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/*
* cancel.c
*
* Description:
* POSIX thread functions related to thread cancellation.
*
* Pthreads-win32 - POSIX Threads Library for Win32
* Copyright (C) 1998
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA
*/
#include "pthread.h"
#include "implement.h"
static void
_pthread_cancel_self(void)
{
#if defined(_MSC_VER) && !defined(__cplusplus)
DWORD exceptionInformation[3];
exceptionInformation[0] = (DWORD) (_PTHREAD_EPS_CANCEL);
exceptionInformation[1] = (DWORD) (0);
exceptionInformation[2] = (DWORD) (0);
RaiseException (
EXCEPTION_PTHREAD_SERVICES,
0,
3,
exceptionInformation);
#else /* _MSC_VER && ! __cplusplus */
# ifdef __cplusplus
throw Pthread_exception_cancel();
# endif /* __cplusplus */
#endif /* _MSC_VER && ! __cplusplus */
/* Never reached */
}
/*
* _pthread_cancel_thread implements asynchronous cancellation.
*/
static void
_pthread_cancel_thread(pthread_t thread)
{
HANDLE threadH = thread->threadH;
(void) pthread_mutex_lock(&thread->cancelLock);
SuspendThread(threadH);
if (WaitForSingleObject(threadH, 0) == WAIT_TIMEOUT)
{
#if defined(_M_IX86) || defined(_X86_)
CONTEXT context;
context.ContextFlags = CONTEXT_CONTROL;
GetThreadContext(threadH, &context);
context.Eip = (DWORD) _pthread_cancel_self;
SetThreadContext(threadH, &context);
#endif
ResumeThread(threadH);
}
(void) pthread_mutex_unlock(&thread->cancelLock);
}
int
pthread_setcancelstate (int state, int *oldstate)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function atomically sets the calling thread's
* cancelability state to 'state' and returns the previous
* cancelability state at the location referenced by
* 'oldstate'
*
* PARAMETERS
* state,
* oldstate
* PTHREAD_CANCEL_ENABLE
* cancellation is enabled,
*
* PTHREAD_CANCEL_DISABLE
* cancellation is disabled
*
*
* DESCRIPTION
* This function atomically sets the calling thread's
* cancelability state to 'state' and returns the previous
* cancelability state at the location referenced by
* 'oldstate'.
*
* NOTES:
* 1) Use to disable cancellation around 'atomic' code that
* includes cancellation points
*
* COMPATIBILITY ADDITIONS
* If 'oldstate' is NULL then the previous state is not returned
* but the function still succeeds. (Solaris)
*
* RESULTS
* 0 successfully set cancelability type,
* EINVAL 'state' is invalid
*
* ------------------------------------------------------
*/
{
int result = 0;
pthread_t self = (pthread_t) pthread_getspecific (_pthread_selfThreadKey);
if (self == NULL
|| (state != PTHREAD_CANCEL_ENABLE
&& state != PTHREAD_CANCEL_DISABLE))
{
return EINVAL;
}
/*
* Lock for async-cancel safety.
*/
(void) pthread_mutex_lock(&self->cancelLock);
if (oldstate != NULL)
{
*oldstate = self->cancelState;
}
self->cancelState = state;
/*
* Check if there is a pending asynchronous cancel
*/
if (self->cancelState == PTHREAD_CANCEL_ENABLE
&& self->cancelType == PTHREAD_CANCEL_ASYNCHRONOUS
&& WaitForSingleObject(self->cancelEvent, 0) == WAIT_OBJECT_0)
{
ResetEvent(self->cancelEvent);
(void) pthread_mutex_unlock(&self->cancelLock);
_pthread_cancel_self();
/* Never reached */
}
(void) pthread_mutex_unlock(&self->cancelLock);
return (result);
} /* pthread_setcancelstate */
int
pthread_setcanceltype (int type, int *oldtype)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function atomically sets the calling thread's
* cancelability type to 'type' and returns the previous
* cancelability type at the location referenced by
* 'oldtype'
*
* PARAMETERS
* type,
* oldtype
* PTHREAD_CANCEL_DEFERRED
* only deferred cancelation is allowed,
*
* PTHREAD_CANCEL_ASYNCHRONOUS
* Asynchronous cancellation is allowed
*
*
* DESCRIPTION
* This function atomically sets the calling thread's
* cancelability type to 'type' and returns the previous
* cancelability type at the location referenced by
* 'oldtype'
*
* NOTES:
* 1) Use with caution; most code is not safe for use
* with asynchronous cancelability.
*
* COMPATIBILITY ADDITIONS
* If 'oldtype' is NULL then the previous type is not returned
* but the function still succeeds. (Solaris)
*
* RESULTS
* 0 successfully set cancelability type,
* EINVAL 'type' is invalid
*
* ------------------------------------------------------
*/
{
int result = 0;
pthread_t self = (pthread_t) pthread_getspecific (_pthread_selfThreadKey);
if (self == NULL
|| (type != PTHREAD_CANCEL_DEFERRED
&& type != PTHREAD_CANCEL_ASYNCHRONOUS))
{
return EINVAL;
}
/*
* Lock for async-cancel safety.
*/
(void) pthread_mutex_lock(&self->cancelLock);
if (oldtype != NULL)
{
*oldtype = self->cancelType;
}
self->cancelType = type;
/*
* Check if there is a pending asynchronous cancel
*/
if (self->cancelState == PTHREAD_CANCEL_ENABLE
&& self->cancelType == PTHREAD_CANCEL_ASYNCHRONOUS
&& WaitForSingleObject(self->cancelEvent, 0) == WAIT_OBJECT_0)
{
ResetEvent(self->cancelEvent);
(void) pthread_mutex_unlock(&self->cancelLock);
_pthread_cancel_self();
/* Never reached */
}
(void) pthread_mutex_unlock(&self->cancelLock);
return (result);
} /* pthread_setcanceltype */
void
pthread_testcancel (void)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function creates a deferred cancellation point
* in the calling thread. The call has no effect if the
* current cancelability state is
* PTHREAD_CANCEL_DISABLE
*
* PARAMETERS
* N/A
*
*
* DESCRIPTION
* This function creates a deferred cancellation point
* in the calling thread. The call has no effect if the
* current cancelability state is
* PTHREAD_CANCEL_DISABLE
*
* NOTES:
* 1) Cancellation is asynchronous. Use pthread_join
* to wait for termination of thread if necessary
*
* RESULTS
* N/A
*
* ------------------------------------------------------
*/
{
pthread_t self = (pthread_t) pthread_getspecific (_pthread_selfThreadKey);
if (self != NULL
&& self->cancelState == PTHREAD_CANCEL_ENABLE
&& WaitForSingleObject (self->cancelEvent, 0) == WAIT_OBJECT_0
)
{
/*
* Canceling!
*/
#if defined(_MSC_VER) && !defined(__cplusplus)
DWORD exceptionInformation[3];
exceptionInformation[0] = (DWORD) (_PTHREAD_EPS_CANCEL);
exceptionInformation[1] = (DWORD) (0);
exceptionInformation[2] = (DWORD) (0);
RaiseException (
EXCEPTION_PTHREAD_SERVICES,
0,
3,
exceptionInformation);
#else /* _MSC_VER && ! __cplusplus */
#ifdef __cplusplus
throw Pthread_exception_cancel();
#endif /* __cplusplus */
#endif /* _MSC_VER && ! __cplusplus */
}
} /* pthread_testcancel */
int
pthread_cancel (pthread_t thread)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function requests cancellation of 'thread'.
*
* PARAMETERS
* thread
* reference to an instance of pthread_t
*
*
* DESCRIPTION
* This function requests cancellation of 'thread'.
* NOTE: cancellation is asynchronous; use pthread_join to
* wait for termination of 'thread' if necessary.
*
* RESULTS
* 0 successfully requested cancellation,
* ESRCH no thread found corresponding to 'thread',
*
* ------------------------------------------------------
*/
{
int result;
int cancel_self;
pthread_t self;
if (thread == NULL )
{
return ESRCH;
}
result = 0;
self = (pthread_t) pthread_getspecific (_pthread_selfThreadKey);
/*
* FIXME!!
*
* Can a thread cancel itself?
*
* The standard doesn't
* specify an error to be returned if the target
* thread is itself.
*
* If it may, then we need to ensure that a thread can't
* deadlock itself trying to cancel itself asyncronously
* (pthread_cancel is required to be an async-cancel
* safe function).
*/
cancel_self = pthread_equal(thread, self);
/*
* Lock for async-cancel safety.
*/
(void) pthread_mutex_lock(&self->cancelLock);
if (thread->cancelType == PTHREAD_CANCEL_ASYNCHRONOUS
&& thread->cancelState == PTHREAD_CANCEL_ENABLE )
{
if (cancel_self)
{
(void) pthread_mutex_unlock(&self->cancelLock);
_pthread_cancel_self();
/* Never reached */
}
_pthread_cancel_thread(thread);
}
else
{
/*
* Set for deferred cancellation.
*/
if (!SetEvent (thread->cancelEvent))
{
result = ESRCH;
}
}
(void) pthread_mutex_unlock(&self->cancelLock);
return (result);
}