nss/getXXbyYY.c

   1 /* Copyright (C) 1996, 1997, 1998, 1999 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <assert.h>
  20 #include <errno.h>
  21 #include <bits/libc-lock.h>
  22 #include <stdlib.h>
  23 #include <resolv.h>
  24
  25 #include "nsswitch.h"
  26
  27 /*******************************************************************\
  28 |* Here we assume several symbols to be defined:                   *|
  29 |*                                                                 *|
  30 |* LOOKUP_TYPE   - the return type of the function                 *|
  31 |*                                                                 *|
  32 |* FUNCTION_NAME - name of the non-reentrant function              *|
  33 |*                                                                 *|
  34 |* DATABASE_NAME - name of the database the function accesses      *|
  35 |*                 (e.g., host, services, ...)                     *|
  36 |*                                                                 *|
  37 |* ADD_PARAMS    - additional parameter, can vary in number        *|
  38 |*                                                                 *|
  39 |* ADD_VARIABLES - names of additional parameter                   *|
  40 |*                                                                 *|
  41 |* BUFLEN        - length of buffer allocated for the non          *|
  42 |*                 reentrant version                               *|
  43 |*                                                                 *|
  44 |* Optionally the following vars can be defined:                   *|
  45 |*                                                                 *|
  46 |* NEED_H_ERRNO  - an extra parameter will be passed to point to   *|
  47 |*                 the global `h_errno' variable.                  *|
  48 |*                                                                 *|
  49 \*******************************************************************/
  50
  51 /* To make the real sources a bit prettier.  */
  52 #define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
  53 #define APPEND_R(name) APPEND_R1 (name)
  54 #define APPEND_R1(name) name##_r
  55 #define INTERNAL(name) INTERNAL1 (name)
  56 #define INTERNAL1(name) __##name
  57
  58 /* Sometimes we need to store error codes in the `h_errno' variable.  */
  59 #ifdef NEED_H_ERRNO
  60 # define H_ERRNO_PARM , int *h_errnop
  61 # define H_ERRNO_VAR , &h_errno_tmp
  62 #else
  63 # define H_ERRNO_PARM
  64 # define H_ERRNO_VAR
  65 #endif
  66
  67
  68 /* Prototype for reentrant version we use here.  */
  69 extern int INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf,
  70                                       char *buffer, size_t buflen,
  71                                       LOOKUP_TYPE **result H_ERRNO_PARM);
  72
  73 /* We need to protect the dynamic buffer handling.  */
  74 __libc_lock_define_initialized (static, lock);
  75
  76 /* This points to the static buffer used.  */
  77 static char *buffer;
  78
  79
  80 LOOKUP_TYPE *
  81 FUNCTION_NAME (ADD_PARAMS)
  82 {
  83   static size_t buffer_size;
  84   static LOOKUP_TYPE resbuf;
  85   LOOKUP_TYPE *result;
  86   int save;
  87 #ifdef NEED_H_ERRNO
  88   int h_errno_tmp = 0;
  89 # ifdef HANDLE_DIGITS_DOTS
  90   int *const h_errnop = &h_errno_tmp;;
  91 # endif
  92 #endif
  93
  94   /* Get lock.  */
  95   __libc_lock_lock (lock);
  96
  97   if (buffer == NULL)
  98     {
  99       buffer_size = BUFLEN;
 100       buffer = malloc (buffer_size);
 101     }
 102
 103   if (buffer != NULL)
 104     {
 105 #ifdef HANDLE_DIGITS_DOTS
 106       /* We have to test for the use of IPv6 which can only be done by
 107          examining `_res'.  */
 108       if ((_res.options & RES_INIT) == 0 && __res_ninit (&_res) == -1)
 109         {
 110 # ifdef NEED_H_ERRNO
 111           h_errno_tmp = NETDB_INTERNAL;
 112 # endif
 113           result = NULL;
 114           goto done;
 115         }
 116 # include "digits_dots.c"
 117 #endif
 118     }
 119
 120   while (buffer != NULL
 121          && (INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, &resbuf, buffer,
 122                                         buffer_size, &result H_ERRNO_VAR)
 123              == ERANGE)
 124 #ifdef NEED_H_ERRNO
 125          && h_errno_tmp == NETDB_INTERNAL
 126 #endif
 127          )
 128     {
 129       char *new_buf;
 130       buffer_size += BUFLEN;
 131       new_buf = realloc (buffer, buffer_size);
 132       if (new_buf == NULL)
 133         {
 134           /* We are out of memory.  Free the current buffer so that the
 135              process gets a chance for a normal termination.  */
 136           save = errno;
 137           free (buffer);
 138           __set_errno (save);
 139         }
 140       buffer = new_buf;
 141     }
 142
 143   if (buffer == NULL)
 144     result = NULL;
 145
 146 #ifdef HANDLE_DIGITS_DOTS
 147 done:
 148 #endif
 149   /* Release lock.  Preserve error value.  */
 150   save = errno;
 151   __libc_lock_unlock (lock);
 152   __set_errno (save);
 153
 154 #ifdef NEED_H_ERRNO
 155   if (h_errno_tmp != 0)
 156     __set_h_errno (h_errno_tmp);
 157 #endif
 158
 159   return result;
 160 }
 161
 162
 163 /* Free all resources if necessary.  */
 164 static void __attribute__ ((unused))
 165 free_mem (void)
 166 {
 167   if (buffer != NULL)
 168     free (buffer);
 169 }
 170
 171 text_set_element (__libc_subfreeres, free_mem);