> On July 30, 2014, 8:54 a.m., Vishesh Handa wrote: > > src/tagwidget.cpp, line 180 > > <https://git.reviewboard.kde.org/r/119543/diff/1/?file=294417#file294417line180> > > > > Any reason you've combined the too functions? I don't remember why, but > > there was a point when it split up. > > > > Also, if one really doesn't need it to be split up, then we should > > probably use a QScopedPointer instead of deleting it outself. > > Felix Eisele wrote: > i did googling yesterday and i think it is not needed. > I am not a fan of class members. you didnt see the dataflow. > We should i use a QScopedPointer? > > Thomas Braxton wrote: > Or you could just make it not a pointer and it cleans itself up. > > Felix Eisele wrote: > Good idea! > > Frank Reininghaus wrote: > No, this is a **very bad** idea. Creating the dialog on the stack as a > child of "this" and then executing its nested event loop will cause crashes > like the ones that are fixed by https://git.reviewboard.kde.org/r/118858/ . > You should use a QPointer for the dialog and delete it after calling exec() > and checking that the QPointer is not null. > > See the links that Dominik added in a comment to that review request of > mine for further info. > > Thomas Braxton wrote: > Since the whole purpose of this function is to get a list of tags using a > dialog, the dialog must exist when it returns from exec(). Otherwise the > whole function is **moot**. > > Frank Reininghaus wrote: > Unfortunately, you can't really control what happens inside the nested > event loop that is started by exec(). Anything can happen in there, including > events that cause the deletion of the parent widget of the dialog. This > parent widget will then try to delete the dialog, which lives on the stack. > This will cause a crash. > > The easiest way to reproduce this is the "quit by D-Bus"-trick, as > described in, e.g., > > > https://blogs.kde.org/2009/03/26/how-crash-almost-every-qtkde-application-and-how-fix-it-0 > http://kate-editor.org/2012/04/06/crash-through-d-bus-calls/ > https://bugs.kde.org/show_bug.cgi?id=293863#c13 > > And even if you say that the user is unlikely to do this D-Bus thing: > there are other ways to achieve the same effect, even if they are much harder > to reproduce. You really cannot assume that the dialog still exists when > exec() returns. Definitely not. Code that assumes this is buggy (even if the > Qt docs for QDialog still suggest this approach - maybe I should try to get > that changed). > > And no, I am really not making this stuff up. We do get bug reports about > crashes that are caused by problems like this. Please do not add new versions > of these bugs when modifying code. > > BTW, your statement that "the whole function is **moot**" if the dialog > does not exist anymore is wrong. After all, the function cannot know what > will happen during exec(). Most of the time, the dialog will still be there, > stuff will get done with the tags, and everything is all right. But > sometimes, the application will quit during exec(), and then the sole > remaining purpose of the function is to return gracefully, without a crash. > And this graceful return is prevented by creating the dialog on the stack.
You're right, QPointer it has to be. - Thomas ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: https://git.reviewboard.kde.org/r/119543/#review63489 ----------------------------------------------------------- On July 30, 2014, 6:05 p.m., Felix Eisele wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://git.reviewboard.kde.org/r/119543/ > ----------------------------------------------------------- > > (Updated July 30, 2014, 6:05 p.m.) > > > Review request for Baloo and Vishesh Handa. > > > Repository: baloo-widgets > > > Description > ------- > > Removed all KDialogs from balooWidgets. Removed not needed includes > > > Diffs > ----- > > src/kedittagsdialog.cpp c83ce9d > src/kedittagsdialog_p.h 0bcf744 > src/tagwidget.h 2843acd > src/tagwidget.cpp f2c3601 > src/tagwidget_p.h 045a185 > > Diff: https://git.reviewboard.kde.org/r/119543/diff/ > > > Testing > ------- > > > Thanks, > > Felix Eisele > >
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