5cf32de7a0
Move the implementation of writing to the system property area
from init to bionic, next to the reader implementation. This
will allow full property testing to be added to bionic tests.
Add new accessor and waiting functions to hide the implementation
from watchprops and various bionic users.
Also hide some of the implementation details of the property area
from init by moving them into _system_properties.h, and other details
from everybody by moving them into system_properties.h.
(cherry picked from commit dc1038b790)
Change-Id: I192d3825ee276c5047bc751039fe6cfe226a7cca
225 lines
6.4 KiB
C
225 lines
6.4 KiB
C
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#include <sys/types.h>
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#include <arpa/inet.h>
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#include "arpa_nameser.h"
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#include <netdb.h>
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#include "resolv_private.h"
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#include "resolv_cache.h"
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#include <pthread.h>
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#include <stdlib.h>
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#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
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#include <sys/_system_properties.h>
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/* Set to 1 to enable debug traces */
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#define DEBUG 0
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#if DEBUG
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# include "libc_logging.h"
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# include <unistd.h> /* for gettid() */
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# define D(...) __libc_format_log(ANDROID_LOG_DEBUG,"libc", __VA_ARGS__)
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#else
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# define D(...) do{}while(0)
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#endif
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static pthread_key_t _res_key;
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static pthread_once_t _res_once;
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typedef struct {
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int _h_errno;
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struct __res_state _nres[1];
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unsigned _serial;
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struct prop_info* _pi;
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struct res_static _rstatic[1];
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} _res_thread;
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static _res_thread*
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_res_thread_alloc(void)
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{
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_res_thread* rt = calloc(1, sizeof(*rt));
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if (rt) {
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rt->_h_errno = 0;
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/* Special system property which tracks any changes to 'net.*'. */
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rt->_serial = 0;
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rt->_pi = (struct prop_info*) __system_property_find("net.change");
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if (rt->_pi) {
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rt->_serial = __system_property_serial(rt->_pi);
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}
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memset(rt->_rstatic, 0, sizeof rt->_rstatic);
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}
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return rt;
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}
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static void
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_res_static_done( res_static rs )
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{
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/* fortunately, there is nothing to do here, since the
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* points in h_addr_ptrs and host_aliases should all
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* point to 'hostbuf'
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*/
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if (rs->hostf) { /* should not happen in theory, but just be safe */
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fclose(rs->hostf);
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rs->hostf = NULL;
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}
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free(rs->servent.s_aliases);
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}
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static void
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_res_thread_free( void* _rt )
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{
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_res_thread* rt = _rt;
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D("%s: rt=%p for thread=%d", __FUNCTION__, rt, gettid());
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_res_static_done(rt->_rstatic);
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res_ndestroy(rt->_nres);
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free(rt);
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}
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static void
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_res_init_key( void )
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{
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pthread_key_create( &_res_key, _res_thread_free );
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}
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static _res_thread*
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_res_thread_get(void)
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{
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_res_thread* rt;
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pthread_once( &_res_once, _res_init_key );
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rt = pthread_getspecific( _res_key );
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if (rt != NULL) {
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/* We already have one thread-specific DNS state object.
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* Check the serial value for any changes to net.* properties */
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D("%s: Called for tid=%d rt=%p rt->pi=%p rt->serial=%d",
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__FUNCTION__, gettid(), rt, rt->_pi, rt->_serial);
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if (rt->_pi == NULL) {
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/* The property wasn't created when _res_thread_get() was
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* called the last time. This should only happen very
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* early during the boot sequence. First, let's try to see if it
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* is here now. */
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rt->_pi = (struct prop_info*) __system_property_find("net.change");
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if (rt->_pi == NULL) {
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/* Still nothing, return current state */
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D("%s: exiting for tid=%d rt=%d since system property not found",
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__FUNCTION__, gettid(), rt);
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return rt;
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}
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}
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if (rt->_serial == __system_property_serial(rt->_pi)) {
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/* Nothing changed, so return the current state */
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D("%s: tid=%d rt=%p nothing changed, returning",
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__FUNCTION__, gettid(), rt);
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return rt;
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}
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/* Update the recorded serial number, and go reset the state */
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rt->_serial = __system_property_serial(rt->_pi);
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goto RESET_STATE;
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}
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/* It is the first time this function is called in this thread,
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* we need to create a new thread-specific DNS resolver state. */
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rt = _res_thread_alloc();
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if (rt == NULL) {
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return NULL;
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}
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pthread_setspecific( _res_key, rt );
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D("%s: tid=%d Created new DNS state rt=%p",
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__FUNCTION__, gettid(), rt);
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RESET_STATE:
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/* Reset the state, note that res_ninit() can now properly reset
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* an existing state without leaking memory.
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*/
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D("%s: tid=%d, rt=%p, resetting DNS state (options RES_INIT=%d)",
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__FUNCTION__, gettid(), rt, (rt->_nres->options & RES_INIT) != 0);
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if ( res_ninit( rt->_nres ) < 0 ) {
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/* This should not happen */
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D("%s: tid=%d rt=%p, woot, res_ninit() returned < 0",
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__FUNCTION__, gettid(), rt);
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_res_thread_free(rt);
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pthread_setspecific( _res_key, NULL );
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return NULL;
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}
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return rt;
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}
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__LIBC_HIDDEN__
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struct __res_state _nres;
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#if 0
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struct resolv_cache*
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__get_res_cache(void)
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{
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_res_thread* rt = _res_thread_get();
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if (!rt)
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return NULL;
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if (!rt->_cache) {
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rt->_cache = _resolv_cache_create();
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}
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return rt->_cache;
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}
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#endif
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int*
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__get_h_errno(void)
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{
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_res_thread* rt = _res_thread_get();
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static int panic = NETDB_INTERNAL;
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return rt ? &rt->_h_errno : &panic;
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}
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res_state
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__res_get_state(void)
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{
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_res_thread* rt = _res_thread_get();
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return rt ? rt->_nres : NULL;
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}
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void
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__res_put_state(res_state res)
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{
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/* nothing to do */
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res=res;
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}
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res_static
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__res_get_static(void)
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{
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_res_thread* rt = _res_thread_get();
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return rt ? rt->_rstatic : NULL;
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}
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