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352f4ff9a2
struct resolv_context objects provide a temporary resolver context which does not change during a name lookup operation. Only when the outmost context is created, the stub resolver configuration is verified to be current (at present, only against previous res_init calls). Subsequent attempts to obtain the context will reuse the result of the initial verification operation. struct resolv_context can also be extended in the future to store data which needs to be deallocated during thread cancellation.
466 lines
13 KiB
C
466 lines
13 KiB
C
/* Copyright (C) 1996-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <atomic.h>
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#include <errno.h>
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#include <stdbool.h>
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#include "nsswitch.h"
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#include "sysdep.h"
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#ifdef USE_NSCD
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# include <nscd/nscd_proto.h>
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#endif
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#ifdef NEED__RES
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# include <resolv/resolv_context.h>
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#endif
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/*******************************************************************\
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|* Here we assume several symbols to be defined: *|
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|* *|
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|* LOOKUP_TYPE - the return type of the function *|
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|* *|
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|* FUNCTION_NAME - name of the non-reentrant function *|
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|* *|
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|* DATABASE_NAME - name of the database the function accesses *|
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|* (e.g., host, services, ...) *|
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|* *|
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|* ADD_PARAMS - additional parameters, can vary in number *|
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|* *|
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|* ADD_VARIABLES - names of additional parameters *|
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|* *|
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|* Optionally the following vars can be defined: *|
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|* *|
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|* EXTRA_PARAMS - optional parameters, can vary in number *|
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|* *|
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|* EXTRA_VARIABLES - names of optional parameter *|
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|* *|
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|* FUNCTION2_NAME - alternative name of the non-reentrant function *|
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|* *|
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|* NEED_H_ERRNO - an extra parameter will be passed to point to *|
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|* the global `h_errno' variable. *|
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|* *|
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|* NEED__RES - obtain a struct resolv_context resolver context *|
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|* *|
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|* PREPROCESS - code run before anything else *|
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|* *|
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|* POSTPROCESS - code run after the lookup *|
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|* *|
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\*******************************************************************/
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/* To make the real sources a bit prettier. */
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#define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
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#ifdef FUNCTION2_NAME
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# define REENTRANT2_NAME APPEND_R (FUNCTION2_NAME)
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#else
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# define REENTRANT2_NAME NULL
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#endif
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#define APPEND_R(name) APPEND_R1 (name)
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#define APPEND_R1(name) name##_r
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#define INTERNAL(name) INTERNAL1 (name)
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#define INTERNAL1(name) __##name
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#define NEW(name) NEW1 (name)
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#define NEW1(name) __new_##name
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#ifdef USE_NSCD
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# define NSCD_NAME ADD_NSCD (REENTRANT_NAME)
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# define ADD_NSCD(name) ADD_NSCD1 (name)
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# define ADD_NSCD1(name) __nscd_##name
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# define NOT_USENSCD_NAME ADD_NOT_NSCDUSE (DATABASE_NAME)
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# define ADD_NOT_NSCDUSE(name) ADD_NOT_NSCDUSE1 (name)
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# define ADD_NOT_NSCDUSE1(name) __nss_not_use_nscd_##name
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# define CONCAT2(arg1, arg2) CONCAT2_2 (arg1, arg2)
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# define CONCAT2_2(arg1, arg2) arg1##arg2
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#endif
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#define FUNCTION_NAME_STRING STRINGIZE (FUNCTION_NAME)
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#define REENTRANT_NAME_STRING STRINGIZE (REENTRANT_NAME)
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#ifdef FUNCTION2_NAME
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# define REENTRANT2_NAME_STRING STRINGIZE (REENTRANT2_NAME)
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#else
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# define REENTRANT2_NAME_STRING NULL
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#endif
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#define DATABASE_NAME_STRING STRINGIZE (DATABASE_NAME)
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#define STRINGIZE(name) STRINGIZE1 (name)
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#define STRINGIZE1(name) #name
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#ifndef DB_LOOKUP_FCT
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# define DB_LOOKUP_FCT CONCAT3_1 (__nss_, DATABASE_NAME, _lookup2)
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# define CONCAT3_1(Pre, Name, Post) CONCAT3_2 (Pre, Name, Post)
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# define CONCAT3_2(Pre, Name, Post) Pre##Name##Post
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#endif
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/* Sometimes we need to store error codes in the `h_errno' variable. */
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#ifdef NEED_H_ERRNO
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# define H_ERRNO_PARM , int *h_errnop
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# define H_ERRNO_VAR , h_errnop
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# define H_ERRNO_VAR_P h_errnop
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#else
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# define H_ERRNO_PARM
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# define H_ERRNO_VAR
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# define H_ERRNO_VAR_P NULL
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#endif
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#ifndef EXTRA_PARAMS
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# define EXTRA_PARAMS
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#endif
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#ifndef EXTRA_VARIABLES
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# define EXTRA_VARIABLES
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#endif
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#ifdef HAVE_AF
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# define AF_VAL af
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#else
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# define AF_VAL AF_INET
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#endif
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/* Set defaults for merge functions that haven't been defined. */
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#ifndef DEEPCOPY_FN
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static inline int
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__copy_einval (LOOKUP_TYPE a,
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const size_t b,
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LOOKUP_TYPE *c,
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char *d,
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char **e)
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{
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return EINVAL;
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}
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# define DEEPCOPY_FN __copy_einval
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#endif
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#ifndef MERGE_FN
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static inline int
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__merge_einval (LOOKUP_TYPE *a,
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char *b,
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char *c,
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size_t d,
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LOOKUP_TYPE *e,
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char *f)
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{
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return EINVAL;
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}
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# define MERGE_FN __merge_einval
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#endif
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#define CHECK_MERGE(err, status) \
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({ \
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do \
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{ \
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if (err) \
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{ \
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__set_errno (err); \
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if (err == ERANGE) \
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status = NSS_STATUS_TRYAGAIN; \
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else \
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status = NSS_STATUS_UNAVAIL; \
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break; \
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} \
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} \
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while (0); \
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})
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/* Type of the lookup function we need here. */
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typedef enum nss_status (*lookup_function) (ADD_PARAMS, LOOKUP_TYPE *, char *,
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size_t, int * H_ERRNO_PARM
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EXTRA_PARAMS);
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/* The lookup function for the first entry of this service. */
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extern int DB_LOOKUP_FCT (service_user **nip, const char *name,
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const char *name2, void **fctp)
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internal_function;
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libc_hidden_proto (DB_LOOKUP_FCT)
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int
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INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
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size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM
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EXTRA_PARAMS)
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{
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static bool startp_initialized;
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static service_user *startp;
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static lookup_function start_fct;
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service_user *nip;
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int do_merge = 0;
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LOOKUP_TYPE mergegrp;
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char *mergebuf = NULL;
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char *endptr = NULL;
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union
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{
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lookup_function l;
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void *ptr;
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} fct;
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int no_more, err;
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enum nss_status status = NSS_STATUS_UNAVAIL;
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#ifdef USE_NSCD
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int nscd_status;
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#endif
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#ifdef NEED_H_ERRNO
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bool any_service = false;
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#endif
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#ifdef NEED__RES
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/* The HANDLE_DIGITS_DOTS case below already needs the resolver
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configuration, so this has to happen early. */
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struct resolv_context *res_ctx = __resolv_context_get ();
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if (res_ctx == NULL)
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{
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*h_errnop = NETDB_INTERNAL;
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*result = NULL;
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return errno;
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}
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#endif /* NEED__RES */
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#ifdef PREPROCESS
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PREPROCESS;
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#endif
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#ifdef HANDLE_DIGITS_DOTS
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switch (__nss_hostname_digits_dots (name, resbuf, &buffer, NULL,
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buflen, result, &status, AF_VAL,
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H_ERRNO_VAR_P))
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{
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case -1:
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return errno;
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case 1:
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#ifdef NEED_H_ERRNO
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any_service = true;
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#endif
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goto done;
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}
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#endif
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#ifdef USE_NSCD
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if (NOT_USENSCD_NAME > 0 && ++NOT_USENSCD_NAME > NSS_NSCD_RETRY)
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NOT_USENSCD_NAME = 0;
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if (!NOT_USENSCD_NAME
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&& !__nss_database_custom[CONCAT2 (NSS_DBSIDX_, DATABASE_NAME)])
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{
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nscd_status = NSCD_NAME (ADD_VARIABLES, resbuf, buffer, buflen, result
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H_ERRNO_VAR);
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if (nscd_status >= 0)
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return nscd_status;
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}
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#endif
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if (! startp_initialized)
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{
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no_more = DB_LOOKUP_FCT (&nip, REENTRANT_NAME_STRING,
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REENTRANT2_NAME_STRING, &fct.ptr);
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if (no_more)
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{
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void *tmp_ptr = (service_user *) -1l;
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#ifdef PTR_MANGLE
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PTR_MANGLE (tmp_ptr);
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#endif
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startp = tmp_ptr;
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}
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else
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{
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void *tmp_ptr = fct.l;
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#ifdef PTR_MANGLE
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PTR_MANGLE (tmp_ptr);
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#endif
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start_fct = tmp_ptr;
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tmp_ptr = nip;
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#ifdef PTR_MANGLE
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PTR_MANGLE (tmp_ptr);
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#endif
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startp = tmp_ptr;
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}
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/* Make sure start_fct and startp are written before
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startp_initialized. */
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atomic_write_barrier ();
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startp_initialized = true;
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}
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else
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{
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fct.l = start_fct;
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nip = startp;
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#ifdef PTR_DEMANGLE
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PTR_DEMANGLE (fct.l);
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PTR_DEMANGLE (nip);
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#endif
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no_more = nip == (service_user *) -1l;
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}
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while (no_more == 0)
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{
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#ifdef NEED_H_ERRNO
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any_service = true;
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#endif
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status = DL_CALL_FCT (fct.l, (ADD_VARIABLES, resbuf, buffer, buflen,
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&errno H_ERRNO_VAR EXTRA_VARIABLES));
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/* The status is NSS_STATUS_TRYAGAIN and errno is ERANGE the
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provided buffer is too small. In this case we should give
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the user the possibility to enlarge the buffer and we should
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not simply go on with the next service (even if the TRYAGAIN
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action tells us so). */
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if (status == NSS_STATUS_TRYAGAIN
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#ifdef NEED_H_ERRNO
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&& *h_errnop == NETDB_INTERNAL
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#endif
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&& errno == ERANGE)
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break;
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if (do_merge)
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{
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if (status == NSS_STATUS_SUCCESS)
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{
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/* The previous loop saved a buffer for merging.
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Perform the merge now. */
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err = MERGE_FN (&mergegrp, mergebuf, endptr, buflen, resbuf,
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buffer);
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CHECK_MERGE (err,status);
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do_merge = 0;
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}
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else
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{
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/* If the result wasn't SUCCESS, copy the saved buffer back
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into the result buffer and set the status back to
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NSS_STATUS_SUCCESS to match the previous pass through the
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loop.
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* If the next action is CONTINUE, it will overwrite the value
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currently in the buffer and return the new value.
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* If the next action is RETURN, we'll return the previously-
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acquired values.
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* If the next action is MERGE, then it will be added to the
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buffer saved from the previous source. */
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err = DEEPCOPY_FN (mergegrp, buflen, resbuf, buffer, NULL);
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CHECK_MERGE (err, status);
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status = NSS_STATUS_SUCCESS;
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}
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}
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/* If we were are configured to merge this value with the next one,
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save the current value of the group struct. */
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if (nss_next_action (nip, status) == NSS_ACTION_MERGE
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&& status == NSS_STATUS_SUCCESS)
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{
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/* Copy the current values into a buffer to be merged with the next
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set of retrieved values. */
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if (mergebuf == NULL)
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{
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/* Only allocate once and reuse it for as many merges as we need
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to perform. */
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mergebuf = malloc (buflen);
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if (mergebuf == NULL)
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{
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__set_errno (ENOMEM);
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status = NSS_STATUS_UNAVAIL;
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break;
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}
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}
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err = DEEPCOPY_FN (*resbuf, buflen, &mergegrp, mergebuf, &endptr);
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CHECK_MERGE (err, status);
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do_merge = 1;
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}
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no_more = __nss_next2 (&nip, REENTRANT_NAME_STRING,
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REENTRANT2_NAME_STRING, &fct.ptr, status, 0);
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}
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free (mergebuf);
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mergebuf = NULL;
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#ifdef HANDLE_DIGITS_DOTS
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done:
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#endif
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*result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
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#ifdef NEED_H_ERRNO
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if (status == NSS_STATUS_UNAVAIL && !any_service && errno != ENOENT)
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/* This happens when we weren't able to use a service for reasons other
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than the module not being found. In such a case, we'd want to tell the
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caller that errno has the real reason for failure. */
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*h_errnop = NETDB_INTERNAL;
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else if (status != NSS_STATUS_SUCCESS && !any_service)
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/* We were not able to use any service. */
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*h_errnop = NO_RECOVERY;
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#endif
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#ifdef POSTPROCESS
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POSTPROCESS;
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#endif
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#ifdef NEED__RES
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/* This has to happen late because the POSTPROCESS stage above might
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need the resolver context. */
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__resolv_context_put (res_ctx);
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#endif /* NEED__RES */
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int res;
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if (status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND)
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res = 0;
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/* Don't pass back ERANGE if this is not for a too-small buffer. */
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else if (errno == ERANGE && status != NSS_STATUS_TRYAGAIN)
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res = EINVAL;
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#ifdef NEED_H_ERRNO
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/* These functions only set errno if h_errno is NETDB_INTERNAL. */
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else if (status == NSS_STATUS_TRYAGAIN && *h_errnop != NETDB_INTERNAL)
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res = EAGAIN;
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#endif
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else
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return errno;
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__set_errno (res);
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return res;
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}
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#ifdef NO_COMPAT_NEEDED
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strong_alias (INTERNAL (REENTRANT_NAME), REENTRANT_NAME);
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#elif !defined FUNCTION2_NAME
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# include <shlib-compat.h>
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# if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1_2)
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# define OLD(name) OLD1 (name)
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# define OLD1(name) __old_##name
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int
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attribute_compat_text_section
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OLD (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
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size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM)
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{
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int ret = INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, resbuf, buffer,
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buflen, result H_ERRNO_VAR);
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if (ret != 0 || result == NULL)
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ret = -1;
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return ret;
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}
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# define do_symbol_version(real, name, version) \
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compat_symbol (libc, real, name, version)
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do_symbol_version (OLD (REENTRANT_NAME), REENTRANT_NAME, GLIBC_2_0);
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# endif
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/* As INTERNAL (REENTRANT_NAME) may be hidden, we need an alias
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in between so that the REENTRANT_NAME@@GLIBC_2.1.2 is not
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hidden too. */
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strong_alias (INTERNAL (REENTRANT_NAME), NEW (REENTRANT_NAME));
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# define do_default_symbol_version(real, name, version) \
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versioned_symbol (libc, real, name, version)
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do_default_symbol_version (NEW (REENTRANT_NAME),
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REENTRANT_NAME, GLIBC_2_1_2);
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#endif
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nss_interface_function (REENTRANT_NAME)
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