Cleanup previous PR

1) Use the passed in db object
2) Delete the temp dir after generating the catalog
3) Use the correct source dir when copying
4) Move copying logic into backend
5) Hold the db read lock while copying

src/calibre/db/backend.py

@@ -1456,6 +1456,15 @@ class DB:
             self.user_version = 1
     # }}}
 
+    def clone_for_readonly_access(self, dest_dir: str) -> str:
+        dbpath = os.path.abspath(self.conn.db_filename('main'))
+        clone_db_path = os.path.join(dest_dir, os.path.basename(dbpath))
+        shutil.copy2(dbpath, clone_db_path)
+        notes_dir = os.path.join(os.path.dirname(dbpath), NOTES_DIR_NAME)
+        if os.path.exists(notes_dir):
+            shutil.copytree(notes_dir, os.path.join(dest_dir, NOTES_DIR_NAME))
+        return clone_db_path
+
     def normpath(self, path):
         path = os.path.abspath(os.path.realpath(path))
         if not self.is_case_sensitive:

src/calibre/db/cache.py

@@ -3513,6 +3513,10 @@ class Cache:
                         dest_value.extend(src_value)
                     self._set_field(field, {dest_id: dest_value})
 
+    @read_api
+    def clone_for_readonly_access(self, dest_dir: str) -> str:
+        return self.backend.clone_for_readonly_access(dest_dir)
+
 
 def import_library(library_key, importer, library_path, progress=None, abort=None):
     from calibre.db.backend import DB

src/calibre/gui2/convert/gui_conversion.py

@@ -50,6 +50,7 @@ def gui_catalog(library_path, temp_db_path, fmt, title, dbspec, ids, out_file_na
     # Open the temp database created while still in the GUI thread
     from calibre.db.legacy import LibraryDatabase
     db = LibraryDatabase(library_path, temp_db_path=temp_db_path)
+    try:
         db.catalog_plugin_on_device_temp_mapping = dbspec
 
         # Create a minimal OptionParser that we can append to
@@ -78,3 +79,7 @@ def gui_catalog(library_path, temp_db_path, fmt, title, dbspec, ids, out_file_na
         # Returns 0 if successful, 1 if no catalog built
         plugin = plugin_for_catalog_format(fmt)
         return plugin.run(out_file_name, opts, db, notification=notification)
+    finally:
+        import shutil
+        db.close()
+        shutil.rmtree(os.path.dirname(temp_db_path))

src/calibre/gui2/tools.py

@@ -10,7 +10,6 @@ Logic for setting up conversion jobs
 '''
 
 import os
-import shutil
 
 from qt.core import QDialog, QProgressDialog, QTimer
 
@@ -376,18 +375,12 @@ def generate_catalog(parent, dbspec, ids, device_manager, db):  # {{{
     # process. The backend looks for the notes directory (.calnotes) in the
     # directory containing the metadata.db file. Copy the one from the current
     # library.
-    from calibre.gui2.ui import get_gui
+    temp_db_directory = PersistentTemporaryDirectory('callib')
-    library_path = get_gui().current_db.library_path
+    temp_db_path = db.new_api.clone_for_readonly_access(temp_db_directory)
-    temp_db_directory = PersistentTemporaryDirectory('_callib')
-    temp_db_path = os.path.join(temp_db_directory, 'metadata.db')
-    shutil.copy(os.path.join(library_path, 'metadata.db'), temp_db_directory)
-    notes_dir = os.path.join(library_path, '.calnotes')
-    if os.path.exists(notes_dir):
-        shutil.copytree(notes_dir, os.path.join(temp_db_directory, '.calnotes'))
 
     # These args are passed inline to gui2.convert.gui_conversion:gui_catalog
     args = [
-        library_path,
+        db.library_path,
         temp_db_path,
         d.catalog_format,
         d.catalog_title,