API for renaming extra files

src/calibre/db/backend.py

@@ -1933,6 +1933,22 @@ class DB:
                         with src:
                             yield relpath, src, stat_result
 
+    def rename_extra_file(self, relpath, newrelpath, book_path, replace=True):
+        bookdir = os.path.join(self.library_path, book_path)
+        src = os.path.abspath(os.path.join(bookdir, relpath))
+        dest = os.path.abspath(os.path.join(bookdir, newrelpath))
+        src, dest = make_long_path_useable(src), make_long_path_useable(dest)
+        if src == dest or not os.path.exists(src):
+            return False
+        if not replace and os.path.exists(dest) and not os.path.samefile(src, dest):
+            return False
+        try:
+            os.replace(src, dest)
+        except FileNotFoundError:
+            os.makedirs(os.path.dirname(dest), exist_ok=True)
+            os.replace(src, dest)
+        return True
+
     def add_extra_file(self, relpath, stream, book_path, replace=True, auto_rename=False):
         bookdir = os.path.join(self.library_path, book_path)
         dest = os.path.abspath(os.path.join(bookdir, relpath))

src/calibre/db/cache.py

@@ -3093,6 +3093,17 @@ class Cache:
         self._clear_extra_files_cache(book_id)
         return added
 
+    @write_api
+    def rename_extra_files(self, book_id, map_of_relpath_to_new_relpath, replace=False):
+        ' Rename extra data files '
+        path = self._field_for('path', book_id).replace('/', os.sep)
+        renamed = set()
+        for relpath, newrelpath in map_of_relpath_to_new_relpath.items():
+            if self.backend.rename_extra_file(relpath, newrelpath, path, replace):
+                renamed.add(relpath)
+        self._clear_extra_files_cache(book_id)
+        return renamed
+
     @write_api
     def merge_extra_files(self, dest_id, src_ids, replace=False):
         ' Merge the extra files from src_ids into dest_id. Conflicting files are auto-renamed unless replace=True in which case they are replaced. '

src/calibre/db/tests/filesystem.py

@@ -137,6 +137,23 @@ class FilesystemTest(BaseTest):
             if x.is_dir():
                 self.assertTrue(os.listdir(x.path))
 
+    def test_rename_of_extra_files(self):
+        cl = self.cloned_library
+        cache = self.init_cache(cl)
+        cache.add_extra_files(1, {'a': BytesIO(b'aaa'), 'b': BytesIO(b'bbb')})
+
+        def relpaths():
+            return {e.relpath for e in cache.list_extra_files(1)}
+
+        self.assertEqual(relpaths(), {'a', 'b'})
+        self.assertEqual(cache.rename_extra_files(1, {'a': 'data/c'}), {'a'})
+        self.assertEqual(relpaths(), {'data/c', 'b'})
+        self.assertEqual(cache.rename_extra_files(1, {'b': 'B'}), {'b'})
+        self.assertEqual(relpaths(), {'data/c', 'B'})
+        self.assertEqual(cache.rename_extra_files(1, {'B': 'data/c'}), set())
+        self.assertEqual(cache.rename_extra_files(1, {'B': 'data/c'}, replace=True), {'B'})
+
+
     @unittest.skipUnless(iswindows, 'Windows only')
     def test_windows_atomic_move(self):
         'Test book file open in another process when changing metadata'