[support.start.term] (original) (raw)

17 Language support library [support]

17.5 Startup and termination [support.start.term]

[Note 1:

The header declares the functions described in this subclause.

— _end note_]

[[noreturn]] void _Exit(int status) noexcept;

Effects: This function has the semantics specified in the C standard library.

Remarks: The program is terminated without executing destructors for objects of automatic, thread, or static storage duration and without calling functions passed toatexit() ([basic.start.term]).

[[noreturn]] void abort() noexcept;

Effects: This function has the semantics specified in the C standard library.

Remarks: The program is terminated without executing destructors for objects of automatic, thread, or static storage duration and without calling functions passed toatexit() ([basic.start.term]).

int atexit(_c-atexit-handler_* f) noexcept;int atexit(_atexit-handler_* f) noexcept;

Effects: Theatexit()functions register the function pointed to by fto be called without arguments at normal program termination.

It is unspecified whether a call to atexit() that does nothappen beforea call to exit() will succeed.

Implementation limits: The implementation shall support the registration of at least 32 functions.

Returns: Theatexit()function returns zero if the registration succeeds, nonzero if it fails.

[[noreturn]] void exit(int status);

Effects:

• First, objects with thread storage duration and associated with the current thread are destroyed.
  Next, objects with static storage duration are destroyed and functions registered by callingatexitare called.216
  (Objects with automatic storage duration are not destroyed as a result of callingexit().)217
  If control leaves a registered function called by exit because the function does not provide a handler for a thrown exception, the function std​::​terminate shall be called ([except.terminate]).
• Next, all open C streams (as mediated by the function signatures declared in ) with unwritten buffered data are flushed, all open C streams are closed, and all files created by callingtmpfile() are removed.
• Finally, control is returned to the host environment.
  If status is zero orEXIT_­SUCCESS, an implementation-defined form of the statussuccessful terminationis returned.
  If status isEXIT_­FAILURE, an implementation-defined form of the statusunsuccessful terminationis returned.
  Otherwise the status returned is implementation-defined.218

int at_quick_exit(_c-atexit-handler_* f) noexcept;int at_quick_exit(_atexit-handler_* f) noexcept;

Effects: The at_­quick_­exit() functions register the function pointed to by fto be called without arguments when quick_­exit is called.

It is unspecified whether a call to at_­quick_­exit() that does nothappen beforeall calls to quick_­exit will succeed.

[Note 3:

Theat_­quick_­exit() functions do not introduce a data race ([res.on.data.races]).

— _end note_]

[Note 4:

The order of registration could be indeterminate if at_­quick_­exit was called from more than one thread.

— _end note_]

[Note 5:

Theat_­quick_­exit registrations are distinct from the atexit registrations, and applications might need to call both registration functions with the same argument.

— _end note_]

Implementation limits: The implementation shall support the registration of at least 32 functions.

Returns: Zero if the registration succeeds, nonzero if it fails.

[[noreturn]] void quick_exit(int status) noexcept;

Effects: Functions registered by calls to at_­quick_­exit are called in the reverse order of their registration, except that a function shall be called after any previously registered functions that had already been called at the time it was registered.

Objects shall not be destroyed as a result of calling quick_­exit.

If control leaves a registered function called by quick_­exit because the function does not provide a handler for a thrown exception, the function std​::​terminate shall be called.

[Note 6:

A function registered via at_­quick_­exitis invoked by the thread that calls quick_­exit, which can be a different thread than the one that registered it, so registered functions cannot rely on the identity of objects with thread storage duration.

— _end note_]

After calling registered functions, quick_­exit shall call _­Exit(status).

Remarks: The function quick_­exit is signal-safewhen the functions registered with at_­quick_­exit are.