Added Task-8-1

Task-8/task_8_1.c

@@ -0,0 +1,65 @@
+// man ftruncate
+
+// pass any message between two processes using shared memory
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+int main(int argc, char *argv[]) {
+
+    const char *memory_name = "/memory";
+    char message[] = "Hello there";
+
+    int fd = shm_open(memory_name, O_CREAT | O_RDWR, 0777);
+    if (fd < 0) {
+        fprintf(stderr, "shm_open: ");
+        exit(EXIT_FAILURE);
+    }
+    printf("Shred memory file descriptor: %d\n", fd);
+
+    if (ftruncate(fd, sizeof(message)) < 0) {
+        fprintf(stderr, "ftruncate: \n");
+        exit(EXIT_FAILURE);
+    }
+
+
+    pid_t pid;
+
+    pid = fork();
+    if (pid == -1) {
+        perror("fork: ");
+        exit(EXIT_FAILURE);
+    }
+    if (pid == 0) {
+        char *addr = mmap(NULL, sizeof(message), PROT_READ, MAP_SHARED, fd, 0);
+        printf("Value: %s\n", addr);
+        if (addr == MAP_FAILED) {
+            fprintf(stderr, "mmap: ");
+            exit(EXIT_FAILURE);
+        }
+        exit(EXIT_SUCCESS);
+    }
+
+    char *addr = mmap(NULL, sizeof(message), PROT_WRITE, MAP_SHARED, fd, 0);
+    if (addr == MAP_FAILED) {
+        fprintf(stderr, "mmap: ");
+        exit(EXIT_FAILURE);
+    }
+    strcpy(addr, message);
+
+    shm_unlink(memory_name);
+
+    int status;
+    wait(&status);
+
+    munmap(addr, sizeof(message));
+
+    return 0;
+}