// Due to undefined behavior with multiple processes and shm, I'm using four independent shm's at the same time
void synchro_logic(const char* my_shm_name, const char* other_shm_name, int number_offset, int times) {
sem_t * my_semdes = SEM_FAILED;
sem_t * other_semdes = SEM_FAILED;
FILE* pts = fopen(PTS_NAME, "w");
my_sem_create((char*)my_shm_name, &my_semdes);
while(my_sem_open((char*)other_shm_name, &other_semdes) != 0) {
usleep(500000);
}
my_sem_wait(&my_semdes);
if (number_offset > 1) {
my_sem_wait(&my_semdes);
}
for(int count = 0; count < times; count++) {
fprintf(pts, "Program %i: Number %i\n", number_offset, (4 * count) + number_offset);
my_sem_post(&other_semdes);
if(count < times - 1) {
my_sem_wait(&my_semdes);
}
}
my_sem_post(&my_semdes);
my_sem_close(&my_semdes);
my_sem_close(&other_semdes);
sem_unlink((char*)my_shm_name);
fclose(pts);
printf("Program %i: Exit\n", number_offset);
}
int main ( void )
{
int r;
pthread_t my_rescuer, grabber;
r= pthread_mutex_init(&mx[0], NULL);
assert(!r);
r= pthread_mutex_init(&mx[1], NULL);
assert(!r);
r= pthread_mutex_init(&mx[2], NULL);
assert(!r);
r= pthread_mutex_init(&mx[3], NULL);
assert(!r);
r= pthread_cond_init(&cv, NULL);
assert(!r);
r= pthread_rwlock_init(&rwl, NULL);
assert(!r);
quit_now = my_sem_init( "quit_now", 0,0 );
assert(quit_now);
r= pthread_create( &grabber, NULL, grab_the_lock, NULL );
assert(!r);
sleep(1); /* let the grabber get there first */
r= pthread_create( &my_rescuer, NULL, rescue_me, NULL );
assert(!r);
/* Do stupid things and hope that rescue_me gets us out of
trouble */
/* mx is bogus */
r= pthread_cond_wait(&cv, (pthread_mutex_t*)(1 + (char*)&mx[0]) );
/* mx is not locked */
r= pthread_cond_wait(&cv, &mx[0]);
/* wrong flavour of lock */
r= pthread_cond_wait(&cv, (pthread_mutex_t*)&rwl );
/* mx is held by someone else. */
r= pthread_cond_wait(&cv, &mx[2] );
r= my_sem_post( quit_now );
assert(!r);
r= my_sem_post( quit_now );
assert(!r);
r= pthread_join( my_rescuer, NULL );
assert(!r);
r= pthread_join( grabber, NULL );
assert(!r);
r= my_sem_destroy( quit_now );
assert(!r);
return 0;
}
int main (int argc, char *argv[])
{
int write_character = -1;
g_prog_mode = PRG_SENDER_MODE;
/*check parameters */
if ((buffer_size = get_buffer_size(argc, argv)) == RETURN_ERROR)
{
return EXIT_FAILURE;
}
/*create semaphore and ringbuffer*/
if (create_environment() == RETURN_ERROR)
{
return EXIT_FAILURE;
}
/*write ringbuffer*/
do
{
/*read stdin input*/
write_character = fgetc(stdin);
/*decrement semaphore*/
if (my_sem_wait() == RETURN_ERROR)
{
return EXIT_FAILURE;
}
/*write ringbuffer*/
write_char_to_buffer(write_character);
/*increment semaphore*/
if (my_sem_post() == RETURN_ERROR)
{
return EXIT_FAILURE;
}
} while (write_character != EOF);
/*check for errors in input of stdin*/
if (ferror(stdin))
{
fprintf(stderr, "%s: %s%s\n", g_program_name, "Error while reading input from \"stdin\".", strerror(errno));
destroy_environment(PRG_ERROR);
return EXIT_FAILURE;
}
/*destroy semaphore and ringbuffer*/
if (destroy_environment(PRG_SUCCESS) == RETURN_ERROR)
{
return EXIT_FAILURE;
}
else
{
return EXIT_SUCCESS;
}
}
void *down(void *ptr)
{
int i;
for (i = 0; i < TOTAL_RUNS; i++)
{
my_sem_wait();
x--;
my_sem_post();
}
printf("Finished subtracting 1 a total of %d times.\n", TOTAL_RUNS);
}
void *up(void *ptr)
{
int i;
for (i = 0; i < TOTAL_RUNS; i++)
{
my_sem_wait();
x++;
my_sem_post();
}
printf("Finished adding 1 a total of %d times.\n", TOTAL_RUNS);
}
