4652cd0d82
If a UTXO entry on disk can't be deserialized, the node treats it as if the coin doesn't exist. Any block that spends that coin is permanently rejected as invalid (BLOCK_FAILED_VALID), silently forking the node from the rest of the network. This can hardly be triggered in practice (details below), but it's still the wrong behavior that could affect us in the future. The root cause is that CDBWrapper::Read() returns false for both missing keys and deserialization failures, so the consensus class CCoinsViewDB::GetCoin() has no way to tell them apart. CCoinsViewErrorCatcher was built to catch database read errors and abort, but it never fires because CDBWrapper::Read() swallows the exception before it can propagate. In practice, this scenario isn't a latent risk at the moment. It requires either a bug in the coin serialization path, or memory corruption before the data reaches LevelDB (at which point we have bigger problems). Any random disk-level bit flips are caught earlier by LevelDB's verification (the verify_checksums=true option enabled by default), which surfaces as a DatabaseError rather than a deserialization failure. This commit switches CCoinsViewDB::GetCoin() to use CDBWrapper::TryRead(), which lets the caller discriminate between all possible outcomes. On deserialization error, the exception now propagates through CCoinsViewErrorCatcher to ExecuteBackedWrapper(), which invokes the shutdown callbacks and aborts the node accordantly. This also fixes PeekCoin(), which delegates to GetCoin() at the CCoinsViewDB level.
Bitcoin Core integration/staging tree
For an immediately usable, binary version of the Bitcoin Core software, see https://bitcoincore.org/en/download/.
What is Bitcoin Core?
Bitcoin Core connects to the Bitcoin peer-to-peer network to download and fully validate blocks and transactions. It also includes a wallet and graphical user interface, which can be optionally built.
Further information about Bitcoin Core is available in the doc folder.
License
Bitcoin Core is released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/license/MIT.
Development Process
The master branch is regularly built (see doc/build-*.md for instructions) and tested, but it is not guaranteed to be
completely stable. Tags are created
regularly from release branches to indicate new official, stable release versions of Bitcoin Core.
The https://github.com/bitcoin-core/gui repository is used exclusively for the development of the GUI. Its master branch is identical in all monotree repositories. Release branches and tags do not exist, so please do not fork that repository unless it is for development reasons.
The contribution workflow is described in CONTRIBUTING.md and useful hints for developers can be found in doc/developer-notes.md.
Testing
Testing and code review is the bottleneck for development; we get more pull requests than we can review and test on short notice. Please be patient and help out by testing other people's pull requests, and remember this is a security-critical project where any mistake might cost people lots of money.
Automated Testing
Developers are strongly encouraged to write unit tests for new code, and to
submit new unit tests for old code. Unit tests can be compiled and run
(assuming they weren't disabled during the generation of the build system) with: ctest. Further details on running
and extending unit tests can be found in /src/test/README.md.
There are also regression and integration tests, written
in Python.
These tests can be run (if the test dependencies are installed) with: build/test/functional/test_runner.py
(assuming build is your build directory).
The CI (Continuous Integration) systems make sure that every pull request is tested on Windows, Linux, and macOS. The CI must pass on all commits before merge to avoid unrelated CI failures on new pull requests.
Manual Quality Assurance (QA) Testing
Changes should be tested by somebody other than the developer who wrote the code. This is especially important for large or high-risk changes. It is useful to add a test plan to the pull request description if testing the changes is not straightforward.
Translations
Changes to translations as well as new translations can be submitted to Bitcoin Core's Transifex page.
Translations are periodically pulled from Transifex and merged into the git repository. See the translation process for details on how this works.
Important: We do not accept translation changes as GitHub pull requests because the next pull from Transifex would automatically overwrite them again.