From 86f6b6b7b2d930e8203114332b04a5c49a780b06 Mon Sep 17 00:00:00 2001
From: Liam <byteslice@airmail.cc>
Date: Thu, 10 Aug 2023 21:34:43 -0400
Subject: vfs: expand support for NCA reading

---
 .../file_sys/fssystem/fssystem_sparse_storage.cpp  | 40 ++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 src/core/file_sys/fssystem/fssystem_sparse_storage.cpp

(limited to 'src/core/file_sys/fssystem/fssystem_sparse_storage.cpp')

diff --git a/src/core/file_sys/fssystem/fssystem_sparse_storage.cpp b/src/core/file_sys/fssystem/fssystem_sparse_storage.cpp
new file mode 100644
index 000000000..05e8820f7
--- /dev/null
+++ b/src/core/file_sys/fssystem/fssystem_sparse_storage.cpp
@@ -0,0 +1,40 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "core/file_sys/fssystem/fssystem_sparse_storage.h"
+
+namespace FileSys {
+
+size_t SparseStorage::Read(u8* buffer, size_t size, size_t offset) const {
+    // Validate preconditions.
+    ASSERT(offset >= 0);
+    ASSERT(this->IsInitialized());
+    ASSERT(buffer != nullptr);
+
+    // Allow zero size.
+    if (size == 0) {
+        return size;
+    }
+
+    SparseStorage* self = const_cast<SparseStorage*>(this);
+
+    if (self->GetEntryTable().IsEmpty()) {
+        BucketTree::Offsets table_offsets;
+        ASSERT(R_SUCCEEDED(self->GetEntryTable().GetOffsets(std::addressof(table_offsets))));
+        ASSERT(table_offsets.IsInclude(offset, size));
+
+        std::memset(buffer, 0, size);
+    } else {
+        self->OperatePerEntry<false, true>(
+            offset, size,
+            [=](VirtualFile storage, s64 data_offset, s64 cur_offset, s64 cur_size) -> Result {
+                storage->Read(reinterpret_cast<u8*>(buffer) + (cur_offset - offset),
+                              static_cast<size_t>(cur_size), data_offset);
+                R_SUCCEED();
+            });
+    }
+
+    return size;
+}
+
+} // namespace FileSys
-- 
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