81 lines
1.6 KiB
C
81 lines
1.6 KiB
C
#include <pthread.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdio.h>
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pthread_mutex_t lock1 = PTHREAD_MUTEX_INITIALIZER;
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pthread_mutex_t lock2 = PTHREAD_MUTEX_INITIALIZER;
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void prepare(void) {
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int err;
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printf("preparing locks...\n");
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if((err = pthread_mutex_lock(&lock1) != 0)) {
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printf("mutex lock error\n");
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}
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if((err = pthread_mutex_lock(&lock2)) != 0) {
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printf("mutex lock error\n");
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}
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}
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void parent(void) {
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int err;
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printf("parent unlocking locks...\n");
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if((err = pthread_mutex_unlock(&lock1)) != 0)
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printf("mutex unlock error\n");
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if((err = pthread_mutex_unlock(&lock2)) != 0)
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printf("mutex unlock error\n");
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}
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void child(void) {
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int err;
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printf("child unlocking locks...\n");
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if((err = pthread_mutex_unlock(&lock1)) != 0)
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printf("mutex unlock error\n");
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if((err = pthread_mutex_unlock(&lock2)) != 0)
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printf("mutex unlock error\n");
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}
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void * thr_fn(void *arg) {
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printf("thread started...\n");
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pause();
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return 0;
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}
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int main(void) {
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int err;
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pid_t pid;
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pthread_t tid;
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if((err = pthread_atfork(prepare, parent, child)) != 0) {
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printf("install fork handlers error\n");
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return -1;
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}
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if((err = pthread_create(&tid, NULL, thr_fn, 0)) != 0) {
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printf("create thread error\n");
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return -1;
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}
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sleep(2);
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printf("parent about to fork...\n");
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if((pid = fork()) < 0) {
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printf("fork failed\n");
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return -1;
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}
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else if (pid == 0) {
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printf("child return from fork\n");
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return 0;
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}
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else {
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printf("parent return from fork\n");
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return 0;
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}
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return 0;
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}
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