pthread_testcancel¶

Synopsis¶

#include <pthread.h>

int pthread_setcancelstate(int state, int *oldstate);

int pthread_setcanceltype(int type, int *oldtype);

void pthread_testcancel(void);

Status¶

pthread_setcancelstate() and pthread_testcancel() are implemented, pthread_setcanceltype() is not implemented

Conformance¶

IEEE Std 1003.1-2017

Description¶

The pthread_setcancelstate() function shall atomically both set the calling thread’s cancelability state to the indicated state and return the previous cancelability state at the location referenced by oldstate. Legal values for state are PTHREAD_CANCEL_ENABLE and PTHREAD_CANCEL_DISABLE.

The cancelability state of any newly created threads, including the thread in which main() was first invoked, shall be PTHREAD_CANCEL_ENABLE.

The pthread_testcancel() function shall create a cancellation point in the calling thread. The pthread_testcancel() function shall have no effect if cancelability is disabled.

Return value¶

If successful, the pthread_setcancelstate() function shall return zero; otherwise, an error number shall be returned to indicate the error.

Errors¶

The pthread_setcancelstate() function may fail if:

EINVAL - The specified state is not PTHREAD_CANCEL_ENABLE or PTHREAD_CANCEL_DISABLE.

These functions shall not return an error code of EINTR.

POSIX deviations¶

PTHREAD_CANCEL_DEFERRED and PTHREAD_CANCEL_ASYNCHRONOUS are not defined.

If cancelability of the target is enabled when another thread calls pthread_cancel(), the cancellation processing does not run in the target thread. pthread_cancel() calls the cleanup handlers and the thread-specific data destructors of the target in the calling thread before it returns, and then terminates the target wherever it is executing, not at a cancellation point. A target blocked in a call handled by posixsrv, such as sem_wait() on a named semaphore or a read from an empty pipe, is terminated only when the call returns. See Blocking operations are not interruptible.

A cancellation request made while cancelability is disabled is acted upon only by pthread_testcancel(), not by the other cancellation points.