e899d4ca6f init: limit bip30 exceptions to coinbase txs (Chris Geihsler)
511eb7fdea Ignore problematic blocks in DisconnectBlock (Chris Geihsler)
Pull request description:
Fixes https://github.com/bitcoin/bitcoin/issues/22596
When using checklevel=4, block verification fails because of duplicate coinbase transactions involving blocks 91812 and 91722. There was already a check in place within `ConnectBlock` to ignore the problematic blocks, but `DisconnectBlock` did not contain a similar check to ignore these blocks when called from `VerifyDB`.
By ignoring these two blocks in `DisconnectBlock`, the block verification process succeeds at checklevel=4.
(Note to reviewers: this is my first contribution to Bitcoin Core, so any feedback is most welcome. Thanks in advance for reviewing!)
## Steps to reproduce:
Use the following bitcoin.conf file and start bitcoind. I only used block data through block ~100000 so that the verification process was much faster.
```
assumevalid=0
checkblocks=0
checklevel=4
```
Without this change, you will see the following error when the blocks are verified:
```
2022-04-14T02:56:44Z init message: Verifying blocks…
2022-04-14T02:56:44Z Verifying last 101881 blocks at level 4
2022-04-14T02:56:44Z [0%]...[10%]...[20%]...[30%]...[40%]...ERROR: VerifyDB(): *** coin database inconsistencies found (last 10160 blocks, 142571 good transactions before that)
2022-04-14T02:57:01Z : Corrupted block database detected.
Please restart with -reindex or -reindex-chainstate to recover.
: Corrupted block database detected.
Please restart with -reindex or -reindex-chainstate to recover.
```
With this change, you will see this instead:
```
2022-04-14T02:32:29Z init message: Verifying blocks…
2022-04-14T02:32:29Z Verifying last 101746 blocks at level 4
2022-04-14T02:32:29Z [0%]...[10%]...[20%]...[30%]...[40%]...[50%]...[60%]...[70%]...[80%]...[90%]...[DONE].
2022-04-14T02:32:48Z No coin database inconsistencies in last 101746 blocks (226126 transactions)
```
ACKs for top commit:
laanwj:
Code review ACK e899d4ca6f
achow101:
ACK e899d4ca6f
jamesob:
(Biased) ACK e899d4ca6f ([`jamesob/ackr/24851.2.seejee.init_ignore_bip_30_verif`](https://github.com/jamesob/bitcoin/tree/ackr/24851.2.seejee.init_ignore_bip_30_verif))
Tree-SHA512: d2f6d25e9619aee32c1a73fe846b1b587698eaa5a4994fa6424f1038f45654f9fd52b74a69843cc84d90168d74827130ccf8e9201502f5d52281acdb20429291
bf95976061 doc: add note about snapshot chainstate init (James O'Beirne)
e4d7995286 test: add testcases for snapshot initialization (James O'Beirne)
cced4e7336 test: move-only-ish: factor out LoadVerifyActivateChainstate() (James O'Beirne)
51fc9241c0 test: allow on-disk coins and block tree dbs in tests (James O'Beirne)
3c361391b8 test: add reset_chainstate parameter for snapshot unittests (James O'Beirne)
00b357c215 validation: add ResetChainstates() (James O'Beirne)
3a29dfbfb2 move-only: test: make snapshot chainstate setup reusable (James O'Beirne)
8153bd9247 blockmanager: avoid undefined behavior during FlushBlockFile (James O'Beirne)
ad67ff377c validation: remove snapshot datadirs upon validation failure (James O'Beirne)
34d1590331 add utilities for deleting on-disk leveldb data (James O'Beirne)
252abd1e8b init: add utxo snapshot detection (James O'Beirne)
f9f1735f13 validation: rename snapshot chainstate dir (James O'Beirne)
d14bebf100 db: add StoragePath to CDBWrapper/CCoinsViewDB (James O'Beirne)
Pull request description:
This is part of the [assumeutxo project](https://github.com/bitcoin/bitcoin/projects/11) (parent PR: https://github.com/bitcoin/bitcoin/pull/15606)
---
Half of the replacement for #24232. The original PR grew larger than expected throughout the review process.
This change adds the ability to initialize a snapshot-based chainstate during init if one is detected on disk. This is of course unused as of now (aside from in unittests) given that we haven't yet enabled actually loading snapshots.
Don't be scared! There are some big move-only commits in here.
Accompanying changes include:
- moving the snapshot coinsdb directory from being called `chainstate_[base blockhash]` to `chainstate_snapshot`, since we only support one snapshot in use at a time. This simplifies some logic, but it necessitates writing that base blockhash out to a file within the coinsdb dir. See [discussion here](https://github.com/bitcoin/bitcoin/pull/24232#discussion_r832762880).
- adding a simple fix in `FlushBlockFile()` that avoids a crash when attemping to flush to disk before `LoadBlockIndexDB()` is called, which happens when calling `MaybeRebalanceCaches()` during multiple chainstate init.
- improving the unittest to allow testing with on-disk chainstates - necessary to test a simulated restart and re-initialization.
ACKs for top commit:
naumenkogs:
utACK bf95976061
ariard:
Code Review ACK bf9597606
ryanofsky:
Code review ACK bf95976061. Changes since last review: rebasing, switching from CAutoFile to AutoFile, adding comments, switching from BOOST_CHECK to Assert in test util, using chainman.GetMutex() in tests, destroying one ChainstateManager before creating a new one in tests
fjahr:
utACK bf95976061
aureleoules:
ACK bf95976061
Tree-SHA512: 15ae75caf19f8d12a12d2647c52897904d27b265a7af6b4ae7b858592eeadb8f9da6c2394b6baebec90adc28742c053e3eb506119577dae7c1e722ebb3b7bcc0
bcb0cacac2 reindex, log, test: fixes#21379 (mruddy)
Pull request description:
Fixes#21379.
The blocks/blk?????.dat files are mutated and become increasingly malformed, or corrupt, as a result of running the re-indexing process.
The mutations occur after the re-indexing process has finished, as new blocks are appended, but are a result of a re-indexing process miscalculation that lingers in the block manager's `m_blockfile_info` `nSize` data until node restart.
These additions to the blk files are non-fatal, but also not desirable.
That is, this is a form of data corruption that the reading code is lenient enough to process (it skips the extra bytes), but it adds some scary looking log messages as it encounters them.
The summary of the problem is that the re-index process double counts the size of the serialization header (magic message start bytes [4 bytes] + length [4 bytes] = 8 bytes) while calculating the blk data file size (both values already account for the serialization header's size, hence why it is over accounted).
This bug manifests itself in a few different ways, after re-indexing, when a new block from a peer is processed:
1. If the new block will not fit into the last blk file processed while re-indexing, while remaining under the 128MiB limit, then the blk file is flushed to disk and truncated to a size that is 8 greater than it should be. The truncation adds zero bytes (see `FlatFileSeq::Flush` and `TruncateFile`).
1. If the last blk file processed while re-indexing has logical space for the new block under the 128 MiB limit:
1. If the blk file was not already large enough to hold the new block, then the zeros are, in effect, added by `fseek` when the file is opened for writing. Eight zero bytes are added to the end of the last blk file just before the new block is written. This happens because the write offset is 8 too great due to the miscalculation. The result is 8 zero bytes between the end of the last block and the beginning of the next block's magic + length + block.
1. If the blk file was already large enough to hold the new block, then the current existing file contents remain in the 8 byte gap between the end of the last block and the beginning of the next block's magic + length + block. Commonly, when this occcurs, it is due to the blk file containing blocks that are not connected to the block tree during reindex and are thus left behind by the reindex process and later overwritten when new blocks are added. The orphaned blocks can be valid blocks, but due to the nature of concurrent block download, the parent may not have been retrieved and written by the time the node was previously shutdown.
ACKs for top commit:
LarryRuane:
tested code-review ACK bcb0cacac2
ryanofsky:
Code review ACK bcb0cacac2. This is a disturbing bug with an easy fix which seems well-worth merging.
mzumsande:
ACK bcb0cacac2 (reviewed code and did some testing, I agree that it fixes the bug).
w0xlt:
tACK bcb0cacac2
Tree-SHA512: acc97927ea712916506772550451136b0f1e5404e92df24cc05e405bb09eb6fe7c3011af3dd34a7723c3db17fda657ae85fa314387e43833791e9169c0febe51
fabf1cdb20 Use steady clock for bench logging (MacroFake)
faed342a23 scripted-diff: Rename time symbols (MacroFake)
Pull request description:
Instead of using `0.001` and similar constants to "convert" an int64_t to milliseconds, use the type-safe `Ticks<>` helper. Also, use steady clock instead of system clock, since the durations are used for benchmarking.
ACKs for top commit:
fanquake:
ACK fabf1cdb20 - validation bench output still looks sane.
Tree-SHA512: e6525b5fdad6045ca500c56014897d7428ad288aaf375933d3b5939feddf257f6910d562eb66ebcde9186bef9a604ee8d763a318253838318d59df2a285be7c2
Simplifies function signatures by removing repetition of all the
ancestor/descendant limits, and increases readability by being
more verbose by naming the limits, while still reducing the LoC.
fa521c9603 Use steady clock for all millis bench logging (MacroFake)
Pull request description:
Currently `GetTimeMillis` is used for bench logging in milliseconds integral precision. Replace it to use a steady clock that is type-safe and steady.
Microsecond or float precision can be done in a follow-up.
ACKs for top commit:
fanquake:
ACK fa521c9603 - started making the same change.
Tree-SHA512: 86a810e496fc663f815acb8771a6c770331593715cde85370226685bc50c13e8e987e3c5efd0b4e48b36ebd2372255357b709204bac750d41e94a9f7d9897fa6
If a UTXO snapshot fails to validate, don't leave the resulting datadir
on disk as this will confuse initialization on next startup and we'll
get an assertion error.
Used in later commits to remove leveldb directories for
- invalid snapshot chainstates, and
- background-vaildation chainstates that have finished serving their
purpose.
Add functionality for activating a snapshot-based chainstate if one is
detected on-disk.
Also cautiously initialize chainstate cache usages so that we don't
somehow blow past our cache allowances during initialization, then
rebalance at the end of init.
Co-authored-by: Russell Yanofsky <russ@yanofsky.org>
This changes the snapshot's leveldb chainstate dir name from
`chainstate_[blockhash]` to `chainstate_snapshot`. This simplifies
later logic that loads snapshot data, and enforces the limitation
of a single snapshot at any given time.
Since we still need to persis the blockhash of the base block, we
write that out to a file (`chainstate_snapshot/base_blockhash`) for
later use during initialization, so that we can reinitialize the
snapshot chainstate.
Co-authored-by: Russell Yanofsky <russ@yanofsky.org>
3add234546 ui: show header pre-synchronization progress (Pieter Wuille)
738421c50f Emit NotifyHeaderTip signals for pre-synchronization progress (Pieter Wuille)
376086fc5a Make validation interface capable of signalling header presync (Pieter Wuille)
93eae27031 Test large reorgs with headerssync logic (Suhas Daftuar)
355547334f Track headers presync progress and log it (Pieter Wuille)
03712dddfb Expose HeadersSyncState::m_current_height in getpeerinfo() (Suhas Daftuar)
150a5486db Test headers sync using minchainwork threshold (Suhas Daftuar)
0b6aa826b5 Add unit test for HeadersSyncState (Suhas Daftuar)
83c6a0c524 Reduce spurious messages during headers sync (Suhas Daftuar)
ed6cddd98e Require callers of AcceptBlockHeader() to perform anti-dos checks (Suhas Daftuar)
551a8d957c Utilize anti-DoS headers download strategy (Suhas Daftuar)
ed470940cd Add functions to construct locators without CChain (Pieter Wuille)
84852bb6bb Add bitdeque, an std::deque<bool> analogue that does bit packing. (Pieter Wuille)
1d4cfa4272 Add function to validate difficulty changes (Suhas Daftuar)
Pull request description:
New nodes starting up for the first time lack protection against DoS from low-difficulty headers. While checkpoints serve as our protection against headers that fork from the main chain below the known checkpointed values, this protection only applies to nodes that have been able to download the honest chain to the checkpointed heights.
We can protect all nodes from DoS from low-difficulty headers by adopting a different strategy: before we commit to storing a header in permanent storage, first verify that the header is part of a chain that has sufficiently high work (either `nMinimumChainWork`, or something comparable to our tip). This means that we will download headers from a given peer twice: once to verify the work on the chain, and a second time when permanently storing the headers.
The p2p protocol doesn't provide an easy way for us to ensure that we receive the same headers during the second download of peer's headers chain. To ensure that a peer doesn't (say) give us the main chain in phase 1 to trick us into permanently storing an alternate, low-work chain in phase 2, we store commitments to the headers during our first download, which we validate in the second download.
Some parameters must be chosen for commitment size/frequency in phase 1, and validation of commitments in phase 2. In this PR, those parameters are chosen to both (a) minimize the per-peer memory usage that an attacker could utilize, and (b) bound the expected amount of permanent memory that an attacker could get us to use to be well-below the memory growth that we'd get from the honest chain (where we expect 1 new block header every 10 minutes).
After this PR, we should be able to remove checkpoints from our code, which is a nice philosophical change for us to make as well, as there has been confusion over the years about the role checkpoints play in Bitcoin's consensus algorithm.
Thanks to Pieter Wuille for collaborating on this design.
ACKs for top commit:
Sjors:
re-tACK 3add234546
mzumsande:
re-ACK 3add234546
sipa:
re-ACK 3add234546
glozow:
ACK 3add234546
Tree-SHA512: e7789d65f62f72141b8899eb4a2fb3d0621278394d2d7adaa004675250118f89a4e4cb42777fe56649d744ec445ad95141e10f6def65f0a58b7b35b2e654a875
This makes a number of changes:
- Get rid of the verification_progress argument in the node interface
NotifyHeaderTip (it was always 0.0).
- Instead of passing a CBlockIndex* in the UI interface's NotifyHeaderTip,
send separate height, timestamp fields. This is becuase in headers presync,
no actual CBlockIndex object is available.
- Add a bool presync argument to both of the above, to identify signals
pertaining to the first headers sync phase.
In order to prevent memory DoS, we must ensure that we don't accept a new
header into memory until we've performed anti-DoS checks, such as verifying
that the header is part of a sufficiently high work chain. This commit adds a
new argument to AcceptBlockHeader() so that we can ensure that all call-sites
which might cause a new header to be accepted into memory have to grapple with
the question of whether the header is safe to accept, or needs further
validation.
This patch also fixes two places where low-difficulty-headers could have been
processed without such validation (processing an unrequested block from the
network, and processing a compact block).
Credit to Niklas Gögge for noticing this issue, and thanks to Sjors Provoost
for test code.
Avoid permanently storing headers from a peer, unless the headers are part of a
chain with sufficiently high work. This prevents memory attacks using low-work
headers.
Designed and co-authored with Pieter Wuille.
Move ChainstateManager options into m_options struct to simplify class
initialization, organize class members, and to name external option variables
differently than internal state variables.
This change was originally in #25862, but it was suggested to split off in
https://github.com/bitcoin/bitcoin/pull/25862#discussion_r951459817 so it could
be merged earlier and reduce conflicts with other PRs.
1dc03dda05 [doc] remove non-signaling mentions of BIP125 (glozow)
32024d40f0 scripted-diff: remove mention of BIP125 from non-signaling var names (glozow)
Pull request description:
We have pretty thorough documentation of our RBF policy in doc/policy/mempool-replacements.md. It enumerates each rule with several sentences of rationale. Also, each rule pretty much has its own function (3 and 4 share one), with extensive comments. The doc states explicitly that our rules are similar but differ from BIP125, and contains a record of historical changes to RBF policy.
We should not use "BIP125" as synonymous with our RBF policy because:
- Our RBF policy is different from what is specified in BIP125, for example:
- the BIP does not mention our rule about the replacement feerate being higher (our Rule 6)
- the BIP uses minimum relay feerate for Rule 4, while we have used incremental relay feerate since #9380
- the "inherited signaling" question (CVE-2021-31876). Call it discrepancy, ambiguous wording, doc misinterpretation, or implementation details, I would recommend users refer to doc/policy/mempool-replacements.md
- the signaling policy is configurable, see #25353
- Our RBF policy may change further
- We have already marked BIP125 as only "partially implemented" in docs/bips.md since 1fd49eb498
- See comments from people who are not me recently:
- https://github.com/bitcoin/bitcoin/pull/25038#discussion_r909507429
- https://github.com/bitcoin/bitcoin/pull/25575#issuecomment-1179519204
This PR removes all non-signaling mentions of BIP125 (if people feel strongly, we can remove all mentions of BIP125 period). It may be useful to refer to the concept of "tx opts in to RBF if it has at least one nSequence less than (0xffffffff - 1)" as "BIP125 signaling" because:
- It is succint.
- It has already been widely marketed as BIP125 opt-in signaling.
- Our API uses it when referring to signaling (e.g. getmempoolentry["bip125-replaceable"] and wallet error message "not BIP 125 replaceable"). Changing those is more invasive.
- If/when we have other ways to signal in the future, we can disambiguate them this way. See #25038 which proposes another way of signaling, and where I pulled these commits from.
Alternatives:
- Changing our policy to match BIP125. This doesn't make sense as, for example, we would have to remove the requirement that a replacement tx has a higher feerate (Rule 6).
- Changing BIP125 to match what we have. This doesn't make sense as it would be a significant change to a BIP years after it was finalized and already used as a spec to implement RBF in other places.
- Document our policy as a new BIP and give it a number. This might make sense if we don't expect things to change a lot, and can be done as a next step.
ACKs for top commit:
darosior:
ACK 1dc03dda05
ariard:
ACK 1dc03dda
t-bast:
ACK 1dc03dda05
Tree-SHA512: a3adc2039ec5785892d230ec442e50f47f7062717392728152bbbe27ce1c564141f85253143f53cb44e1331cf47476d74f5d2f4b3cd873fc3433d7a0aa783e02
eeee5ada23 Make adjusted time type safe (MacroFake)
fa3be799fe Add time helpers (MacroFake)
Pull request description:
This makes follow-ups easier to review. Also, it makes sense by itself.
ACKs for top commit:
ryanofsky:
Code review ACK eeee5ada23. Confirmed type changes and equivalent code changes only.
Tree-SHA512: 51bf1ae5428552177286113babdd49e82459d6c710a07b6e80a0a045d373cf51045ee010461aba98e0151d8d71b9b3b5f8f73e302d46ba4558e0b55201f99e9f
9376a6dae4 refactor: make active_chain_tip a reference (Aurèle Oulès)
Pull request description:
This PR fixes a TODO introduced in #21055.
Makes `active_chain_tip` argument in `CheckFinalTxAtTip` function a reference instead of a pointer.
ACKs for top commit:
dongcarl:
ACK 9376a6dae4
Tree-SHA512: c36d1769e0b9598b7f79334704b26b73e958d54caa3bd7e4eff954f3964fcf3f5e3a44a5a760497afad51b76e1614c86314fe035e4083c855e3574a620de7f4d
Our RBF policy is different from the rules specified in BIP125. For
example, the BIP does not mention Rule 6, and our Rule 4 uses the
(configurable) incremental relay feerate (distinct from the
minimum relay feerate). Those interested in our policy should refer to
doc/policy/mempool-replacements.md instead. These rules may also
continue to diverge with package RBF and other RBF improvements. Keep
references to the BIP125 signaling wrt sequence numbers, since that is
still correct and widely used. It is helpful to refer to this as "BIP125
signaling" since it is unambiguous and succint, especially if we have
multiple ways to signal replaceability in the future.
The rule numbers in doc/policy/mempool-replacements.md correspond
largely to those of BIP 125, so we can still refer to them like "Rule 5."
faab8dceb3 Remove unused SetTip(nullptr) code (MacroFake)
Pull request description:
Now that this path is no longer used after commit b51e60f914, we can remove it.
Future code should reset `CChain` by simply discarding it and constructing a fresh one.
ACKs for top commit:
ryanofsky:
Code review ACK faab8dceb3. Just moved an assert statement since last review
Tree-SHA512: 7dc273b11133d85d32ca2a69c0c7c07b39cdd338141ef5b51496e7de334a809864d5459eb95535497866c8b1e468aae84ed8f91b543041e6ee20130d5622874e
Also:
- Make DEFAULT_MAX_SIG_CACHE_SIZE into constexpr
DEFAULT_MAX_SIG_CACHE_BYTES to utilize the compile-time integer
arithmetic overflow checking available to constexpr.
- Fix comment (MiB instead of MB) for DEFAULT_MAX_SIG_CACHE_BYTES.
- Pass in max_size_bytes parameter to InitS*Cache(), modify log line to
no longer allude to maxsigcachesize being split evenly between the two
validation caches.
- Fix possible integer truncation and add a comment.
[META] I've kept the integer types as int64_t in order to not introduce
unintended behaviour changes, in the next commit we will make
them size_t.
This fixes an potential overflow which existed prior to this patchset.
If CuckooCache::cache<Element, Hash>::setup_bytes is called with a
`size_t bytes` which, when divided by sizeof(Element), does not fit into
an uint32_t, the implicit conversion to uint32_t in the call to setup
will result in an overflow.
At least on x86_64, this overflow is possible:
static_assert(std::numeric_limits<size_t>::max() / 32 <= std::numeric_limits<uint32_t>::max());
static_assert(std::numeric_limits<size_t>::max() / 4 <= std::numeric_limits<uint32_t>::max());
This commit detects such cases and signals to callers that the `size_t
bytes` input is too large.
1. -maxsigcachesize is a DEBUG_ONLY option
2. Almost 7 years has passed since its semantics change in
830e3f3d02 from "number of entries" to
"number of mebibytes"
3. A std::new_handler was added to the codebase after the original PR
which introduced this limit, which will terminate immediately instead
of causing trouble by being caught somewhere unexpected.
Returning the approximate total size eliminates the need for
InitS*Cache() to do nElems*sizeof(uint256). The cuckoocache has a better
idea of this information.
Our RBF policy is different from the rules specified in BIP125 (refer to
doc/policy/mempool-replacements.md instead), and will continue to
diverge with package RBF. Keep references to BIP125 sequence number,
since that is still useful and correct.
-BEGIN VERIFY SCRIPT-
ren() { sed -i "s:\<$1\>:$2:g" $(git grep -l "\<$1\>" ./src ./test); }
ren m_allow_bip125_replacement m_allow_replacement
ren allow_bip125_replacement allow_replacement
ren MAX_BIP125_REPLACEMENT_CANDIDATES MAX_REPLACEMENT_CANDIDATES
-END VERIFY SCRIPT-
dd065dae9f refactor: Make mapBlocksUnknownParent local, and rename it (Hennadii Stepanov)
Pull request description:
This PR is a second attempt at #19594. This PR has two motivations:
- Improve code hygiene by eliminating a global variable, `mapBlocksUnknownParent`
- Fix fuzz test OOM when running too long ([see #19594 comment](https://github.com/bitcoin/bitcoin/pull/19594#issuecomment-958801638))
A minor added advantage is to release `mapBlocksUnknownParent` memory when the reindexing phase is done. The current situation is somewhat similar to a memory leak because this map exists unused for the remaining lifetime of the process. It's true that this map should be empty of data elements after use, but its internal metadata (indexing structures, etc.) can have non-trivial size because there can be many thousands of simultaneous elements in this map.
This PR helps our efforts to reduce the use of global variables. This variable isn't just global, it's hidden inside a function (it looks like a local variable but has the `static` attribute).
This global variable exists because the `-reindex` processing code calls `LoadExternalBlockFile()` multiple times (once for each block file), but that function must preserve some state between calls (the `mapBlocksUnknownParent` map). This PR fixes this by allocating this map as a local variable in the caller's scope and passing it in on each call. When reindexing completes, the map goes out of scope and is deallocated.
I tested this manually by reindexing on mainnet and signet. Also, the existing `feature_reindex.py` functional test passes.
ACKs for top commit:
mzumsande:
re-ACK dd065dae9f
theStack:
re-ACK dd065dae9f
shaavan:
reACK dd065dae9f
Tree-SHA512: 9cd20e44d2fa1096dd405bc107bc065ea8f904f5b3f63080341b08d8cf57b790df565f58815c2f331377d044d5306708b4bf6bdfc5ef8d0ed85d8e97d744732c
3a61fc56a0 refactor: move CBlockIndex#ToString() from header to implementation (Jon Atack)
57865eb512 CDiskBlockIndex: rename GetBlockHash() to ConstructBlockHash() (Jon Atack)
99e8ec8721 CDiskBlockIndex: remove unused ToString() class member (Jon Atack)
14aeece462 CBlockIndex: ensure phashBlock is not nullptr before dereferencing (Jon Atack)
Pull request description:
Fix a few design issues, potential footguns and inconsistent behavior in the CBlockIndex and CDiskBlockIndex classes.
- Ensure phashBlock in `CBlockIndex#GetBlockHash()` is not nullptr before dereferencing and remove a now-redundant assert preceding a GetBlockHash() caller. This protects against UB here, and in case of failure (which would indicate a consensus bug), the debug log will print `bitcoind: chain.h:265: uint256 CBlockIndex::GetBlockHash() const: Assertion 'phashBlock != nullptr' failed. Aborted` instead of `Segmentation fault`.
- Remove the unused `CDiskBlockIndex#ToString()` class member, and mark the inherited `CBlockIndex#ToString()` public interface member as deleted to disallow calling it in the derived CDiskBlockIndex class.
- Rename the `CDiskBlockIndex GetBlockHash()` class member to `ConstructBlockHash()`, which also makes sense as they perform different operations to return a blockhash, and mark the inherited `CBlockIndex#GetBlockHash()` public interface member as deleted to disallow calling it in the derived CDiskBlockIndex class.
- Move `CBlockIndex#ToString()` from header to implementation, which also allows dropping `tinyformat.h` from the header file.
Rationale and discussion regarding the CDiskBlockIndex changes:
Here is a failing test on master that demonstrates the inconsistent behavior of the current design: calling the same inherited public interface functions on the same CDiskBlockIndex object should yield identical behavior, but does not.
```diff
diff --git a/src/test/validation_chainstatemanager_tests.cpp b/src/test/validation_chainstatemanager_tests.cpp
index 6dc522b421..dac3840f32 100644
--- a/src/test/validation_chainstatemanager_tests.cpp
+++ b/src/test/validation_chainstatemanager_tests.cpp
@@ -240,6 +240,15 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_activate_snapshot, TestChain100Setup)
const CBlockIndex* tip = chainman.ActiveTip();
BOOST_CHECK_EQUAL(tip->nChainTx, au_data.nChainTx);
+ // CDiskBlockIndex "is a" CBlockIndex, as it publicly inherits from it.
+ // Test that calling the same inherited interface functions on the same
+ // object yields identical behavior.
+ CDiskBlockIndex index{tip};
+ CBlockIndex *pB = &index;
+ CDiskBlockIndex *pD = &index;
+ BOOST_CHECK_EQUAL(pB->GetBlockHash(), pD->GetBlockHash());
+ BOOST_CHECK_EQUAL(pB->ToString(), pD->ToString());
```
(build and run: `$ ./src/test/test_bitcoin -t validation_chainstatemanager_tests`)
The GetBlockHash() test assertion only passes on master because the different methods invoked by the current design happen to return the same result. If one of the two is changed, it fails like the ToString() assertion does.
Redefining inherited non-virtual functions is well-documented as incorrect design to avoid inconsistent behavior (see Scott Meyers, Effective C++, Item 36). Class usage is confusing when the behavior depends on the pointer definition instead of the object definition (static binding happening where dynamic binding was expected). This can lead to unsuspected or hard-to-track bugs.
Outside of critical hot spots, correctness usually comes before optimisation, but the current design dates back to main.cpp and it may possibly have been chosen to avoid the overhead of dynamic dispatch. This solution does the same: the class sizes are unchanged and no vptr or vtbl is added.
There are better designs for doing this that use composition instead of inheritance, or that separate the public interface from the private implementations. One example of the latter would be a non-virtual public interface that calls private virtual implementation methods, i.e. the Template pattern via the Non-Virtual Interface (NVI) idiom.
ACKs for top commit:
vasild:
ACK 3a61fc56a0
Tree-SHA512: 9ff358ab0a6d010b8f053ad8303c6d4d061e62d9c3755a56b9c9f5eab855d02f02bee42acc77dfa0cbf4bb5cb775daa72d675e1560610a29bd285c46faa85ab7
and remove a now-redundant assert preceding a GetBlockHash() caller.
This protects against UB here, and in case of failure (which would
indicate a consensus bug), the debug log will print
bitcoind: chain.h:265: uint256 CBlockIndex::GetBlockHash() const: Assertion `phashBlock != nullptr' failed.
Aborted
instead of
Segmentation fault
facc2fa7b8 Use AutoFile where possible (MacroFake)
6666803c89 streams: Add AutoFile without ser-type and ser-version (MacroFake)
Pull request description:
This was done in the context of https://github.com/bitcoin/bitcoin/pull/25284 , but I think it also makes sense standalone.
The basic idea is that serialization type should not be initialized when it is not needed. Same for the serialization version.
So do this here for `AutoFile`. `CAutoFile` remains in places where it is not yet possible.
ACKs for top commit:
laanwj:
Code review ACK facc2fa7b8
fanquake:
ACK facc2fa7b8
Tree-SHA512: d82d024d55af57565ac53d9d1517afafc12b46964effba0332de62a6c77869356fa77f89e6d4834438fff44c45b64fccdf5a1358bfea03e28dfe55013b3c099d
