loader/nso: Check if read succeeded in IdentifyFile() before checking magic value

We should always assume the filesystem is volatile and check each IO
operation. While we're at it reorganize checks so that early-out errors
are near one another.

src/common/file_util.cpp

@@ -592,7 +592,7 @@ std::string GetBundleDirectory() {
 #endif
 
 #ifdef _WIN32
-const std::string& GetExeDirectory() {
+std::string& GetExeDirectory() {
     static std::string exe_path;
     if (exe_path.empty()) {
         wchar_t wchar_exe_path[2048];

src/common/file_util.h

@@ -133,7 +133,7 @@ std::string GetBundleDirectory();
 #endif
 
 #ifdef _WIN32
-const std::string& GetExeDirectory();
+std::string& GetExeDirectory();
 std::string AppDataRoamingDirectory();
 #endif
 

src/core/file_sys/vfs.cpp

@@ -116,14 +116,14 @@ bool VfsDirectory::IsRoot() const {
 
 size_t VfsDirectory::GetSize() const {
     const auto& files = GetFiles();
-    const auto file_total =
-        std::accumulate(files.begin(), files.end(), 0ull,
-                        [](const auto& f1, const auto& f2) { return f1 + f2->GetSize(); });
+    const auto sum_sizes = [](const auto& range) {
+        return std::accumulate(range.begin(), range.end(), 0ULL,
+                               [](const auto& f1, const auto& f2) { return f1 + f2->GetSize(); });
+    };
 
+    const auto file_total = sum_sizes(files);
     const auto& sub_dir = GetSubdirectories();
-    const auto subdir_total =
-        std::accumulate(sub_dir.begin(), sub_dir.end(), 0ull,
-                        [](const auto& f1, const auto& f2) { return f1 + f2->GetSize(); });
+    const auto subdir_total = sum_sizes(sub_dir);
 
     return file_total + subdir_total;
 }

src/core/loader/nso.cpp

@@ -55,13 +55,15 @@ AppLoader_NSO::AppLoader_NSO(FileSys::VirtualFile file) : AppLoader(std::move(fi
 
 FileType AppLoader_NSO::IdentifyType(const FileSys::VirtualFile& file) {
     u32 magic = 0;
-    file->ReadObject(&magic);
-
-    if (Common::MakeMagic('N', 'S', 'O', '0') == magic) {
-        return FileType::NSO;
+    if (file->ReadObject(&magic) != sizeof(magic)) {
+        return FileType::Error;
     }
 
-    return FileType::Error;
+    if (Common::MakeMagic('N', 'S', 'O', '0') != magic) {
+        return FileType::Error;
+    }
+
+    return FileType::NSO;
 }
 
 static std::vector<u8> DecompressSegment(const std::vector<u8>& compressed_data,

src/video_core/renderer_opengl/gl_rasterizer.cpp

@@ -795,7 +795,9 @@ void RasterizerOpenGL::SyncClipCoef() {
 void RasterizerOpenGL::SyncCullMode() {
     const auto& regs = Core::System::GetInstance().GPU().Maxwell3D().regs;
 
-    state.cull.enabled = regs.cull.enabled != 0;
+    // TODO(bunnei): Enable the below once more things work - until then, this may hide regressions
+    // state.cull.enabled = regs.cull.enabled != 0;
+    state.cull.enabled = false;
 
     if (state.cull.enabled) {
         state.cull.front_face = MaxwellToGL::FrontFace(regs.cull.front_face);