.\" $OpenBSD: pthread_cancel.3,v 1.6 2000/02/10 11:45:35 d Exp $
.Dd January 17, 1999
.Dt PTHREAD_CANCEL 3
.Os
.Sh NAME
.Nm pthread_cancel ,
.Nm pthread_setcancelstate ,
.Nm pthread_setcanceltype
.Nd cancel execution of a thread
.Sh SYNOPSIS
.Fd #include <pthread.h>
.Ft int
.Fn pthread_cancel "pthread_t thread"
.Ft int
.Fn pthread_setcancelstate "int state" "int *oldstate"
.Ft int
.Fn pthread_setcanceltype "int type" "int *oldtype"
.Sh DESCRIPTION
The
.Fn pthread_cancel
function requests that
.Fa thread
be cancelled. The target thread's cancelability state and type determines
when the cancellation takes effect. When the cancellation is acted on,
the cancellation cleanup handlers for
.Fa thread
are called. When the last cancellation cleanup handler returns,
the thread-specific data destructor functions will be called for
.Fa thread .
When the last destructor function returns,
.Fa thread
will be terminated.
.Pp
The cancellation processing in the target thread runs asynchronously with
respect to the calling thread returning from
.Fn pthread_cancel .
.Pp
A status of
.Dv PTHREAD_CANCELED
is made available to any threads joining with the target. The symbolic
constant
.Dv PTHREAD_CANCELED
expands to a constant expression of type
.Ft "(void *)"
whose value matches no pointer to an object in memory nor the value
.Dv NULL .
.Sh RETURN VALUES
If successful,  the
.Fn pthread_cancel
functions will return zero. Otherwise an error number will be returned to
indicate the error.
.Sh ERRORS
.Fn pthread_cancel
will fail if:
.Bl -tag -width Er
.It Bq Er ESRCH
No thread could be found corresponding to that specified by the given
thread ID.
.El
.Sh SEE ALSO
.Xr pthread_cleanup_pop 3 ,
.Xr pthread_cleanup_push 3 ,
.Xr pthread_exit 3 ,
.Xr pthread_join 3 ,
.Xr pthread_setcancelstate 3 ,
.Xr pthread_setcanceltype 3 ,
.Xr pthread_testcancel 3
.Sh STANDARDS
.Fn pthread_cancel ,
.Fn pthread_setcancelstate ,
and
.Fn pthread_setcanceltype
conform to ISO/IEC 9945-1 ANSI/IEEE
.Pq Dq Tn POSIX
Std 1003.1 Second Edition 1996-07-12.