Asynchronous signal safe function
An asynchronous signal-safe function is a function permitted to execute in an asynchronous signal handler without violating signal-handling rules.
Modern C
An asynchronous signal safe function is a function that may be called from a handler for an asynchronous signal without violating the signal-handling rules.
- How it is used
- Constrains which functions an asynchronous signal handler may call without uncontrolled changes to program state.
- How deep it goes
- Defines the rule, lists C-standard guarantees, and distinguishes portable guarantees from broader platform allowances.
- Examples
- Uses a handler that calls quick_exit or _Exit and resets handling with signal.
- What you can do after
- Evaluate/understand whether a proposed handler call has a C-standard safety guarantee rather than assuming ordinary library calls are safe.
Read how Modern C explains asynchronous signal safe function →
Modern C, Third Edition
An asynchronous signal-safe function is a function permitted to execute in an asynchronous signal handler without uncontrolled access to program state.
- How it is used
- Constrains which functions an asynchronous C signal handler may call without uncontrolled access to program state.
- How deep it goes
- Defines the safety rule and lists narrow standard guarantees, while deferring fuller treatment of atomic operations.
- Examples
- Uses a conditionally compiled atomic signal counter and contrasts permitted termination calls with `exit` and I/O.
- What you can do after
- Evaluate/understand whether a signal-handler call has a stated C-standard safety guarantee rather than assuming one.
Read how Modern C, Third Edition explains asynchronous signal safe function →
Related concepts
- signal handlercontrasts with · A signal handler is a function or mechanism that specifies or performs a response when a signal or notification is delivered.
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