1/* Copyright (C) 2001-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2001.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <netdb.h>
20#include <pthread.h>
21#include <stdlib.h>
22#include <gai_misc.h>
23
24#if !PTHREAD_IN_LIBC
25/* The available function names differ outside of libc. (In libc, we
26 need to use hidden aliases to avoid the PLT.) */
27#define __pthread_attr_init pthread_attr_init
28#define __pthread_attr_setdetachstate pthread_attr_setdetachstate
29#define __pthread_cond_signal pthread_cond_signal
30#define __pthread_cond_timedwait pthread_cond_timedwait
31#define __pthread_create pthread_create
32#endif
33
34struct notify_func
35 {
36 void (*func) (sigval_t);
37 sigval_t value;
38 };
39
40static void *
41notify_func_wrapper (void *arg)
42{
43 gai_start_notify_thread ();
44 struct notify_func *const n = arg;
45 void (*func) (sigval_t) = n->func;
46 sigval_t value = n->value;
47 free (n);
48 (*func) (value);
49 return NULL;
50}
51
52
53int
54__gai_notify_only (struct sigevent *sigev, pid_t caller_pid)
55{
56 int result = 0;
57
58 /* Send the signal to notify about finished processing of the request. */
59 if (sigev->sigev_notify == SIGEV_THREAD)
60 {
61 /* We have to start a thread. */
62 pthread_t tid;
63 pthread_attr_t attr, *pattr;
64
65 pattr = (pthread_attr_t *) sigev->sigev_notify_attributes;
66 if (pattr == NULL)
67 {
68 __pthread_attr_init (&attr);
69 __pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
70 pattr = &attr;
71 }
72
73 /* SIGEV may be freed as soon as we return, so we cannot let the
74 notification thread use that pointer. Even though a sigval_t is
75 only one word and the same size as a void *, we cannot just pass
76 the value through pthread_create as the argument and have the new
77 thread run the user's function directly, because on some machines
78 the calling convention for a union like sigval_t is different from
79 that for a pointer type like void *. */
80 struct notify_func *nf = malloc (sizeof *nf);
81 if (nf == NULL)
82 result = -1;
83 else
84 {
85 nf->func = sigev->sigev_notify_function;
86 nf->value = sigev->sigev_value;
87 if (__pthread_create (&tid, pattr, notify_func_wrapper, nf) < 0)
88 {
89 free (nf);
90 result = -1;
91 }
92 }
93 }
94 else if (sigev->sigev_notify == SIGEV_SIGNAL)
95 /* We have to send a signal. */
96 if (__gai_sigqueue (sigev->sigev_signo, sigev->sigev_value, caller_pid)
97 < 0)
98 result = -1;
99
100 return result;
101}
102
103
104void
105__gai_notify (struct requestlist *req)
106{
107 struct waitlist *waitlist;
108
109 /* Now also notify possibly waiting threads. */
110 waitlist = req->waiting;
111 while (waitlist != NULL)
112 {
113 struct waitlist *next = waitlist->next;
114
115 if (waitlist->sigevp == NULL)
116 {
117#ifdef DONT_NEED_GAI_MISC_COND
118 GAI_MISC_NOTIFY (waitlist);
119#else
120 /* Decrement the counter. */
121 --*waitlist->counterp;
122
123 pthread_cond_signal (waitlist->cond);
124#endif
125 }
126 else
127 /* This is part of an asynchronous `getaddrinfo_a' operation. If
128 this request is the last one, send the signal. */
129 if (--*waitlist->counterp == 0)
130 {
131 __gai_notify_only (waitlist->sigevp, waitlist->caller_pid);
132 /* This is tricky. See getaddrinfo_a.c for the reason why
133 this works. */
134 free ((void *) waitlist->counterp);
135 }
136
137 waitlist = next;
138 }
139}
140