destroy added

kernel/syscall/skeleton.cc

@@ -49,23 +49,38 @@ bool sem_init(Vault &vault, size_t id, uint32_t value) {
   if (id >= vault.MAX_SEMS) {
     return false;             // out‐of‐range id
   }
+  if (vault.sems[id].used==1){
+    return false;  //already in use
+  }
+
   vault.sems[id].counter=value;
 	return true;
 }
 
-void sem_destroy(Vault &vault, size_t id) {
-	(void)vault;
-	(void)id;
+bool sem_destroy(Vault &vault, size_t id) {
+  if (id >= vault.MAX_SEMS) {
+    return false;             // out‐of‐range id
+  }
+  if (vault.sems[id].used==0){
+    return false;  //already in free
+  }
+
+  vault.sems[id].used=0;
+  vault.sems[id].counter=0;
+	return true;
 }
 
-void sem_signal(Vault &vault, size_t id) {
+bool sem_signal(Vault &vault, size_t id) {
 	(void)vault;
 	(void)id;
+
+  return true;
 }
 
-void sem_wait(Vault &vault, size_t id) {
+bool sem_wait(Vault &vault, size_t id) {
 	(void)vault;
 	(void)id;
+  return true;
 }
 
 void exit(Vault &vault) { (void)vault; }