properly free memory

linked-list.c

@@ -63,12 +63,16 @@ void list_add(list_t * list, list_node_t * item) {
   }
 }
 
-void list_remove(list_t * list, list_node_t * item) {
+list_node_t * list_remove(list_t * list, list_node_t * item) {
   list_node_t *cur;
 
+  if (list_empty(list))
+    return NULL;
+
   if (list->head->data == item->data) {
+    list_node_t * removed = list->head;
     list->head = list->head->next;
-    return;
+    return removed;
   }
 
   cur = list->head;
@@ -76,14 +80,18 @@ void list_remove(list_t * list, list_node_t * item) {
 
   while (cur->next != NULL) {
     if (cur->next->data == item->data) {
+      list_node_t * removed = cur->next;
       cur->next = cur->next->next;
-      return;                   /* just the first */
+      return removed;                   /* just the first */
     }
     cur = cur->next;
   }
+
+  return NULL;
 }
 
 void list_revert(list_t *list) {
+  /* FIXME: work without 'reverted?' */
   list_t reverted;
   reverted.head = NULL;
 
@@ -101,8 +109,8 @@ void list_revert(list_t *list) {
   list->head = reverted.head;
 }
 
-list_node_t* list_elementat(list_t *list, int i) {
-  if (i > list_length(list)-1) {
+list_node_t* list_elementat(list_t *list, unsigned int i) {
+  if (list_empty(list) || i > list_length(list)-1) {
     return NULL;
   }
 
@@ -115,17 +123,28 @@ list_node_t* list_elementat(list_t *list, int i) {
 }
 
 int main(int argc, char *argv[]) {
+
+  /* Test empty list */
   list_t *emptylist = malloc(sizeof(list_t));
   list_init(emptylist);
   assert(list_length(emptylist) == 0);
   assert(list_empty(emptylist) == true);
   list_print(emptylist);
   printf("list_length = %d\n", list_length(emptylist));
+  assert(list_elementat(emptylist, 0) == NULL);
+  assert(list_elementat(emptylist, 1) == NULL);
+  assert(list_elementat(emptylist, 2) == NULL);
+  free(emptylist);
 
+  /* Setup foolist for the following tests. */
   list_t *foolist = malloc(sizeof(list_t));
   list_init(foolist);
-  list_node_t foo = { 1, NULL };
-  list_add(foolist, &foo);
+
+  /* Add one element */
+  list_node_t * foo = malloc(sizeof(list_node_t));
+  assert(foo != NULL);
+  *foo = (list_node_t) { 1, NULL };
+  list_add(foolist, foo);
 
   assert(list_length(foolist) == 1);
   assert(list_empty(foolist) == false);
@@ -133,8 +152,9 @@ int main(int argc, char *argv[]) {
   printf("list_length = %d\n", list_length(foolist));
 
   // append something to foo
-  list_node_t bar = { 2, NULL };
-  list_add(foolist, &bar);
+  list_node_t * bar = malloc(sizeof(list_node_t));
+  *bar = (list_node_t) { 23, NULL };
+  list_add(foolist, bar);
 
   assert(list_length(foolist) == 2);
   list_print(foolist);
@@ -144,8 +164,7 @@ int main(int argc, char *argv[]) {
   const int howmany = 100;
   for (int i = 0; i < howmany; i++) {
     list_node_t *newnode = malloc(sizeof(list_node_t));
-    newnode->data = i;
-    newnode->next = NULL;
+    *newnode = (list_node_t) { i, NULL };
 
     list_add(foolist, newnode);
   }
@@ -155,28 +174,28 @@ int main(int argc, char *argv[]) {
 
   // remove something
   list_node_t toremove = { 23, NULL };
-  list_remove(foolist, &toremove);
+  free(list_remove(foolist, &toremove));
   assert(list_length(foolist) == 2 + howmany - 1);
   list_print(foolist);
   printf("list_length = %d\n", list_length(foolist));
 
   // remove last item
   toremove.data = howmany - 1;
-  list_remove(foolist, &toremove);
+  free(list_remove(foolist, &toremove));
   assert(list_length(foolist) == 2 + howmany - 2);
   list_print(foolist);
   printf("list_length = %d\n", list_length(foolist));
 
   // remove something
   toremove.data = 1;
-  list_remove(foolist, &toremove);
+  free(list_remove(foolist, &toremove));
   assert(list_length(foolist) == 2 + howmany - 3);
   list_print(foolist);
   printf("list_length = %d\n", list_length(foolist));
 
   // remove something
   toremove.data = 1;
-  list_remove(foolist, &toremove);
+  free(list_remove(foolist, &toremove));
   assert(list_length(foolist) == 2 + howmany - 4);
   list_print(foolist);
   printf("list_length = %d\n", list_length(foolist));
@@ -184,9 +203,9 @@ int main(int argc, char *argv[]) {
   /* remove everything */
   for (int i = 0; i < howmany; i++) {
     toremove.data = i;
-    list_remove(foolist, &toremove);
+    free(list_remove(foolist, &toremove));
   }
-  assert(list_length(foolist) == 1);
+  assert(list_length(foolist) == 0);
   list_print(foolist);
   printf("list_length = %d\n", list_length(foolist));
 
@@ -228,5 +247,16 @@ int main(int argc, char *argv[]) {
   list_print(foolist);
   printf("list_length = %d\n", list_length(foolist));
 
-  /* FIXME: frees */
+  /* Test upper bound */
+  assert(list_elementat(foolist, list_length(foolist)-1) != NULL);
+  assert(list_elementat(foolist, list_length(foolist)  ) == NULL);
+  assert(list_elementat(foolist, list_length(foolist)+1) == NULL);
+  assert(list_elementat(foolist, list_length(foolist)+2) == NULL);
+
+  /* Free up remaining items and the list. */
+  while(!list_empty(foolist)) {
+    list_node_t *el = list_elementat(foolist, 0);
+    free(list_remove(foolist, el));
+  }
+  free(foolist);
 }