1/* Notify initiator of AIO request.
2 Copyright (C) 1997-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#include <errno.h>
21#include <pthreadP.h>
22#include <stdlib.h>
23#include <unistd.h>
24#include <aio_misc.h>
25#include <signal.h>
26
27#if !PTHREAD_IN_LIBC
28# define __pthread_attr_init pthread_attr_init
29# define __pthread_attr_setdetachstate pthread_attr_setdetachstate
30#endif
31
32#ifndef aio_start_notify_thread
33# define aio_start_notify_thread() do { } while (0)
34#endif
35
36struct notify_func
37 {
38 void (*func) (sigval_t);
39 sigval_t value;
40 };
41
42static void *
43notify_func_wrapper (void *arg)
44{
45 aio_start_notify_thread ();
46 struct notify_func *const n = arg;
47 void (*func) (sigval_t) = n->func;
48 sigval_t value = n->value;
49 free (n);
50 (*func) (value);
51 return NULL;
52}
53
54
55int
56__aio_notify_only (struct sigevent *sigev)
57{
58 int result = 0;
59
60 /* Send the signal to notify about finished processing of the request. */
61 if (__glibc_unlikely (sigev->sigev_notify == SIGEV_THREAD))
62 {
63 /* We have to start a thread. */
64 pthread_t tid;
65 pthread_attr_t attr, *pattr;
66
67 pattr = (pthread_attr_t *) sigev->sigev_notify_attributes;
68 if (pattr == NULL)
69 {
70 __pthread_attr_init (&attr);
71 __pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
72 pattr = &attr;
73 }
74
75 /* SIGEV may be freed as soon as we return, so we cannot let the
76 notification thread use that pointer. Even though a sigval_t is
77 only one word and the same size as a void *, we cannot just pass
78 the value through pthread_create as the argument and have the new
79 thread run the user's function directly, because on some machines
80 the calling convention for a union like sigval_t is different from
81 that for a pointer type like void *. */
82 struct notify_func *nf = malloc (sizeof *nf);
83 if (nf == NULL)
84 result = -1;
85 else
86 {
87 nf->func = sigev->sigev_notify_function;
88 nf->value = sigev->sigev_value;
89 if (__pthread_create (&tid, pattr, notify_func_wrapper, nf) < 0)
90 {
91 free (nf);
92 result = -1;
93 }
94 }
95 }
96 else if (sigev->sigev_notify == SIGEV_SIGNAL)
97 {
98 /* We have to send a signal. */
99#if _POSIX_REALTIME_SIGNALS > 0
100 /* Note that the standard gives us the option of using a plain
101 non-queuing signal here when SA_SIGINFO is not set for the signal. */
102 if (__aio_sigqueue (sigev->sigev_signo, sigev->sigev_value, getpid ())
103 < 0)
104 result = -1;
105#else
106 /* There are no queued signals on this system at all. */
107 result = raise (sigev->sigev_signo);
108#endif
109 }
110
111 return result;
112}
113
114
115void
116__aio_notify (struct requestlist *req)
117{
118 struct waitlist *waitlist;
119 struct aiocb *aiocbp = &req->aiocbp->aiocb;
120
121 if (__aio_notify_only (&aiocbp->aio_sigevent) != 0)
122 {
123 /* XXX What shall we do if already an error is set by
124 read/write/fsync? */
125 aiocbp->__error_code = errno;
126 aiocbp->__return_value = -1;
127 }
128
129 /* Now also notify possibly waiting threads. */
130 waitlist = req->waiting;
131 while (waitlist != NULL)
132 {
133 struct waitlist *next = waitlist->next;
134
135 if (waitlist->sigevp == NULL)
136 {
137 if (waitlist->result != NULL && aiocbp->__return_value == -1)
138 *waitlist->result = -1;
139
140#ifdef DONT_NEED_AIO_MISC_COND
141 AIO_MISC_NOTIFY (waitlist);
142#else
143 /* Decrement the counter. */
144 --*waitlist->counterp;
145
146 pthread_cond_signal (waitlist->cond);
147#endif
148 }
149 else
150 /* This is part of an asynchronous `lio_listio' operation. If
151 this request is the last one, send the signal. */
152 if (--*waitlist->counterp == 0)
153 {
154 __aio_notify_only (waitlist->sigevp);
155 /* This is tricky. See lio_listio.c for the reason why
156 this works. */
157 free ((void *) waitlist->counterp);
158 }
159
160 waitlist = next;
161 }
162}
163