Kernel: Improve "out of memory" error handling

It can now boot with fairly low memory while not crashing and instead
gracefully failing the operation. Userland still does not properly
handle errors.

2 files changed, 19 insertions, 9 deletions

diff --git a/kernel/lib/list.c b/kernel/lib/list.c
index c663230..e4d4b23 100644
--- a/kernel/lib/list.c
+++ b/kernel/lib/list.c
@@ -2,15 +2,13 @@
 #include <kmalloc.h>
 #include <lib/list.h>
 
-int list_init(struct list *list) {
-  // TODO: Make it dynamic
+void list_init(struct list *list) {
   list->capacity = 5;
+  list->tail_index = -1;
   list->entries = kmalloc(sizeof(void *) * list->capacity);
   if (!list->entries) {
-    return 0;
+    list->capacity = 0;
   }
-  list->tail_index = -1;
-  return 1;
 }
 
 void list_reset(struct list *list) {
@@ -24,15 +22,24 @@ int list_clone(struct list *in, struct list *out) {
     if (!list_get(in, i, &output)) {
       break;
     }
-    list_add(out, output, NULL);
+    if (!list_add(out, output, NULL)) {
+      list_free(out);
+      return 0;
+    }
   }
   return 1;
 }
 
 int list_add(struct list *list, void *entry, int *index) {
   if (list->tail_index + 1 >= list->capacity) {
-    list->capacity += 25;
-    list->entries = krealloc(list->entries, sizeof(void *) * list->capacity);
+    int new_capacity = list->capacity + 25;
+    void *new_allocation =
+        krealloc(list->entries, sizeof(void *) * new_capacity);
+    if (!new_allocation) {
+      return 0;
+    }
+    list->entries = new_allocation;
+    list->capacity = new_capacity;
   }
   list->tail_index++;
   list->entries[list->tail_index] = entry;
@@ -60,5 +67,8 @@ int list_get(const struct list *list, int index, void **out) {
 }
 
 void list_free(struct list *list) {
+  list->capacity = 0;
+  list->tail_index = -1;
   kfree(list->entries);
+  list->entries = NULL;
 }
diff --git a/kernel/lib/list.h b/kernel/lib/list.h
index b1f0127..2d1fa0f 100644
--- a/kernel/lib/list.h
+++ b/kernel/lib/list.h
@@ -6,7 +6,7 @@ struct list {
   int tail_index;
 };
 
-int list_init(struct list *list);
+void list_init(struct list *list);
 void list_reset(struct list *list);
 void list_free(struct list *list);
 int list_clone(struct list *in, struct list *out);