a month of rest before he can return to work. Botha on Thursday named Constitutional Development Minister Chris Heunis, the senior-ranking Cabinet member and a longtime ally, as acting president. "Everything is normal and under control," Heunis said Thursday, promising that "no government functions will be interrupted." No one has indicated how long Heunis is likely to serve as acting president.