fspy preload can abort or deadlock cached tasks during signals, fork, or teardown

fspy’s Unix preload must not make a traced process less reliable. Interposed calls can run from signal handlers, post-fork() children, or during teardown, where unsafe runtime state can cause deadlocks or aborts.

Expected behavior:

• Never panic, abort, or deadlock the workload.
• Preserve the original call’s result and errno.
• Work safely during signals, after fork(), and during teardown on Linux and macOS.
• If tracing fails, let the workload continue but skip caching the incomplete trace.
• Add regression coverage for these contexts.

Individua gli entry point Unix preload di fspy e segui i percorsi cached-task, signal, post-fork e teardown. Verifica come le interposed calls preservano i risultati e errno, quindi esegui la test suite esistente prima di aggiungere la copertura di regressione per Linux e macOS in ogni contesto. Il lavoro è completo quando i fallimenti saltano il caching incompleto senza interrompere l’esecuzione, causare deadlock o modificare i risultati del workload.