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 #include <sys/types.h>
  24
  25 /* Prepare to begin reading and/or writing mount table entries from the
  26    beginning of FILE.  MODE is as for `fopen'.  */
  27 FILE *
  28 setmntent (const char *file, const char *mode)
  29 {
  30   return fopen (file, mode);
  31 }
  32
  33 /* Close a stream opened with `setmntent'.  */
  34 int
  35 endmntent (FILE *stream)
  36 {
  37   if (stream)           /* SunOS 4.x allows for NULL stream */
  38     fclose (stream);
  39   return 1;             /* SunOS 4.x says to always return 1 */
  40 }
  41
  42
  43 /* Read one mount table entry from STREAM.  Returns a pointer to storage
  44    reused on the next call, or null for EOF or error (use feof/ferror to
  45    check).  */
  46 struct mntent *
  47 getmntent (FILE *stream)
  48 {
  49   static char *buf;
  50   static size_t bufsiz;
  51   static struct mntent m;
  52   ssize_t nread;
  53   char *head;
  54
  55   do
  56     {
  57       nread = getline (&buf, &bufsiz, stream);
  58       if (nread <= 0)
  59         return NULL;
  60
  61       if (buf[nread - 1] == '\n')       /* chop newline */
  62         buf[nread - 1] = '\0';
  63
  64       head = buf + strspn (buf, " \t");
  65       /* skip empty lines and comment lines:  */
  66     } while (head[0] == '\0' || head[0] == '#');
  67
  68   m.mnt_fsname = strsep (&head, " \t") ?: (char *) "";
  69   if (head)
  70     head += strspn (head, " \t");
  71   m.mnt_dir = strsep (&head, " \t") ?: (char *) "";
  72   if (head)
  73     head += strspn (head, " \t");
  74   m.mnt_type = strsep (&head, " \t") ?: (char *) "";
  75   if (head)
  76     head += strspn (head, " \t");
  77   m.mnt_opts = strsep (&head, " \t") ?: (char *) "";
  78   switch (head ? sscanf (head, " %d %d ", &m.mnt_freq, &m.mnt_passno) : 0)
  79     {
  80     case 0:
  81       m.mnt_freq = 0;
  82     case 1:
  83       m.mnt_passno = 0;
  84     case 2:
  85     }
  86
  87   return &m;
  88 }
  89
  90 /* Write the mount table entry described by MNT to STREAM.
  91    Return zero on success, nonzero on failure.  */
  92 int
  93 addmntent (FILE *stream, const struct mntent *mnt)
  94 {
  95   if (fseek (stream, 0, SEEK_END))
  96     return 1;
  97
  98   return (fprintf (stream, "%s %s %s %s %d %d\n",
  99                    mnt->mnt_fsname,
 100                    mnt->mnt_dir,
 101                    mnt->mnt_type,
 102                    mnt->mnt_opts,
 103                    mnt->mnt_freq,
 104                    mnt->mnt_passno)
 105           < 0 ? 1 : 0);
 106 }
 107
 108 /* Search MNT->mnt_opts for an option matching OPT.
 109    Returns the address of the substring, or null if none found.  */
 110 char *
 111 hasmntopt (const struct mntent *mnt, const char *opt)
 112 {
 113   const size_t optlen = strlen (opt);
 114   char *rest = mnt->mnt_opts, *p;
 115
 116   while ((p = strstr (rest, opt)) != NULL)
 117     {
 118       if (p == rest || p[-1] == ',' &&
 119           (p[optlen] == '\0' ||
 120            p[optlen] == '=' ||
 121            p[optlen] == ','))
 122         return p;
 123
 124       rest = strchr (rest, ',');
 125     }
 126
 127   return NULL;
 128 }