[gnome-disk-utility] restore: don't attempt to open target read-only

[Kai Lüke <kailueke src gnome org>]

commit bfd153d73d1e9a32b1afab01566ae87779d2ed78
Author: Will Thompson <will willthompson co uk>
Date:   Tue Jan 16 16:36:48 2018 +0000

    restore: don't attempt to open target read-only
    
    This code seems to be duplicated from gducreatediskimagedialog.c, but in
    this context we need 'fd' to be writable. We could still attempt to
    open() the device directly (with O_WRONLY) but as the comment says, by
    definition /dev/sr* is read-only by nature (or at least, cannot be
    written to in this way), so it is unlikely to be of any use.
    
    In any case, in practice this code path will never be taken since the
    "Restore" action is not available for optical media.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=792581

 src/disks/gdurestorediskimagedialog.c |   56 ++++++++++++---------------------
 1 files changed, 20 insertions(+), 36 deletions(-)
---
diff --git a/src/disks/gdurestorediskimagedialog.c b/src/disks/gdurestorediskimagedialog.c
index 2dfdc86..1110bc5 100644
--- a/src/disks/gdurestorediskimagedialog.c
+++ b/src/disks/gdurestorediskimagedialog.c
@@ -690,49 +690,33 @@ copy_thread_func (gpointer user_data)
   gint fd = -1;
   gint buffer_size;
   guint64 num_bytes_completed = 0;
+  GUnixFDList *fd_list = NULL;
+  GVariant *fd_index = NULL;
 
   /* default to 1 MiB blocks */
   buffer_size = (1 * 1024 * 1024);
 
-  /* Most OSes put ACLs for logged-in users on /dev/sr* nodes (this is
-   * so CD burning tools etc. work) so see if we can open the device
-   * file ourselves. If so, great, since this avoids a polkit dialog.
-   *
-   * As opposed to udisks' OpenForBackup() we also avoid O_EXCL since
-   * the disc is read-only by its very nature. As a side-effect this
-   * allows creating a disk image of a mounted disc.
-   */
-  if (g_str_has_prefix (udisks_block_get_device (data->block), "/dev/sr"))
-    {
-      fd = open (udisks_block_get_device (data->block), O_RDONLY);
-    }
+  /* request the fd from udisks */
+  if (!udisks_block_call_open_for_restore_sync (data->block,
+                                                g_variant_new ("a{sv}", NULL), /* options */
+                                                NULL, /* fd_list */
+                                                &fd_index,
+                                                &fd_list,
+                                                NULL, /* cancellable */
+                                                &error))
+    goto out;
 
-  /* Otherwise, request the fd from udisks */
-  if (fd == -1)
+  fd = g_unix_fd_list_get (fd_list, g_variant_get_handle (fd_index), &error);
+  if (error != NULL)
     {
-      GUnixFDList *fd_list = NULL;
-      GVariant *fd_index = NULL;
-      if (!udisks_block_call_open_for_restore_sync (data->block,
-                                                    g_variant_new ("a{sv}", NULL), /* options */
-                                                    NULL, /* fd_list */
-                                                    &fd_index,
-                                                    &fd_list,
-                                                    NULL, /* cancellable */
-                                                    &error))
-        goto out;
-
-      fd = g_unix_fd_list_get (fd_list, g_variant_get_handle (fd_index), &error);
-      if (error != NULL)
-        {
-          g_prefix_error (&error,
-                          "Error extracing fd with handle %d from D-Bus message: ",
-                          g_variant_get_handle (fd_index));
-          goto out;
-        }
-      if (fd_index != NULL)
-        g_variant_unref (fd_index);
-      g_clear_object (&fd_list);
+      g_prefix_error (&error,
+                      "Error extracing fd with handle %d from D-Bus message: ",
+                      g_variant_get_handle (fd_index));
+      goto out;
     }
+  if (fd_index != NULL)
+    g_variant_unref (fd_index);
+  g_clear_object (&fd_list);
 
   g_assert (fd != -1);