github.com/afumu/libc@v0.0.6/musl/src/unistd/alarm.c (about)

     1  #include <unistd.h>
     2  #include <sys/time.h>
     3  #include "syscall.h"
     4  
     5  unsigned alarm(unsigned seconds)
     6  {
     7  	struct itimerval it = { .it_value.tv_sec = seconds }, old = { 0 };
     8  	setitimer(ITIMER_REAL, &it, &old);
     9  	return old.it_value.tv_sec + !!old.it_value.tv_usec;
    10  }