/*      $NetBSD: mtctxres.c,v 1.1.1.1 2009/04/12 15:33:56 christos Exp $        */

#include <port_before.h>
#ifdef DO_PTHREADS
#include <pthread.h>
#endif
#include <errno.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <resolv_mt.h>
#include <irs.h>
#include <port_after.h>

#ifdef DO_PTHREADS
static pthread_key_t    key;
static int              mt_key_initialized = 0;

static int              __res_init_ctx(void);
static void             __res_destroy_ctx(void *);

#if defined(sun) && !defined(__GNUC__)
#pragma init    (_mtctxres_init)
#endif
#endif

static mtctxres_t       sharedctx;

#ifdef DO_PTHREADS
/*
* Initialize the TSD key. By doing this at library load time, we're
* implicitly running without interference from other threads, so there's
* no need for locking.
*/
static void
_mtctxres_init(void) {
       int pthread_keycreate_ret;

       pthread_keycreate_ret = pthread_key_create(&key, __res_destroy_ctx);
       if (pthread_keycreate_ret == 0)
               mt_key_initialized = 1;
}
#endif

/*
* To support binaries that used the private MT-safe interface in
* Solaris 8, we still need to provide the __res_enable_mt()
* and __res_disable_mt() entry points. They're do-nothing routines.
*/
int
__res_enable_mt(void) {
       return (-1);
}

int
__res_disable_mt(void) {
       return (0);
}

#ifdef DO_PTHREADS
static int
__res_init_ctx(void) {

       mtctxres_t      *mt;
       int             ret;


       if (pthread_getspecific(key) != 0) {
               /* Already exists */
               return (0);
       }

       if ((mt = malloc(sizeof (mtctxres_t))) == 0) {
               errno = ENOMEM;
               return (-1);
       }

       memset(mt, 0, sizeof (mtctxres_t));

       if ((ret = pthread_setspecific(key, mt)) != 0) {
               free(mt);
               errno = ret;
               return (-1);
       }

       return (0);
}

static void
__res_destroy_ctx(void *value) {

       mtctxres_t      *mt = (mtctxres_t *)value;

       if (mt != 0)
               free(mt);
}
#endif

mtctxres_t *
___mtctxres(void) {
#ifdef DO_PTHREADS
       mtctxres_t      *mt;

       /*
        * This if clause should only be executed if we are linking
        * statically.  When linked dynamically _mtctxres_init() should
        * be called at binding time due the #pragma above.
        */
       if (!mt_key_initialized) {
               static pthread_mutex_t keylock = PTHREAD_MUTEX_INITIALIZER;
               if (pthread_mutex_lock(&keylock) == 0) {
                       _mtctxres_init();
                       (void) pthread_mutex_unlock(&keylock);
               }
       }

       /*
        * If we have already been called in this thread return the existing
        * context.  Otherwise recreat a new context and return it.  If
        * that fails return a global context.
        */
       if (mt_key_initialized) {
               if (((mt = pthread_getspecific(key)) != 0) ||
                   (__res_init_ctx() == 0 &&
                    (mt = pthread_getspecific(key)) != 0)) {
                       return (mt);
               }
       }
#endif
       return (&sharedctx);
}