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#include <iostream>
#include <cerrno>
#include <cstring>
#include <pthread.h>
#include <semaphore.h>
struct FailedOn
{
FailedOn(const char *f, int e) : func(f), eno(e) {}
std::string func;
int eno;
};
int main(void)
{
try {
sem_t mySemaphore;
if (sem_init(&mySemaphore, 0, 0) != 0)
throw FailedOn("sem_init", errno);
std::cerr << "Calling sem_trywait\n";
if (sem_trywait(&mySemaphore) != 0) {
if (errno != EAGAIN)
throw FailedOn("sem_trywait", errno);
std::cerr << "Wait would have blocked" << std::endl;
} else {
std::cerr << "Wait succeeded" << std::endl;
}
if (sem_destroy(&mySemaphore) != 0)
throw FailedOn("sem_destroy", errno);
return 0;
} catch (FailedOn &e) {
std::cerr << e.func << " failed: " << strerror(e.eno) << std::endl;
} catch (...) {
std::cerr << "Unknown exception" << std::endl;
}
return -1;
}
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