1 #include <iostream> 2 #include <cerrno> 3 #include <cstring> 4 #include <pthread.h> 5 #include <semaphore.h> 6 7 struct FailedOn 8 { 9 FailedOn(const char *f, int e) : func(f), eno(e) {} 10 std::string func; 11 int eno; 12 }; 13 14 int main(void) 15 { 16 try { 17 sem_t mySemaphore; 18 if (sem_init(&mySemaphore, 0, 0) != 0) 19 throw FailedOn("sem_init", errno); 20 21 std::cerr << "Calling sem_trywait\n"; 22 if (sem_trywait(&mySemaphore) != 0) { 23 if (errno != EAGAIN) 24 throw FailedOn("sem_trywait", errno); 25 26 std::cerr << "Wait would have blocked" << std::endl; 27 } else { 28 std::cerr << "Wait succeeded" << std::endl; 29 } 30 31 if (sem_destroy(&mySemaphore) != 0) 32 throw FailedOn("sem_destroy", errno); 33 34 return 0; 35 } catch (FailedOn &e) { 36 std::cerr << e.func << " failed: " << strerror(e.eno) << std::endl; 37 } catch (...) { 38 std::cerr << "Unknown exception" << std::endl; 39 } 40 41 return -1; 42 } 43
