1 /* Copyright (C) 2001-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18 #include <netdb.h>
19 #include <pthread.h>
20 #include <stdlib.h>
21 #include <gai_misc.h>
22
23 #if !PTHREAD_IN_LIBC
24 /* The available function names differ outside of libc. (In libc, we
25 need to use hidden aliases to avoid the PLT.) */
26 #define __pthread_attr_init pthread_attr_init
27 #define __pthread_attr_setdetachstate pthread_attr_setdetachstate
28 #define __pthread_cond_signal pthread_cond_signal
29 #define __pthread_cond_timedwait pthread_cond_timedwait
30 #define __pthread_create pthread_create
31 #endif
32
33 struct notify_func
34 {
35 void (*func) (sigval_t);
36 sigval_t value;
37 };
38
39 static void *
40 notify_func_wrapper (void *arg)
41 {
42 gai_start_notify_thread ();
43 struct notify_func *const n = arg;
44 void (*func) (sigval_t) = n->func;
45 sigval_t value = n->value;
46 free (n);
47 (*func) (value);
48 return NULL;
49 }
50
51
52 int
53 __gai_notify_only (struct sigevent *sigev, pid_t caller_pid)
54 {
55 int result = 0;
56
57 /* Send the signal to notify about finished processing of the request. */
58 if (sigev->sigev_notify == SIGEV_THREAD)
59 {
60 /* We have to start a thread. */
61 pthread_t tid;
62 pthread_attr_t attr, *pattr;
63
64 pattr = (pthread_attr_t *) sigev->sigev_notify_attributes;
65 if (pattr == NULL)
66 {
67 __pthread_attr_init (&attr);
68 __pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
69 pattr = &attr;
70 }
71
72 /* SIGEV may be freed as soon as we return, so we cannot let the
73 notification thread use that pointer. Even though a sigval_t is
74 only one word and the same size as a void *, we cannot just pass
75 the value through pthread_create as the argument and have the new
76 thread run the user's function directly, because on some machines
77 the calling convention for a union like sigval_t is different from
78 that for a pointer type like void *. */
79 struct notify_func *nf = malloc (sizeof *nf);
80 if (nf == NULL)
81 result = -1;
82 else
83 {
84 nf->func = sigev->sigev_notify_function;
85 nf->value = sigev->sigev_value;
86 if (__pthread_create (&tid, pattr, notify_func_wrapper, nf) < 0)
87 {
88 free (nf);
89 result = -1;
90 }
91 }
92 }
93 else if (sigev->sigev_notify == SIGEV_SIGNAL)
94 /* We have to send a signal. */
95 if (__gai_sigqueue (sigev->sigev_signo, sigev->sigev_value, caller_pid)
96 < 0)
97 result = -1;
98
99 return result;
100 }
101
102
103 void
104 __gai_notify (struct requestlist *req)
105 {
106 struct waitlist *waitlist;
107
108 /* Now also notify possibly waiting threads. */
109 waitlist = req->waiting;
110 while (waitlist != NULL)
111 {
112 struct waitlist *next = waitlist->next;
113
114 if (waitlist->sigevp == NULL)
115 {
116 #ifdef DONT_NEED_GAI_MISC_COND
117 GAI_MISC_NOTIFY (waitlist);
118 #else
119 /* Decrement the counter. */
120 --*waitlist->counterp;
121
122 pthread_cond_signal (waitlist->cond);
123 #endif
124 }
125 else
126 /* This is part of an asynchronous `getaddrinfo_a' operation. If
127 this request is the last one, send the signal. */
128 if (--*waitlist->counterp == 0)
129 {
130 __gai_notify_only (waitlist->sigevp, waitlist->caller_pid);
131 /* This is tricky. See getaddrinfo_a.c for the reason why
132 this works. */
133 free ((void *) waitlist->counterp);
134 }
135
136 waitlist = next;
137 }
138 }