ipc test: add workaround to block_reserved_weight exception test
What the developer wrote
Authored by Ryan Ofsky
ipc test: add workaround to block_reserved_weight exception test
libmultiprocess currently handles uncaught exceptions from IPC methods badly
when an `mp.Context` parameter is passed and the IPC call executes on an a
worker thread, with the uncaught exception leading to a std::terminate call.
https://github.com/bitcoin-core/libmultiprocess/pull/218 was created to fix
this, but before that change is available, update an IPC test which can trigger
this behavior to handle it and recover when mp.Context parameters are added in
the an upcoming commit.
Having this workaround makes the test a little more complicated and less strict
but reduces dependencies between pending PRs so they don't need to be reviewed
or merged in a particular order.
What changed, and why it matters
This is a test-only change in Bitcoin Core. It adds a temporary workaround in an automated test so the test can keep running even when a known bug in a supporting library (libmultiprocess) causes the tested program to crash. The change does not alter normal Bitcoin node behavior, wallet handling, consensus rules, or network protocol handling, so it is not a security vulnerability in Bitcoin Core itself.
No immediate action required for Bitcoin Core users or operators. Treat as a test maintenance commit. Monitor libmultiprocess PR #218 for the upstream fix and revert or tighten the test workaround once it is available and integrated.
Security signals we found
Known upstream library bug referenced (libmultiprocess PR #218)
std::terminate and node disconnect behavior in test scenario
No change to production code, consensus, networking, or wallet logic
Test-only exception-handling relaxation
Evidence from the diff
The commit modifies test/functional/interface_ipc_mining.py. The test exercises the IPC mining interface and previously expected a specific Cap’n Proto exception (‘FAILED’ with a ‘block_reserved_weight’ message) when blockReservedWeight is set too low. Because libmultiprocess currently fails to propagate uncaught exceptions correctly when an mp.Context parameter is passed and the call runs on a worker thread—resulting in std::terminate and node disconnect—the test now also accepts a ‘DISCONNECTED’ exception, waits for the node to stop, and restarts it. This is a workaround for a known upstream bug fixed by libmultiprocess PR #218. It is purely a test-harness adjustment.
Changed components
test/functional/interface_ipc_mining.pyInspect captured patch +16 / −6
diff --git a/test/functional/interface_ipc_mining.py b/test/functional/interface_ipc_mining.py
index 61c050e7..d4a0d87e 100755
--- a/test/functional/interface_ipc_mining.py
+++ b/test/functional/interface_ipc_mining.py
@@ -6,6 +6,7 @@
import asyncio
from contextlib import AsyncExitStack
from io import BytesIO
+import re
from test_framework.blocktools import NULL_OUTPOINT
from test_framework.messages import (
MAX_BLOCK_WEIGHT,
@@ -257,12 +258,21 @@ class IPCMiningTest(BitcoinTestFramework):
empty_block = await mining_get_block(empty_template, ctx)
assert_equal(len(empty_block.vtx), 1)
- self.log.debug("Enforce minimum reserved weight for IPC clients too")
- opts.blockReservedWeight = 0
- try:
- await mining.createNewBlock(opts)
- raise AssertionError("createNewBlock unexpectedly succeeded")
- except capnp.lib.capnp.KjException as e:
+ self.log.debug("Enforce minimum reserved weight for IPC clients too")
+ opts.blockReservedWeight = 0
+ try:
+ await mining.createNewBlock(opts)
+ raise AssertionError("createNewBlock unexpectedly succeeded")
+ except capnp.lib.capnp.KjException as e:
+ if e.type == "DISCONNECTED":
+ # The remote exception isn't caught currently and leads to a
+ # std::terminate call. Just detect and restart in this case.
+ # This bug is fixed with
+ # https://github.com/bitcoin-core/libmultiprocess/pull/218
+ assert_equal(e.description, "Peer disconnected.")
+ self.nodes[0].wait_until_stopped(expected_ret_code=(-11, -6, 1, 66), expected_stderr=re.compile(""))
+ self.start_node(0)
+ else:
assert_equal(e.description, "remote exception: std::exception: block_reserved_weight (0) must be at least 2000 weight units")
assert_equal(e.type, "FAILED")
Why this scored 16/100
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