142 lines
2.7 KiB
C
142 lines
2.7 KiB
C
#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <port_before.h>
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#ifdef DO_PTHREADS
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#include <pthread.h>
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#ifdef _LIBC
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#include <pthread_np.h>
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#endif
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#endif
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#include <errno.h>
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#include <netdb.h>
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#include <stdlib.h>
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#include <string.h>
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#include <resolv_mt.h>
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#include <port_after.h>
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#ifdef DO_PTHREADS
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static pthread_key_t key;
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static int mt_key_initialized = 0;
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static int __res_init_ctx(void);
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static void __res_destroy_ctx(void *);
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#if defined(sun) && !defined(__GNUC__)
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#pragma init (_mtctxres_init)
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#endif
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#endif
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static mtctxres_t sharedctx;
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#ifdef DO_PTHREADS
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/*
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* Initialize the TSD key. By doing this at library load time, we're
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* implicitly running without interference from other threads, so there's
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* no need for locking.
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*/
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static void
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_mtctxres_init(void) {
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int pthread_keycreate_ret;
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pthread_keycreate_ret = pthread_key_create(&key, __res_destroy_ctx);
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if (pthread_keycreate_ret == 0)
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mt_key_initialized = 1;
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}
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#endif
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#ifndef _LIBC
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/*
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* To support binaries that used the private MT-safe interface in
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* Solaris 8, we still need to provide the __res_enable_mt()
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* and __res_disable_mt() entry points. They're do-nothing routines.
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*/
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int
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__res_enable_mt(void) {
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return (-1);
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}
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int
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__res_disable_mt(void) {
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return (0);
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}
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#endif
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#ifdef DO_PTHREADS
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static int
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__res_init_ctx(void) {
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mtctxres_t *mt;
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int ret;
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if (pthread_getspecific(key) != 0) {
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/* Already exists */
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return (0);
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}
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if ((mt = malloc(sizeof (mtctxres_t))) == 0) {
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errno = ENOMEM;
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return (-1);
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}
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memset(mt, 0, sizeof (mtctxres_t));
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if ((ret = pthread_setspecific(key, mt)) != 0) {
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free(mt);
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errno = ret;
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return (-1);
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}
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return (0);
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}
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static void
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__res_destroy_ctx(void *value) {
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mtctxres_t *mt = (mtctxres_t *)value;
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if (mt != 0)
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free(mt);
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}
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#endif
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mtctxres_t *
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___mtctxres(void) {
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#ifdef DO_PTHREADS
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mtctxres_t *mt;
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#ifdef _LIBC
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if (pthread_main_np() != 0)
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return (&sharedctx);
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#endif
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/*
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* This if clause should only be executed if we are linking
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* statically. When linked dynamically _mtctxres_init() should
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* be called at binding time due the #pragma above.
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*/
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if (!mt_key_initialized) {
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static pthread_mutex_t keylock = PTHREAD_MUTEX_INITIALIZER;
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if (pthread_mutex_lock(&keylock) == 0) {
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_mtctxres_init();
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(void) pthread_mutex_unlock(&keylock);
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}
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}
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/*
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* If we have already been called in this thread return the existing
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* context. Otherwise recreat a new context and return it. If
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* that fails return a global context.
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*/
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if (mt_key_initialized) {
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if (((mt = pthread_getspecific(key)) != 0) ||
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(__res_init_ctx() == 0 &&
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(mt = pthread_getspecific(key)) != 0)) {
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return (mt);
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}
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}
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#endif
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return (&sharedctx);
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}
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