builder: Unbreak hardlinks when eu-stripping

Otherwise this breaks with rofiles-fuse if the build produces
hardlinked installed files. For instance, as done by mesa.

builder/builder-module.c

@@ -997,6 +997,12 @@ builder_module_handle_debuginfo (BuilderModule  *self,
                     }
 
                   g_print ("stripping %s to %s\n", path, debug_path);
+
+                  /* Some files are hardlinked and eu-strip modifies in-place,
+                     which breaks rofiles-fuse. Unlink them */
+                  if (!flatpak_unbreak_hardlink (file, error))
+                    return FALSE;
+
                   if (!eu_strip (error, "--remove-comment", "--reloc-debug-sections",
                                  "-f", debug_path,
                                  "-F", real_debug_path,

common/flatpak-utils.c

@@ -498,6 +498,36 @@ flatpak_get_bwrap (void)
   return HELPER;
 }
 
+gboolean
+flatpak_unbreak_hardlink (GFile *file, GError **error)
+{
+  g_autofree char *path = g_file_get_path (file);
+  struct stat st_buf;
+
+  if (stat (path, &st_buf) == 0 && st_buf.st_nlink > 1)
+    {
+      g_autoptr(GFile) dir = g_file_get_parent (file);
+      g_autoptr(GFile) tmp = NULL;
+
+      tmp = flatpak_file_new_tmp_in (dir, ".eustripXXXXXX", error);
+      if (tmp == NULL)
+        return FALSE;
+
+      if (!g_file_copy (file, tmp,
+                        G_FILE_COPY_OVERWRITE,
+                        NULL, NULL, NULL, error))
+        return FALSE;
+
+      if (rename (flatpak_file_get_path_cached (tmp), path) != 0)
+        {
+          glnx_set_error_from_errno (error);
+          return FALSE;
+        }
+    }
+
+  return TRUE;
+}
+
 /* We only migrate the user dir, because thats what most people used with xdg-app,
  * and its where all per-user state/config are stored.
  */

common/flatpak-utils.h

@@ -78,6 +78,7 @@ void flatpak_migrate_from_xdg_app (void);
 GFile *flatpak_file_new_tmp_in (GFile *dir,
                                 const char *templatename,
                                 GError        **error);
+gboolean flatpak_unbreak_hardlink (GFile *file, GError **error);
 
 gboolean flatpak_write_update_checksum (GOutputStream  *out,
                                         gconstpointer   data,