misc/mntent.c

   1 /* Utilities for reading/writing fstab, mtab, etc.
   2 Copyright (C) 1995 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
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <mntent.h>
  21 #include <stdio.h>
  22 #include <string.h>
  23
  24 /* Prepare to begin reading and/or writing mount table entries from the
  25    beginning of FILE.  MODE is as for `fopen'.  */
  26 FILE *
  27 setmntent (const char *file, const char *mode)
  28 {
  29   return fopen (file, mode);
  30 }
  31
  32 /* Close a stream opened with `setmntent'.  */
  33 int
  34 endmntent (FILE *stream)
  35 {
  36   return fclose (stream);
  37 }
  38
  39
  40 /* Read one mount table entry from STREAM.  Returns a pointer to storage
  41    reused on the next call, or null for EOF or error (use feof/ferror to
  42    check).  */
  43 struct mntent *
  44 getmntent (FILE *stream)
  45 {
  46   static char *buf;
  47   static size_t bufsiz;
  48   static struct mntent m;
  49   char *head;
  50
  51   do
  52     {
  53       if (getline (&buf, &bufsiz, stream) < 0)
  54         return NULL;
  55
  56       head = buf;
  57     } while (head[0] == '#');   /* Skip comment lines.  */
  58
  59   m.mnt_fsname = strsep (&head, " \t") ?: (char *) "";
  60   m.mnt_dir = strsep (&head, " \t") ?: (char *) "";
  61   m.mnt_type = strsep (&head, " \t") ?: (char *) "";
  62   m.mnt_opts = strsep (&head, " \t") ?: (char *) "";
  63   switch (sscanf (head, "%d %d\n", &m.mnt_freq, &m.mnt_passno))
  64     {
  65     case 0:
  66       m.mnt_freq = 0;
  67     case 1:
  68       m.mnt_passno = 0;
  69     case 2:
  70     }
  71
  72   return &m;
  73 }
  74
  75 /* Write the mount table entry described by MNT to STREAM.
  76    Return zero on success, nonzero on failure.  */
  77 int
  78 addmntent (FILE *stream, const struct mntent *mnt)
  79 {
  80   return (fprintf (stream, "%s %s %s %s %d %d\n",
  81                    mnt->mnt_fsname,
  82                    mnt->mnt_dir,
  83                    mnt->mnt_type,
  84                    mnt->mnt_opts,
  85                    mnt->mnt_freq,
  86                    mnt->mnt_passno)
  87           < 0 ? -1 : 0);
  88 }
  89
  90 /* Search MNT->mnt_opts for an option matching OPT.
  91    Returns the address of the substring, or null if none found.  */
  92 char *
  93 hasmntopt (const struct mntent *mnt, const char *opt)
  94 {
  95   const size_t optlen = strlen (opt);
  96   char *rest = mnt->mnt_opts, *p;
  97
  98   while ((p = strstr (rest, opt)) != NULL)
  99     {
 100       if (p == rest || p[-1] == ',' &&
 101           (p[optlen] == '\0' ||
 102            p[optlen] == '=' ||
 103            p[optlen] == ','))
 104         return p;
 105
 106       rest = strchr (rest, ',');
 107     }
 108
 109   return NULL;
 110 }
 111