[crashtracker] Enable client to configure which signals to trap #856
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danielsn
commented
Feb 5, 2025
| SigHandler::Handler(f) => f(signum), | ||
| SigHandler::SigAction(f) => f(signum, sig_info, ucontext), | ||
| }; | ||
| eprintln!("Unexpected signal number {signum}, can't chain the handlers"); |
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What should we do here? abort?
danielsn
commented
Feb 5, 2025
| unsafe { create_alt_stack()? }; | ||
| } | ||
| let mut old_handlers = HashMap::new(); | ||
| // TODO: if this fails, we end in a situation where handlers have been registered with no chain |
danielsn
commented
Feb 5, 2025
| let boxed_ptr = Box::into_raw(Box::new(old_handlers)); | ||
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| let res = OLD_HANDLERS.compare_exchange(ptr::null_mut(), boxed_ptr, SeqCst, SeqCst); | ||
| anyhow::ensure!( |
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This leaks the old_handlers, if we care?
danielsn
commented
Feb 5, 2025
| @@ -674,9 +665,11 @@ pub fn restore_old_handlers(inside_signal_handler: bool) -> anyhow::Result<()> { | |||
| anyhow::ensure!(!prev.is_null(), "No crashtracking previous signal handlers"); | |||
| // Safety: The only nonnull pointer stored here comes from Box::into_raw() | |||
| let prev = unsafe { Box::from_raw(prev) }; | |||
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We could flip this around, and only rehydrate into a box when we are ready to drop it
BenchmarksComparisonBenchmark execution time: 2025-02-07 21:47:55 Comparing candidate commit ab7383e in PR branch Found 0 performance improvements and 4 performance regressions! Performance is the same for 48 metrics, 2 unstable metrics. scenario:credit_card/is_card_number/37828224631000521389798
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BaselineOmitted due to size. |
danielsn
commented
Feb 5, 2025
| before_len == signals.len(), | ||
| "Signals contained duplicate elements" | ||
| ); | ||
|
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Could also check that the ints are valid here?
danielsn
commented
Feb 5, 2025
| ddog_crasht_Config config = { | ||
| .create_alt_stack = false, | ||
| .endpoint = endpoint, | ||
| .resolve_frames = DDOG_CRASHT_STACKTRACE_COLLECTION_ENABLED_WITH_INPROCESS_SYMBOLS, | ||
| .signals = INIT_FROM_SLICE(signals), |
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Is there a nicer way to do this?
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danielsn
commented
Feb 6, 2025
| @@ -320,6 +328,7 @@ fn test_altstack_use_create() -> anyhow::Result<()> { | |||
| eprintln!("Expected SIGSEGV handler to have SA_ONSTACK"); | |||
| std::process::exit(-9); | |||
| } | |||
| // TODO, the other signals | |||
Codecov ReportAttention: Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #856 +/- ##
==========================================
- Coverage 72.08% 71.81% -0.28%
==========================================
Files 323 323
Lines 47941 48207 +266
==========================================
+ Hits 34560 34618 +58
- Misses 13381 13589 +208
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One thing I strongly recommend is: let's put in some defaults! In past features "leaving it up to implementer" often meant unintended inconsistency as things get picked semi-randomly; I think in general it's nice to have a pattern of "if you don't want to choose, we pick a reasonable default, don't worry about it". |
https://github.com/DataDog/libdatadog/pull/856/files#diff-fded76796d1b1945fd14d3cdb6230e4692e94608fc4887d26e2530a004df451aR59 |
Ahaha my bad for scrolling too fast through the PR, and amazing work in getting this in :D :D :D |
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What does this PR do?
Instead of hardcoding the signals to trap, allow the client to specify them
Motivation
We wanted to catch sigabort and sigill in addition to sigsegv and sigbus, and I figured lets just make it generic.
Additional Notes
Anything else we should know when reviewing?
How to test the change?