[gnome-commander/gcmd-1-12: 1/2] set_fs_directory_to_opposite: Fix segv when no directory is chosen

[Uwe Scholz <uwescholz src gnome org>]

commit d8c97aade32c7146ea4c24880476bf2dc6d05baf
Author: Mamoru TASAKA <mtasaka fedoraproject org>
Date:   Wed May 12 00:34:45 2021 +0900

    set_fs_directory_to_opposite: Fix segv when no directory is chosen
    
    When doing CTRL+LEFT or CTRL+RIGHT, "GnomeCmdMainWin::set_fs_directory_to_opposite" is executed.
    When a file list is chosen and active, set_fs_directory_to_opposite try to set the opposite
    directory to the chosen list.
    However, when no file is chosen and any file list is inactive, get_selected_file() returns nullptr,
    this leads file->GetGfileAttributeUInt32() segfault.
    
    (Note that with optimization, even if file is nullptr, file->GetGfileAttributeUInt32() will be
     usually called, because compiler guesses file cannot be null when compilation.
     But in file->GetGfileAttributeUInt32(), this->gFile is accessed, which causes segfault anyway.)
    
    To fix this, check if get_selected_file() returned non-null pointer or not (i.e.
    some file list is active or not.)

 src/gnome-cmd-main-win.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/gnome-cmd-main-win.cc b/src/gnome-cmd-main-win.cc
index 783b1da2..0d024754 100644
--- a/src/gnome-cmd-main-win.cc
+++ b/src/gnome-cmd-main-win.cc
@@ -1253,7 +1253,7 @@ void GnomeCmdMainWin::set_fs_directory_to_opposite(FileSelectorID fsID)
     {
         GnomeCmdFile *file = other->file_list()->get_selected_file();
 
-        if (file->GetGfileAttributeUInt32(G_FILE_ATTRIBUTE_STANDARD_TYPE) == G_FILE_TYPE_DIRECTORY)
+        if (file && (file->GetGfileAttributeUInt32(G_FILE_ATTRIBUTE_STANDARD_TYPE) == G_FILE_TYPE_DIRECTORY))
             dir = GNOME_CMD_IS_DIR (file) ? GNOME_CMD_DIR (file) : gnome_cmd_dir_new_from_info (file->info, 
dir);
     }