aoc: Read DLC base title ID from RegisteredCache

Falls back to title ID + 0x1000, which is what HOS does.

src/core/file_sys/control_metadata.cpp

@@ -56,6 +56,10 @@ u64 NACP::GetTitleId() const {
     return raw->title_id;
 }
 
+u64 NACP::GetDLCBaseTitleId() const {
+    return raw->dlc_base_title_id;
+}
+
 std::string NACP::GetVersionString() const {
     return Common::StringFromFixedZeroTerminatedBuffer(raw->version_string.data(), 0x10);
 }

src/core/file_sys/control_metadata.h

@@ -79,6 +79,7 @@ public:
     std::string GetApplicationName(Language language = Language::Default) const;
     std::string GetDeveloperName(Language language = Language::Default) const;
     u64 GetTitleId() const;
+    u64 GetDLCBaseTitleId() const;
     std::string GetVersionString() const;
 
 private:

src/core/hle/service/aoc/aoc_u.cpp

@@ -7,8 +7,10 @@
 #include <vector>
 #include "common/logging/log.h"
 #include "core/file_sys/content_archive.h"
+#include "core/file_sys/control_metadata.h"
 #include "core/file_sys/nca_metadata.h"
 #include "core/file_sys/partition_filesystem.h"
+#include "core/file_sys/patch_manager.h"
 #include "core/file_sys/registered_cache.h"
 #include "core/hle/ipc_helpers.h"
 #include "core/hle/kernel/process.h"
@@ -19,7 +21,7 @@
 namespace Service::AOC {
 
 constexpr u64 DLC_BASE_TITLE_ID_MASK = 0xFFFFFFFFFFFFE000;
-constexpr u64 DLC_BASE_TO_AOC_ID_MASK = 0x1000;
+constexpr u64 DLC_BASE_TO_AOC_ID = 0x1000;
 
 static bool CheckAOCTitleIDMatchesBase(u64 base, u64 aoc) {
     return (aoc & DLC_BASE_TITLE_ID_MASK) == base;
@@ -105,7 +107,16 @@ void AOC_U::ListAddOnContent(Kernel::HLERequestContext& ctx) {
 void AOC_U::GetAddOnContentBaseId(Kernel::HLERequestContext& ctx) {
     IPC::ResponseBuilder rb{ctx, 4};
     rb.Push(RESULT_SUCCESS);
-    rb.Push(Core::System::GetInstance().CurrentProcess()->GetTitleID() | DLC_BASE_TO_AOC_ID_MASK);
+    const auto title_id = Core::System::GetInstance().CurrentProcess()->GetTitleID();
+    FileSys::PatchManager pm{title_id};
+
+    const auto res = pm.GetControlMetadata();
+    if (res.first == nullptr) {
+        rb.Push(title_id + DLC_BASE_TO_AOC_ID);
+        return;
+    }
+
+    rb.Push(res.first->GetDLCBaseTitleId());
 }
 
 void AOC_U::PrepareAddOnContent(Kernel::HLERequestContext& ctx) {