struct itimerspec as timer_create's parameter invalid argument - c

Question

I was trying POSIX timers togheter with POSIX signals handling.
When I try to excecute the code you can find downhere, I get:
Errore timer_settime: Invalid argument
On GAPIL book, that is based upon Advanced Linux Programming and Unix network programming, I read that this can happen when inside new_value.value you specified a negative time value or a number of nanoseconds higher than 999999999.
But I think that parameters I have used are okay...
#include <string.h>
#include <stdio.h>
#include <fcntl.h>
#include <time.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/fcntl.h>
#include <sys/wait.h>
#include <stdbool.h>
void termination_handler(int signum)
{
printf("Timer scaduto\n");
}
int main()
{
timer_t timer1;
struct sigevent sigeventStruct;
sigeventStruct.sigev_notify = SIGEV_SIGNAL;
sigeventStruct.sigev_signo = 10;
if(timer_create(_POSIX_MONOTONIC_CLOCK, &sigeventStruct, &timer1) == -1)
{
printf( "Errore timer_create: %s\n", strerror( errno ) );
}
printf("timer_create eseguito\n");
struct itimerspec tempoIniziale;
tempoIniziale.it_value.tv_nsec = 0;
struct itimerspec tempoFinale;
tempoFinale.it_value.tv_nsec = 10000000;
if(timer_settime(timer1, 0, &tempoIniziale, &tempoFinale) == -1)
{
printf( "Errore timer_settime: %s\n", strerror( errno ) );
}
struct sigaction newSigAzione, oldSigAzione;
newSigAzione.sa_handler = termination_handler;
//oldSigAzione.sa_handler = termination_handler;
sigemptyset (&newSigAzione.sa_mask);
newSigAzione.sa_flags = 0;
sigaction (SIGEV_SIGNAL, NULL, &oldSigAzione);
if(oldSigAzione.sa_handler != SIG_IGN)
{
//sigaction (SIGEV_SIGNAL, newSigAzione, NULL);
}
/*sigaction (SIGINT, NULL, &oldSigAzione);
if (oldSigAzione.sa_handler != SIG_IGN)
sigaction (SIGINT, &newSigAzione, NULL);
sigaction (SIGHUP, NULL, &oldSigAzione);
if (oldSigAzione.sa_handler != SIG_IGN)
sigaction (SIGHUP, &newSigAzione, NULL);
sigaction (SIGTERM, NULL, &oldSigAzione);
if (oldSigAzione.sa_handler != SIG_IGN)
sigaction (SIGTERM, &newSigAzione, NULL);*/
/*sigaction (SIGTERM, &newSigAzione, NULL);*/
return 0;
}

Answer 1

_POSIX_MONOTONIC_CLOCK is a feature test macro that tells you whether monotonic clocks are available on the system.
The available clock ids you can pass to timer_create() on Linux are:
CLOCK_REALTIME
System-wide realtime clock. Setting this clock requires appropriate privileges.
CLOCK_MONOTONIC
Clock that cannot be set and represents monotonic time since some unspecified starting point.
CLOCK_PROCESS_CPUTIME_ID
High-resolution per-process timer from the CPU.
CLOCK_THREAD_CPUTIME_ID
Thread-specific CPU-time clock.
You must also initialize all the members in struct sigevent and struct itimerspec.
E.g. you don't set .tv_sec in the structitimer_spec, only .tv_nsec , which results in garbage values in those members.
...
memset(&sigeventStruct, 0, sizeof sigeventStruct);
...
and
struct itimerspec tempoFinale;
memset(&tempoFinale, 0, sizeof tempoFinale);
tempoFinale.it_value.tv_nsec = 10000000;