fix: AOT interop with managed .NET runtimes

[jpnurmi]

📜 Description

TLDR; reorder .NET/Mono vs. Sentry Cocoa signal handlers to allow the .NET runtime to convert certain signals to managed .NET exceptions where appropriate, and chain actual native crashes to Sentry Cocoa.

Before

┌──────────────┐     ┌───────────┐     ┌────────┐
│ Sentry Cocoa │────>│ .NET/Mono │────>│ System │
└──────────────┘     └───────────┘     └────────┘

After:

┌───────────┐     ┌──────────────┐     ┌────────┐
│ .NET/Mono │────>│ Sentry Cocoa │────>│ System │
└───────────┘     └──────────────┘     └────────┘

Changes

Mostly gated by the SENTRY_CRASH_MANAGED_RUNTIME compile-time flag to minimize impact on normal SDK operation:

1. Signal handler preloading — A __attribute__((constructor)) preloads SentryCrash's signal handlers before the managed runtime starts, ensuring the correct handler chain order: managed runtime → SentryCrash → system. This lets the managed runtime handle signals like SIGSEGV (for NullReferenceException) and SIGFPE (for DivideByZeroException) before SentryCrash sees them.

2. Mach exception mask filtering — Excludes EXC_MASK_BAD_ACCESS and EXC_MASK_ARITHMETIC from Mach exception monitoring, since these correspond to signals the managed runtime handles. Other Mach exceptions (EXC_BAD_INSTRUCTION, EXC_SOFTWARE, EXC_BREAKPOINT) are still monitored.

3. ignoreNextSignal: API — New method on PrivateSentrySDKOnly that tells SentryCrash to ignore the next occurrence of a given signal on the calling thread (thread-local, one-shot). Used by hybrid SDKs to prevent duplicate crash reports when the managed runtime is about to raise a signal (e.g. SIGABRT via abort()) for an exception that has already been captured: https://github.com/dotnet/macios/blob/d0d53e8230a79fd505ddf7cef2642493249ccb78/runtime/runtime.m#L1003-L1011

4. NULL-guard g_onExceptionEvent — Prevents a crash if a signal fires between the constructor preload and sentrycrash_install().

5. volatile crash pointer — The +[SentrySDK crash] test method now uses volatile to force an actual SIGSEGV instead of letting the compiler optimize the null dereference into a trap instruction (SIGTRAP).

💡 Motivation and Context

Fixes redundant native crash events when using Sentry with .NET on iOS:

• Managed exceptions (e.g. ApplicationException) produced a duplicate SIGABRT event
• NullReferenceException in AOT mode produced a duplicate EXC_BAD_ACCESS event

See: getsentry/sentry-dotnet#3954

💚 How did you test it?

Sentry .NET integration tests for iOS:

• https://github.com/getsentry/sentry-dotnet/blob/7ce86930def380bbf09a7f9b79c838922922f280/integration-test/ios.Tests.ps1#L102
• https://github.com/getsentry/sentry-dotnet/blob/7ce86930def380bbf09a7f9b79c838922922f280/integration-test/ios.Tests.ps1#L129

📝 Checklist

You have to check all boxes before merging:

• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

[codecov]

Codecov Report

❌ Patch coverage is 22.72727% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.419%. Comparing base (bab8d5e) to head (27df7b7).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...ash/Recording/Monitors/SentryCrashMonitor_Signal.c	17.647%	14 Missing ⚠️
Sources/Sentry/PrivateSentrySDKOnly.m	0.000%	1 Missing ⚠️
Sources/Sentry/SentrySDKInternal.m	0.000%	1 Missing ⚠️
Sources/SentryCrash/Recording/SentryCrashC.c	0.000%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #6193       +/-   ##
=============================================
- Coverage   85.455%   85.419%   -0.037%     
=============================================
  Files          487       487               
  Lines        29166     29183       +17     
  Branches     12612     12643       +31     
=============================================
+ Hits         24924     24928        +4     
- Misses        4192      4204       +12     
- Partials        50        51        +1     

Files with missing lines	Coverage Δ
...entryCrash/Recording/Monitors/SentryCrashMonitor.c	84.210% <100.000%> (+0.210%)	⬆️
...ording/Monitors/SentryCrashMonitor_MachException.c	36.286% <ø> (ø)
Sources/Sentry/PrivateSentrySDKOnly.m	72.727% <0.000%> (-0.607%)	⬇️
Sources/Sentry/SentrySDKInternal.m	84.716% <0.000%> (ø)
Sources/SentryCrash/Recording/SentryCrashC.c	76.829% <0.000%> (-0.949%)	⬇️
...ash/Recording/Monitors/SentryCrashMonitor_Signal.c	55.200% <17.647%> (-6.062%)	⬇️

... and 6 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update bab8d5e...27df7b7. Read the comment docs.

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1222.57 ms	1262.87 ms	40.30 ms
Size	24.14 KiB	1.13 MiB	1.11 MiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
4d1f3fb	1217.77 ms	1253.84 ms	36.08 ms
f84c826	1216.38 ms	1241.98 ms	25.60 ms
ee272e8	1210.98 ms	1245.10 ms	34.12 ms
2c4362a	1231.50 ms	1255.95 ms	24.45 ms
5b1e2a1	1217.63 ms	1245.49 ms	27.86 ms
bffd360	1218.16 ms	1249.86 ms	31.70 ms
3060db6	1229.84 ms	1257.53 ms	27.70 ms
5d67f5d	1225.33 ms	1262.76 ms	37.43 ms
e701dc8	1215.89 ms	1254.06 ms	38.17 ms
a8ec727	1225.29 ms	1259.59 ms	34.30 ms

App size

Revision	Plain	With Sentry	Diff
4d1f3fb	24.14 KiB	1.13 MiB	1.10 MiB
f84c826	24.14 KiB	1.04 MiB	1.02 MiB
ee272e8	24.14 KiB	1.10 MiB	1.08 MiB
2c4362a	24.14 KiB	1.07 MiB	1.04 MiB
5b1e2a1	24.14 KiB	1.11 MiB	1.09 MiB
bffd360	24.14 KiB	1.11 MiB	1.09 MiB
3060db6	24.14 KiB	1.12 MiB	1.10 MiB
5d67f5d	24.14 KiB	1.06 MiB	1.04 MiB
e701dc8	24.14 KiB	1.06 MiB	1.04 MiB
a8ec727	24.14 KiB	1.12 MiB	1.10 MiB

Previous results on branch: jpnurmi/mono-interop

Startup times

Revision	Plain	With Sentry	Diff
efedb0c	1218.20 ms	1256.60 ms	38.40 ms
4a46856	1236.53 ms	1262.79 ms	26.26 ms
58546af	1217.57 ms	1248.98 ms	31.40 ms
3a8f309	1223.75 ms	1245.77 ms	22.02 ms
2488cd0	1215.08 ms	1241.24 ms	26.16 ms
446c562	1227.20 ms	1256.17 ms	28.97 ms
444f214	1223.69 ms	1249.73 ms	26.04 ms

App size

Revision	Plain	With Sentry	Diff
efedb0c	24.14 KiB	1.13 MiB	1.10 MiB
4a46856	24.14 KiB	1.13 MiB	1.10 MiB
58546af	24.14 KiB	1.13 MiB	1.11 MiB
3a8f309	24.14 KiB	1.13 MiB	1.10 MiB
2488cd0	24.14 KiB	1.13 MiB	1.11 MiB
446c562	24.14 KiB	1.13 MiB	1.10 MiB
444f214	24.14 KiB	1.13 MiB	1.11 MiB

[jpnurmi]

Screen.Recording.2025-09-18.at.11.54.52.mov

[philprime]

Hey @jpnurmi what's the progress on this PR?

[jpnurmi]

I had quite some trouble passing the CI last time I tried. 😅 I should totally revive this because Sentry .NET is still very much in need of a solution for eliminating redundant EXC_BAD_ACCESS for managed exceptions that were handled by the managed runtime.

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

This is how your changes will appear in the changelog.
Entries from this PR are highlighted with a left border (blockquote style).

---

New Features ✨

• Implement strict trace continuation by antonis in #7705

Bug Fixes 🐛

• (replay) Scope clipOut masking to active clip bounds by denrase in #7780

• AOT interop with managed .NET runtimes by jpnurmi in #6193

Internal Changes 🔧

Deps

• Bump addressable from 2.8.9 to 2.9.0 by dependabot in #7783
• Update clang-format version by sentry-mobile-updater in #7782
• Bump mikepenz/action-junit-report from 6.3.1 to 6.4.0 by dependabot in #7773
• Bump ruby/setup-ruby from 1.298.0 to 1.299.0 by dependabot in #7772
• Bump fastlane-plugin-sentry from 2.5.0 to 2.5.1 by dependabot in #7771

---

_{🤖 This preview updates automatically when you update the PR.}

[jpnurmi]

@supervacuus thanks for the view! 🙏 I've addressed the close/reinstall scenario.

[jpnurmi]

By the way, there are integration tests prepared in sentry-dotnet. This patch fixes both scenarios with redundant native exceptions:

• https://github.com/getsentry/sentry-dotnet/blob/3e2eae9230101d229a65a1d667cf5d2203410d94/integration-test/ios.Tests.ps1#L102-L104
• https://github.com/getsentry/sentry-dotnet/blob/3e2eae9230101d229a65a1d667cf5d2203410d94/integration-test/ios.Tests.ps1#L129-L135

With this PR and expected failures removed:

$ pwsh integration-test/ios.Tests.ps1
[...]
[+] /Users/jpnurmi/Projects/sentry/sentry-dotnet/integration-test/ios.Tests.ps1 180.08s (178.93s|113ms)
Tests completed in 180.08s
Tests Passed: 6, Failed: 0, Skipped: 0, Inconclusive: 0, NotRun: 0

[jpnurmi]

Hi @philipphofmann @philprime @noahsmartin @itaybre, this PR is ready for review when you get a chance. It adds managed runtime (.NET/Mono) signal handler interop, solving a long-standing issue for .NET on iOS (getsentry/sentry-dotnet#3954). Most of it is gated behind SENTRY_CRASH_MANAGED_RUNTIME to minimize the impact on normal SDK operation. @supervacuus already provided feedback on the lifecycle concerns, which have been addressed in the latest commits. Thanks! 🙏

[itaybre]

Almost LGTM, can we document SENTRY_CRASH_MANAGED_RUNTIME and the constructor in the develop_docs folder for future reference?

[jpnurmi]

Thanks for the review! Sounds good, I'll take a look tomorrow.

P.S. The .NET ecosystem likes to own the term "managed" but technically, many other runtimes are managed too. I might rename it to SENTRY_CRASH_DOTNET_RUNTIME, or maybe just SENTRY_CRASH_DOTNET. What do you think?

[itaybre]

Thanks for the review! Sounds good, I'll take a look tomorrow.

P.S. The .NET ecosystem likes to own the term "managed" but technically, many other runtimes are managed too. I might rename it to SENTRY_CRASH_DOTNET_RUNTIME, or maybe just SENTRY_CRASH_DOTNET. What do you think?

I would prefer to avoid DOTNET in the name, just in case some other SDK needs this in the future.
Aside from that, I am fine with that

[jpnurmi]

Fair enough, I kept SENTRY_CRASH_MANAGED_RUNTIME and only mentioned .NET/Mono as an example in the developer docs. Hard to say how compatible this would be with some other managed runtimes, but we can leave the door open.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

[itaybre]

LGTM

[itaybre]

LGTM