A 50 year-old chronic alcoholic male patient, after a large binge of alcohol, presented to the emergency depament in subconscious state. He vomited several times, few of them mixed with blood. He had a history of hea burn and dyspeptic symptoms for past few tears. On physical exam, he had a temperature of 102degF, a pulse of 110, respiratory rate of 20 per minute and a blood pressure of 90/60. On physical examination there was abdominal guarding and tenderness. A plane erect chest X-ray reveals air under diaphragm. Probable diagnosis is