fix(error-tracking): correct frame addresses, ordering, and in-app detection#549
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fix(error-tracking): correct frame addresses, ordering, and in-app detection#549
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…tection Four correctness fixes for iOS stack trace capture: - Zero-pad instruction addresses to 16 hex digits (0x%016llx) so the format is consistent and cymbal can always parse them reliably. - Strip PAC bits from arm64e pointers (mask 0x0000_000f_ffff_ffff) before storing addresses. Modern iPhones embed pointer authentication codes in the high bits; without stripping, dladdr lookups and cymbal symbolication fail or produce wrong results. - Reverse frames to bottom-up order (outermost/main first, crash site last) in both PostHogExceptionProcessor and PostHogCrashReportProcessor. callStackReturnAddresses and PLCrashReport both deliver frames top-down; the Sentry event format (which cymbal consumes) expects bottom-up. - Add isSystemPath() helper to PostHogStackTraceProcessor to catch system binaries not in the hardcoded module-name list (e.g. private frameworks like 'Gestures', 'Accessibility' from UIKitCore) by checking their binary path against /System/ and /usr/lib/ prefixes. Pass package path to isInApp() so the path check is applied.
ioannisj
approved these changes
Apr 3, 2026
…ked in-app Two complementary fixes for frames that dladdr cannot resolve to a path: 1. When dladdr succeeds but dli_fname is nil (e.g. shared-cache private frameworks like Gestures/UIKitCore on Simulator, or on-device dyld shared cache binaries), inApp now defaults to false instead of falling through to inAppByDefault=true. We have no evidence that a frame with no resolvable binary path is user code. 2. Extend systemPrefixes with known private UIKit sub-frameworks (Gestures, UIKitCore, Accessibility, UpdateCycle, TextInput, etc.) and common system dylibs (libobjc, dyld, libsystem_c, etc.) so that frames from these modules are rejected by isSystemFramework() even when dladdr does return a path.
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posthog-ios Compliance ReportDate: 2026-04-03 17:34:24 UTC ✅ All Tests Passed!0/0 tests passed |
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What
Four correctness fixes for iOS stack trace capture.
Fixes
Zero-padded addresses
Instruction addresses are now formatted as 16-digit zero-padded hex (
0x%016llx), consistent with what cymbal expects for address lookup.PAC bit stripping (arm64e)
Modern iPhones embed pointer authentication codes in the high bits of pointers. Addresses are now masked with
0x0000_000f_ffff_ffffbefore being stored, sodladdrlookups and cymbal symbolication work correctly on arm64e devices.Frame ordering
Both
PostHogExceptionProcessorandPostHogCrashReportProcessorwere emitting frames in top-down order (crash site first). The Sentry event format that cymbal consumes expects bottom-up (outermost/main first, crash site last). Frames are now reversed before serialization.System path detection
isInApp()was only checking a hardcoded list of module names for system frameworks. Private frameworks not in that list (e.g.Gestures,Accessibilityfrom UIKitCore) were incorrectly marked as in-app. A newisSystemPath()helper checks the binary path against/System/and/usr/lib/prefixes, covering both device and Simulator paths.