gio/tests: Add testcase for bug 787731

Add testcase for function g_file_query_filesystem_info()
reporting outdated info for "filesystem::readonly" attribute
when said attribute was different in a previous mounted
partition in the same device (as GIO maintains a mounts cache
per 'st_dev' stat() member).

To trigger a mount operation, testcase uses program 'bindfs'
instead of 'mount --bind' as bindfs does not require root
privileges. And 'fusermount -u' command is used to unmount said
bindfs mount.

As a reference in Fedora, 'bindfs' is installed from 'bindfs'
package and 'fusermount' from 'fuse' package (this one is installed
by default as being part of 'System Tools' group).

The test creates a directory with a file in it, then mounts it
readonly over another directory (the mountpoint), it then checks
that g_file_query_filesystem_info() for the file in it indeed reports
"filesystem::readonly" as TRUE. Then unmounts and mounts again this
time rw (not readonly), it then checks again if g_file_query_filesystem_info()
is reporting "filesystem::readonly" as TRUE, if that's the case, it
confirms the bug by opening said file in write mode.

Testcase is only added for Unix builds.

https://bugzilla.gnome.org/show_bug.cgi?id=787731

gio/tests/Makefile.am

@@ -249,6 +249,7 @@ test_programs += \
 	stream-rw_all				\
 	unix-fd					\
 	unix-streams				\
+	g-file-info-filesystem-readonly		\
 	$(NULL)
 
 test_extra_programs += \

gio/tests/g-file-info-filesystem-readonly.c

@@ -0,0 +1,176 @@
+/* Testcase for bug in GIO function g_file_query_filesystem_info()
+ * Author: Nelson Benítez León
+ *
+ * This work is provided "as is"; redistribution and modification
+ * in whole or in part, in any medium, physical or electronic is
+ * permitted without restriction.
+ *
+ * This work is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * In no event shall the authors or contributors be liable for any
+ * direct, indirect, incidental, special, exemplary, or consequential
+ * damages (including, but not limited to, procurement of substitute
+ * goods or services; loss of use, data, or profits; or business
+ * interruption) however caused and on any theory of liability, whether
+ * in contract, strict liability, or tort (including negligence or
+ * otherwise) arising in any way out of the use of this software, even
+ * if advised of the possibility of such damage.
+ */
+
+#include <glib.h>
+#include <glib/gstdio.h>
+#include <gio/gio.h>
+#include <gio/gunixmounts.h>
+
+static void
+test_filesystem_readonly (gconstpointer with_mount_monitor)
+{
+  GFileInfo *file_info;
+  GFile *mounted_file;
+  GUnixMountMonitor *mount_monitor;
+  gchar *bindfs, *fusermount;
+  gchar *command_mount, *command_mount_ro, *command_umount;
+  gchar *curdir, *dir_to_mount, *dir_mountpoint;
+  gchar *file_in_mount, *file_in_mountpoint;
+
+  /* installed by package 'bindfs' in Fedora */
+  bindfs = g_find_program_in_path ("bindfs");
+
+  /* installed by package 'fuse' in Fedora */
+  fusermount = g_find_program_in_path ("fusermount");
+
+  if (bindfs == NULL || fusermount == NULL)
+    {
+      /* We need these because "mount --bind" requires root privileges */
+      g_test_skip ("'bindfs' and 'fusermount' commands are needed to run this test");
+      return;
+    }
+
+  curdir = g_get_current_dir ();
+  dir_to_mount = g_strdup_printf ("%s/dir_bindfs_to_mount", curdir);
+  file_in_mount = g_strdup_printf ("%s/example.txt", dir_to_mount);
+  dir_mountpoint = g_strdup_printf ("%s/dir_bindfs_mountpoint", curdir);
+
+  g_mkdir (dir_to_mount, 0777);
+  g_mkdir (dir_mountpoint, 0777);
+  if (! g_file_set_contents (file_in_mount, "Example", -1, NULL))
+    {
+      g_test_skip ("Failed to create file needed to proceed further with the test");
+      return;
+    }
+
+  if (with_mount_monitor)
+    {
+      mount_monitor = g_unix_mount_monitor_get ();
+    }
+
+  /* Use bindfs, which does not need root privileges, to mount the contents of one dir
+   * into another dir (and do the mount as readonly as per passed '-o ro' option) */
+  command_mount_ro = g_strdup_printf ("%s -n -o ro '%s' '%s'", bindfs, dir_to_mount, dir_mountpoint);
+  g_spawn_command_line_sync (command_mount_ro, NULL, NULL, NULL, NULL);
+
+  /* Let's check now, that the file is in indeed in a readonly filesystem */
+  file_in_mountpoint = g_strdup_printf ("%s/example.txt", dir_mountpoint);
+  mounted_file = g_file_new_for_path (file_in_mountpoint);
+
+  if (with_mount_monitor)
+    {
+     /* Let UnixMountMonitor process its 'mounts-changed'
+      * signal triggered by mount operation above */
+      while (g_main_context_iteration (NULL, FALSE));
+    }
+
+  file_info = g_file_query_filesystem_info (mounted_file,
+                                            G_FILE_ATTRIBUTE_FILESYSTEM_READONLY, NULL, NULL);
+  if (! g_file_info_get_attribute_boolean (file_info, G_FILE_ATTRIBUTE_FILESYSTEM_READONLY))
+    {
+      g_test_skip ("Failed to create readonly file needed to proceed further with the test");
+      return;
+    }
+
+  /* Now we unmount, and mount again but this time rw (not readonly) */
+  command_umount = g_strdup_printf ("%s -u '%s'", fusermount, dir_mountpoint);
+  g_spawn_command_line_sync (command_umount, NULL, NULL, NULL, NULL);
+  command_mount = g_strdup_printf ("%s -n '%s' '%s'", bindfs, dir_to_mount, dir_mountpoint);
+  g_spawn_command_line_sync (command_mount, NULL, NULL, NULL, NULL);
+
+  if (with_mount_monitor)
+    {
+     /* Let UnixMountMonitor process its 'mounts-changed' signal
+      * triggered by mount/umount operations above */
+      while (g_main_context_iteration (NULL, FALSE));
+    }
+
+  /* Now let's test if GIO will report the new filesystem state */
+  g_clear_object (&file_info);
+  g_clear_object (&mounted_file);
+  mounted_file = g_file_new_for_path (file_in_mountpoint);
+  file_info = g_file_query_filesystem_info (mounted_file,
+                                            G_FILE_ATTRIBUTE_FILESYSTEM_READONLY, NULL, NULL);
+
+  if (g_file_info_get_attribute_boolean (file_info, G_FILE_ATTRIBUTE_FILESYSTEM_READONLY))
+    {
+      /* ¡¡ GIO still reports filesystem as being Readonly !!
+       * Let's check if that's true by trying to write to file */
+      GFileOutputStream *write_stream;
+      write_stream = g_file_append_to (mounted_file, G_FILE_CREATE_NONE, NULL, NULL);
+      if (write_stream != NULL)
+        {
+          /* The file has been opened for writing without error, so ¡¡ GIO IS WRONG !! */
+          g_object_unref (write_stream);
+          g_test_fail (); /* Marking test as FAILED */
+        }
+    }
+
+  /* Clean up */
+  if (with_mount_monitor)
+    g_clear_object (&mount_monitor);
+
+  g_clear_object (&file_info);
+  g_clear_object (&mounted_file);
+  g_spawn_command_line_sync (command_umount, NULL, NULL, NULL, NULL); /* unmount */
+
+  g_remove (file_in_mount);
+  g_remove (dir_to_mount);
+  g_remove (dir_mountpoint);
+
+  g_free (bindfs);
+  g_free (fusermount);
+  g_free (curdir);
+  g_free (dir_to_mount);
+  g_free (dir_mountpoint);
+  g_free (command_mount);
+  g_free (command_mount_ro);
+  g_free (command_umount);
+  g_free (file_in_mount);
+  g_free (file_in_mountpoint);
+}
+
+int
+main (int argc, char *argv[])
+{
+  /* To avoid unnecessary D-Bus calls, see http://goo.gl/ir56j2 */
+  g_setenv ("GIO_USE_VFS", "local", FALSE);
+
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_bug_base ("http://bugzilla.gnome.org/");
+  g_test_bug ("787731");
+
+  g_test_add_data_func ("/g-file-info-filesystem-readonly/test-fs-ro",
+                        GINT_TO_POINTER (FALSE), test_filesystem_readonly);
+
+  /* This second test is using a running GUnixMountMonitor, so the calls to:
+   *  g_unix_mount_get(&time_read) - To fill the time_read parameter
+   *  g_unix_mounts_changed_since()
+   *
+   * made from inside g_file_query_filesystem_info() will use the mount_poller_time
+   * from the monitoring of /proc/self/mountinfo , while in the previous test new
+   * created timestamps are returned from those g_unix_mount* functions. */
+  g_test_add_data_func ("/g-file-info-filesystem-readonly/test-fs-ro-with-mount-monitor",
+                        GINT_TO_POINTER (TRUE), test_filesystem_readonly);
+
+  return g_test_run ();
+}

gio/tests/meson.build

@@ -114,6 +114,7 @@ if host_machine.system() != 'windows'
     'stream-rw_all',
     'unix-fd',
     'unix-streams',
+    'g-file-info-filesystem-readonly',
     'gschema-compile',
   ]