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
25struct notify_func
26 {
27 void (*func) (sigval_t);
28 sigval_t value;
29 };
30
31static void *
32notify_func_wrapper (void *arg)
33{
34 gai_start_notify_thread ();
35 struct notify_func *const n = arg;
36 void (*func) (sigval_t) = n->func;
37 sigval_t value = n->value;
38 free (n);
39 (*func) (value);
40 return NULL;
41}
42
43
44int
45__gai_notify_only (struct sigevent *sigev, pid_t caller_pid)
46{
47 int result = 0;
48
49 /* Send the signal to notify about finished processing of the request. */
50 if (sigev->sigev_notify == SIGEV_THREAD)
51 {
52 /* We have to start a thread. */
53 pthread_t tid;
54 pthread_attr_t attr, *pattr;
55
56 pattr = (pthread_attr_t *) sigev->sigev_notify_attributes;
57 if (pattr == NULL)
58 {
59 pthread_attr_init (&attr);
60 pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
61 pattr = &attr;
62 }
63
64 /* SIGEV may be freed as soon as we return, so we cannot let the
65 notification thread use that pointer. Even though a sigval_t is
66 only one word and the same size as a void *, we cannot just pass
67 the value through pthread_create as the argument and have the new
68 thread run the user's function directly, because on some machines
69 the calling convention for a union like sigval_t is different from
70 that for a pointer type like void *. */
71 struct notify_func *nf = malloc (sizeof *nf);
72 if (nf == NULL)
73 result = -1;
74 else
75 {
76 nf->func = sigev->sigev_notify_function;
77 nf->value = sigev->sigev_value;
78 if (pthread_create (&tid, pattr, notify_func_wrapper, nf) < 0)
79 {
80 free (nf);
81 result = -1;
82 }
83 }
84 }
85 else if (sigev->sigev_notify == SIGEV_SIGNAL)
86 /* We have to send a signal. */
87 if (__gai_sigqueue (sigev->sigev_signo, sigev->sigev_value, caller_pid)
88 < 0)
89 result = -1;
90
91 return result;
92}
93
94
95void
96__gai_notify (struct requestlist *req)
97{
98 struct waitlist *waitlist;
99
100 /* Now also notify possibly waiting threads. */
101 waitlist = req->waiting;
102 while (waitlist != NULL)
103 {
104 struct waitlist *next = waitlist->next;
105
106 if (waitlist->sigevp == NULL)
107 {
108#ifdef DONT_NEED_GAI_MISC_COND
109 GAI_MISC_NOTIFY (waitlist);
110#else
111 /* Decrement the counter. */
112 --*waitlist->counterp;
113
114 pthread_cond_signal (waitlist->cond);
115#endif
116 }
117 else
118 /* This is part of an asynchronous `getaddrinfo_a' operation. If
119 this request is the last one, send the signal. */
120 if (--*waitlist->counterp == 0)
121 {
122 __gai_notify_only (waitlist->sigevp, waitlist->caller_pid);
123 /* This is tricky. See getaddrinfo_a.c for the reason why
124 this works. */
125 free ((void *) waitlist->counterp);
126 }
127
128 waitlist = next;
129 }
130}
131