/*
 * Compile with:
 *
 * clang -fPIC -DANDROID -ffunction-sections -fdata-sections -Os -pipe -g3 frida-gum-example.c -o frida-gum-example -L. -lfrida-gum -llog -ldl -lm -pthread -Wl,--gc-sections,-z,noexecstack,-z,relro,-z,now -fuse-ld=gold -fuse-ld=gold -Wl,--icf=all
 *
 * Visit https://frida.re to learn more about Frida.
 */

#include "frida-gum.h"

#include <fcntl.h>
#include <unistd.h>

typedef struct _ExampleListener ExampleListener;
typedef enum _ExampleHookId ExampleHookId;

struct _ExampleListener
{
  GObject parent;

  guint num_calls;
};

enum _ExampleHookId
{
  EXAMPLE_HOOK_OPEN,
  EXAMPLE_HOOK_CLOSE
};

static void example_listener_iface_init (gpointer g_iface, gpointer iface_data);

#define EXAMPLE_TYPE_LISTENER (example_listener_get_type ())
G_DECLARE_FINAL_TYPE (ExampleListener, example_listener, EXAMPLE, LISTENER, GObject)
G_DEFINE_TYPE_EXTENDED (ExampleListener,
                        example_listener,
                        G_TYPE_OBJECT,
                        0,
                        G_IMPLEMENT_INTERFACE (GUM_TYPE_INVOCATION_LISTENER,
                            example_listener_iface_init))

int
main (int argc,
      char * argv[])
{
  GumInterceptor * interceptor;
  GumInvocationListener * listener;

  gum_init_embedded ();

  interceptor = gum_interceptor_obtain ();
  listener = g_object_new (EXAMPLE_TYPE_LISTENER, NULL);

  gum_interceptor_begin_transaction (interceptor);
  gum_interceptor_attach (interceptor,
      GSIZE_TO_POINTER (gum_module_find_export_by_name (NULL, "open")),
      listener,
      GSIZE_TO_POINTER (EXAMPLE_HOOK_OPEN));
  gum_interceptor_attach (interceptor,
      GSIZE_TO_POINTER (gum_module_find_export_by_name (NULL, "close")),
      listener,
      GSIZE_TO_POINTER (EXAMPLE_HOOK_CLOSE));
  gum_interceptor_end_transaction (interceptor);

  close (open ("/etc/hosts", O_RDONLY));
  close (open ("/etc/fstab", O_RDONLY));

  g_print ("[*] listener got %u calls\n", EXAMPLE_LISTENER (listener)->num_calls);

  gum_interceptor_detach (interceptor, listener);

  close (open ("/etc/hosts", O_RDONLY));
  close (open ("/etc/fstab", O_RDONLY));

  g_print ("[*] listener still has %u calls\n", EXAMPLE_LISTENER (listener)->num_calls);

  g_object_unref (listener);
  g_object_unref (interceptor);

  gum_deinit_embedded ();

  return 0;
}

static void
example_listener_on_enter (GumInvocationListener * listener,
                           GumInvocationContext * ic)
{
  ExampleListener * self = EXAMPLE_LISTENER (listener);
  ExampleHookId hook_id = GUM_IC_GET_FUNC_DATA (ic, ExampleHookId);

  switch (hook_id)
  {
    case EXAMPLE_HOOK_OPEN:
      g_print ("[*] open(\"%s\")\n", (const gchar *) gum_invocation_context_get_nth_argument (ic, 0));
      break;
    case EXAMPLE_HOOK_CLOSE:
      g_print ("[*] close(%d)\n", GPOINTER_TO_INT (gum_invocation_context_get_nth_argument (ic, 0)));
      break;
  }

  self->num_calls++;
}

static void
example_listener_on_leave (GumInvocationListener * listener,
                           GumInvocationContext * ic)
{
}

static void
example_listener_class_init (ExampleListenerClass * klass)
{
  (void) EXAMPLE_IS_LISTENER;
  (void) glib_autoptr_cleanup_ExampleListener;
}

static void
example_listener_iface_init (gpointer g_iface,
                             gpointer iface_data)
{
  GumInvocationListenerInterface * iface = g_iface;

  iface->on_enter = example_listener_on_enter;
  iface->on_leave = example_listener_on_leave;
}

static void
example_listener_init (ExampleListener * self)
{
}