Core: Add a passthrough backend for the filesystem, exposed as SDMC.

src/core/file_sys/file_sdmc.cpp

@@ -0,0 +1,63 @@
+// Copyright 2014 Citra Emulator Project
+// Licensed under GPLv2
+// Refer to the license.txt file included.
+
+#include <sys/stat.h>
+
+#include "common/common_types.h"
+#include "common/file_util.h"
+
+#include "core/file_sys/file_sdmc.h"
+#include "core/file_sys/archive_sdmc.h"
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// FileSys namespace
+
+namespace FileSys {
+
+File_SDMC::File_SDMC(const Archive_SDMC* archive, const std::string& path, const Mode mode) {
+    // TODO(Link Mauve): normalize path into an absolute path without "..", it can currently bypass
+    // the root directory we set while opening the archive.
+    // For example, opening /../../etc/passwd can give the emulated program your users list.
+    std::string real_path = archive->GetMountPoint() + path;
+
+    if (!mode.create_flag && !FileUtil::Exists(real_path)) {
+        file = nullptr;
+        return;
+    }
+
+    std::string mode_string;
+    if (mode.read_flag)
+        mode_string += "r";
+    if (mode.write_flag)
+        mode_string += "w";
+
+    file = new FileUtil::IOFile(real_path, mode_string.c_str());
+}
+
+File_SDMC::~File_SDMC() {
+    Close();
+}
+
+size_t File_SDMC::Read(const u64 offset, const u32 length, u8* buffer) const {
+    file->Seek(offset, SEEK_SET);
+    return file->ReadBytes(buffer, length);
+}
+
+size_t File_SDMC::Write(const u64 offset, const u32 length, const u32 flush, const u8* buffer) const {
+    file->Seek(offset, SEEK_SET);
+    size_t written = file->WriteBytes(buffer, length);
+    if (flush)
+        file->Flush();
+    return written;
+}
+
+size_t File_SDMC::GetSize() const {
+    return file->GetSize();
+}
+
+bool File_SDMC::Close() const {
+    return file->Close();
+}
+
+} // namespace FileSys