When switching to a library with a corrupted database, offer the user the option of rebuilding the database instead of erroring out.

src/calibre/db/__init__.py

@@ -64,4 +64,6 @@ Various things that require other things before they can be migrated:
                     columns/categories/searches info into
                     self.field_metadata. Finally, implement metadata dirtied
                     functionality.
+    2. Catching DatabaseException and sqlite.Error when creating new
+    libraries/switching/on calibre startup.
 '''

src/calibre/gui2/actions/choose_library.py

@@ -405,13 +405,12 @@ class ChooseLibraryAction(InterfaceAction):
             else:
                 return
 
-        prefs['library_path'] = loc
         #from calibre.utils.mem import memory
         #import weakref
         #from PyQt4.Qt import QTimer
         #self.dbref = weakref.ref(self.gui.library_view.model().db)
         #self.before_mem = memory()/1024**2
-        self.gui.library_moved(loc)
+        self.gui.library_moved(loc, allow_rebuild=True)
         #QTimer.singleShot(5000, self.debug_leak)
 
     def debug_leak(self):
@@ -455,7 +454,8 @@ class ChooseLibraryAction(InterfaceAction):
         self.choose_dialog_library_renamed = getattr(c, 'library_renamed', False)
 
     def choose_library_callback(self, newloc, copy_structure=False):
-        self.gui.library_moved(newloc, copy_structure=copy_structure)
+        self.gui.library_moved(newloc, copy_structure=copy_structure,
+                allow_rebuild=True)
         if getattr(self, 'choose_dialog_library_renamed', False):
             self.stats.rename(self.pre_choose_dialog_location, prefs['library_path'])
         self.build_menus()

src/calibre/gui2/dialogs/choose_library.py

@@ -13,7 +13,6 @@ from calibre.gui2.dialogs.choose_library_ui import Ui_Dialog
 from calibre.gui2 import error_dialog, choose_dir
 from calibre.constants import filesystem_encoding, iswindows
 from calibre import isbytestring, patheq
-from calibre.utils.config import prefs
 from calibre.gui2.wizard import move_library
 from calibre.library.database2 import LibraryDatabase2
 
@@ -77,7 +76,6 @@ class ChooseLibrary(QDialog, Ui_Dialog):
 
     def perform_action(self, ac, loc):
         if ac in ('new', 'existing'):
-            prefs['library_path'] = loc
             self.callback(loc, copy_structure=self.copy_structure.isChecked())
         else:
             self.db.prefs.disable_setting = True

src/calibre/gui2/dialogs/restore_library.py

@@ -120,18 +120,18 @@ def restore_database(db, parent=None):
         _show_success_msg(r, parent=parent)
     return True
 
-def repair_library_at(library_path):
-    d = DBRestore(None, library_path)
+def repair_library_at(library_path, parent=None):
+    d = DBRestore(parent, library_path)
     d.exec_()
     if d.rejected:
         return False
     r = d.restorer
     if r.tb is not None:
-        error_dialog(None, _('Failed'),
+        error_dialog(parent, _('Failed'),
         _('Restoring database failed, click Show details to see details'),
         det_msg=r.tb, show=True)
         return False
-    _show_success_msg(r)
+    _show_success_msg(r, parent=parent)
     return True
 
 

src/calibre/gui2/ui.py

@@ -18,8 +18,8 @@ from PyQt4.Qt import (Qt, SIGNAL, QTimer, QHelpEvent, QAction,
                      QMenu, QIcon, pyqtSignal, QUrl,
                      QDialog, QSystemTrayIcon, QApplication)
 
-from calibre import  prints
-from calibre.constants import __appname__, isosx
+from calibre import prints, force_unicode
+from calibre.constants import __appname__, isosx, filesystem_encoding
 from calibre.utils.config import prefs, dynamic
 from calibre.utils.ipc.server import Server
 from calibre.library.database2 import LibraryDatabase2
@@ -41,7 +41,7 @@ from calibre.gui2.search_box import SearchBoxMixin, SavedSearchBoxMixin
 from calibre.gui2.search_restriction_mixin import SearchRestrictionMixin
 from calibre.gui2.tag_browser.ui import TagBrowserMixin
 from calibre.gui2.keyboard import Manager
-
+from calibre.library.sqlite import sqlite, DatabaseException
 
 class Listener(Thread): # {{{
 
@@ -475,7 +475,8 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin, # {{{
     def booklists(self):
         return self.memory_view.model().db, self.card_a_view.model().db, self.card_b_view.model().db
 
-    def library_moved(self, newloc, copy_structure=False, call_close=True):
+    def library_moved(self, newloc, copy_structure=False, call_close=True,
+            allow_rebuild=False):
         if newloc is None: return
         default_prefs = None
         try:
@@ -484,7 +485,26 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin, # {{{
                 default_prefs = olddb.prefs
         except:
             olddb = None
-        db = LibraryDatabase2(newloc, default_prefs=default_prefs)
+        try:
+            db = LibraryDatabase2(newloc, default_prefs=default_prefs)
+        except (DatabaseException, sqlite.Error):
+            if not allow_rebuild: raise
+            import traceback
+            repair = question_dialog(self, _('Corrupted database'),
+                    _('The library database at %s appears to be corrupted. Do '
+                    'you want calibre to try and rebuild it automatically? '
+                    'The rebuild may not be completely successful.')
+                    % force_unicode(newloc, filesystem_encoding),
+                    det_msg=traceback.format_exc()
+                    )
+            if repair:
+                from calibre.gui2.dialogs.restore_library import repair_library_at
+                if repair_library_at(newloc, parent=self):
+                    db = LibraryDatabase2(newloc, default_prefs=default_prefs)
+                else:
+                    return
+            else:
+                return
         if self.content_server is not None:
             self.content_server.set_database(db)
         self.library_path = newloc