misc/mntent.c

   1 /* Utilities for reading/writing fstab, mtab, etc.
   2    Copyright (C) 1995-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <mntent.h>
  20 #include <stdlib.h>
  21 #include <allocate_once.h>
  22
  23 struct mntent_buffer
  24 {
  25   struct mntent m;
  26   char buffer[4096];
  27 };
  28
  29 /* We don't want to allocate the static buffer all the time since it
  30    is not always used (in fact, rather infrequently).  */
  31 libc_freeres_ptr (static void *mntent_buffer);
  32
  33 static void *
  34 allocate (void *closure)
  35 {
  36   return malloc (sizeof (struct mntent_buffer));
  37 }
  38
  39 static void
  40 deallocate (void *closure, void *ptr)
  41 {
  42   free (ptr);
  43 }
  44
  45 struct mntent *
  46 getmntent (FILE *stream)
  47 {
  48   struct mntent_buffer *buffer = allocate_once (&mntent_buffer,
  49                                                 allocate, deallocate, NULL);
  50   if (buffer == NULL)
  51     /* If no core is available we don't have a chance to run the
  52        program successfully and so returning NULL is an acceptable
  53        result.  */
  54     return NULL;
  55
  56   return __getmntent_r (stream, &buffer->m,
  57                         buffer->buffer, sizeof (buffer->buffer));
  58 }