First rough implementation of shared memory.

programs/tests/t_shmget.c

@@ -0,0 +1,60 @@
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ipc.h>
+#include <sys/sem.h>
+#include <sys/shm.h>
+#include <sys/unistd.h>
+#include <sys/wait.h>
+
+#define MEM_SIZE sizeof(int) * 2
+
+int main(void)
+{
+    int semid, shmid;
+    pid_t cpid;
+    int *array;
+
+    // Create shared memory.
+    shmid = shmget(IPC_PRIVATE, MEM_SIZE, IPC_CREAT | 0600);
+    if (shmid == -1) {
+        perror("shmget");
+        return EXIT_FAILURE;
+    }
+    // Create a semaphore set containing one semaphore.
+    semid = semget(IPC_PRIVATE, 1, IPC_CREAT | 0600);
+    if (semid == -1) {
+        perror("semget");
+        return EXIT_FAILURE;
+    }
+
+    cpid = fork();
+
+    if (cpid == 0) {
+        array = (int *)shmat(shmid, NULL, 0);
+        printf("C: %p\n", array);
+        array[0] = 1;
+        return 0;
+    } else {
+        array = (int *)shmat(shmid, NULL, 0);
+        printf("F: %p\n", array);
+        array[1] = 2;
+    }
+
+    while (wait(NULL) != -1) continue;
+
+    printf("array[%d] : %d\n", 0, array[0]);
+    printf("array[%d] : %d\n", 1, array[1]);
+
+    // Remove the shared memory.
+    if (shmctl(shmid, IPC_RMID, NULL) == -1) {
+        perror("shmctl");
+        return EXIT_FAILURE;
+    }
+    // Remove the semaphore set.
+    if (semctl(semid, 0, IPC_RMID, NULL) == -1) {
+        perror("semctl");
+        return EXIT_FAILURE;
+    }
+    return EXIT_SUCCESS;
+}