HackStudio: Embed a Terminal widget below the text editor

This will be very useful for running (and interacting with) programs
after we build them. :^)

DevTools/HackStudio/Makefile

@@ -2,6 +2,7 @@ include ../../Makefile.common
 
 OBJS = \
     Project.o \
+    TerminalWrapper.o \
     main.o
 
 APP = HackStudio
@@ -11,7 +12,7 @@ DEFINES += -DUSERLAND
 all: $(APP)
 
 $(APP): $(OBJS)
-	$(LD) -o $(APP) $(LDFLAGS) $(OBJS) -lgui -ldraw -lcore -lc
+	$(LD) -o $(APP) $(LDFLAGS) $(OBJS) -lvt -lgui -ldraw -lcore -lc
 
 .cpp.o:
 	@echo "CXX $<"; $(CXX) $(CXXFLAGS) -o $@ -c $<

DevTools/HackStudio/TerminalWrapper.cpp

@@ -0,0 +1,95 @@
+#include "TerminalWrapper.h"
+#include <AK/String.h>
+#include <LibCore/CConfigFile.h>
+#include <LibGUI/GBoxLayout.h>
+#include <LibVT/TerminalWidget.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+static void run_command(int ptm_fd, const String& command)
+{
+    pid_t pid = fork();
+    if (pid == 0) {
+        const char* tty_name = ptsname(ptm_fd);
+        if (!tty_name) {
+            perror("ptsname");
+            exit(1);
+        }
+        close(ptm_fd);
+        int pts_fd = open(tty_name, O_RDWR);
+        if (pts_fd < 0) {
+            perror("open");
+            exit(1);
+        }
+
+        // NOTE: It's okay if this fails.
+        (void)ioctl(0, TIOCNOTTY);
+
+        close(0);
+        close(1);
+        close(2);
+
+        int rc = dup2(pts_fd, 0);
+        if (rc < 0) {
+            perror("dup2");
+            exit(1);
+        }
+        rc = dup2(pts_fd, 1);
+        if (rc < 0) {
+            perror("dup2");
+            exit(1);
+        }
+        rc = dup2(pts_fd, 2);
+        if (rc < 0) {
+            perror("dup2");
+            exit(1);
+        }
+        rc = close(pts_fd);
+        if (rc < 0) {
+            perror("close");
+            exit(1);
+        }
+        rc = ioctl(0, TIOCSCTTY);
+        if (rc < 0) {
+            perror("ioctl(TIOCSCTTY)");
+            exit(1);
+        }
+        const char* args[4] = { "/bin/Shell", nullptr, nullptr, nullptr };
+        if (!command.is_empty()) {
+            args[1] = "-c";
+            args[2] = command.characters();
+        }
+        const char* envs[] = { "TERM=xterm", "PATH=/bin:/usr/bin:/usr/local/bin", nullptr };
+        rc = execve("/bin/Shell", const_cast<char**>(args), const_cast<char**>(envs));
+        if (rc < 0) {
+            perror("execve");
+            exit(1);
+        }
+        ASSERT_NOT_REACHED();
+    }
+}
+
+TerminalWrapper::TerminalWrapper(GWidget* parent)
+    : GWidget(parent)
+{
+    set_layout(make<GBoxLayout>(Orientation::Vertical));
+
+    int ptm_fd = open("/dev/ptmx", O_RDWR);
+    if (ptm_fd < 0) {
+        perror("open(ptmx)");
+        ASSERT_NOT_REACHED();
+    }
+
+    run_command(ptm_fd, "/bin/Shell");
+
+    RefPtr<CConfigFile> config = CConfigFile::get_for_app("Terminal");
+    m_terminal_widget = TerminalWidget::construct(ptm_fd, config);
+    add_child(*m_terminal_widget);
+}
+
+TerminalWrapper::~TerminalWrapper()
+{
+}

DevTools/HackStudio/TerminalWrapper.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <LibGUI/GWidget.h>
+
+class TerminalWidget;
+
+class TerminalWrapper final : public GWidget {
+    C_OBJECT(TerminalWrapper)
+public:
+    virtual ~TerminalWrapper() override;
+
+private:
+    explicit TerminalWrapper(GWidget* parent);
+
+    RefPtr<TerminalWidget> m_terminal_widget;
+};

DevTools/HackStudio/main.cpp

@@ -1,4 +1,5 @@
 #include "Project.h"
+#include "TerminalWrapper.h"
 #include <LibCore/CFile.h>
 #include <LibGUI/GAction.h>
 #include <LibGUI/GApplication.h>
@@ -39,13 +40,14 @@ int main(int argc, char** argv)
 
     auto toolbar = GToolBar::construct(widget);
 
-    auto splitter = GSplitter::construct(Orientation::Horizontal, widget);
-    auto project_list_view = GListView::construct(splitter);
+    auto outer_splitter = GSplitter::construct(Orientation::Horizontal, widget);
+    auto project_list_view = GListView::construct(outer_splitter);
     project_list_view->set_model(project->model());
     project_list_view->set_size_policy(SizePolicy::Fixed, SizePolicy::Fill);
     project_list_view->set_preferred_size(200, 0);
 
-    auto text_editor = GTextEditor::construct(GTextEditor::MultiLine, splitter);
+    auto inner_splitter = GSplitter::construct(Orientation::Vertical, outer_splitter);
+    auto text_editor = GTextEditor::construct(GTextEditor::MultiLine, inner_splitter);
     text_editor->set_ruler_visible(true);
 
     project_list_view->on_activation = [&](auto& index) {
@@ -58,6 +60,8 @@ int main(int argc, char** argv)
         text_editor->set_text(file->read_all());
     };
 
+    auto terminal_wrapper = TerminalWrapper::construct(inner_splitter);
+
     auto statusbar = GStatusBar::construct(widget);
 
     text_editor->on_cursor_change = [&] {