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9a1d73fdffFix segfault when shutdown during wallet open (John Moffett) Pull request description: Fixes #689 ## Summary If you open a wallet and send a shutdown signal during that process, you'll get a segfault when the wallet finishes opening. That's because the `WalletController` object gets deleted manually in bitcoin.cpp during shutdown, but copies of the pointer (and pointers to child objects) are dangling in various places and are accessed in queued events after the deletion. ## Details The issue in #689 is caused by the following sequence of events: 1. Wallet open modal dialog is shown and worker thread does the actual work. 2. Every 200ms, the main event loop checks to see if a shutdown has been requested, but only if a modal is not being shown. 3. Request a shutdown while the modal window is shown. 4. The wallet open process completes, the modal window is dismissed, and various `finish` signals are sent. 5. During handling of one of the `finish` signals, `qApp->processEvents()` is [called](e9262ea32a/src/qt/sendcoinsdialog.cpp (L603)), which causes the main event loop to detect the shutdown (now that the modal window has been dismissed). The `WalletController` and all the `WalletModel`s are [deleted](65de8eeeca/src/qt/bitcoin.cpp (L394-L401)). 6. Control returns to the `finish` method, which eventually tries to send a [signal](e9262ea32a/src/qt/sendcoinsdialog.cpp (L167)) from a wallet model, but it's been deleted already (and the signal is sent from a now-[dangling](d8bdee0fc8/src/qt/walletview.cpp (L65)) pointer). The simplest fix for that is to change the `qApp->processEvents()` into a `QueuedConnection` call. (The `qApp->processEvents() was a [workaround](https://github.com/bitcoin/bitcoin/pull/593#issuecomment-3050699) to get the GUI to scroll to the last item in a list that just got added, and this is just a safer way of doing that). However, once that segfault is fixed, another segfault occurs due to some queued wallet events happening after the wallet controller object is deleted here:65de8eeeca/src/qt/bitcoin.cpp (L394-L401)Since `m_wallet_controller` is a copy of that pointer in `bitcoingui.cpp`, it's now dangling and `if(null)` checks won't work correctly. For instance, this line:65de8eeeca/src/qt/bitcoingui.cpp (L413)sets up a `QueuedConnection` to `setCurrentWallet`, but by the time control reaches that method (one event cycle after shutdown deleted `m_wallet_controller` in `bitcoin.cpp`), the underlying objects have been destroyed (but the pointers are still dangling). Ideally, we'd use a `QPointer` or `std::shared_ptr / std::weak_ptr`s for these, but the changes would be more involved. This is a minimal fix for the issues. Just set `m_wallet_controller` to `nullptr` in `bitcoingui.cpp`, check its value in a couple places, and avoid a use of `qApp->processEvents`. ACKs for top commit: hebasto: ACK9a1d73fdff, I have reviewed the code and it looks OK. furszy: ACK9a1d73fdffTree-SHA512: a1b94676eb2fcb7606e68fab443b1565b4122aab93c35382b561842a049f4b43fecc459535370d67a64d6ebc4bcec0ebcda981fff633ebd41bdba6f7093ea540
This directory contains the source code for the Bitcoin Core graphical user interface (GUI). It uses the Qt cross-platform framework.
The current precise version for Qt 5 is specified in qt.mk.
Compile and run
See build instructions: Unix, macOS, Windows, FreeBSD, NetBSD, OpenBSD
When following your systems build instructions, make sure to install the Qt dependencies.
To run:
./src/qt/bitcoin-qt
Files and Directories
forms/
- A directory that contains Designer UI files. These files specify the characteristics of form elements in XML. Qt UI files can be edited with Qt Creator or using any text editor.
locale/
- Contains translations. They are periodically updated and an effort is made to support as many languages as possible. The process of contributing translations is described in doc/translation_process.md.
res/
- Contains graphical resources used to enhance the UI experience.
test/
- Functional tests used to ensure proper functionality of the GUI. Significant changes to the GUI code normally require new or updated tests.
bitcoingui.(h/cpp)
- Represents the main window of the Bitcoin UI.
*model.(h/cpp)
- The model. When it has a corresponding controller, it generally inherits from QAbstractTableModel. Models that are used by controllers as helpers inherit from other Qt classes like QValidator.
- ClientModel is used by the main application
bitcoinguiand several models likepeertablemodel.
*page.(h/cpp)
- A controller.
:NAMEpage.cppgenerally includes:NAMEmodel.handforms/:NAME.page.uiwith a similar:NAME.
*dialog.(h/cpp)
- Various dialogs, e.g. to open a URL. Inherit from QDialog.
paymentserver.(h/cpp)
- (Deprecated) Used to process BIP21 payment URI requests. Also handles URI-based application switching (e.g. when following a bitcoin:... link from a browser).
walletview.(h/cpp)
- Represents the view to a single wallet.
Other .h/cpp files
- UI elements like BitcoinAmountField, which inherit from QWidget.
bitcoinstrings.cpp: automatically generatedbitcoinunits.(h/cpp): BTC / mBTC / etc. handlingcallback.hguiconstants.h: UI colors, app name, etc.guiutil.h: several helper functionsmacdockiconhandler.(h/mm): macOS dock icon handlermacnotificationhandler.(h/mm): display notifications in macOS
Contribute
See CONTRIBUTING.md for general guidelines.
Note: Do not change local/bitcoin_en.ts. It is updated automatically.
Using Qt Creator as an IDE
Qt Creator is a powerful tool which packages a UI designer tool (Qt Designer) and a C++ IDE into one application. This is especially useful if you want to change the UI layout.
Download Qt Creator
On Unix and macOS, Qt Creator can be installed through your package manager. Alternatively, you can download a binary from the Qt Website.
Note: If installing from a binary grabbed from the Qt Website: During the installation process, uncheck everything except for Qt Creator.
macOS
brew install qt-creator
Ubuntu & Debian
sudo apt-get install qtcreator
Setup Qt Creator
- Make sure you've installed all dependencies specified in your systems build instructions
- Follow the compile instructions for your system, run
./configurewith the--enable-debugflag - Start Qt Creator. At the start page, do:
New->Import Project->Import Existing Project - Enter
bitcoin-qtas the Project Name and enter the absolute path tosrc/qtas Location - Check over the file selection, you may need to select the
formsdirectory (necessary if you intend to edit *.ui files) - Confirm the
Summarypage - In the
Projectstab, selectManage Kits...
macOS
- Under
Kits: select the default "Desktop" kit - Under
Compilers: select"Clang (x86 64bit in /usr/bin)" - Under
Debuggers: select"LLDB"as debugger (you might need to set the path to your LLDB installation)
Ubuntu & Debian
Note: Some of these options may already be set
- Under
Kits: select the default "Desktop" kit - Under
Compilers: select"GCC (x86 64bit in /usr/bin)" - Under
Debuggers: select"GDB"as debugger
- While in the
Projectstab, ensure that you have thebitcoin-qtexecutable specified underRun
- If the executable is not specified: click
"Choose...", navigate tosrc/qt, and selectbitcoin-qt
- You're all set! Start developing, building, and debugging the Bitcoin Core GUI