nss/getXXbyYY.c

   1 /* Copyright (C) 1996-2017 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, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <assert.h>
  19 #include <errno.h>
  20 #include <libc-lock.h>
  21 #include <stdlib.h>
  22 #include <resolv.h>
  23
  24 #include "nsswitch.h"
  25
  26 /*******************************************************************\
  27 |* Here we assume several symbols to be defined:                   *|
  28 |*                                                                 *|
  29 |* LOOKUP_TYPE   - the return type of the function                 *|
  30 |*                                                                 *|
  31 |* FUNCTION_NAME - name of the non-reentrant function              *|
  32 |*                                                                 *|
  33 |* DATABASE_NAME - name of the database the function accesses      *|
  34 |*                 (e.g., host, services, ...)                     *|
  35 |*                                                                 *|
  36 |* ADD_PARAMS    - additional parameter, can vary in number        *|
  37 |*                                                                 *|
  38 |* ADD_VARIABLES - names of additional parameter                   *|
  39 |*                                                                 *|
  40 |* BUFLEN        - length of buffer allocated for the non          *|
  41 |*                 reentrant version                               *|
  42 |*                                                                 *|
  43 |* Optionally the following vars can be defined:                   *|
  44 |*                                                                 *|
  45 |* NEED_H_ERRNO  - an extra parameter will be passed to point to   *|
  46 |*                 the global `h_errno' variable.                  *|
  47 |*                                                                 *|
  48 \*******************************************************************/
  49
  50 /* To make the real sources a bit prettier.  */
  51 #define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
  52 #define APPEND_R(name) APPEND_R1 (name)
  53 #define APPEND_R1(name) name##_r
  54 #define INTERNAL(name) INTERNAL1 (name)
  55 #define INTERNAL1(name) __##name
  56
  57 /* Sometimes we need to store error codes in the `h_errno' variable.  */
  58 #ifdef NEED_H_ERRNO
  59 # define H_ERRNO_PARM , int *h_errnop
  60 # define H_ERRNO_VAR , &h_errno_tmp
  61 # define H_ERRNO_VAR_P &h_errno_tmp
  62 #else
  63 # define H_ERRNO_PARM
  64 # define H_ERRNO_VAR
  65 # define H_ERRNO_VAR_P NULL
  66 #endif
  67
  68 #ifdef HAVE_AF
  69 # define AF_VAL af
  70 #else
  71 # define AF_VAL AF_INET
  72 #endif
  73
  74 /* Prototype for reentrant version we use here.  */
  75 extern int INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf,
  76                                       char *buffer, size_t buflen,
  77                                       LOOKUP_TYPE **result H_ERRNO_PARM);
  78
  79 /* We need to protect the dynamic buffer handling.  */
  80 __libc_lock_define_initialized (static, lock);
  81
  82 /* This points to the static buffer used.  */
  83 libc_freeres_ptr (static char *buffer);
  84
  85
  86 LOOKUP_TYPE *
  87 FUNCTION_NAME (ADD_PARAMS)
  88 {
  89   static size_t buffer_size;
  90   static LOOKUP_TYPE resbuf;
  91   LOOKUP_TYPE *result;
  92 #ifdef NEED_H_ERRNO
  93   int h_errno_tmp = 0;
  94 #endif
  95
  96   /* Get lock.  */
  97   __libc_lock_lock (lock);
  98
  99   if (buffer == NULL)
 100     {
 101       buffer_size = BUFLEN;
 102       buffer = (char *) malloc (buffer_size);
 103     }
 104
 105 #ifdef HANDLE_DIGITS_DOTS
 106   if (buffer != NULL)
 107     {
 108       if (__nss_hostname_digits_dots (name, &resbuf, &buffer,
 109                                       &buffer_size, 0, &result, NULL, AF_VAL,
 110                                       H_ERRNO_VAR_P))
 111         goto done;
 112     }
 113 #endif
 114
 115   while (buffer != NULL
 116          && (INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, &resbuf, buffer,
 117                                         buffer_size, &result H_ERRNO_VAR)
 118              == ERANGE)
 119 #ifdef NEED_H_ERRNO
 120          && h_errno_tmp == NETDB_INTERNAL
 121 #endif
 122          )
 123     {
 124       char *new_buf;
 125       buffer_size *= 2;
 126       new_buf = (char *) realloc (buffer, buffer_size);
 127       if (new_buf == NULL)
 128         {
 129           /* We are out of memory.  Free the current buffer so that the
 130              process gets a chance for a normal termination.  */
 131           free (buffer);
 132           __set_errno (ENOMEM);
 133         }
 134       buffer = new_buf;
 135     }
 136
 137   if (buffer == NULL)
 138     result = NULL;
 139
 140 #ifdef HANDLE_DIGITS_DOTS
 141 done:
 142 #endif
 143   /* Release lock.  */
 144   __libc_lock_unlock (lock);
 145
 146 #ifdef NEED_H_ERRNO
 147   if (h_errno_tmp != 0)
 148     __set_h_errno (h_errno_tmp);
 149 #endif
 150
 151   return result;
 152 }
 153
 154 nss_interface_function (FUNCTION_NAME)