nss/getXXent.c

   1 /* Copyright (C) 1996, 1997, 1998 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 |* GETFUNC_NAME  - name of the non-reentrant getXXXent function    *|
  31 |*                                                                 *|
  32 |* BUFLEN        - size of static buffer                           *|
  33 |*                                                                 *|
  34 |* Optionally the following vars can be defined:                   *|
  35 |*                                                                 *|
  36 |* NEED_H_ERRNO  - an extra parameter will be passed to point to   *|
  37 |*                 the global `h_errno' variable.                  *|
  38 |*                                                                 *|
  39 \*******************************************************************/
  40
  41 /* To make the real sources a bit prettier.  */
  42 #define REENTRANT_GETNAME APPEND_R (GETFUNC_NAME)
  43 #define APPEND_R(name) APPEND_R1 (name)
  44 #define APPEND_R1(name) name##_r
  45 #define INTERNAL(name) INTERNAL1 (name)
  46 #define INTERNAL1(name) __##name
  47
  48 /* Sometimes we need to store error codes in the `h_errno' variable.  */
  49 #ifdef NEED_H_ERRNO
  50 # define H_ERRNO_PARM , int *h_errnop
  51 # define H_ERRNO_VAR , &h_errno
  52 #else
  53 # define H_ERRNO_PARM
  54 # define H_ERRNO_VAR
  55 #endif
  56
  57 /* Prototype of the reentrant version.  */
  58 extern int INTERNAL (REENTRANT_GETNAME) (LOOKUP_TYPE *resbuf, char *buffer,
  59                                          size_t buflen, LOOKUP_TYPE **result
  60                                          H_ERRNO_PARM);
  61
  62 /* We need to protect the dynamic buffer handling.  */
  63 __libc_lock_define_initialized (static, lock);
  64
  65
  66 LOOKUP_TYPE *
  67 GETFUNC_NAME (void)
  68 {
  69   static char *buffer;
  70   static size_t buffer_size;
  71   static LOOKUP_TYPE resbuf;
  72   LOOKUP_TYPE *result;
  73   int save, save_errno;
  74
  75   /* Get lock.  */
  76   __libc_lock_lock (lock);
  77
  78   if (buffer == NULL)
  79     {
  80       buffer_size = BUFLEN;
  81       buffer = malloc (buffer_size);
  82     }
  83
  84   /* We don't want to pass errno == 0 or errno == ERANGE back */
  85   save_errno = errno;
  86
  87   while (buffer != NULL
  88          && INTERNAL (REENTRANT_GETNAME) (&resbuf, buffer, buffer_size, &result
  89                                           H_ERRNO_VAR) != 0
  90 #ifdef NEED_H_ERRNO
  91          && h_errno == NETDB_INTERNAL
  92 #endif
  93          && errno == ERANGE)
  94     {
  95       char *new_buf;
  96       buffer_size += BUFLEN;
  97       __set_errno (0);
  98       new_buf = realloc (buffer, buffer_size);
  99       if (new_buf == NULL)
 100         {
 101           /* We are out of memory.  Free the current buffer so that the
 102              process gets a chance for a normal termination.  */
 103           save = errno;
 104           free (buffer);
 105           __set_errno (save);
 106         }
 107       buffer = new_buf;
 108     }
 109
 110   if (errno == 0)
 111     __set_errno (save_errno);
 112
 113   if (buffer == NULL)
 114     result = NULL;
 115
 116   /* Release lock.  Preserve error value.  */
 117   save = errno;
 118   __libc_lock_unlock (lock);
 119   __set_errno (save);
 120
 121   return result;
 122 }