pthread_setcancelstate()

Implementations may make other interfaces async-signal-safe.

It is implementation-defined which additional interfaces, if any, are also async-signal-safe.

If a thread has deferred cancellation enabled, a signal catching function is called in that thread during execution of a function that is not async-cancel-safe, and the signal catching function calls any function that is a cancellation point while a cancellation is pending for the thread, the behavior is undefined.

If a thread has deferred cancellation enabled, a signal catching function is called in that thread during execution of a function that is not async-cancel-safe, and the signal catching function calls any function that is a cancellation point while a cancellation is pending for the thread, without first disabling cancellation, the behavior is undefined.

In order to write a signal handler for an asynchronous signal which can run safely in a cancellable thread, pthread_setcancelstate() must be used to disable cancellation for the duration of any calls that the signal handler makes which are cancellation points. However, the standard does not permit strictly conforming applications to call pthread_setcancelstate() from a signal handler since it is not currently required to be async-signal-safe. On implementations where pthread_setcancelstate() is not async-signal-safe, alternatives are to ensure either that the corresponding signals are blocked during execution of functions that are not async-cancel-safe or that cancellation is disabled during times when those signals could be delivered. Implementations are strongly encouraged to make pthread_setcancelstate() async-signal-safe.

In order to write a signal handler for an asynchronous signal which can run safely in a cancellable thread, pthread_setcancelstate() must be used to disable cancellation for the duration of any calls that the signal handler makes which are cancellation points. However, earlier versions of the standard did not permit strictly conforming applications to call pthread_setcancelstate() from a signal handler since it was not required to be async-signal-safe. On non-conforming implementations where pthread_setcancelstate() is not async-signal-safe, alternatives are to ensure either that the corresponding signals are blocked during execution of functions that are not async-cancel-safe or that cancellation is disabled during times when those signals could be delivered.

The pthread_setcancelstate() function shall be async-signal-safe.

The pthread_setcancelstate() function may be added to the table of async-signal-safe functions in section 2.4.3 on page 489.

None.