nss/getXXbyYY_r.c

   1 /* Copyright (C) 1996 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
   4
   5 The GNU C Library is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 License, or (at your option) any later version.
   9
  10 The GNU C Library is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18 Boston, MA 02111-1307, USA.  */
  19
  20 #include "nsswitch.h"
  21
  22 /*******************************************************************\
  23 |* Here we assume several symbols to be defined:                   *|
  24 |*                                                                 *|
  25 |* LOOKUP_TYPE   - the return type of the function                 *|
  26 |*                                                                 *|
  27 |* FUNCTION_NAME - name of the non-reentrant function              *|
  28 |*                                                                 *|
  29 |* DATABASE_NAME - name of the database the function accesses      *|
  30 |*                 (e.g., host, services, ...)                     *|
  31 |*                                                                 *|
  32 |* ADD_PARAMS    - additional parameter, can vary in number        *|
  33 |*                                                                 *|
  34 |* ADD_VARIABLES - names of additional parameter                   *|
  35 |*                                                                 *|
  36 |* Optionally the following vars can be defined:                   *|
  37 |*                                                                 *|
  38 |* NEED_H_ERRNO  - an extra parameter will be passed to point to   *|
  39 |*                 the global `h_errno' variable.                  *|
  40 |*                                                                 *|
  41 |* NEED__RES     - the global _res variable might be used so we    *|
  42 |*                 will have to initialize it if necessary         *|
  43 |*                                                                 *|
  44 \*******************************************************************/
  45
  46 /* To make the real sources a bit prettier.  */
  47 #define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
  48 #define APPEND_R(name) APPEND_R1 (name)
  49 #define APPEND_R1(name) name##_r
  50
  51 #define FUNCTION_NAME_STRING STRINGIZE (FUNCTION_NAME)
  52 #define REENTRANT_NAME_STRING STRINGIZE (REENTRANT_NAME)
  53 #define DATABASE_NAME_STRING STRINGIZE (DATABASE_NAME)
  54 #define STRINGIZE(name) STRINGIZE1 (name)
  55 #define STRINGIZE1(name) #name
  56
  57 #define DB_LOOKUP_FCT CONCAT3_1 (__nss_, DATABASE_NAME, _lookup)
  58 #define CONCAT3_1(Pre, Name, Post) CONCAT3_2 (Pre, Name, Post)
  59 #define CONCAT3_2(Pre, Name, Post) Pre##Name##Post
  60
  61 /* Sometimes we need to store error codes in the `h_errno' variable.  */
  62 #ifdef NEED_H_ERRNO
  63 # define H_ERRNO_PARM , int *h_errnop
  64 # define H_ERRNO_VAR , h_errnop
  65 #else
  66 # define H_ERRNO_PARM
  67 # define H_ERRNO_VAR
  68 #endif
  69
  70
  71 /* Type of the lookup function we need here.  */
  72 typedef int (*lookup_function) (ADD_PARAMS, LOOKUP_TYPE *, char *, int
  73                                 H_ERRNO_PARM);
  74
  75 /* Some usages of this file might use this variable.  */
  76 extern struct __res_state _res;
  77
  78 /* The lookup function for the first entry of this service.  */
  79 extern int DB_LOOKUP_FCT (service_user **nip, const char *name, void **fctp);
  80
  81
  82
  83 LOOKUP_TYPE *
  84 REENTRANT_NAME (ADD_PARAMS, LOOKUP_TYPE *result, char *buffer, int buflen
  85                 H_ERRNO_PARM)
  86 {
  87   static service_user *startp = NULL;
  88   static lookup_function start_fct;
  89   service_user *nip;
  90   lookup_function fct;
  91   int no_more;
  92   enum nss_status status = NSS_STATUS_UNAVAIL;
  93
  94   if (startp == NULL)
  95     {
  96       no_more = DB_LOOKUP_FCT (&nip, REENTRANT_NAME_STRING, (void **) &fct);
  97       if (no_more)
  98         startp = (service_user *) -1;
  99       else
 100         {
 101           startp = nip;
 102           start_fct = fct;
 103
 104 #ifdef NEED__RES
 105           /* The resolver code will really be used so we have to
 106              initialize it.  */
 107           if ((_res.options & RES_INIT) == 0 && res_init () == -1)
 108             {
 109               *h_errnop = NETDB_INTERNAL;
 110               return NULL;
 111             }
 112 #endif /* need _res */
 113         }
 114     }
 115   else
 116     {
 117       fct = start_fct;
 118       no_more = (nip = startp) == (service_user *) -1;
 119     }
 120
 121   while (no_more == 0)
 122     {
 123       status = (*fct) (ADD_VARIABLES, result, buffer, buflen H_ERRNO_VAR);
 124
 125       no_more = __nss_next (&nip, REENTRANT_NAME_STRING,
 126                             (void **) &fct, status, 0);
 127     }
 128
 129   return status == NSS_STATUS_SUCCESS ? result : NULL;
 130 }