AK: Add trivial structure validation to SharedBuffer

If we're sharing buffers, we only want to share trivial structures
as anything else could potentially share internal pointers, which
most likely is going to cause problems due to different address
spaces.

Fix the GUI::SystemTheme structure, which was not trivial, which
is now caught at compile time.

Fixes #3650

AK/SharedBuffer.h

@@ -44,8 +44,21 @@ public:
     int shbuf_id() const { return m_shbuf_id; }
     void seal();
     int size() const { return m_size; }
-    void* data() { return m_data; }
-    const void* data() const { return m_data; }
+
+    template<typename T>
+    T* data()
+    {
+        static_assert(IsVoid<T>::value || is_trivial<T>());
+        return (T*)m_data;
+    }
+
+    template<typename T>
+    const T* data() const
+    {
+        static_assert(IsVoid<T>::value || is_trivial<T>());
+        return (const T*)m_data;
+    }
+
     void set_volatile();
     [[nodiscard]] bool set_nonvolatile();
 

Libraries/LibAudio/Buffer.h

@@ -120,7 +120,7 @@ public:
 
     const Sample* samples() const { return (const Sample*)data(); }
     int sample_count() const { return m_sample_count; }
-    const void* data() const { return m_buffer->data(); }
+    const void* data() const { return m_buffer->data<void>(); }
     int size_in_bytes() const { return m_sample_count * (int)sizeof(Sample); }
     int shbuf_id() const { return m_buffer->shbuf_id(); }
     SharedBuffer& shared_buffer() { return *m_buffer; }
@@ -130,7 +130,7 @@ private:
         : m_buffer(*SharedBuffer::create_with_size(samples.size() * sizeof(Sample)))
         , m_sample_count(samples.size())
     {
-        memcpy(m_buffer->data(), samples.data(), samples.size() * sizeof(Sample));
+        memcpy(m_buffer->data<void>(), samples.data(), samples.size() * sizeof(Sample));
     }
 
     explicit Buffer(NonnullRefPtr<SharedBuffer>&& buffer, int sample_count)

Libraries/LibGUI/Clipboard.cpp

@@ -90,7 +90,7 @@ Clipboard::DataAndType Clipboard::data_and_type() const
         dbgprintf("GUI::Clipboard::data() clipping contents size is greater than shared buffer size\n");
         return {};
     }
-    auto data = ByteBuffer::copy(shared_buffer->data(), response->data_size());
+    auto data = ByteBuffer::copy(shared_buffer->data<void>(), response->data_size());
     auto type = response->mime_type();
     auto metadata = response->metadata().entries();
     return { data, type, metadata };
@@ -104,7 +104,7 @@ void Clipboard::set_data(ReadonlyBytes data, const String& type, const HashMap<S
         return;
     }
     if (!data.is_empty())
-        memcpy(shared_buffer->data(), data.data(), data.size());
+        memcpy(shared_buffer->data<void>(), data.data(), data.size());
     shared_buffer->seal();
     shared_buffer->share_with(connection().server_pid());
 

Libraries/LibGUI/Menu.cpp

@@ -118,7 +118,7 @@ static int ensure_realized_icon(IconContainerType& container)
             auto shared_buffer = SharedBuffer::create_with_size(container.icon()->size_in_bytes());
             ASSERT(shared_buffer);
             auto shared_icon = Gfx::Bitmap::create_with_shared_buffer(Gfx::BitmapFormat::RGBA32, *shared_buffer, container.icon()->size());
-            memcpy(shared_buffer->data(), container.icon()->scanline_u8(0), container.icon()->size_in_bytes());
+            memcpy(shared_buffer->template data<u8>(), container.icon()->scanline_u8(0), container.icon()->size_in_bytes());
             shared_buffer->seal();
             shared_buffer->share_with(WindowServerConnection::the().server_pid());
             container.set_icon(shared_icon);

Libraries/LibGfx/Bitmap.cpp

@@ -169,7 +169,7 @@ RefPtr<Bitmap> Bitmap::create_with_shared_buffer(BitmapFormat format, NonnullRef
 
 Bitmap::Bitmap(BitmapFormat format, NonnullRefPtr<SharedBuffer>&& shared_buffer, const IntSize& size, const Vector<RGBA32>& palette)
     : m_size(size)
-    , m_data(shared_buffer->data())
+    , m_data(shared_buffer->data<void>())
     , m_pitch(minimum_pitch(size.width(), format))
     , m_format(format)
     , m_shared_buffer(move(shared_buffer))
@@ -255,7 +255,7 @@ RefPtr<Bitmap> Bitmap::to_bitmap_backed_by_shared_buffer() const
     auto bitmap = Bitmap::create_with_shared_buffer(m_format, *buffer, m_size, palette_to_vector());
     if (!bitmap)
         return nullptr;
-    memcpy(buffer->data(), scanline(0), size_in_bytes());
+    memcpy(buffer->data<void>(), scanline(0), size_in_bytes());
     return bitmap;
 }
 

Libraries/LibGfx/Palette.cpp

@@ -52,13 +52,13 @@ Palette::~Palette()
 
 const SystemTheme& PaletteImpl::theme() const
 {
-    return *(const SystemTheme*)m_theme_buffer->data();
+    return *m_theme_buffer->data<SystemTheme>();
 }
 
 Color PaletteImpl::color(ColorRole role) const
 {
     ASSERT((int)role < (int)ColorRole::__Count);
-    return theme().color[(int)role];
+    return Color::from_rgba(theme().color[(int)role]);
 }
 
 int PaletteImpl::metric(MetricRole role) const
@@ -76,7 +76,7 @@ String PaletteImpl::path(PathRole role) const
 NonnullRefPtr<PaletteImpl> PaletteImpl::clone() const
 {
     auto new_theme_buffer = SharedBuffer::create_with_size(m_theme_buffer->size());
-    memcpy(new_theme_buffer->data(), m_theme_buffer->data(), m_theme_buffer->size());
+    memcpy(new_theme_buffer->data<SystemTheme>(), &theme(), m_theme_buffer->size());
     return adopt(*new PaletteImpl(*new_theme_buffer));
 }
 
@@ -85,7 +85,7 @@ void Palette::set_color(ColorRole role, Color color)
     if (m_impl->ref_count() != 1)
         m_impl = m_impl->clone();
     auto& theme = const_cast<SystemTheme&>(impl().theme());
-    theme.color[(int)role] = color;
+    theme.color[(int)role] = color.value();
 }
 
 void Palette::set_metric(MetricRole role, int value)
@@ -101,7 +101,8 @@ void Palette::set_path(PathRole role, String path)
     if (m_impl->ref_count() != 1)
         m_impl = m_impl->clone();
     auto& theme = const_cast<SystemTheme&>(impl().theme());
-    theme.path[(int)role] = path;
+    memcpy(theme.path[(int)role], path.characters(), min(path.length() + 1, sizeof(theme.path[(int)role])));
+    theme.path[(int)role][sizeof(theme.path[(int)role]) - 1] = '\0';
 }
 
 PaletteImpl::~PaletteImpl()

Libraries/LibGfx/SystemTheme.cpp

@@ -27,6 +27,7 @@
 #include <AK/SharedBuffer.h>
 #include <LibCore/ConfigFile.h>
 #include <LibGfx/SystemTheme.h>
+#include <string.h>
 
 namespace Gfx {
 
@@ -49,7 +50,7 @@ int current_system_theme_buffer_id()
 void set_system_theme(SharedBuffer& buffer)
 {
     theme_buffer = buffer;
-    theme_page = (SystemTheme*)theme_buffer->data();
+    theme_page = theme_buffer->data<SystemTheme>();
 }
 
 RefPtr<SharedBuffer> load_system_theme(const String& path)
@@ -57,7 +58,7 @@ RefPtr<SharedBuffer> load_system_theme(const String& path)
     auto file = Core::ConfigFile::open(path);
     auto buffer = SharedBuffer::create_with_size(sizeof(SystemTheme));
 
-    auto* data = (SystemTheme*)buffer->data();
+    auto* data = buffer->data<SystemTheme>();
 
     auto get_color = [&](auto& name) {
         auto color_string = file->read_entry("Colors", name);
@@ -100,7 +101,7 @@ RefPtr<SharedBuffer> load_system_theme(const String& path)
 
 #undef __ENUMERATE_COLOR_ROLE
 #define __ENUMERATE_COLOR_ROLE(role) \
-    data->color[(int)ColorRole::role] = get_color(#role);
+    data->color[(int)ColorRole::role] = get_color(#role).value();
     ENUMERATE_COLOR_ROLES(__ENUMERATE_COLOR_ROLE)
 #undef __ENUMERATE_COLOR_ROLE
 
@@ -111,8 +112,12 @@ RefPtr<SharedBuffer> load_system_theme(const String& path)
     DO_METRIC(TitleButtonWidth);
     DO_METRIC(TitleButtonHeight);
 
-#define DO_PATH(x) \
-    data->path[(int)PathRole::x] = get_path(#x, (int)PathRole::x)
+#define DO_PATH(x)                                                                                               \
+    do {                                                                                                         \
+        auto path = get_path(#x, (int)PathRole::x);                                                              \
+        memcpy(data->path[(int)PathRole::x], path, min(strlen(path) + 1, sizeof(data->path[(int)PathRole::x]))); \
+        data->path[(int)PathRole::x][sizeof(data->path[(int)PathRole::x]) - 1] = '\0';                           \
+    } while (0)
 
     DO_PATH(TitleButtonIcons);
 

Libraries/LibGfx/SystemTheme.h

@@ -143,9 +143,9 @@ enum class PathRole {
 };
 
 struct SystemTheme {
-    Color color[(int)ColorRole::__Count];
+    RGBA32 color[(int)ColorRole::__Count];
     int metric[(int)MetricRole::__Count];
-    String path[(int)PathRole::__Count];
+    char path[(int)PathRole::__Count][256]; // TODO: PATH_MAX?
 };
 
 const SystemTheme& current_system_theme();

Libraries/LibImageDecoderClient/Client.cpp

@@ -57,7 +57,7 @@ RefPtr<Gfx::Bitmap> Client::decode_image(const ByteBuffer& encoded_data)
         return nullptr;
     }
 
-    memcpy(encoded_buffer->data(), encoded_data.data(), encoded_data.size());
+    memcpy(encoded_buffer->data<void>(), encoded_data.data(), encoded_data.size());
 
     encoded_buffer->seal();
     encoded_buffer->share_with(server_pid());

Libraries/LibProtocol/Download.cpp

@@ -50,7 +50,7 @@ void Download::did_finish(Badge<Client>, bool success, Optional<u32> status_code
     RefPtr<SharedBuffer> shared_buffer;
     if (success && shbuf_id != -1) {
         shared_buffer = SharedBuffer::create_from_shbuf_id(shbuf_id);
-        payload = ByteBuffer::wrap(shared_buffer->data(), total_size);
+        payload = ByteBuffer::wrap(shared_buffer->data<void>(), total_size);
     }
 
     // FIXME: It's a bit silly that we copy the response headers here just so we can move them into a HashMap with different traits.

Services/Clipboard/ClientConnection.cpp

@@ -83,7 +83,7 @@ OwnPtr<Messages::ClipboardServer::GetClipboardDataResponse> ClientConnection::ha
         //        It would be even nicer if a SharedBuffer could have an arbitrary number of clients..
         RefPtr<SharedBuffer> shared_buffer = SharedBuffer::create_with_size(storage.data_size());
         ASSERT(shared_buffer);
-        memcpy(shared_buffer->data(), storage.data(), storage.data_size());
+        memcpy(shared_buffer->data<void>(), storage.data(), storage.data_size());
         shared_buffer->seal();
         shared_buffer->share_with(client_pid());
         shbuf_id = shared_buffer->shbuf_id();

Services/Clipboard/Storage.cpp

@@ -46,7 +46,7 @@ Storage::~Storage()
 
 void Storage::set_data(NonnullRefPtr<SharedBuffer> data, size_t data_size, const String& mime_type, const HashMap<String, String>& metadata)
 {
-    dbg() << "Storage::set_data <- [" << mime_type << "] " << data->data() << " (" << data_size << " bytes)";
+    dbg() << "Storage::set_data <- [" << mime_type << "] " << data->data<void>() << " (" << data_size << " bytes)";
     for (auto& it : metadata) {
         dbg() << "  " << it.key << ": " << it.value;
     }

Services/Clipboard/Storage.h

@@ -47,7 +47,7 @@ public:
     {
         if (!has_data())
             return nullptr;
-        return static_cast<const u8*>(m_shared_buffer->data());
+        return m_shared_buffer->data<u8>();
     }
 
     size_t data_size() const

Services/ImageDecoder/ClientConnection.cpp

@@ -79,7 +79,7 @@ OwnPtr<Messages::ImageDecoderServer::DecodeImageResponse> ClientConnection::hand
     dbg() << "Trying to decode " << message.encoded_size() << " bytes of image(?) data in shbuf_id=" << message.encoded_shbuf_id() << " (shbuf size: " << encoded_buffer->size() << ")";
 #endif
 
-    auto decoder = Gfx::ImageDecoder::create((const u8*)encoded_buffer->data(), message.encoded_size());
+    auto decoder = Gfx::ImageDecoder::create(encoded_buffer->data<u8>(), message.encoded_size());
     auto bitmap = decoder->bitmap();
 
     if (!bitmap) {

Services/ProtocolServer/ClientConnection.cpp

@@ -91,7 +91,7 @@ void ClientConnection::did_finish_download(Badge<Download>, Download& download,
     RefPtr<SharedBuffer> buffer;
     if (success && download.payload().size() > 0 && !download.payload().is_null()) {
         buffer = SharedBuffer::create_with_size(download.payload().size());
-        memcpy(buffer->data(), download.payload().data(), download.payload().size());
+        memcpy(buffer->data<void>(), download.payload().data(), download.payload().size());
         buffer->seal();
         buffer->share_with(client_pid());
         m_shared_buffers.set(buffer->shbuf_id(), buffer);

Services/WebContent/PageHost.cpp

@@ -50,7 +50,7 @@ void PageHost::setup_palette()
 {
     // FIXME: Get the proper palette from our peer somehow
     auto buffer = SharedBuffer::create_with_size(sizeof(Gfx::SystemTheme));
-    auto* theme = (Gfx::SystemTheme*)buffer->data();
+    auto* theme = buffer->data<Gfx::SystemTheme>();
     theme->color[(int)Gfx::ColorRole::Window] = Color::Magenta;
     theme->color[(int)Gfx::ColorRole::WindowText] = Color::Cyan;
     m_palette_impl = Gfx::PaletteImpl::create_with_shared_buffer(*buffer);