Implement support for parsing/interacting with NCAs. (#942)

* fs: implement support for interacting with ncas.

* spl: extend to use virtual keyslots

libraries/libstratosphere/source/fssystem/fssystem_allocator_utility.cpp

@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <stratosphere.hpp>
+
+namespace ams::fssystem {
+
+    namespace {
+
+        constexpr bool UseDefaultAllocators = false;
+
+        bool g_used_default_allocator;
+
+        void *DefaultAllocate(size_t size) {
+            g_used_default_allocator = true;
+            return std::malloc(size);
+        }
+
+        void DefaultDeallocate(void *ptr, size_t size) {
+            std::free(ptr);
+        }
+
+        AllocateFunction g_allocate_func     = UseDefaultAllocators ? DefaultAllocate   : nullptr;
+        DeallocateFunction g_deallocate_func = UseDefaultAllocators ? DefaultDeallocate : nullptr;
+
+    }
+
+    void *Allocate(size_t size) {
+        AMS_ASSERT(g_allocate_func != nullptr);
+        return g_allocate_func(size);
+    }
+
+    void Deallocate(void *ptr, size_t size) {
+        AMS_ASSERT(g_deallocate_func != nullptr);
+        return g_deallocate_func(ptr, size);
+    }
+
+    void InitializeAllocator(AllocateFunction allocate_func, DeallocateFunction deallocate_func) {
+        AMS_ASSERT(allocate_func != nullptr);
+        AMS_ASSERT(deallocate_func != nullptr);
+
+        if constexpr (UseDefaultAllocators) {
+            AMS_ASSERT(g_used_default_allocator == false);
+        } else {
+            AMS_ASSERT(g_allocate_func == nullptr);
+            AMS_ASSERT(g_deallocate_func == nullptr);
+        }
+
+        g_allocate_func   = allocate_func;
+        g_deallocate_func = deallocate_func;
+    }
+
+}