base: Remove startup items not necessary for GUI startup

No client functionality yet, but it's a start.

CMakeLists.txt

@@ -45,8 +45,10 @@ endif()
 
 add_subdirectory(libluna)
 add_subdirectory(libos)
+add_subdirectory(libui)
 add_subdirectory(libc)
 add_subdirectory(kernel)
 add_subdirectory(apps)
 add_subdirectory(tests)
 add_subdirectory(shell)
+add_subdirectory(wind)

base/etc/init/01-motd

@@ -1,4 +0,0 @@
-Name=motd
-Description=Show the message of the day to the user.
-Command=/usr/bin/cat /etc/motd
-Wait=true

base/etc/init/98-listen

@@ -1,6 +0,0 @@
-Name=listen
-Description=Start a Unix domain socket test server.
-Command=/usr/bin/socket-test
-StandardOutput=/dev/uart0
-StandardError=/dev/uart0
-Restart=true

base/etc/init/99-login

@@ -1,4 +1,6 @@
 Name=login
-Description=Start the command-line login program.
-Command=/usr/bin/login
+Description=Start the display server.
+Command=/usr/bin/wind --user=selene
+StandardOutput=/dev/uart0
+StandardError=/dev/uart0
 Restart=true

kernel/src/arch/x86_64/PS2Mouse.cpp

@@ -43,8 +43,8 @@ static void process_mouse_event(u8 data)
     packet.buttons = 0;
 
     u8 flags = g_mouse_packet[0];
-    if (flags & PS2_MOUSE_X_SIGN) packet.xdelta = -packet.xdelta;
-    if (flags & PS2_MOUSE_Y_SIGN) packet.ydelta = -packet.ydelta;
+    if (flags & PS2_MOUSE_X_SIGN) packet.xdelta = -(256 - packet.xdelta);
+    if (flags & PS2_MOUSE_Y_SIGN) packet.ydelta = -(256 - packet.ydelta);
 
     if (flags & PS2_MOUSE_MIDDLE_BTN) packet.buttons |= moon::MouseButton::Middle;
     if (flags & PS2_MOUSE_RIGHT_BTN) packet.buttons |= moon::MouseButton::Right;

kernel/src/net/Socket.h

@@ -65,6 +65,10 @@ class Socket : public VFS::FileInode
         m_metadata.nlinks--;
     }
 
+    virtual bool can_accept_connections() const = 0;
+
+    virtual bool can_read_data() const = 0;
+
     virtual ~Socket() = default;
 
   protected:

kernel/src/net/UnixSocket.h

@@ -17,6 +17,16 @@ class UnixSocket : public Socket
         return (m_state == Connected || m_state == Reset) && !m_data.size();
     }
 
+    bool can_read_data() const override
+    {
+        return (m_state == Connected || m_state == Reset) && m_data.size();
+    }
+
+    bool can_accept_connections() const override
+    {
+        return !m_listen_queue.is_empty();
+    }
+
     Result<usize> send(const u8*, usize, int) override;
     Result<usize> recv(u8*, usize, int) const override;
 

kernel/src/sys/exec.cpp

@@ -100,7 +100,7 @@ Result<u64> sys_execve(Registers* regs, SyscallArgs args)
     {
         auto& descriptor = current->fd_table[i];
         if (!descriptor.has_value()) continue;
-        if (descriptor->description->flags & O_CLOEXEC) { descriptor = {}; }
+        if (descriptor->flags & O_CLOEXEC) { descriptor = {}; }
     }
 
     if (VFS::is_setuid(inode)) current->auth.euid = current->auth.suid = inode->metadata().uid;

kernel/src/sys/file.cpp

@@ -124,28 +124,28 @@ Result<u64> sys_fcntl(Registers*, SyscallArgs args)
 
         current->fd_table[new_fd] = descriptor;
 
-        if (is_cloexec) current->fd_table[new_fd]->flags() |= O_CLOEXEC;
+        if (is_cloexec) current->fd_table[new_fd]->flags |= O_CLOEXEC;
         else
-            current->fd_table[new_fd]->flags() &= ~O_CLOEXEC;
+            current->fd_table[new_fd]->flags &= ~O_CLOEXEC;
 
         return (u64)new_fd;
     }
-    case F_GETFD: return (u64) !!(descriptor.flags() & O_CLOEXEC);
+    case F_GETFD: return (u64) !!(descriptor.flags & O_CLOEXEC);
     case F_SETFD: {
         int arg = (int)args[2];
-        if (arg == FD_CLOEXEC) descriptor.flags() |= O_CLOEXEC;
+        if (arg == FD_CLOEXEC) descriptor.flags |= O_CLOEXEC;
         else
-            descriptor.flags() &= ~O_CLOEXEC;
+            descriptor.flags &= ~O_CLOEXEC;
         return 0;
     }
-    case F_GETFL: return (u64)(descriptor.flags() & ~O_CLOEXEC);
+    case F_GETFL: return (u64)descriptor.status_flags();
     case F_SETFL: {
         int arg = (int)args[2];
 
-        descriptor.flags() &= ~(O_APPEND | O_NONBLOCK);
+        descriptor.status_flags() &= ~(O_APPEND | O_NONBLOCK);
         arg &= (O_APPEND | O_NONBLOCK);
 
-        descriptor.flags() |= arg;
+        descriptor.status_flags() |= arg;
 
         return 0;
     }
@@ -189,7 +189,7 @@ Result<u64> sys_dup2(Registers*, SyscallArgs args)
     if (newfd == oldfd) return (u64)newfd;
 
     current->fd_table[newfd] = descriptor;
-    current->fd_table[newfd]->flags() &= ~O_CLOEXEC;
+    current->fd_table[newfd]->flags &= ~O_CLOEXEC;
 
     return (u64)newfd;
 }

kernel/src/sys/open.cpp

@@ -7,7 +7,7 @@
 #include <bits/open-flags.h>
 
 // These flags are needed after open(), the rest only affect open().
-constexpr int FLAGS_TO_KEEP = O_RDWR | O_APPEND | O_NONBLOCK | O_CLOEXEC;
+constexpr int FLAGS_TO_KEEP = O_RDWR | O_APPEND | O_NONBLOCK;
 
 Result<u64> sys_openat(Registers*, SyscallArgs args)
 {
@@ -87,7 +87,8 @@ Result<u64> sys_openat(Registers*, SyscallArgs args)
     kdbgln("openat: opening file %s from dirfd %d, flags %d, mode %#o = fd %d", path.chars(), dirfd, flags, mode, fd);
 #endif
 
-    current->fd_table[fd] = FileDescriptor { TRY(make_shared<OpenFileDescription>(inode, flags & FLAGS_TO_KEEP)), 0 };
+    current->fd_table[fd] =
+        FileDescriptor { TRY(make_shared<OpenFileDescription>(inode, flags & FLAGS_TO_KEEP)), 0, flags & O_CLOEXEC };
 
     return (u64)fd;
 }

kernel/src/sys/poll.cpp

@@ -1,6 +1,7 @@
 #include "Log.h"
 #include "fs/VFS.h"
 #include "memory/MemoryManager.h"
+#include "net/Socket.h"
 #include "sys/Syscall.h"
 #include "thread/Scheduler.h"
 #include <bits/poll.h>
@@ -43,12 +44,27 @@ Result<u64> sys_poll(Registers* regs, SyscallArgs args)
             auto& inode = inodes[i];
             if (!inode) continue;
 
-            if (kfds[i].events & POLLIN && !inode->will_block_if_read())
+            if (kfds[i].events & POLLIN)
+            {
+                if (inode->type() == VFS::InodeType::Socket)
+                {
+                    auto socket = (Socket*)inode.ptr();
+                    if (socket->can_read_data() || socket->can_accept_connections())
                     {
                         fds_with_events++;
                         kfds[i].revents |= POLLIN;
                     }
                 }
+                else
+                {
+                    if (!inode->will_block_if_read())
+                    {
+                        fds_with_events++;
+                        kfds[i].revents |= POLLIN;
+                    }
+                }
+            }
+        }
 
         if (!fds_with_events && (timeout > 0 || infinite))
         {

kernel/src/thread/Thread.h

@@ -41,6 +41,7 @@ struct FileDescriptor
 {
     SharedPtr<OpenFileDescription> description;
     usize offset { 0 };
+    int flags { 0 };
 
     bool should_append();
     bool should_block();
@@ -52,7 +53,7 @@ struct FileDescriptor
         return description->inode;
     }
 
-    int& flags()
+    int& status_flags()
     {
         return description->flags;
     }

libluna/include/luna/CircularQueue.h

@@ -16,7 +16,7 @@ template <typename T, usize Size> class CircularQueue
     {
     }
 
-    bool is_empty()
+    bool is_empty() const
     {
         return m_tail.load() == m_head.load();
     }
@@ -76,7 +76,7 @@ template <typename T> class DynamicCircularQueue
         if (m_data) free_impl(m_data);
     }
 
-    bool is_empty()
+    bool is_empty() const
     {
         return m_tail.load() == m_head.load();
     }

libos/CMakeLists.txt

@@ -13,6 +13,7 @@ set(SOURCES
     src/Path.cpp
     src/Mode.cpp
     src/Prompt.cpp
+    src/LocalServer.cpp
 )
 
 add_library(os ${SOURCES})

libos/include/os/LocalServer.h

@@ -0,0 +1,132 @@
+#pragma once
+#include <luna/Result.h>
+#include <luna/SharedPtr.h>
+#include <luna/StringView.h>
+
+namespace os
+{
+    /**
+     * @brief A local domain server, used to communicate between processes on the same machine.
+     */
+    class LocalServer : public Shareable
+    {
+      public:
+        /**
+         * @brief Create a new server object and bind it to a local address.
+         *
+         * @param path The path to use for the server socket.
+         * @param blocking Whether the server should block if no connections are available when calling accept().
+         * @return Result<SharedPtr<LocalServer>> An error, or a new server object.
+         */
+        static Result<SharedPtr<LocalServer>> create(StringView path, bool blocking);
+
+        /**
+         * @brief Activate the server and start listening for connections.
+         *
+         * @param backlog The number of unaccepted connections to keep.
+         * @return Result<void> Whether the operation succeded.
+         */
+        Result<void> listen(int backlog);
+
+        /**
+         * @brief Return the underlying socket file descriptor used by this object.
+         *
+         * @return int The file descriptor.
+         */
+        int fd() const
+        {
+            return m_fd;
+        }
+
+        /**
+         * @brief An interface to communicate with clients connected to a local server.
+         */
+        class Client : public Shareable
+        {
+          public:
+            /**
+             * @brief Read arbitrary data from the client. The call will block if there is no data and the parent server
+             * object has not been created as non-blocking.
+             *
+             * @param buf The buffer to read data into.
+             * @param length The maximum amount of bytes to read.
+             * @return Result<usize> An error, or the number of bytes read.
+             */
+            Result<usize> recv(u8* buf, usize length);
+
+            /**
+             * @brief Read an object from the client. The call will block if there is no data and the parent server
+             * object has not been created as non-blocking.
+             *
+             * @tparam T The type of the object.
+             * @param out A reference to the object to read data into.
+             * @return Result<void> Whether the operation succeded.
+             */
+            template <typename T> Result<void> recv_typed(T& out)
+            {
+                TRY(recv((u8*)&out, sizeof(T)));
+                return {};
+            }
+
+            /**
+             * @brief Send arbitrary data to the client.
+             *
+             * @param buf The buffer to send data from.
+             * @param length The amount of bytes to send.
+             * @return Result<usize> An error, or the number of bytes actually sent.
+             */
+            Result<usize> send(const u8* buf, usize length);
+
+            /**
+             * @brief Send an object to the client.
+             *
+             * @tparam T The type of the object.
+             * @param out A reference to the object to send data from.
+             * @return Result<void> Whether the operation succeded.
+             */
+            template <typename T> Result<void> send_typed(const T& out)
+            {
+                TRY(send((const u8*)&out, sizeof(T)));
+                return {};
+            }
+
+            /**
+             * @brief Disconnect from the attached client.
+             *
+             * This will make any further reads on the client return ECONNRESET, and will make this object invalid.
+             */
+            void disconnect();
+
+            /**
+             * @brief Return the underlying socket file descriptor used by this object.
+             *
+             * @return int The file descriptor.
+             */
+            int fd() const
+            {
+                return m_fd;
+            }
+
+            Client(int fd);
+            ~Client();
+
+          private:
+            int m_fd;
+        };
+
+        /**
+         * @brief Accept a new incoming connection and return a handle to it. If there are no incoming connections,
+         * accept() either blocks until there is one (if the object was created with blocking=true), or returns EAGAIN
+         * (if the object was created with blocking=false).
+         *
+         * @return Result<SharedPtr<Client>> An error, or a handle to the new connection.
+         */
+        Result<SharedPtr<Client>> accept();
+
+        ~LocalServer();
+
+      private:
+        int m_fd;
+        bool m_blocking;
+    };
+}

libos/src/LocalServer.cpp

@@ -0,0 +1,87 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <os/FileSystem.h>
+#include <os/LocalServer.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+namespace os
+{
+    Result<SharedPtr<LocalServer>> LocalServer::create(StringView path, bool blocking)
+    {
+        auto server = TRY(make_shared<LocalServer>());
+
+        (void)os::FileSystem::remove(path); // We explicitly ignore any error here, either it doesn't exist (which is
+                                            // fine), or it cannot be removed, which will make bind() fail later.
+
+        int sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
+        if (sockfd < 0) return err(errno);
+
+        struct sockaddr_un un;
+        un.sun_family = AF_UNIX;
+        strncpy(un.sun_path, path.chars(), sizeof(un.sun_path));
+
+        if (bind(sockfd, (struct sockaddr*)&un, sizeof(un)) < 0)
+        {
+            close(sockfd);
+            return err(errno);
+        }
+
+        if (!blocking) { fcntl(sockfd, F_SETFL, O_NONBLOCK); }
+        server->m_blocking = blocking;
+
+        fcntl(sockfd, F_SETFD, FD_CLOEXEC);
+
+        server->m_fd = sockfd;
+        return server;
+    }
+
+    Result<void> LocalServer::listen(int backlog)
+    {
+        if (::listen(m_fd, backlog) < 0) return err(errno);
+        return {};
+    }
+
+    Result<SharedPtr<LocalServer::Client>> LocalServer::accept()
+    {
+        int fd = ::accept(m_fd, nullptr, nullptr);
+        if (fd < 0) return err(errno);
+        if (!m_blocking) fcntl(fd, F_SETFL, O_NONBLOCK);
+        return make_shared<Client>(fd);
+    }
+
+    LocalServer::~LocalServer()
+    {
+        close(m_fd);
+    }
+
+    LocalServer::Client::Client(int fd) : m_fd(fd)
+    {
+    }
+
+    LocalServer::Client::~Client()
+    {
+        if (m_fd >= 0) close(m_fd);
+    }
+
+    Result<usize> LocalServer::Client::recv(u8* buf, usize length)
+    {
+        ssize_t nread = read(m_fd, buf, length);
+        if (nread < 0) return err(errno);
+        return nread;
+    }
+
+    Result<usize> LocalServer::Client::send(const u8* buf, usize length)
+    {
+        ssize_t nwrite = write(m_fd, buf, length);
+        if (nwrite < 0) return err(errno);
+        return nwrite;
+    }
+
+    void LocalServer::Client::disconnect()
+    {
+        close(m_fd);
+        m_fd = -1;
+    }
+}

libui/CMakeLists.txt

@@ -0,0 +1,15 @@
+# The UI and graphics library for Luna.
+
+file(GLOB HEADERS include/ui/*.h)
+
+set(SOURCES
+    ${HEADERS}
+    src/Canvas.cpp
+    src/Color.cpp
+    src/Rect.cpp
+)
+
+add_library(ui ${SOURCES})
+target_compile_options(ui PRIVATE ${COMMON_FLAGS})
+target_include_directories(ui PUBLIC ${CMAKE_CURRENT_LIST_DIR}/include/)
+target_include_directories(ui PUBLIC ${LUNA_BASE}/usr/include)

libui/include/ui/Canvas.h

@@ -0,0 +1,56 @@
+#pragma once
+#include <luna/Result.h>
+#include <luna/Types.h>
+#include <ui/Color.h>
+#include <ui/Point.h>
+#include <ui/Rect.h>
+
+namespace ui
+{
+    /**
+     * @brief A drawable surface.
+     */
+    struct Canvas
+    {
+        int width;
+        int height;
+        int stride;
+        u8* ptr;
+
+        /**
+         * @brief Create a new Canvas object.
+         *
+         * @param ptr The memory to use for the canvas. It must be of at least width * height * 4 bytes of length.
+         * @param width The width of the canvas.
+         * @param height The height of the canvas.
+         * @return Canvas The new Canvas object.
+         */
+        static Canvas create(u8* ptr, int width, int height);
+
+        /**
+         * @brief Return a new Canvas that represents a subsection of the current one.
+         *
+         * @param rect The dimensions of the new canvas. If these exceed the bounds of the current canvas, they will be
+         * clamped.
+         * @return Canvas The new Canvas object.
+         */
+        Canvas subcanvas(Rect rect);
+
+        /**
+         * @brief Return the dimensions of the current canvas.
+         *
+         * @return Rect This canvas's dimensions, as a Rect object.
+         */
+        Rect rect()
+        {
+            return Rect { .pos = { 0, 0 }, .width = width, .height = height };
+        }
+
+        /**
+         * @brief Fill the entire canvas with one color.
+         *
+         * @param color The color to use.
+         */
+        void fill(Color color);
+    };
+};

libui/include/ui/Color.h

@@ -0,0 +1,63 @@
+#pragma once
+#include <luna/Types.h>
+
+namespace ui
+{
+    /**
+     * @brief A 32-bit ARGB color.
+     */
+    struct Color
+    {
+        union {
+            u32 raw;
+            u8 colors[4];
+        };
+
+        /**
+         * @brief Construct a new color from a 32-bit ARGB integer.
+         *
+         * @param raw The integer representing the color.
+         * @return constexpr Color The new color.
+         */
+        static constexpr Color from_u32(u32 raw)
+        {
+            return Color { .raw = raw };
+        }
+
+        /**
+         * @brief Construct a new color from its separate RGBA values (from 0 to 255).
+         *
+         * @param red The red value.
+         * @param green The green value.
+         * @param blue The blue value.
+         * @param alpha The alpha value.
+         * @return constexpr Color The new color.
+         */
+        static constexpr Color from_rgba(u8 red, u8 green, u8 blue, u8 alpha)
+        {
+            return Color { .colors = { blue, green, red, alpha } };
+        }
+
+        /**
+         * @brief Construct a new color from its separate RGB values (from 0 to 255).
+         *
+         * @param red The red value.
+         * @param green The green value.
+         * @param blue The blue value.
+         * @return constexpr Color The new color.
+         */
+        static constexpr Color from_rgb(u8 red, u8 green, u8 blue)
+        {
+            return from_rgba(red, green, blue, 0xff);
+        }
+    };
+
+    static constexpr Color WHITE = Color::from_rgb(0xff, 0xff, 0xff);
+    static constexpr Color BLACK = Color::from_rgb(0x00, 0x00, 0x00);
+
+    static constexpr Color BLUE = Color::from_rgb(0x00, 0x00, 0xff);
+    static constexpr Color GREEN = Color::from_rgb(0x00, 0xff, 0x00);
+    static constexpr Color RED = Color::from_rgb(0xff, 0x00, 0x00);
+
+    static constexpr Color CYAN = Color::from_rgb(0x00, 0xff, 0xff);
+};

libui/include/ui/Point.h

@@ -0,0 +1,13 @@
+#pragma once
+
+namespace ui
+{
+    /**
+     * @brief A point in 2D space.
+     */
+    struct Point
+    {
+        int x { 0 };
+        int y { 0 };
+    };
+}

libui/include/ui/Rect.h

@@ -0,0 +1,39 @@
+#pragma once
+#include <ui/Point.h>
+
+namespace ui
+{
+    /**
+     * @brief A simple rectangle.
+     */
+    struct Rect
+    {
+        Point pos;
+        int width;
+        int height;
+
+        /**
+         * @brief Check if a point is contained in this rectangle.
+         *
+         * @param point The point to check.
+         * @return true The point is contained inside the rectangle.
+         * @return false The point is not contained inside the rectangle.
+         */
+        bool contains(Point point);
+
+        /**
+         * @brief Normalize a point to fit inside this rectangle.
+         *
+         * @param point The original point.
+         * @return Point The normalized point.
+         */
+        Point normalize(Point point);
+
+        /**
+         * @brief Return a copy of this rectangle with no negative values (normalized to 0).
+         *
+         * @return Rect The new rectangle.
+         */
+        Rect absolute();
+    };
+}

libui/src/Canvas.cpp

@@ -0,0 +1,45 @@
+#include <string.h>
+#include <ui/Canvas.h>
+
+namespace ui
+{
+    Canvas Canvas::create(u8* ptr, int width, int height)
+    {
+        return Canvas { .width = width, .height = height, .stride = width, .ptr = ptr };
+    }
+
+    Canvas Canvas::subcanvas(Rect rect)
+    {
+        if (rect.pos.x < 0)
+        {
+            rect.pos.x = 0;
+            rect.width = rect.width + rect.pos.x;
+        }
+        if (rect.pos.y < 0)
+        {
+            rect.pos.y = 0;
+            rect.height = rect.height + rect.pos.y;
+        }
+        if (rect.pos.x + rect.width > width) rect.width = width - rect.pos.x;
+        if (rect.pos.y + rect.height > height) rect.height = height - rect.pos.y;
+
+        u8* p = ptr + rect.pos.x * sizeof(Color) + (rect.pos.y * sizeof(Color) * stride);
+
+        return Canvas { .width = rect.width, .height = rect.height, .stride = stride, .ptr = p };
+    }
+
+    void Canvas::fill(Color color)
+    {
+        u8* p = ptr;
+        for (int i = 0; i < height; i++)
+        {
+            u32* colorp = (u32*)p;
+            for (int j = 0; j < width; j++)
+            {
+                *colorp = color.raw;
+                colorp++;
+            }
+            p += stride * sizeof(Color);
+        }
+    }
+}

libui/src/Rect.cpp

@@ -0,0 +1,24 @@
+#include <ui/Rect.h>
+
+namespace ui
+{
+    bool Rect::contains(Point point)
+    {
+        return (point.x >= pos.x) && (point.y >= pos.y) && (point.x <= (pos.x + width)) &&
+               (point.y <= (pos.y + height));
+    }
+
+    Point Rect::normalize(Point point)
+    {
+        if (point.x < pos.x) point.x = pos.x;
+        if (point.y < pos.y) point.y = pos.y;
+        if (point.x > pos.x + width) point.x = pos.x + width;
+        if (point.y > pos.y + height) point.y = pos.y + height;
+        return point;
+    }
+
+    Rect Rect::absolute()
+    {
+        return Rect { ui::Point { pos.x < 0 ? 0 : pos.x, pos.y < 0 ? 0 : pos.y }, width, height };
+    }
+};

tools/install-headers.sh

@@ -8,10 +8,12 @@ cd $LUNA_ROOT
 mkdir -p $LUNA_BASE
 mkdir -p $LUNA_BASE/usr/include
 mkdir -p $LUNA_BASE/usr/include/luna
+mkdir -p $LUNA_BASE/usr/include/ui
 mkdir -p $LUNA_BASE/usr/include/os
 mkdir -p $LUNA_BASE/usr/include/moon
 
 cp --preserve=timestamps -RT libc/include/ $LUNA_BASE/usr/include
 cp --preserve=timestamps -RT libluna/include/luna/ $LUNA_BASE/usr/include/luna
+cp --preserve=timestamps -RT libui/include/ui/ $LUNA_BASE/usr/include/ui
 cp --preserve=timestamps -RT libos/include/os/ $LUNA_BASE/usr/include/os
 cp --preserve=timestamps -RT kernel/src/api/ $LUNA_BASE/usr/include/moon

tools/sources.sh

@@ -4,7 +4,7 @@ source $(dirname $0)/env.sh
 
 cd $LUNA_ROOT
 
-FOLDERS=(kernel libc libos libluna apps shell tests)
+FOLDERS=(kernel libc libos libui libluna apps shell tests)
 
 SOURCES=($(find ${FOLDERS[@]} -type f -name "*.cpp"))
 SOURCES+=($(find ${FOLDERS[@]} -type f -name "*.h"))

wind/CMakeLists.txt

@@ -0,0 +1,16 @@
+set(SOURCES
+    main.cpp
+    Screen.h
+    Screen.cpp
+    Mouse.h
+    Mouse.cpp
+    Window.h
+    Window.cpp
+)
+
+add_executable(wind ${SOURCES})
+target_compile_options(wind PRIVATE -Os ${COMMON_FLAGS} -Wno-write-strings)
+add_dependencies(wind libc)
+target_include_directories(wind PRIVATE ${LUNA_BASE}/usr/include ${CMAKE_CURRENT_LIST_DIR})
+target_link_libraries(wind PRIVATE os ui)
+install(TARGETS wind DESTINATION ${LUNA_BASE}/usr/bin)

wind/Mouse.cpp

@@ -0,0 +1,53 @@
+#include "Mouse.h"
+#include <os/File.h>
+
+Mouse::Mouse(ui::Canvas& screen)
+{
+    m_position.x = screen.width / 2;
+    m_position.y = screen.height / 2;
+    m_screen_rect = screen.rect();
+}
+
+void Mouse::draw(ui::Canvas& screen)
+{
+    auto canvas = screen.subcanvas(ui::Rect { m_position, 10, 10 });
+    canvas.fill(ui::WHITE);
+}
+
+void Mouse::update(const moon::MousePacket& packet)
+{
+    m_position.x += packet.xdelta;
+    m_position.y -= packet.ydelta;
+    m_position = m_screen_rect.normalize(m_position);
+
+    if ((packet.buttons & moon::MouseButton::Left) && !m_dragging_window)
+    {
+        g_windows.for_each_reversed([this](Window* window) {
+            if (!this->m_dragging_window && window->surface.contains(this->m_position))
+            {
+                this->m_dragging_window = window;
+                this->m_initial_drag_position = ui::Point { this->m_position.x - window->surface.pos.x,
+                                                            this->m_position.y - window->surface.pos.y };
+                os::println("Started drag: window at (%d,%d,%d,%d) with offset (%d,%d)", window->surface.pos.x,
+                            window->surface.pos.y, window->surface.width, window->surface.height,
+                            this->m_initial_drag_position.x, this->m_initial_drag_position.y);
+            }
+        });
+    }
+    else if (m_dragging_window && !(packet.buttons & moon::MouseButton::Left))
+    {
+        os::println("Stopped drag: window at (%d,%d,%d,%d) with offset (%d,%d)", m_dragging_window->surface.pos.x,
+                    m_dragging_window->surface.pos.y, m_dragging_window->surface.width,
+                    m_dragging_window->surface.height, this->m_initial_drag_position.x,
+                    this->m_initial_drag_position.y);
+        m_dragging_window = nullptr;
+    }
+
+    if (m_dragging_window)
+    {
+        m_dragging_window->surface.pos =
+            ui::Point { m_position.x - m_initial_drag_position.x, m_position.y - m_initial_drag_position.y };
+        m_dragging_window->surface = m_dragging_window->surface.absolute();
+        m_dragging_window->focus();
+    }
+}

wind/Mouse.h

@@ -0,0 +1,22 @@
+#pragma once
+#include "Screen.h"
+#include "Window.h"
+#include <moon/Mouse.h>
+#include <ui/Canvas.h>
+
+class Mouse
+{
+  public:
+    Mouse(ui::Canvas& screen);
+
+    void update(const moon::MousePacket& packet);
+
+    void draw(ui::Canvas& screen);
+
+  private:
+    ui::Point m_position;
+    ui::Rect m_screen_rect;
+
+    Window* m_dragging_window = nullptr;
+    ui::Point m_initial_drag_position;
+};

wind/Screen.cpp

@@ -0,0 +1,32 @@
+#include "Screen.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+Result<Screen> Screen::open()
+{
+    int fd = ::open("/dev/fb0", O_RDWR);
+    if (fd < 0) return err(errno);
+
+    int width = ioctl(fd, FB_GET_WIDTH);
+    int height = ioctl(fd, FB_GET_HEIGHT);
+
+    void* p = mmap(nullptr, width * height * BYTES_PER_PIXEL, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+    close(fd);
+
+    if (p == MAP_FAILED) { return err(errno); }
+
+    Screen screen;
+
+    screen.m_canvas = ui::Canvas::create((u8*)p, width, height);
+    screen.m_size = width * height * BYTES_PER_PIXEL;
+
+    return screen;
+}
+
+void Screen::sync()
+{
+    msync(m_canvas.ptr, size(), MS_SYNC);
+}

wind/Screen.h

@@ -0,0 +1,27 @@
+#pragma once
+#include <luna/OwnedPtr.h>
+#include <ui/Canvas.h>
+
+constexpr int BYTES_PER_PIXEL = 4;
+
+class Screen
+{
+  public:
+    static Result<Screen> open();
+
+    ui::Canvas& canvas()
+    {
+        return m_canvas;
+    }
+
+    int size() const
+    {
+        return m_size;
+    }
+
+    void sync();
+
+  private:
+    ui::Canvas m_canvas;
+    int m_size;
+};

wind/Window.cpp

@@ -0,0 +1,20 @@
+#include "Window.h"
+
+LinkedList<Window> g_windows;
+
+void Window::draw(ui::Canvas& screen)
+{
+    screen.subcanvas(surface).fill(color);
+}
+
+void Window::focus()
+{
+    // Bring the window to the front of the list.
+    g_windows.remove(this);
+    g_windows.append(this);
+}
+
+Window::Window(ui::Rect r, ui::Color c) : surface(r), color(c)
+{
+    g_windows.append(this);
+}

wind/Window.h

@@ -0,0 +1,19 @@
+#pragma once
+#include <luna/LinkedList.h>
+#include <ui/Canvas.h>
+#include <ui/Color.h>
+#include <ui/Rect.h>
+
+struct Window : public LinkedListNode<Window>
+{
+    ui::Rect surface;
+    ui::Color color;
+
+    Window(ui::Rect, ui::Color);
+
+    void focus();
+
+    void draw(ui::Canvas& screen);
+};
+
+extern LinkedList<Window> g_windows;

wind/main.cpp

@@ -0,0 +1,117 @@
+#include "Mouse.h"
+#include "Screen.h"
+#include "Window.h"
+#include <errno.h>
+#include <moon/Keyboard.h>
+#include <os/ArgumentParser.h>
+#include <os/File.h>
+#include <os/LocalServer.h>
+#include <pwd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/poll.h>
+#include <unistd.h>
+
+Result<int> luna_main(int argc, char** argv)
+{
+    StringView socket_path = "/tmp/wind.sock";
+    StringView user;
+
+    os::ArgumentParser parser;
+    parser.add_description("The display server for Luna's graphical user interface."_sv);
+    parser.add_system_program_info("wind"_sv);
+    parser.add_value_argument(socket_path, 's', "socket"_sv, "the path for the local IPC socket"_sv);
+    parser.add_value_argument(user, 'u', "user"_sv, "the user to run as"_sv);
+    parser.parse(argc, argv);
+
+    if (geteuid() != 0)
+    {
+        os::eprintln("error: wind must be run as root to initialize resources, run with --user=<USERNAME> to drop "
+                     "privileges afterwards");
+        return 1;
+    }
+
+    auto mouse = TRY(os::File::open("/dev/mouse", os::File::ReadOnly));
+    mouse->set_buffer(os::File::NotBuffered);
+    mouse->set_close_on_exec();
+
+    auto keyboard = TRY(os::File::open("/dev/kbd", os::File::ReadOnly));
+    keyboard->set_buffer(os::File::NotBuffered);
+    keyboard->set_close_on_exec();
+
+    auto screen = TRY(Screen::open());
+
+    auto server = TRY(os::LocalServer::create(socket_path, false));
+    TRY(server->listen(20));
+
+    Mouse mouse_pointer { screen.canvas() };
+
+    ioctl(STDIN_FILENO, TTYSETGFX, 1);
+
+    setpgid(0, 0);
+
+    int fd = open("/dev/null", O_RDONLY);
+    if (fd >= 0)
+    {
+        dup2(fd, STDIN_FILENO);
+        close(fd);
+    }
+
+    clearenv();
+
+    if (!user.is_empty())
+    {
+        auto* pwd = getpwnam(user.chars());
+        if (pwd)
+        {
+            setgid(pwd->pw_gid);
+            setuid(pwd->pw_uid);
+        }
+    }
+
+    ui::Color background = ui::BLACK;
+
+    TRY(make<Window>(ui::Rect { 200, 200, 600, 400 }, ui::GREEN));
+    TRY(make<Window>(ui::Rect { 100, 100, 300, 200 }, ui::RED));
+    TRY(make<Window>(ui::Rect { 600, 130, 350, 250 }, ui::CYAN));
+
+    Vector<SharedPtr<os::LocalServer::Client>> clients;
+
+    while (1)
+    {
+        screen.canvas().fill(background);
+        for (auto* window : g_windows) window->draw(screen.canvas());
+        mouse_pointer.draw(screen.canvas());
+        screen.sync();
+
+        struct pollfd fds[] = {
+            { .fd = mouse->fd(), .events = POLLIN, .revents = 0 },
+            { .fd = keyboard->fd(), .events = POLLIN, .revents = 0 },
+            { .fd = server->fd(), .events = POLLIN, .revents = 0 },
+        };
+
+        int rc = poll(fds, 3, 1000);
+        if (!rc) continue;
+        if (rc < 0) { os::println("poll: error: %s", strerror(errno)); }
+
+        if (fds[0].revents & POLLIN)
+        {
+            moon::MousePacket packet;
+            TRY(mouse->read_typed(packet));
+            mouse_pointer.update(packet);
+        }
+        if (fds[1].revents & POLLIN)
+        {
+            moon::KeyboardPacket packet;
+            TRY(keyboard->read_typed(packet));
+            background = ui::Color::from_rgb(0x00, 0x00, packet.key * 2);
+        }
+        if (fds[2].revents & POLLIN)
+        {
+            auto client = TRY(server->accept());
+            os::println("wind: New client connected!");
+            TRY(clients.try_append(client));
+        }
+    }
+}