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_key_slot_cache.hpp

@@ -0,0 +1,133 @@
+/*
+ * 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/>.
+ */
+#pragma once
+#include <stratosphere.hpp>
+
+namespace ams::fssystem {
+
+    class KeySlotCacheAccessor : public ::ams::fs::impl::Newable {
+        NON_COPYABLE(KeySlotCacheAccessor);
+        NON_MOVEABLE(KeySlotCacheAccessor);
+        private:
+            std::unique_lock<os::Mutex> lk;
+            const s32 slot_index;
+        public:
+            KeySlotCacheAccessor(s32 idx, std::unique_lock<os::Mutex> &&l) : lk(std::move(l)), slot_index(idx) { /* ... */ }
+
+            s32 GetKeySlotIndex() const { return this->slot_index; }
+    };
+
+    class KeySlotCacheEntry : public util::IntrusiveListBaseNode<KeySlotCacheEntry> {
+        NON_COPYABLE(KeySlotCacheEntry);
+        NON_MOVEABLE(KeySlotCacheEntry);
+        public:
+            static constexpr size_t KeySize = crypto::AesDecryptor128::KeySize;
+        private:
+            const s32 slot_index;
+            u8 key1[KeySize];
+            s32 key2;
+        public:
+            explicit KeySlotCacheEntry(s32 idx) : slot_index(idx), key2(-1) {
+                std::memset(this->key1, 0, sizeof(this->key1));
+            }
+
+            bool Contains(const void *key, size_t key_size, s32 key2) const {
+                AMS_ASSERT(key_size == KeySize);
+                return key2 == this->key2 && std::memcmp(this->key1, key, KeySize) == 0;
+            }
+
+            s32 GetKeySlotIndex() const { return this->slot_index; }
+
+            void SetKey(const void *key, size_t key_size, s32 key2) {
+                AMS_ASSERT(key_size == KeySize);
+                std::memcpy(this->key1, key, key_size);
+                this->key2 = key2;
+            }
+    };
+
+    class KeySlotCache {
+        NON_COPYABLE(KeySlotCache);
+        NON_MOVEABLE(KeySlotCache);
+        private:
+            using KeySlotCacheEntryList = util::IntrusiveListBaseTraits<KeySlotCacheEntry>::ListType;
+        private:
+            os::Mutex mutex;
+            KeySlotCacheEntryList high_priority_mru_list;
+            KeySlotCacheEntryList low_priority_mru_list;
+        public:
+            constexpr KeySlotCache() : mutex(false), high_priority_mru_list(), low_priority_mru_list() { /* ... */ }
+
+            Result AllocateHighPriority(std::unique_ptr<KeySlotCacheAccessor> *out, const void *key, size_t key_size, s32 key2) {
+                return this->AllocateFromLru(out, this->high_priority_mru_list, key, key_size, key2);
+            }
+
+            Result AllocateLowPriority(std::unique_ptr<KeySlotCacheAccessor> *out, const void *key, size_t key_size, s32 key2) {
+                return this->AllocateFromLru(out, this->high_priority_mru_list, key, key_size, key2);
+            }
+
+            Result Find(std::unique_ptr<KeySlotCacheAccessor> *out, const void *key, size_t key_size, s32 key2) {
+                std::unique_lock lk(this->mutex);
+
+                KeySlotCacheEntryList *lists[2] = { std::addressof(this->high_priority_mru_list), std::addressof(this->low_priority_mru_list) };
+                for (auto list : lists) {
+                    for (auto it = list->begin(); it != list->end(); ++it) {
+                        if (it->Contains(key, key_size, key2)) {
+                            std::unique_ptr accessor = std::make_unique<KeySlotCacheAccessor>(it->GetKeySlotIndex(), std::move(lk));
+                            R_UNLESS(accessor != nullptr, fs::ResultAllocationFailure());
+
+                            *out = std::move(accessor);
+
+                            this->UpdateMru(list, it);
+                            return ResultSuccess();
+                        }
+                    }
+                }
+
+                return fs::ResultTargetNotFound();
+            }
+
+            void AddEntry(KeySlotCacheEntry *entry) {
+                std::unique_lock lk(this->mutex);
+                this->low_priority_mru_list.push_front(*entry);
+            }
+        private:
+            Result AllocateFromLru(std::unique_ptr<KeySlotCacheAccessor> *out, KeySlotCacheEntryList &dst_list, const void *key, size_t key_size, s32 key2) {
+                std::unique_lock lk(this->mutex);
+
+                KeySlotCacheEntryList &src_list = this->low_priority_mru_list.empty() ? this->high_priority_mru_list : this->low_priority_mru_list;
+                AMS_ASSERT(!src_list.empty());
+
+                auto it = src_list.rbegin();
+                std::unique_ptr accessor = std::make_unique<KeySlotCacheAccessor>(it->GetKeySlotIndex(), std::move(lk));
+                *out = std::move(accessor);
+
+                it->SetKey(key, key_size, key2);
+
+                auto *entry = std::addressof(*it);
+                src_list.pop_back();
+                dst_list.push_front(*entry);
+
+                return ResultSuccess();
+            }
+
+            void UpdateMru(KeySlotCacheEntryList *list, KeySlotCacheEntryList::iterator it) {
+                auto *entry = std::addressof(*it);
+                list->erase(it);
+                list->push_front(*entry);
+            }
+    };
+
+}