Enrico Fraccaroli (Galfurian)
69 lines
1.4 KiB
C
69 lines
1.4 KiB
C
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/ipc.h>
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#include <sys/sem.h>
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#include <sys/shm.h>
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#include <sys/unistd.h>
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#include <sys/wait.h>
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#define MEM_SIZE sizeof(int) * 2
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int main(void)
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{
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int shmid;
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pid_t cpid;
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int *array;
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// Create shared memory.
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shmid = shmget(IPC_PRIVATE, MEM_SIZE, IPC_CREAT | 0600);
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if (shmid == -1) {
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perror("shmget");
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return EXIT_FAILURE;
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}
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printf("shmid = %d;\n", shmid);
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// Create a child.
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cpid = fork();
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if (cpid == 0) {
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// Child attaches the shared memory.
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array = (int *)shmat(shmid, NULL, 0);
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if (array == NULL) {
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perror("shmat");
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return EXIT_FAILURE;
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}
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printf("C: %p\n", array);
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array[0] = 1;
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return 0;
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}
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// Father attaches the shared memory.
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array = (int *)shmat(shmid, NULL, 0);
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if (array == NULL) {
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perror("shmat");
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return EXIT_FAILURE;
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}
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// Wait for the child to finish.
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while (wait(NULL) != -1) continue;
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printf("F: %p\n", array);
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array[1] = 2;
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printf("array[%d] : %d\n", 0, array[0]);
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printf("array[%d] : %d\n", 1, array[1]);
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// Detatch the shared memory.
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if (shmdt(array) < 0) {
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perror("shmdt");
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return EXIT_FAILURE;
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}
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// Remove the shared memory.
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if (shmctl(shmid, IPC_RMID, NULL) == -1) {
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perror("shmctl");
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return EXIT_FAILURE;
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}
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return EXIT_SUCCESS;
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}
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