nss/getXXbyYY.c

   1 /* Copyright (C) 1996,1997,1998,1999,2000,2001 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    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 # define H_ERRNO_VAR_P &h_errno_tmp
  63 #else
  64 # define H_ERRNO_PARM
  65 # define H_ERRNO_VAR
  66 # define H_ERRNO_VAR_P NULL
  67 #endif
  68
  69 #ifndef HAVE_TYPE
  70 # define TYPE_VAR_P NULL
  71 # define FLAGS_VAR 0
  72 #endif
  73
  74 #ifdef HAVE_AF
  75 # define AF_VAR_P &af
  76 #else
  77 # define AF_VAR_P NULL
  78 #endif
  79
  80 /* Prototype for reentrant version we use here.  */
  81 extern int INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf,
  82                                       char *buffer, size_t buflen,
  83                                       LOOKUP_TYPE **result H_ERRNO_PARM);
  84
  85 /* We need to protect the dynamic buffer handling.  */
  86 __libc_lock_define_initialized (static, lock);
  87
  88 /* This points to the static buffer used.  */
  89 static char *buffer;
  90
  91
  92 LOOKUP_TYPE *
  93 FUNCTION_NAME (ADD_PARAMS)
  94 {
  95   static size_t buffer_size;
  96   static LOOKUP_TYPE resbuf;
  97   LOOKUP_TYPE *result;
  98   int save;
  99 #ifdef NEED_H_ERRNO
 100   int h_errno_tmp = 0;
 101 #endif
 102
 103   /* Get lock.  */
 104   __libc_lock_lock (lock);
 105
 106   if (buffer == NULL)
 107     {
 108       buffer_size = BUFLEN;
 109       buffer = malloc (buffer_size);
 110     }
 111
 112 #ifdef HANDLE_DIGITS_DOTS
 113   if (buffer != NULL)
 114     {
 115       if (__nss_hostname_digits_dots (name, &resbuf, &buffer,
 116                                       &buffer_size,
 117                                       0, &result, NULL, TYPE_VAR_P,
 118                                       FLAGS_VAR, AF_VAR_P,
 119                                       H_ERRNO_VAR_P))
 120         goto done;
 121     }
 122 #endif
 123
 124   while (buffer != NULL
 125          && (INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, &resbuf, buffer,
 126                                         buffer_size, &result H_ERRNO_VAR)
 127              == ERANGE)
 128 #ifdef NEED_H_ERRNO
 129          && h_errno_tmp == NETDB_INTERNAL
 130 #endif
 131          )
 132     {
 133       char *new_buf;
 134       buffer_size += BUFLEN;
 135       new_buf = realloc (buffer, buffer_size);
 136       if (new_buf == NULL)
 137         {
 138           /* We are out of memory.  Free the current buffer so that the
 139              process gets a chance for a normal termination.  */
 140           save = errno;
 141           free (buffer);
 142           __set_errno (save);
 143         }
 144       buffer = new_buf;
 145     }
 146
 147   if (buffer == NULL)
 148     result = NULL;
 149
 150 #ifdef HANDLE_DIGITS_DOTS
 151 done:
 152 #endif
 153   /* Release lock.  Preserve error value.  */
 154   save = errno;
 155   __libc_lock_unlock (lock);
 156   __set_errno (save);
 157
 158 #ifdef NEED_H_ERRNO
 159   if (h_errno_tmp != 0)
 160     __set_h_errno (h_errno_tmp);
 161 #endif
 162
 163   return result;
 164 }
 165
 166
 167 /* Free all resources if necessary.  */
 168 static void __attribute__ ((unused))
 169 free_mem (void)
 170 {
 171   free (buffer);
 172 }
 173
 174 text_set_element (__libc_subfreeres, free_mem);