100 lines
2.7 KiB
C
100 lines
2.7 KiB
C
#include <stdio.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <string.h>
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#include <pthread.h>
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#include <time.h>
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#include <signal.h>
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#include <semaphore.h>
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#include <errno.h>
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enum events{
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EVENT_VICTIM_THREAD_READY,
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EVENT_PRINT_BUFFER_UPDATED,
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EVENTS_NR
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};
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enum threads_roles {
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ROLE_VICTIM,
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ROLE_KILLER,
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ROLE_PRINTER,
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ROLES_NR
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};
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#define ERR_PTR(ret) ((void*)(long)ret)
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#define PRINTER_TIMEOUT_SECS 2
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#define PRINT_BUFF_SIZE 256
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static sem_t sems[EVENTS_NR];
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static pthread_t threads[ROLES_NR];
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static char print_buffer[PRINT_BUFF_SIZE];
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static volatile bool run = true;
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void sig_handler(int signal)
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{
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snprintf(print_buffer, PRINT_BUFF_SIZE, "signal %d recieved", signal);
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pthread_exit(ERR_PTR(sem_post(&sems[EVENT_PRINT_BUFFER_UPDATED])));
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}
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void *killer_thread(void* _)
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{
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sigset_t ss;
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sigemptyset(&ss);
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sigaddset(&ss, SIGUSR1);
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if (pthread_sigmask(SIG_BLOCK, &ss, NULL))
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pthread_exit(ERR_PTR(-EFAULT));
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int ret = sem_wait(&sems[EVENT_VICTIM_THREAD_READY]);
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if (ret) pthread_exit(ERR_PTR(ret));
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pthread_exit(ERR_PTR(pthread_kill(threads[ROLE_VICTIM], SIGUSR1)));
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}
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void *victim_thread(void* _)
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{
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int ret = sem_post(&sems[EVENT_VICTIM_THREAD_READY]);
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if (ret) pthread_exit(ERR_PTR(ret));
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volatile int x = 0; // for compiler not to optimize infinite loop
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while (run) {
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x++;
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}
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pthread_exit(NULL);
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}
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void *printer_thread(void* _)
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{
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sigset_t ss;
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sigemptyset(&ss);
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sigaddset(&ss, SIGUSR1);
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if (pthread_sigmask(SIG_BLOCK, &ss, NULL)) pthread_exit(ERR_PTR(-EFAULT));
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while (run) {
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struct timespec ts = {0};
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int ret = timespec_get(&ts, TIME_UTC);
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if (ret != TIME_UTC) pthread_exit(ERR_PTR(-EFAULT));
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ts.tv_sec += PRINTER_TIMEOUT_SECS;
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if (sem_timedwait(&sems[EVENT_PRINT_BUFFER_UPDATED], &ts))
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pthread_exit(ERR_PTR(-EFAULT));
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puts(print_buffer);
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memset(print_buffer, 0, PRINT_BUFF_SIZE);
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}
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pthread_exit(NULL);
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}
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#define DO_OR_FAIL(cond) if (cond) return EXIT_FAILURE
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int main()
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{
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struct sigaction sa = {
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.sa_handler = sig_handler,
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};
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DO_OR_FAIL(sigaction(SIGUSR1, &sa, NULL));
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DO_OR_FAIL(sem_init(&sems[EVENT_VICTIM_THREAD_READY], 0, 0));
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DO_OR_FAIL(sem_init(&sems[EVENT_PRINT_BUFFER_UPDATED], 0, 0));
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DO_OR_FAIL(pthread_create(&threads[ROLE_KILLER], NULL, killer_thread, NULL));
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DO_OR_FAIL(pthread_create(&threads[ROLE_PRINTER], NULL, printer_thread, NULL));
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DO_OR_FAIL(pthread_create(&threads[ROLE_VICTIM], NULL, victim_thread, NULL));
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for (size_t i = 0; i < ROLES_NR; i++) {
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DO_OR_FAIL(pthread_join(threads[i], NULL));
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}
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return EXIT_SUCCESS;
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}
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