misc/mntent.c

   1 /* Utilities for reading/writing fstab, mtab, etc.
   2    Copyright (C) 1995-2017 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <mntent.h>
  20 #include <stdlib.h>
  21 #include <libc-lock.h>
  22
  23 /* We don't want to allocate the static buffer all the time since it
  24    is not always used (in fact, rather infrequently).  Accept the
  25    extra cost of a `malloc'.  */
  26 libc_freeres_ptr (static char *getmntent_buffer);
  27
  28 /* This is the size of the buffer.  This is really big.  */
  29 #define BUFFER_SIZE     4096
  30
  31
  32 static void
  33 allocate (void)
  34 {
  35   getmntent_buffer = (char *) malloc (BUFFER_SIZE);
  36 }
  37
  38
  39 struct mntent *
  40 getmntent (FILE *stream)
  41 {
  42   static struct mntent m;
  43   __libc_once_define (static, once);
  44   __libc_once (once, allocate);
  45
  46   if (getmntent_buffer == NULL)
  47     /* If no core is available we don't have a chance to run the
  48        program successfully and so returning NULL is an acceptable
  49        result.  */
  50     return NULL;
  51
  52   return __getmntent_r (stream, &m, getmntent_buffer, BUFFER_SIZE);
  53 }