Added OOM/fragmentation handler

allocator_internal.h

@@ -13,6 +13,8 @@ const char RT_WATERMARK = 2;
 const char COLOR_RED = 0;
 const char COLOR_BLACK = 1;
 
+const uintptr_t MIN_NEW_MEM_SIZE = 4096;
+
 typedef struct Arena {
   struct FreeSpace *root_freespace;
   struct TreeAlloc *root_treealloc;

tree_alloc.c

@@ -209,6 +209,23 @@ void insert_left(TreeAlloc** root_ptr, TreeAlloc* to_insert, TreeAlloc* before)
 	repair_tree_after_insert(to_insert);
 }
 
+int *add_new_region(Arena *arena, uintptr_t size, uintptr_t padding, uintptr_t align) {
+    uintptr_t realsize = size + align + padding - 1;
+    if (realsize < MIN_NEW_MEM_SIZE) {
+      realsize = MIN_NEW_MEM_SIZE;
+    }
+    FreeSpace *newreg = (FreeSpace*) arena->get_new_region(size);
+    if (newreg == NULL) {
+      arena->error("can't allocate a new memory region!");
+      return 0;
+    } else {
+      newreg = align_after(newreg, alignof(WatermarkAlloc));
+      newreg->left = NULL;
+      newreg->right = NULL;
+    }
+    return 1;
+}
+
 void unalloc(Arena *arena, void *addr) {
   if (arena->root_treealloc == NULL) {
     arena->error("attempt to unallocate when there are no allocations!");
@@ -261,12 +278,20 @@ void unalloc(Arena *arena, void *addr) {
 
 void *alloc(Arena *arena, uintptr_t size, uintptr_t align) {
   if (arena->root_freespace == NULL) {
-    // TODO: handle out-of-memory
+    // Handle being out of freespace.
+    if (!add_new_region(arena, size, sizeof(TreeAlloc), align)) {
+      return NULL;
+    }
+    return alloc(arena, size, align);
   } else {
     uintptr_t actual_align = lcm(alignof(struct WatermarkAlloc), align);
     TreeAlloc *region = search_by_size((TreeAlloc*) arena->root_freespace, sizeof(TreeAlloc), actual_align, size);
     if (region == NULL) {
-      // TODO: handle memory fragmentation (or OOM)
+      // Handle insufficient freespace or fragmentation.
+      if (!add_new_region(arena, size, sizeof(TreeAlloc), align)) {
+        return NULL;
+      }
+      return alloc(arena, size, align);
     }
     remove_node((TreeAlloc**) &arena->root_freespace, region);
     void *true_end = align_after(align_after(region + sizeof(TreeAlloc), actual_align) + size, alignof(WatermarkAlloc));