feat: 2106 misc

labs/cs2106/lectures/l5/1.c

@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/shm.h>
+
+int main() {
+    int shmid, *shm;
+
+    shmid = shmget(IPC_PRIVATE, 4, IPC_CREAT | 0600);
+
+    if (shmid == -1) {
+        printf("Cannot create shared memory!\n");
+        exit(1);
+    } else {
+        printf("Shared memory ID = %d\n", shmid);
+    }
+    shm = (int*) shmat(shmid, NULL, 0);
+    if (shm == (int*) -1) {
+        printf("Cannot attach shared memory!\n");
+        exit(1);
+    }
+    shm[0] = 0;
+    while(shm[0] == 0) {
+        sleep(3);
+    }
+    for(int i = 0; i < 3; i++) {
+        printf("Read %d from shared memory. \n", shm[i+1]);
+    }
+    shmdt((char*) shm);
+    shmctl(shmid, IPC_RMID, 0);
+}
+

labs/cs2106/lectures/l5/2.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/shm.h>
+
+int main() {
+    int shmid, input, *shm;
+  printf("Shared memory id: ");
+  scanf("%d", &shmid);
+
+  shm = (int*) shmat(shmid, NULL, 0);
+  if (shm == (int*) -1) {
+    printf("Error: Cannot attach!\n");
+    exit(1);
+  }
+
+  for(int i = 0; i < 3; i++) {
+    scanf("%d", &input);
+    shm[i+1] = input;
+  }
+  shm[0] = 1;
+
+  shmdt((char*) shm);
+  return 0;
+
+}

labs/cs2106/lectures/l5/3.c

@@ -0,0 +1,24 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#define READ_END 0
+#define WRITE_END 1
+
+int main() {
+  int pipeFd[2], pid, len;
+
+  char buf[100], *str = "Hello There!";
+
+  pipe(pipeFd);
+
+  if ((pid = fork()) > 0) {
+    close(pipeFd[READ_END]);
+    write(pipeFd[WRITE_END], str, strlen(str) +1);
+    close(pipeFd[WRITE_END]);
+  } else {
+    close(pipeFd[WRITE_END]);
+    len = read(pipeFd[READ_END], buf, sizeof(buf));
+    printf("Proc %d read: %s\n", pid, buf);
+    close(pipeFd[READ_END]);
+  }
+}

labs/cs2106/lectures/l5/4.c

@@ -0,0 +1,21 @@
+#include <stdio.h>
+#include <signal.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+void myOwnHandler(int signo) {
+  if (signo == SIGSEGV) {
+    printf("Memory Access blows up!\n");
+    exit(1);
+  }
+}
+
+int main() {
+  int *ip = NULL;
+
+  if (signal(SIGSEGV, myOwnHandler) == SIG_ERR) 
+    printf("Failed to register handler\n");
+
+  *ip = 123;
+  return 0;
+}