1 files changed, 102 insertions, 0 deletions

diff --git a/src/core/hle/romfs.cpp b/src/core/hle/romfs.cpp
new file mode 100644
index 000000000..3157df71d
--- /dev/null
+++ b/src/core/hle/romfs.cpp
@@ -0,0 +1,102 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <cstring>
+#include "common/swap.h"
+#include "core/hle/romfs.h"
+
+namespace RomFS {
+
+struct Header {
+    u32_le header_length;
+    u32_le dir_hash_table_offset;
+    u32_le dir_hash_table_length;
+    u32_le dir_table_offset;
+    u32_le dir_table_length;
+    u32_le file_hash_table_offset;
+    u32_le file_hash_table_length;
+    u32_le file_table_offset;
+    u32_le file_table_length;
+    u32_le data_offset;
+};
+
+static_assert(sizeof(Header) == 0x28, "Header has incorrect size");
+
+struct DirectoryMetadata {
+    u32_le parent_dir_offset;
+    u32_le next_dir_offset;
+    u32_le first_child_dir_offset;
+    u32_le first_file_offset;
+    u32_le same_hash_next_dir_offset;
+    u32_le name_length; // in bytes
+    // followed by directory name
+};
+
+static_assert(sizeof(DirectoryMetadata) == 0x18, "DirectoryMetadata has incorrect size");
+
+struct FileMetadata {
+    u32_le parent_dir_offset;
+    u32_le next_file_offset;
+    u64_le data_offset;
+    u64_le data_length;
+    u32_le same_hash_next_file_offset;
+    u32_le name_length; // in bytes
+    // followed by file name
+};
+
+static_assert(sizeof(FileMetadata) == 0x20, "FileMetadata has incorrect size");
+
+static bool MatchName(const u8* buffer, u32 name_length, const std::u16string& name) {
+    std::vector<char16_t> name_buffer(name_length / sizeof(char16_t));
+    std::memcpy(name_buffer.data(), buffer, name_length);
+    return name == std::u16string(name_buffer.begin(), name_buffer.end());
+}
+
+const u8* GetFilePointer(const u8* romfs, const std::vector<std::u16string>& path) {
+    constexpr u32 INVALID_FIELD = 0xFFFFFFFF;
+
+    // Split path into directory names and file name
+    std::vector<std::u16string> dir_names = path;
+    dir_names.pop_back();
+    const std::u16string& file_name = path.back();
+
+    Header header;
+    std::memcpy(&header, romfs, sizeof(header));
+
+    // Find directories of each level
+    DirectoryMetadata dir;
+    const u8* current_dir = romfs + header.dir_table_offset;
+    std::memcpy(&dir, current_dir, sizeof(dir));
+    for (const std::u16string& dir_name : dir_names) {
+        u32 child_dir_offset;
+        child_dir_offset = dir.first_child_dir_offset;
+        while (true) {
+            if (child_dir_offset == INVALID_FIELD) {
+                return nullptr;
+            }
+            const u8* current_child_dir = romfs + header.dir_table_offset + child_dir_offset;
+            std::memcpy(&dir, current_child_dir, sizeof(dir));
+            if (MatchName(current_child_dir + sizeof(dir), dir.name_length, dir_name)) {
+                current_dir = current_child_dir;
+                break;
+            }
+            child_dir_offset = dir.next_dir_offset;
+        }
+    }
+
+    // Find the file
+    FileMetadata file;
+    u32 file_offset = dir.first_file_offset;
+    while (file_offset != INVALID_FIELD) {
+        const u8* current_file = romfs + header.file_table_offset + file_offset;
+        std::memcpy(&file, current_file, sizeof(file));
+        if (MatchName(current_file + sizeof(file), file.name_length, file_name)) {
+            return romfs + header.data_offset + file.data_offset;
+        }
+        file_offset = file.next_file_offset;
+    }
+    return nullptr;
+}
+
+} // namespace RomFS