misc/mntent.c

   1 /* Utilities for reading/writing fstab, mtab, etc.
   2    Copyright (C) 1995, 1996, 1997 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <mntent.h>
  21 #include <stdlib.h>
  22 #include <bits/libc-lock.h>
  23
  24 /* We don't want to allocate the static buffer all the time since it
  25    is not always used (in fact, rather infrequently).  Accept the
  26    extra cost of a `malloc'.  */
  27 static char *getmntent_buffer;
  28
  29 /* This is the size of the buffer.  This is really big.  */
  30 #define BUFFER_SIZE     4096
  31
  32
  33 static void
  34 allocate (void)
  35 {
  36   getmntent_buffer = (char *) malloc (BUFFER_SIZE);
  37 }
  38
  39
  40 struct mntent *
  41 getmntent (FILE *stream)
  42 {
  43   static struct mntent m;
  44   __libc_once_define (static, once);
  45   __libc_once (once, allocate);
  46
  47   if (getmntent_buffer == NULL)
  48     /* If no core is available we don't have a chance to run the
  49        program successfully and so returning NULL is an acceptable
  50        result.  */
  51     return NULL;
  52
  53   return __getmntent_r (stream, &m, getmntent_buffer, BUFFER_SIZE);
  54 }
  55
  56
  57 /* Make sure the memory is freed if the programs ends while in
  58    memory-debugging mode and something actually was allocated.  */
  59 static void
  60 __attribute__ ((unused))
  61 free_mem (void)
  62 {
  63   if (getmntent_buffer != NULL)
  64     free (getmntent_buffer);
  65 }
  66
  67 text_set_element (__libc_subfreeres, free_mem);