Speedup windows_get_fileid

Also make it more robust by avoiding registry/time lookups. Fixes #1898110 [Cannot load Calibre 64 bit](https://bugs.launchpad.net/calibre/+bug/1898110)

src/calibre/utils/filenames.py

@@ -9,6 +9,7 @@ import os
 import shutil
 import time
 from math import ceil
+from contextlib import suppress
 
 from calibre import force_unicode, isbytestring, prints, sanitize_file_name
 from calibre.constants import (
@@ -218,9 +219,10 @@ def case_preserving_open_file(path, mode='wb', mkdir_mode=0o777):
     return ans, fpath
 
 
-def windows_get_fileid(path):
+def old_windows_get_fileid(path):
-    ''' The fileid uniquely identifies actual file contents (it is the same for
+    # we dont use this anymore as the win32 implementation reads the windows
-    all hardlinks to a file). Similar to inode number on linux. '''
+    # registry to convert file times which is slow and breaks on systems with
+    # registry issues.
     import win32file
     from pywintypes import error
     if isbytestring(path):
@@ -237,6 +239,20 @@ def windows_get_fileid(path):
     return data[4], data[8], data[9]
 
 
+def windows_get_fileid(path):
+    ''' The fileid uniquely identifies actual file contents (it is the same for
+    all hardlinks to a file). Similar to inode number on linux. '''
+    try:
+        get_file_id = plugins['winutil'][0].get_file_id
+    except AttributeError:
+        # running from source without updating binary
+        return old_windows_get_fileid(path)
+    if isbytestring(path):
+        path = path.decode(filesystem_encoding)
+    with suppress(OSError):
+        return get_file_id(path)
+
+
 def samefile_windows(src, dst):
     samestring = (os.path.normcase(os.path.abspath(src)) ==
             os.path.normcase(os.path.abspath(dst)))

src/calibre/utils/windows/winutil.c

@@ -380,6 +380,7 @@ extern PyObject *winutil_friendly_name(PyObject *self, PyObject *args);
 extern PyObject *winutil_notify_associations_changed(PyObject *self, PyObject *args);
 extern PyObject *winutil_move_to_trash(PyObject *self, PyObject *args);
 extern PyObject *winutil_manage_shortcut(PyObject *self, PyObject *args);
+extern PyObject *winutil_get_file_id(PyObject *self, PyObject *args);
 
 static PyMethodDef winutil_methods[] = {
     {"special_folder_path", winutil_folder_path, METH_VARARGS,
@@ -471,6 +472,10 @@ be a unicode string. Returns unicode strings."
         "manage_shortcut()\n\nManage a shortcut"
     },
 
+    {"get_file_id", (PyCFunction)winutil_get_file_id, METH_VARARGS,
+        "get_file_id(path)\n\nGet the windows file id (volume_num, file_index_high, file_index_low)"
+    },
+
     {NULL, NULL, 0, NULL}
 };
 

src/calibre/utils/windows/winutilpp.cpp

@@ -114,6 +114,23 @@ py_to_wchar(PyObject *obj, wchar_raii *output) {
 
 extern "C" {
 
+PyObject*
+winutil_get_file_id(PyObject *self, PyObject *args) {
+	wchar_raii path;
+	if (!PyArg_ParseTuple(args, "O&", py_to_wchar, &path)) return NULL;
+	if (path.ptr()) {
+		HANDLE h = CreateFileW(path.ptr(), 0, 0, NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
+		if (h == INVALID_HANDLE_VALUE) return PyErr_SetExcFromWindowsErrWithFilenameObject(PyExc_OSError, 0, PyTuple_GET_ITEM(args, 0));
+		BY_HANDLE_FILE_INFORMATION info = {0};
+		BOOL ok = GetFileInformationByHandle(h, &info);
+		CloseHandle(h);
+		if (!ok) return PyErr_SetExcFromWindowsErrWithFilenameObject(PyExc_OSError, 0, PyTuple_GET_ITEM(args, 0));
+		unsigned long volnum = info.dwVolumeSerialNumber, index_high = info.nFileIndexHigh, index_low = info.nFileIndexLow;
+		return Py_BuildValue("kkk", volnum, index_high, index_low);
+	}
+	Py_RETURN_NONE;
+}
+
 PyObject *
 winutil_add_to_recent_docs(PyObject *self, PyObject *args) {
 	wchar_raii path, app_id;