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#include <assert.h>
#include <pthread.h>
#include <semaphore.h>
#include <stdbool.h>
#include <stdlib.h>
pthread_t start_worker_thread(void *(*start_routine)(void *))
{
pthread_t worker_thread;
const pthread_attr_t *const attributes = NULL;
void *const worker_argument = NULL;
const int create_status =
pthread_create(&worker_thread, attributes, start_routine, worker_argument);
assert(create_status == 0);
return worker_thread;
}
void join_thread(const pthread_t thread)
{
const int join_status = pthread_join(thread, NULL);
assert(join_status == 0);
}
sem_t create_semaphore(int initial_value)
{
const int shared_between_processes = false;
sem_t semaphore;
const int init_error =
sem_init(&semaphore, shared_between_processes, initial_value);
assert(init_error == false);
return semaphore;
}
void destroy_semaphore(sem_t *const semaphore)
{
int destroy_error = sem_destroy(semaphore);
assert(destroy_error == false);
}
sem_t global_semaphore;
int global_value;
void *worker(void *arguments)
{
const int wait_error = sem_wait(&global_semaphore);
assert(wait_error == false);
assert(global_value == 42);
pthread_exit(NULL);
}
int main(void)
{
global_semaphore = create_semaphore(0);
global_value = 0;
const pthread_t worker_thread1 = start_worker_thread(&worker);
global_value = 42;
const int post_error = sem_post(&global_semaphore);
assert(post_error == false);
join_thread(worker_thread1);
destroy_semaphore(&global_semaphore);
return EXIT_SUCCESS;
}
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