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/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()
+{
+}