nss/getXXbyYY.c

   1 /* Copyright (C) 1996 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 <errno.h>
  20 #include <libc-lock.h>
  21 #include <stdlib.h>
  22
  23 #include "nsswitch.h"
  24
  25 /*******************************************************************\
  26 |* Here we assume several symbols to be defined:                   *|
  27 |*                                                                 *|
  28 |* LOOKUP_TYPE   - the return type of the function                 *|
  29 |*                                                                 *|
  30 |* FUNCTION_NAME - name of the non-reentrant function              *|
  31 |*                                                                 *|
  32 |* DATABASE_NAME - name of the database the function accesses      *|
  33 |*                 (e.g., host, services, ...)                     *|
  34 |*                                                                 *|
  35 |* ADD_PARAMS    - additional parameter, can vary in number        *|
  36 |*                                                                 *|
  37 |* ADD_VARIABLES - names of additional parameter                   *|
  38 |*                                                                 *|
  39 |* BUFLEN        - length of buffer allocated for the non          *|
  40 |*                 reentrant version                               *|
  41 |*                                                                 *|
  42 |* Optionally the following vars can be defined:                   *|
  43 |*                                                                 *|
  44 |* NEED_H_ERRNO  - an extra parameter will be passed to point to   *|
  45 |*                 the global `h_errno' variable.                  *|
  46 |*                                                                 *|
  47 \*******************************************************************/
  48
  49 /* To make the real sources a bit prettier.  */
  50 #define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
  51 #define APPEND_R(name) APPEND_R1 (name)
  52 #define APPEND_R1(name) name##_r
  53 #define INTERNAL(name) INTERNAL1 (name)
  54 #define INTERNAL1(name) __##name
  55
  56 /* Sometimes we need to store error codes in the `h_errno' variable.  */
  57 #ifdef NEED_H_ERRNO
  58 # define H_ERRNO_PARM , int *h_errnop
  59 # define H_ERRNO_VAR , &h_errno
  60 #else
  61 # define H_ERRNO_PARM
  62 # define H_ERRNO_VAR
  63 #endif
  64
  65
  66 /* Prototype for reentrant version we use here.  */
  67 extern int INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf,
  68                                       char *buffer, size_t buflen,
  69                                       LOOKUP_TYPE **result H_ERRNO_PARM);
  70
  71 /* We need to protect the dynamic buffer handling.  */
  72 __libc_lock_define_initialized (static, lock);
  73
  74
  75 LOOKUP_TYPE *
  76 FUNCTION_NAME (ADD_PARAMS)
  77 {
  78   static char *buffer;
  79   static size_t buffer_size;
  80   static LOOKUP_TYPE resbuf;
  81   LOOKUP_TYPE *result;
  82   int save;
  83
  84   /* Get lock.  */
  85   __libc_lock_lock (lock);
  86
  87   if (buffer == NULL)
  88     {
  89       buffer_size = BUFLEN;
  90       buffer = malloc (buffer_size);
  91     }
  92
  93   while (buffer != NULL
  94          && INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, &resbuf, buffer,
  95                                        buffer_size, &result H_ERRNO_VAR) != 0
  96          && errno == ERANGE)
  97     {
  98       char *new_buf;
  99       buffer_size += BUFLEN;
 100       new_buf = realloc (buffer, buffer_size);
 101       if (new_buf == NULL)
 102         /* We are out of memory.  Free the current buffer so that the
 103            process gets a chance for a normal termination.  */
 104         free (buffer);
 105       buffer = new_buf;
 106     }
 107
 108   /* Release lock.  Preserve error value.  */
 109   save = errno;
 110   __libc_lock_unlock (lock);
 111   __set_errno (save);
 112
 113   return result;
 114 }