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/* Notify initiator of AIO request.
Copyright (C) 1997-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <pthreadP.h>
#include <stdlib.h>
#include <unistd.h>
#include <aio_misc.h>
#include <signal.h>
#if !PTHREAD_IN_LIBC
# define __pthread_attr_init pthread_attr_init
# define __pthread_attr_setdetachstate pthread_attr_setdetachstate
#endif
#ifndef aio_start_notify_thread
# define aio_start_notify_thread() do { } while (0)
#endif
struct notify_func
{
void (*func) (sigval_t);
sigval_t value;
};
static void *
notify_func_wrapper (void *arg)
{
aio_start_notify_thread ();
struct notify_func *const n = arg;
void (*func) (sigval_t) = n->func;
sigval_t value = n->value;
free (n);
(*func) (value);
return NULL;
}
int
__aio_notify_only (struct sigevent *sigev)
{
int result = 0;
/* Send the signal to notify about finished processing of the request. */
if (__glibc_unlikely (sigev->sigev_notify == SIGEV_THREAD))
{
/* We have to start a thread. */
pthread_t tid;
pthread_attr_t attr, *pattr;
pattr = (pthread_attr_t *) sigev->sigev_notify_attributes;
if (pattr == NULL)
{
__pthread_attr_init (&attr);
__pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
pattr = &attr;
}
/* SIGEV may be freed as soon as we return, so we cannot let the
notification thread use that pointer. Even though a sigval_t is
only one word and the same size as a void *, we cannot just pass
the value through pthread_create as the argument and have the new
thread run the user's function directly, because on some machines
the calling convention for a union like sigval_t is different from
that for a pointer type like void *. */
struct notify_func *nf = malloc (sizeof *nf);
if (nf == NULL)
result = -1;
else
{
nf->func = sigev->sigev_notify_function;
nf->value = sigev->sigev_value;
if (__pthread_create (&tid, pattr, notify_func_wrapper, nf) < 0)
{
free (nf);
result = -1;
}
}
}
else if (sigev->sigev_notify == SIGEV_SIGNAL)
{
/* We have to send a signal. */
#if _POSIX_REALTIME_SIGNALS > 0
/* Note that the standard gives us the option of using a plain
non-queuing signal here when SA_SIGINFO is not set for the signal. */
if (__aio_sigqueue (sigev->sigev_signo, sigev->sigev_value, getpid ())
< 0)
result = -1;
#else
/* There are no queued signals on this system at all. */
result = raise (sigev->sigev_signo);
#endif
}
return result;
}
void
__aio_notify (struct requestlist *req)
{
struct waitlist *waitlist;
struct aiocb *aiocbp = &req->aiocbp->aiocb;
if (__aio_notify_only (&aiocbp->aio_sigevent) != 0)
{
/* XXX What shall we do if already an error is set by
read/write/fsync? */
aiocbp->__error_code = errno;
aiocbp->__return_value = -1;
}
/* Now also notify possibly waiting threads. */
waitlist = req->waiting;
while (waitlist != NULL)
{
struct waitlist *next = waitlist->next;
if (waitlist->sigevp == NULL)
{
if (waitlist->result != NULL && aiocbp->__return_value == -1)
*waitlist->result = -1;
#ifdef DONT_NEED_AIO_MISC_COND
AIO_MISC_NOTIFY (waitlist);
#else
/* Decrement the counter. */
--*waitlist->counterp;
pthread_cond_signal (waitlist->cond);
#endif
}
else
/* This is part of an asynchronous `lio_listio' operation. If
this request is the last one, send the signal. */
if (--*waitlist->counterp == 0)
{
__aio_notify_only (waitlist->sigevp);
/* This is tricky. See lio_listio.c for the reason why
this works. */
free ((void *) waitlist->counterp);
}
waitlist = next;
}
}
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