1/*	$NetBSD: mtctxres.c,v 1.1.1.1 2009/04/12 15:33:56 christos Exp $	*/
2
3#include <port_before.h>
4#ifdef DO_PTHREADS
5#include <pthread.h>
6#endif
7#include <errno.h>
8#include <netdb.h>
9#include <stdlib.h>
10#include <string.h>
11#include <resolv_mt.h>
12#include <irs.h>
13#include <port_after.h>
14
15#ifdef DO_PTHREADS
16static pthread_key_t	key;
17static int		mt_key_initialized = 0;
18
19static int		__res_init_ctx(void);
20static void		__res_destroy_ctx(void *);
21
22#if defined(sun) && !defined(__GNUC__)
23#pragma init	(_mtctxres_init)
24#endif
25#endif
26
27static mtctxres_t	sharedctx;
28
29#ifdef DO_PTHREADS
30/*
31 * Initialize the TSD key. By doing this at library load time, we're
32 * implicitly running without interference from other threads, so there's
33 * no need for locking.
34 */
35static void
36_mtctxres_init(void) {
37	int pthread_keycreate_ret;
38
39	pthread_keycreate_ret = pthread_key_create(&key, __res_destroy_ctx);
40	if (pthread_keycreate_ret == 0)
41		mt_key_initialized = 1;
42}
43#endif
44
45/*
46 * To support binaries that used the private MT-safe interface in
47 * Solaris 8, we still need to provide the __res_enable_mt()
48 * and __res_disable_mt() entry points. They're do-nothing routines.
49 */
50int
51__res_enable_mt(void) {
52	return (-1);
53}
54
55int
56__res_disable_mt(void) {
57	return (0);
58}
59
60#ifdef DO_PTHREADS
61static int
62__res_init_ctx(void) {
63
64	mtctxres_t	*mt;
65	int		ret;
66
67
68	if (pthread_getspecific(key) != 0) {
69		/* Already exists */
70		return (0);
71	}
72
73	if ((mt = malloc(sizeof (mtctxres_t))) == 0) {
74		errno = ENOMEM;
75		return (-1);
76	}
77
78	memset(mt, 0, sizeof (mtctxres_t));
79
80	if ((ret = pthread_setspecific(key, mt)) != 0) {
81		free(mt);
82		errno = ret;
83		return (-1);
84	}
85
86	return (0);
87}
88
89static void
90__res_destroy_ctx(void *value) {
91
92	mtctxres_t	*mt = (mtctxres_t *)value;
93
94	if (mt != 0)
95		free(mt);
96}
97#endif
98
99mtctxres_t *
100___mtctxres(void) {
101#ifdef DO_PTHREADS
102	mtctxres_t	*mt;
103
104	/*
105	 * This if clause should only be executed if we are linking
106	 * statically.  When linked dynamically _mtctxres_init() should
107	 * be called at binding time due the #pragma above.
108	 */
109	if (!mt_key_initialized) {
110		static pthread_mutex_t keylock = PTHREAD_MUTEX_INITIALIZER;
111                if (pthread_mutex_lock(&keylock) == 0) {
112			_mtctxres_init();
113			(void) pthread_mutex_unlock(&keylock);
114		}
115	}
116
117	/*
118	 * If we have already been called in this thread return the existing
119	 * context.  Otherwise recreat a new context and return it.  If
120	 * that fails return a global context.
121	 */
122	if (mt_key_initialized) {
123		if (((mt = pthread_getspecific(key)) != 0) ||
124		    (__res_init_ctx() == 0 &&
125		     (mt = pthread_getspecific(key)) != 0)) {
126			return (mt);
127		}
128	}
129#endif
130	return (&sharedctx);
131}
132