UNIX/OSX version of semtimedop
You can break out of a semop() call (and most other blocking calls) by getting a signal, such as one caused by alarm().
untested example:
#include <signal.h>#include <stdio.h>#include <sys/types.h>#include <sys/ipc.h>#include <sys/sem.h>volatile int alarm_triggered = 0;void alarm_handler(int sig){ alarm_triggered = 1;}int main(int argc, char **argv){ int rc; /* set up signal handler */ signal(SIGALRM, alarm_handler); /* ... */ alarm(30); /* 30 second timeout */ rc = semop(...); if (rc == -1 && errno == EINTR) { if (alarm_triggered) { /* timed out! */ } } alarm(0); /* disable alarm */ /* ... */}