nss/getXXent.c

   1 /* Copyright (C) 1996-2021 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    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <libc-lock.h>
  20 #include <stdlib.h>
  21
  22 #include "nsswitch.h"
  23
  24 /*******************************************************************\
  25 |* Here we assume several symbols to be defined:                   *|
  26 |*                                                                 *|
  27 |* LOOKUP_TYPE   - the return type of the function                 *|
  28 |*                                                                 *|
  29 |* GETFUNC_NAME  - name of the non-reentrant getXXXent function    *|
  30 |*                                                                 *|
  31 |* BUFLEN        - size of static buffer                           *|
  32 |*                                                                 *|
  33 |* Optionally the following vars can be defined:                   *|
  34 |*                                                                 *|
  35 |* NEED_H_ERRNO  - an extra parameter will be passed to point to   *|
  36 |*                 the global `h_errno' variable.                  *|
  37 |*                                                                 *|
  38 \*******************************************************************/
  39
  40 /* To make the real sources a bit prettier.  */
  41 #define REENTRANT_GETNAME APPEND_R (GETFUNC_NAME)
  42 #define APPEND_R(name) APPEND_R1 (name)
  43 #define APPEND_R1(name) name##_r
  44 #define INTERNAL(name) INTERNAL1 (name)
  45 #define INTERNAL1(name) __##name
  46
  47 /* Sometimes we need to store error codes in the `h_errno' variable.  */
  48 #ifdef NEED_H_ERRNO
  49 # define H_ERRNO_PARM , int *h_errnop
  50 # define H_ERRNO_VAR &h_errno
  51 #else
  52 # define H_ERRNO_PARM
  53 # define H_ERRNO_VAR NULL
  54 #endif
  55
  56 /* Prototype of the reentrant version.  */
  57 extern int INTERNAL (REENTRANT_GETNAME) (LOOKUP_TYPE *resbuf, char *buffer,
  58                                          size_t buflen, LOOKUP_TYPE **result
  59                                          H_ERRNO_PARM) attribute_hidden;
  60
  61 /* We need to protect the dynamic buffer handling.  */
  62 __libc_lock_define_initialized (static, lock);
  63
  64 /* This points to the static buffer used.  */
  65 libc_freeres_ptr (static char *buffer);
  66
  67
  68 LOOKUP_TYPE *
  69 GETFUNC_NAME (void)
  70 {
  71   static size_t buffer_size;
  72   static union
  73   {
  74     LOOKUP_TYPE l;
  75     void *ptr;
  76   } resbuf;
  77   LOOKUP_TYPE *result;
  78   int save;
  79
  80   /* Get lock.  */
  81   __libc_lock_lock (lock);
  82
  83   result = (LOOKUP_TYPE *)
  84     __nss_getent ((getent_r_function) INTERNAL (REENTRANT_GETNAME),
  85                   &resbuf.ptr, &buffer, BUFLEN, &buffer_size,
  86                   H_ERRNO_VAR);
  87
  88   save = errno;
  89   __libc_lock_unlock (lock);
  90   __set_errno (save);
  91   return result;
  92 }
  93
  94 nss_interface_function (GETFUNC_NAME)