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Create shared memory if we don't have it yet (#120)

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Wolfgang Hommel
2019-08-13 19:35:45 +02:00
parent aa091db286
commit 7498c405ed
1 changed files with 70 additions and 0 deletions
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70
src/libfaketime.c
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@@ -276,11 +276,81 @@ static void ftpl_init (void) __attribute__ ((constructor));
* =======================================================================
*/
static void ft_shm_create(void) {
char sem_name[256], shm_name[256];
int shm_fdN;
sem_t *semN;
struct ft_shared_s *ft_sharedN;
char shared_objsN[513];
snprintf(sem_name, 255, "/faketime_sem_%ld", (long)getpid());
snprintf(shm_name, 255, "/faketime_shm_%ld", (long)getpid());
if (SEM_FAILED == (semN = sem_open(sem_name, O_CREAT|O_EXCL, S_IWUSR|S_IRUSR, 1)))
{
perror("sem_open");
exit(EXIT_FAILURE);
}
/* create shm */
if (-1 == (shm_fdN = shm_open(shm_name, O_CREAT|O_EXCL|O_RDWR, S_IWUSR|S_IRUSR)))
{
perror("shm_open");
exit(EXIT_FAILURE);
}
/* set shm size */
if (-1 == ftruncate(shm_fdN, sizeof(uint64_t)))
{
perror("ftruncate");
exit(EXIT_FAILURE);
}
/* map shm */
if (MAP_FAILED == (ft_sharedN = mmap(NULL, sizeof(struct ft_shared_s), PROT_READ|PROT_WRITE,
MAP_SHARED, shm_fdN, 0)))
{
perror("mmap");
exit(EXIT_FAILURE);
}
if (sem_wait(semN) == -1)
{
perror("sem_wait");
exit(EXIT_FAILURE);
}
/* init elapsed time ticks to zero */
ft_sharedN->ticks = 0;
ft_sharedN->file_idx = 0;
ft_sharedN->start_time.real.tv_sec = 0;
ft_sharedN->start_time.real.tv_nsec = -1;
ft_sharedN->start_time.mon.tv_sec = 0;
ft_sharedN->start_time.mon.tv_nsec = -1;
ft_sharedN->start_time.mon_raw.tv_sec = 0;
ft_sharedN->start_time.mon_raw.tv_nsec = -1;
if (-1 == munmap(ft_sharedN, (sizeof(struct ft_shared_s))))
{
perror("munmap");
exit(EXIT_FAILURE);
}
if (sem_post(semN) == -1)
{
perror("semop");
exit(EXIT_FAILURE);
}
snprintf(shared_objsN, sizeof(shared_objsN), "%s %s", sem_name, shm_name);
setenv("FAKETIME_SHARED", shared_objsN, true);
sem_close(semN);
}
static void ft_shm_init (void)
{
int ticks_shm_fd;
char sem_name[256], shm_name[256], *ft_shared_env = getenv("FAKETIME_SHARED");
if (ft_shared_env == NULL)
{
ft_shm_create();
ft_shared_env = getenv("FAKETIME_SHARED");
}
if (ft_shared_env != NULL)
{
if (sscanf(ft_shared_env, "%255s %255s", sem_name, shm_name) < 2)