Windows: Check if any of the files of a book are in use before changing the title/author, this (usually) prevents the creation of duplicate files if one of the files is open in another program

src/calibre/gui2/metadata/basic_widgets.py

@@ -270,7 +270,7 @@ class AuthorsEdit(EditWithComplete):
                 import traceback
                 fname = err.filename if err.filename else 'file'
                 error_dialog(self, _('Permission denied'),
-                        _('Could not open %s. Is it being used by another'
+                        _('Could not open "%s". Is it being used by another'
                         ' program?')%fname, det_msg=traceback.format_exc(),
                         show=True)
                 return False

src/calibre/library/database2.py

@@ -7,7 +7,7 @@ __docformat__ = 'restructuredtext en'
 The database used to store ebook metadata
 '''
 import os, sys, shutil, cStringIO, glob, time, functools, traceback, re, \
-        json, uuid, hashlib, copy
+        json, uuid, hashlib, copy, errno
 from collections import defaultdict
 import threading, random
 from itertools import repeat
@@ -30,7 +30,8 @@ from calibre.ptempfile import (PersistentTemporaryFile,
         base_dir, SpooledTemporaryFile)
 from calibre.customize.ui import run_plugins_on_import
 from calibre import isbytestring
-from calibre.utils.filenames import ascii_filename, samefile
+from calibre.utils.filenames import (ascii_filename, samefile,
+            windows_is_folder_in_use)
 from calibre.utils.date import (utcnow, now as nowf, utcfromtimestamp,
         parse_only_date, UNDEFINED_DATE)
 from calibre.utils.config import prefs, tweaks, from_json, to_json
@@ -649,6 +650,13 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         spath = os.path.join(self.library_path, *current_path.split('/'))
 
         if current_path and os.path.exists(spath): # Migrate existing files
+            if iswindows:
+                uf = windows_is_folder_in_use(spath)
+                if uf is not None:
+                    err = IOError(errno.EACCES,
+                            _('File is open in another process'))
+                    err.filename = uf
+                    raise err
             cdata = self.cover(id, index_is_id=True)
             if cdata is not None:
                 with lopen(os.path.join(tpath, 'cover.jpg'), 'wb') as f:

src/calibre/utils/filenames.py

@@ -249,4 +249,32 @@ def samefile(src, dst):
             os.path.normcase(os.path.abspath(dst)))
     return samestring
 
+def windows_is_file_opened(path):
+    import win32file, winerror
+    from pywintypes import error
+    if isbytestring(path): path = path.decode(filesystem_encoding)
+    try:
+        h = win32file.CreateFile(path, win32file.GENERIC_READ, 0, None,
+            win32file.OPEN_EXISTING, 0, 0)
+    except error as e:
+        if getattr(e, 'winerror', 0) == winerror.ERROR_SHARING_VIOLATION:
+            return True
+    else:
+        win32file.CloseHandle(h)
+    return False
+
+def windows_is_folder_in_use(path):
+    '''
+    Returns the path to a file that is used in another process in the specified
+    folder, or None if no such file exists. Note
+    that this function is not a guarantee. A file may well be opened in the
+    folder after this function returns. However, it is useful to handle the
+    common case of a sharing violation gracefully most of the time.
+    '''
+    if isbytestring(path): path = path.decode(filesystem_encoding)
+    for x in os.listdir(path):
+        f = os.path.join(path, x)
+        if windows_is_file_opened(f):
+            return f
+    return None