grp/fgetgrent.c

   1 /* Copyright (C) 1991, 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 <grp.h>
  21 #include <libc-lock.h>
  22 #include <stdlib.h>
  23
  24
  25 /* We need to protect the dynamic buffer handling.  */
  26 __libc_lock_define_initialized (static, lock);
  27
  28 /* Read one entry from the given stream.  */
  29 struct group *
  30 fgetgrent (FILE *stream)
  31 {
  32   static char *buffer;
  33   static size_t buffer_size;
  34   static struct group resbuf;
  35   struct group *result;
  36   int save, save_errno;
  37
  38   /* Get lock.  */
  39   __libc_lock_lock (lock);
  40
  41   /* Allocate buffer if not yet available.  */
  42   if (buffer == NULL)
  43     {
  44       buffer_size = NSS_BUFLEN_GROUP;
  45       buffer = malloc (buffer_size);
  46     }
  47
  48   /* We don't want to pass errno == 0 or errno == ERANGE back */
  49   save_errno = errno;
  50
  51   while (buffer != NULL
  52          && __fgetgrent_r (stream, &resbuf, buffer, buffer_size, &result) != 0
  53          && errno == ERANGE)
  54     {
  55       char *new_buf;
  56       buffer_size += NSS_BUFLEN_GROUP;
  57       __set_errno (0);
  58       new_buf = realloc (buffer, buffer_size);
  59       if (new_buf == NULL)
  60         {
  61           /* We are out of memory.  Free the current buffer so that the
  62              process gets a chance for a normal termination.  */
  63           save = errno;
  64           free (buffer);
  65           __set_errno (save);
  66         }
  67       buffer = new_buf;
  68     }
  69
  70   if (errno == 0)
  71     __set_errno (save_errno);
  72
  73   if (buffer == NULL)
  74     result = NULL;
  75
  76   /* Release lock.  Preserve error value.  */
  77   save = errno;
  78   __libc_lock_unlock (lock);
  79   __set_errno (save);
  80
  81   return result;
  82 }