[glib: 1/2] glocalfile: Only ignore FS full information for FUSE and ncpfs

[Philip Withnall <pwithnall src gnome org>]

commit 61a348f28728b0a0c7acbad08410d336b46d1e84
Author: Philip Withnall <withnall endlessm com>
Date:   Tue Jul 10 15:01:11 2018 +0200

    glocalfile: Only ignore FS full information for FUSE and ncpfs
    
    Previously, glocalfile.c would not set file system metadata for
    the free/used key for file systems which reported 0 free space. This is
    because some file systems don’t set that metadata when you call
    statfs(), so we can’t reliably report it. However, some do, and they
    can legitimately set f_bavail and f_bfree to 0 if the file system is
    full.
    
    In order to avoid that, always set the file system metadata unless the
    file system is FUSE or ncpfs.
    
    This is a partial revert of commit 0b9f24c1e1: instead of the changes
    made in that commit, I think we should maintain a blacklist of file
    systems which are known to not correctly report free space.
    
    Signed-off-by: Philip Withnall <withnall endlessm com>
    
    https://gitlab.gnome.org/GNOME/glib/issues/328

 gio/glocalfile.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)
---
diff --git a/gio/glocalfile.c b/gio/glocalfile.c
index 2d928cc31..30fa2281c 100644
--- a/gio/glocalfile.c
+++ b/gio/glocalfile.c
@@ -983,15 +983,20 @@ g_local_file_query_filesystem_info (GFile         *file,
   block_size = statfs_buffer.f_bsize;
   
   /* Many backends can't report free size (for instance the gvfs fuse
-     backend for backend not supporting this), and set f_bfree to 0,
-     but it can be 0 for real too. We treat the available == 0 and
-     free == 0 case as "both of these are invalid".
-   */
-#ifndef G_OS_WIN32
+   * backend for backend not supporting this), and set f_bfree to 0,
+   *  but it can be 0 for real too. We treat the available == 0 and
+   * free == 0 case as "both of these are invalid", but only on file systems
+   * which are known to not support this (otherwise we can omit metadata for
+   * systems which are legitimately full). */
+#if defined(__linux__)
   if (statfs_result == 0 &&
-      statfs_buffer.f_bavail == 0 && statfs_buffer.f_bfree == 0)
+      statfs_buffer.f_bavail == 0 && statfs_buffer.f_bfree == 0 &&
+      (/* linux/ncp_fs.h: NCP_SUPER_MAGIC == 0x564c */
+       statfs_buffer.f_type == 0x564c ||
+       /* man statfs: FUSE_SUPER_MAGIC == 0x65735546 */
+       statfs_buffer.f_type == 0x65735546))
     no_size = TRUE;
-#endif /* G_OS_WIN32 */
+#endif  /* __linux__ */
   
 #elif defined(USE_STATVFS)
   statfs_result = statvfs (local->filename, &statfs_buffer);