[gparted] Make FS_Info (blkid) cache incrementally loadable (#148)

[Curtis Gedak <gedakc src gnome org>]

commit 1e813d83a5088d3afaaac96dd1bacba3d146f282
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Mon Mar 29 20:31:48 2021 +0100

    Make FS_Info (blkid) cache incrementally loadable (#148)
    
    Since changes for issue #131 "GParted hangs when non-named device is
    hung" FS_Info cache is initialised, cleared and loaded via one call to
    load_cache_for_paths().  It runs blkid for named or found disk devices
    and associated found partitions from /proc/partitions, rather than
    running blkid and letting it report for all block devices.
    
    To avoid the possibility of using blkid on an encryption mapping on a
    non-specified and possibly hung block device GParted can't just specify
    all encryption mappings.  Instead only encryption mappings which belong
    to the above identified block devices should be probed.  That requires
    identifying LUKS encryption data in the block devices first so will
    require subsequently loading additional data into the FS_Info cache and
    running blkid again.
    
    To accommodate this make the FS_Info cache incrementally loadable,
    rather than doing everything in a single call to load_cache_for_paths().
    Have a separate clear_cache() call which initialises and clears the
    cache and make load_cache_for_paths() just run blkid and insert data for
    the named paths.
    
    Closes 148 - Encrypted file systems are no longer recognised

 include/FS_Info.h   |  1 +
 src/FS_Info.cc      | 12 ++++++++++--
 src/GParted_Core.cc |  1 +
 3 files changed, 12 insertions(+), 2 deletions(-)
---
diff --git a/include/FS_Info.h b/include/FS_Info.h
index 5421ab87..e0a40c19 100644
--- a/include/FS_Info.h
+++ b/include/FS_Info.h
@@ -38,6 +38,7 @@ struct FS_Entry
 class FS_Info
 {
 public:
+       static void clear_cache();
        static void load_cache_for_paths(const std::vector<Glib::ustring>& paths);
        static Glib::ustring get_fs_type( const Glib::ustring & path );
        static Glib::ustring get_label( const Glib::ustring & path, bool & found );
diff --git a/src/FS_Info.cc b/src/FS_Info.cc
index c095db13..4bd22165 100644
--- a/src/FS_Info.cc
+++ b/src/FS_Info.cc
@@ -51,15 +51,23 @@ bool FS_Info::need_blkid_vfat_cache_update_workaround = true;
 std::vector<FS_Entry> FS_Info::fs_info_cache;
 
 
-void FS_Info::load_cache_for_paths(const std::vector<Glib::ustring>& paths)
+void FS_Info::clear_cache()
 {
        set_commands_found();
        fs_info_cache.clear();
-       run_blkid_load_cache(paths);
        fs_info_cache_initialized = true;
 }
 
 
+void FS_Info::load_cache_for_paths(const std::vector<Glib::ustring>& paths)
+{
+       if (not_initialised_then_error())
+               return;
+
+       run_blkid_load_cache(paths);
+}
+
+
 // Retrieve the file system type for the path
 Glib::ustring FS_Info::get_fs_type( const Glib::ustring & path )
 {
diff --git a/src/GParted_Core.cc b/src/GParted_Core.cc
index 7841868d..afbd116a 100644
--- a/src/GParted_Core.cc
+++ b/src/GParted_Core.cc
@@ -248,6 +248,7 @@ void GParted_Core::set_devices_thread( std::vector<Device> * pdevices )
        }
 
        // Initialise and load caches needed for content discovery.
+       FS_Info::clear_cache();
        const std::vector<Glib::ustring>& device_and_partition_paths =
                        Proc_Partitions_Info::get_device_and_partition_paths_for(device_paths);
        FS_Info::load_cache_for_paths(device_and_partition_paths);