asynchronous-safe [[GNU Pth]]
A function is asynchronous-safe, or asynchronous-signal safe, if it can be called safely and without side effects from within a signal handler context. That is, it must be able to be interrupted at any point and run linearly out of sequence without causing an inconsistent state. Some asynchronous-safe operations are listed below:
- call the
signal()function to reinstall a signal handler - unconditionally modify a
volatile sig_atomic_tvariable (as modification to this type is atomic) - call the
_Exit()function to immediately terminate program execution - invoke an async-safe function, as specified by your implementation
Very few functions are asynchronous-safe. If a function performs any other operations, it is probably not asynchronous-safe.
free-standing environment [[Banahan 03]]
An environment without the C standard libraries. Common for stand-alone programs, such as operating systems or firmware.
hosted environment [[Banahan 03]]
An environment that supplies the C standard libraries.
implementation [[ISO/IEC 9899-1999]]
Particular set of software, running in a particular translation environment under particular control options, that performs translation of programs for, and supports execution of functions in, a particular execution environment.
implementation-defined behavior [[ISO/IEC 9899-1999]]
Unspecified behavior where each implementation documents how the choice is made.
locale-specific behavior [[ISO/IEC 9899-1999]]
Behavior that depends on local conventions of nationality, culture, and language that each implementation documents.
reentrant [[Dowd 06]]
A function is reentrant if multiple instances of the same function can run in the same address space concurrently without creating the potential for inconsistent states.
undefined behavior [[ISO/IEC 9899-1999]]
Behavior, upon use of a nonportable or erroneous program construct or of erroneous data, for which the standard imposes no requirements. An example of undefined behavior is the behavior on integer overflow.
unspecified behavior [[ISO/IEC 9899-1999]]
Behavior where the standard provides two or more possibilities and imposes no further requirements on which is chosen in any instance.
validation [[IEC 61508-4]]
Confirmation by examination and provision of objective evidence that the particular requirements for a specific intended use are fulfilled.
verification [[IEC 61508-4]]
Confirmation by examination and provision of objective evidence that the requirements have been fulfilled.