[gnome-builder] flatpak: use additional pipe[2] for D-Bus transport

[Christian Hergert <chergert src gnome org>]

commit 17c759c8d2b29d3a9f66776b1d5fafb41868e1e7
Author: Christian Hergert <chergert redhat com>
Date:   Thu Nov 18 16:48:54 2021 -0800

    flatpak: use additional pipe[2] for D-Bus transport
    
    Instead of relying on stdin/stdout we can use a read/write pipe[2] pair.
    This is less brittle in the cases of random g_print() code landing in the
    gnome-builder-flatpak process.

 src/plugins/flatpak/daemon/gnome-builder-flatpak.c |  15 +-
 src/plugins/flatpak/gbp-flatpak-client.c           | 154 +++++++++++++++------
 2 files changed, 119 insertions(+), 50 deletions(-)
---
diff --git a/src/plugins/flatpak/daemon/gnome-builder-flatpak.c 
b/src/plugins/flatpak/daemon/gnome-builder-flatpak.c
index 42d7f92ac..de90278ed 100644
--- a/src/plugins/flatpak/daemon/gnome-builder-flatpak.c
+++ b/src/plugins/flatpak/daemon/gnome-builder-flatpak.c
@@ -166,6 +166,7 @@ main (gint argc,
   g_autoptr(GInputStream) stdin_stream = NULL;
   g_autoptr(GIOStream) stream = NULL;
   g_autoptr(GMainLoop) main_loop = NULL;
+  g_autoptr(GOptionContext) context = NULL;
   g_autoptr(GError) error = NULL;
 
   g_set_prgname ("gnome-builder-flatpak");
@@ -183,13 +184,19 @@ main (gint argc,
 
   g_log_set_default_handler (log_func, GINT_TO_POINTER (isatty (STDOUT_FILENO)));
 
-  if (!g_unix_set_fd_nonblocking (STDIN_FILENO, TRUE, &error) ||
-      !g_unix_set_fd_nonblocking (STDOUT_FILENO, TRUE, &error))
+  context = g_option_context_new ("");
+  g_option_context_add_main_entries (context, main_entries, NULL);
+
+  if (!g_option_context_parse (context, &argc, &argv, &error))
+    goto error;
+
+  if (!g_unix_set_fd_nonblocking (read_fileno, TRUE, &error) ||
+      !g_unix_set_fd_nonblocking (write_fileno, TRUE, &error))
     goto error;
 
   main_loop = g_main_loop_new (NULL, FALSE);
-  stdin_stream = g_unix_input_stream_new (STDIN_FILENO, FALSE);
-  stdout_stream = g_unix_output_stream_new (STDOUT_FILENO, FALSE);
+  stdin_stream = g_unix_input_stream_new (read_fileno, FALSE);
+  stdout_stream = g_unix_output_stream_new (write_fileno, FALSE);
   stream = g_simple_io_stream_new (stdin_stream, stdout_stream);
 
   if (!(connection = create_connection (stream, main_loop, &error)))
diff --git a/src/plugins/flatpak/gbp-flatpak-client.c b/src/plugins/flatpak/gbp-flatpak-client.c
index 5c5d19112..6bd0e0478 100644
--- a/src/plugins/flatpak/gbp-flatpak-client.c
+++ b/src/plugins/flatpak/gbp-flatpak-client.c
@@ -49,16 +49,102 @@ enum {
 
 G_DEFINE_FINAL_TYPE (GbpFlatpakClient, gbp_flatpak_client, IDE_TYPE_OBJECT)
 
+static void
+gbp_flatpak_client_reset (GbpFlatpakClient *self)
+{
+  g_autoptr(GInputStream) input_stream = NULL;
+  g_autoptr(GOutputStream) output_stream = NULL;
+  g_autoptr(GIOStream) io_stream = NULL;
+  g_autoptr(GDBusConnection) service_connection = NULL;
+  g_autoptr(IdeSubprocessLauncher) launcher = NULL;
+  g_autoptr(GError) error = NULL;
+  struct {
+    int read;
+    int write;
+  } pipe_fds[2] = {{-1, -1}, {-1, -1}};
+
+  IDE_ENTRY;
+
+  g_assert (GBP_IS_FLATPAK_CLIENT (self));
+
+  if (pipe ((int *)&pipe_fds[0]) != 0)
+    IDE_GOTO (handle_error);
+
+  if (pipe ((int *)&pipe_fds[1]) != 0)
+    IDE_GOTO (handle_error);
+
+  g_assert (pipe_fds[0].read >= 0);
+  g_assert (pipe_fds[0].write >= 0);
+  g_assert (pipe_fds[1].read >= 0);
+  g_assert (pipe_fds[1].write >= 0);
+
+  if (!g_unix_set_fd_nonblocking (pipe_fds[0].read, TRUE, &error) ||
+      !g_unix_set_fd_nonblocking (pipe_fds[0].write, TRUE, &error) ||
+      !g_unix_set_fd_nonblocking (pipe_fds[1].read, TRUE, &error) ||
+      !g_unix_set_fd_nonblocking (pipe_fds[1].write, TRUE, &error))
+    IDE_GOTO (handle_error);
+
+  input_stream = g_unix_input_stream_new (pipe_fds[0].read, TRUE);
+  pipe_fds[0].read = -1;
+
+  output_stream = g_unix_output_stream_new (pipe_fds[1].write, TRUE);
+  pipe_fds[1].write = -1;
+
+  io_stream = g_simple_io_stream_new (input_stream, output_stream);
+  service_connection = g_dbus_connection_new_sync (io_stream, NULL,
+                                                   G_DBUS_CONNECTION_FLAGS_DELAY_MESSAGE_PROCESSING,
+                                                   NULL, NULL, NULL);
+  g_dbus_connection_set_exit_on_close (service_connection, FALSE);
+
+  launcher = ide_subprocess_launcher_new (0);
+  ide_subprocess_launcher_set_cwd (launcher, g_get_home_dir ());
+  ide_subprocess_launcher_set_clear_env (launcher, FALSE);
+
+  if (ide_log_get_verbosity () > 0)
+    ide_subprocess_launcher_setenv (launcher, "G_MESSAGES_DEBUG", "all", TRUE);
+
+  if (g_getenv ("BUILDER_FLATPAK_DEBUG") != NULL)
+    {
+      ide_subprocess_launcher_setenv (launcher, "G_DEBUG", "fatal-criticals", TRUE);
+      ide_subprocess_launcher_push_argv (launcher, "gdbserver");
+      ide_subprocess_launcher_push_argv (launcher, "localhost:8888");
+    }
+
+  ide_subprocess_launcher_take_fd (launcher, pipe_fds[1].read, 3);
+  pipe_fds[1].read = -1;
+
+  ide_subprocess_launcher_take_fd (launcher, pipe_fds[0].write, 4);
+  pipe_fds[0].write = -1;
+
+  ide_subprocess_launcher_push_argv (launcher, PACKAGE_LIBEXECDIR"/gnome-builder-flatpak");
+  ide_subprocess_launcher_push_argv (launcher, "--read-fd=3");
+  ide_subprocess_launcher_push_argv (launcher, "--write-fd=4");
+
+  g_set_object (&self->connection, service_connection);
+
+  ide_object_lock (IDE_OBJECT (self));
+  if (self->supervisor != NULL)
+    ide_subprocess_supervisor_set_launcher (self->supervisor, launcher);
+  ide_object_unlock (IDE_OBJECT (self));
+
+handle_error:
+  if (error != NULL)
+    g_warning ("Error resetting daemon: %s", error->message);
+
+  if (pipe_fds[0].read != -1)  close (pipe_fds[0].read);
+  if (pipe_fds[0].write != -1) close (pipe_fds[0].write);
+  if (pipe_fds[1].read != -1)  close (pipe_fds[1].read);
+  if (pipe_fds[1].write != -1) close (pipe_fds[1].write);
+
+  IDE_EXIT;
+}
+
 static void
 gbp_flatpak_client_subprocess_spawned (GbpFlatpakClient        *self,
                                        IdeSubprocess           *subprocess,
                                        IdeSubprocessSupervisor *supervisor)
 {
-  g_autoptr(GIOStream) stream = NULL;
-  GOutputStream *output;
-  GInputStream *input;
   GList *queued;
-  gint fd;
 
   IDE_ENTRY;
 
@@ -69,27 +155,13 @@ gbp_flatpak_client_subprocess_spawned (GbpFlatpakClient        *self,
   ide_object_lock (IDE_OBJECT (self));
 
   g_assert (self->service == NULL);
+  g_assert (self->connection != NULL);
+
+  ide_subprocess_supervisor_set_launcher (self->supervisor, NULL);
 
   if (self->state == STATE_SPAWNING)
     self->state = STATE_RUNNING;
 
-  input = ide_subprocess_get_stdout_pipe (subprocess);
-  output = ide_subprocess_get_stdin_pipe (subprocess);
-  stream = g_simple_io_stream_new (input, output);
-
-  g_assert (G_IS_UNIX_INPUT_STREAM (input));
-  g_assert (G_IS_UNIX_OUTPUT_STREAM (output));
-
-  fd = g_unix_input_stream_get_fd (G_UNIX_INPUT_STREAM (input));
-  g_unix_set_fd_nonblocking (fd, TRUE, NULL);
-
-  fd = g_unix_output_stream_get_fd (G_UNIX_OUTPUT_STREAM (output));
-  g_unix_set_fd_nonblocking (fd, TRUE, NULL);
-
-  self->connection = g_dbus_connection_new_sync (stream, NULL,
-                                                 G_DBUS_CONNECTION_FLAGS_DELAY_MESSAGE_PROCESSING,
-                                                 NULL, NULL, NULL);
-  g_dbus_connection_set_exit_on_close (self->connection, FALSE);
   g_dbus_connection_start_message_processing (self->connection);
 
   self->service = ipc_flatpak_service_proxy_new_sync (self->connection,
@@ -134,14 +206,15 @@ gbp_flatpak_client_subprocess_exited (GbpFlatpakClient        *self,
   g_assert (IDE_IS_SUBPROCESS_SUPERVISOR (supervisor));
 
   ide_object_lock (IDE_OBJECT (self));
-
   if (self->state == STATE_RUNNING)
     self->state = STATE_SPAWNING;
-
+  g_clear_object (&self->connection);
   g_clear_object (&self->service);
-
   ide_object_unlock (IDE_OBJECT (self));
 
+  if (!ide_object_in_destruction (IDE_OBJECT (self)))
+    gbp_flatpak_client_reset (self);
+
   IDE_EXIT;
 }
 
@@ -154,6 +227,9 @@ gbp_flatpak_client_destroy (IdeObject *object)
   if (supervisor != NULL)
     ide_subprocess_supervisor_stop (supervisor);
 
+  g_clear_object (&self->connection);
+  g_clear_object (&self->service);
+
   IDE_OBJECT_CLASS (gbp_flatpak_client_parent_class)->destroy (object);
 }
 
@@ -161,47 +237,33 @@ static void
 gbp_flatpak_client_parent_set (IdeObject *object,
                                IdeObject *parent)
 {
-  GbpFlatpakClient *self=  (GbpFlatpakClient *)object;
-  g_autoptr(IdeSubprocessLauncher) launcher = NULL;
+  GbpFlatpakClient *self = (GbpFlatpakClient *)object;
+
+  IDE_ENTRY;
 
   g_assert (GBP_IS_FLATPAK_CLIENT (self));
   g_assert (!parent || IDE_IS_OBJECT (parent));
 
   if (parent == NULL)
-    return;
+    IDE_EXIT;
 
   ide_object_lock (IDE_OBJECT (self));
-
-  launcher = ide_subprocess_launcher_new (G_SUBPROCESS_FLAGS_STDOUT_PIPE |
-                                          G_SUBPROCESS_FLAGS_STDIN_PIPE);
-  ide_subprocess_launcher_set_cwd (launcher, g_get_home_dir ());
-  ide_subprocess_launcher_set_clear_env (launcher, FALSE);
-
-  if (g_getenv ("BUILDER_FLATPAK_DEBUG") != NULL)
-    {
-      ide_subprocess_launcher_setenv (launcher, "G_DEBUG", "fatal-criticals", TRUE);
-      ide_subprocess_launcher_push_argv (launcher, "gdbserver");
-      ide_subprocess_launcher_push_argv (launcher, "localhost:8888");
-    }
-
-  ide_subprocess_launcher_push_argv (launcher, PACKAGE_LIBEXECDIR"/gnome-builder-flatpak");
-
   self->supervisor = ide_subprocess_supervisor_new ();
-  ide_subprocess_supervisor_set_launcher (self->supervisor, launcher);
-
   g_signal_connect_object (self->supervisor,
                            "spawned",
                            G_CALLBACK (gbp_flatpak_client_subprocess_spawned),
                            self,
                            G_CONNECT_SWAPPED);
-
   g_signal_connect_object (self->supervisor,
                            "exited",
                            G_CALLBACK (gbp_flatpak_client_subprocess_exited),
                            self,
                            G_CONNECT_SWAPPED);
-
   ide_object_unlock (IDE_OBJECT (self));
+
+  gbp_flatpak_client_reset (self);
+
+  IDE_EXIT;
 }
 
 static void