[gparted] Ensure FS_Info (blkid) cache is populated before first use (#131)

[Curtis Gedak <gedakc src gnome org>]

commit 52ed42de28b16a8eb6efb8dda54059231af379fd
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Sun Jan 31 12:51:13 2021 +0000

    Ensure FS_Info (blkid) cache is populated before first use (#131)
    
    Now we always want to run blkid naming all paths, ensure the FS_Info
    cache is explicitly loaded first.  Report an error if not done so and
    remove the cache loading code from running blkid without naming all
    paths.  Fewer code paths to consider and reason about.
    
    Closes #131 - GParted hangs when non-named device is hung

 include/FS_Info.h |  2 +-
 src/FS_Info.cc    | 37 ++++++++++++++++++++++++-------------
 2 files changed, 25 insertions(+), 14 deletions(-)
---
diff --git a/include/FS_Info.h b/include/FS_Info.h
index 44e14a28..19c2e10f 100644
--- a/include/FS_Info.h
+++ b/include/FS_Info.h
@@ -46,7 +46,7 @@ public:
        static Glib::ustring get_path_by_label( const Glib::ustring & label );
 
 private:
-       static void initialize_if_required();
+       static bool not_initialised_then_error();
        static void set_commands_found();
        static const FS_Entry & get_cache_entry_by_path( const Glib::ustring & path );
        static void load_fs_info_cache(const std::vector<Glib::ustring>& paths);
diff --git a/src/FS_Info.cc b/src/FS_Info.cc
index fbd754f9..dbfba9a6 100644
--- a/src/FS_Info.cc
+++ b/src/FS_Info.cc
@@ -19,6 +19,7 @@
 #include "BlockSpecial.h"
 #include "Utils.h"
 
+#include <iostream>
 #include <glibmm/ustring.h>
 #include <glibmm/miscutils.h>
 #include <glibmm/shell.h>
@@ -61,7 +62,9 @@ void FS_Info::load_cache_for_paths(const std::vector<Glib::ustring>& paths)
 // Retrieve the file system type for the path
 Glib::ustring FS_Info::get_fs_type( const Glib::ustring & path )
 {
-       initialize_if_required();
+       if (not_initialised_then_error())
+               return "";
+
        const FS_Entry & fs_entry = get_cache_entry_by_path( path );
        Glib::ustring fs_type = fs_entry.type;
        Glib::ustring fs_sec_type = fs_entry.sec_type;
@@ -93,7 +96,12 @@ Glib::ustring FS_Info::get_fs_type( const Glib::ustring & path )
 // Retrieve the label and set found indicator for the path
 Glib::ustring FS_Info::get_label( const Glib::ustring & path, bool & found )
 {
-       initialize_if_required();
+       if (not_initialised_then_error())
+       {
+               found = false;
+               return "";
+       }
+
        BlockSpecial bs = BlockSpecial( path );
        for ( unsigned int i = 0 ; i < fs_info_cache.size() ; i ++ )
                if ( bs == fs_info_cache[i].path )
@@ -119,7 +127,9 @@ Glib::ustring FS_Info::get_label( const Glib::ustring & path, bool & found )
 // Retrieve the uuid given for the path
 Glib::ustring FS_Info::get_uuid( const Glib::ustring & path )
 {
-       initialize_if_required();
+       if (not_initialised_then_error())
+               return "";
+
        const FS_Entry & fs_entry = get_cache_entry_by_path( path );
        return fs_entry.uuid;
 }
@@ -127,7 +137,9 @@ Glib::ustring FS_Info::get_uuid( const Glib::ustring & path )
 // Retrieve the path given the uuid
 Glib::ustring FS_Info::get_path_by_uuid( const Glib::ustring & uuid )
 {
-       initialize_if_required();
+       if (not_initialised_then_error())
+               return "";
+
        for ( unsigned int i = 0 ; i < fs_info_cache.size() ; i ++ )
                if ( uuid == fs_info_cache[i].uuid )
                        return fs_info_cache[i].path.m_name;
@@ -138,7 +150,9 @@ Glib::ustring FS_Info::get_path_by_uuid( const Glib::ustring & uuid )
 // Retrieve the path given the label
 Glib::ustring FS_Info::get_path_by_label( const Glib::ustring & label )
 {
-       initialize_if_required();
+       if (not_initialised_then_error())
+               return "";
+
        update_fs_info_cache_all_labels();
        for ( unsigned int i = 0 ; i < fs_info_cache.size() ; i ++ )
                if ( label == fs_info_cache[i].label )
@@ -149,17 +163,14 @@ Glib::ustring FS_Info::get_path_by_label( const Glib::ustring & label )
 
 // Private methods
 
-void FS_Info::initialize_if_required()
+bool FS_Info::not_initialised_then_error()
 {
-       if ( ! fs_info_cache_initialized )
-       {
-               set_commands_found();
-               std::vector<Glib::ustring> empty;
-               load_fs_info_cache(empty);
-               fs_info_cache_initialized = true;
-       }
+       if (! fs_info_cache_initialized)
+               std::cerr << "GParted Bug: FS_Info (blkid) cache not loaded before use" << std::endl;
+       return ! fs_info_cache_initialized;
 }
 
+
 void FS_Info::set_commands_found()
 {
        //Set status of commands found