Thread Synchronization-2

#include <stdio.h>#include <unistd.h>#include <stdlib.h>#include <string.h>#include <pthread.h>#include <semaphore.h>void *thread_function(void *arg);pthread_mutex_t work_mutex;#define WORK_SIZE 1024char work_area[WORK_SIZE];int time_to_exit = 0;int main() {int res;pthread_t a_thread;void *thread_result;res = pthread_mutex_init(&work_mutex, NULL);if(res != 0) {perror("Mutex initialization failed");exit(EXIT_FAILURE);}res = pthread_create(&a_thread, NULL, thread_function, NULL);if(res != 0) {perror("Thread creation failed");exit(EXIT_FAILURE);}pthread_mutex_lock(&work_mutex);printf("Input some text. Enter 'end' to finish\n");while(!time_to_exit) {fgets(work_area, WORK_SIZE, stdin);pthread_mutex_unlock(&work_mutex);while(1) {pthread_mutex_lock(&work_mutex);if(work_area[0] != '\0') {pthread_mutex_unlock(&work_mutex);sleep(1);} else {break;}}}pthread_mutex_unlock(&work_mutex);printf("\nWaiting for thread to finish....\n");res = pthread_join(a_thread, &thread_result);if(res != 0) {perror("Thread join failed");exit(EXIT_FAILURE);}printf("Thread join\n");pthread_mutex_destroy(&work_mutex);exit(EXIT_SUCCESS);}void *thread_function(void *arg) {sleep(1);pthread_mutex_lock(&work_mutex);while(strncmp("end", work_area, 3) != 0) {printf("You input %d characters\n", strlen(work_area) - 1);work_area[0] = '\0';pthread_mutex_unlock(&work_mutex);sleep(1);pthread_mutex_lock(&work_mutex);while(work_area[0] == '\0') {pthread_mutex_unlock(&work_mutex);sleep(1);pthread_mutex_lock(&work_mutex);}}time_to_exit = 1;work_area[0] = '\0';pthread_mutex_unlock(&work_mutex);pthread_exit(0);}