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#include <sys/types.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <signal.h>
#include <errno.h>
#include <time.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
typedef struct Timer Timer;
struct Timer {
int pid, signal;
struct itimerval itimer;
};
Timer timers[3] = {
{0, SIGALRM},
{0, SIGVTALRM},
{0, SIGPROF},
};
void
timerloop(Timer *timer, const struct timeval tval)
{
pid_t ppid;
struct timespec t, s;
ppid = getppid();
t.tv_sec = tval.tv_sec;
t.tv_nsec = tval.tv_usec*1000;
for(;;){
nanosleep(&t, &s);
kill(ppid, timer->signal);
}
}
int
setitimer(int which, const struct itimerval *new, struct itimerval *curr)
{
pid_t pid;
int status;
Timer *timer;
if(which < 0 || which >= 3){
errno = EINVAL;
return -1;
}
timer = timers+which;
if(timer->pid != 0){
kill(timer->pid, SIGKILL);
waitpid(timer->pid, &status, 0);
}
switch(pid = fork()){
default:
timer->pid = pid;
if(curr != NULL)
*curr = timer->itimer;
timer->itimer = *new;
break;
case -1:
errno = EFAULT;
return -1;
case 0:
timerloop(timer, new->it_interval);
exit(0);
}
return 0;
}
int
getitimer(int which, struct itimerval *curr)
{
Timer *timer;
if(which < 0 || which >= 3){
errno = EINVAL;
return -1;
}
timer = timers+which;
*curr = timer->itimer;
return 0;
}
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