misc/mntent_r.c

   1 /* Utilities for reading/writing fstab, mtab, etc.
   2    Copyright (C) 1995, 1996, 1997, 1998, 1999 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 <alloca.h>
  21 #include <mntent.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <sys/types.h>
  25
  26 #ifdef USE_IN_LIBIO
  27 # define flockfile(s) _IO_flockfile (s)
  28 # define funlockfile(s) _IO_funlockfile (s)
  29 #endif
  30
  31 /* Prepare to begin reading and/or writing mount table entries from the
  32    beginning of FILE.  MODE is as for `fopen'.  */
  33 FILE *
  34 __setmntent (const char *file, const char *mode)
  35 {
  36   return fopen (file, mode);
  37 }
  38 weak_alias (__setmntent, setmntent)
  39
  40
  41 /* Close a stream opened with `setmntent'.  */
  42 int
  43 __endmntent (FILE *stream)
  44 {
  45   if (stream)           /* SunOS 4.x allows for NULL stream */
  46     fclose (stream);
  47   return 1;             /* SunOS 4.x says to always return 1 */
  48 }
  49 weak_alias (__endmntent, endmntent)
  50
  51
  52 /* Since the values in a line are separated by spaces, a name cannot
  53    contain a space.  Therefore some programs encode spaces in names
  54    by the strings "\040".  We undo the encoding when reading an entry.
  55    The decoding happens in place.  */
  56 static char *
  57 decode_name (char *buf)
  58 {
  59   char *rp = buf;
  60   char *wp = buf;
  61
  62   do
  63     if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '4' && rp[3] == '0')
  64       {
  65         /* \040 is a SPACE.  */
  66         *wp++ = ' ';
  67         rp += 3;
  68       }
  69     else if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '1' && rp[3] == '2')
  70       {
  71         /* \012 is a TAB.  */
  72         *wp++ = '\t';
  73         rp += 3;
  74       }
  75     else if (rp[0] == '\\' && rp[1] == '\\')
  76       {
  77         /* We have to escape \\ to be able to represent all characters.  */
  78         *wp++ = '\\';
  79         rp += 1;
  80       }
  81     else
  82       *wp++ = *rp;
  83   while (*rp++ != '\0');
  84
  85   return buf;
  86 }
  87
  88
  89 /* Read one mount table entry from STREAM.  Returns a pointer to storage
  90    reused on the next call, or null for EOF or error (use feof/ferror to
  91    check).  */
  92 struct mntent *
  93 __getmntent_r (FILE *stream, struct mntent *mp, char *buffer, int bufsiz)
  94 {
  95   char *cp;
  96   char *head;
  97
  98   flockfile (stream);
  99   do
 100     {
 101       char *end_ptr;
 102
 103       if (fgets_unlocked (buffer, bufsiz, stream) == NULL)
 104         {
 105           funlockfile (stream);
 106           return NULL;
 107         }
 108
 109       end_ptr = strchr (buffer, '\n');
 110       if (end_ptr != NULL)      /* chop newline */
 111         *end_ptr = '\0';
 112       else
 113         {
 114           /* Not the whole line was read.  Do it now but forget it.  */
 115           char tmp[1024];
 116           while (fgets_unlocked (tmp, sizeof tmp, stream) != NULL)
 117             if (strchr (tmp, '\n') != NULL)
 118               break;
 119         }
 120
 121       head = buffer + strspn (buffer, " \t");
 122       /* skip empty lines and comment lines:  */
 123     }
 124   while (head[0] == '\0' || head[0] == '#');
 125
 126   cp = __strsep (&head, " \t");
 127   mp->mnt_fsname = cp != NULL ? decode_name (cp) : (char *) "";
 128   if (head)
 129     head += strspn (head, " \t");
 130   cp = __strsep (&head, " \t");
 131   mp->mnt_dir = cp != NULL ? decode_name (cp) : (char *) "";
 132   if (head)
 133     head += strspn (head, " \t");
 134   cp = __strsep (&head, " \t");
 135   mp->mnt_type = cp != NULL ? decode_name (cp) : (char *) "";
 136   if (head)
 137     head += strspn (head, " \t");
 138   cp = __strsep (&head, " \t");
 139   mp->mnt_opts = cp != NULL ? decode_name (cp) : (char *) "";
 140   switch (head ? sscanf (head, " %d %d ", &mp->mnt_freq, &mp->mnt_passno) : 0)
 141     {
 142     case 0:
 143       mp->mnt_freq = 0;
 144     case 1:
 145       mp->mnt_passno = 0;
 146     case 2:
 147     }
 148   funlockfile (stream);
 149
 150   return mp;
 151 }
 152 weak_alias (__getmntent_r, getmntent_r)
 153
 154
 155 /* We have to use an encoding for names if they contain spaces or tabs.
 156    To be able to represent all characters we also have to escape the
 157    backslash itself.  This "function" must be a macro since we use
 158    `alloca'.  */
 159 #define encode_name(name) \
 160   do {                                                                        \
 161     const char *rp = name;                                                    \
 162                                                                               \
 163     while (*rp != '\0')                                                       \
 164       if (*rp == ' ' || *rp == '\t' || *rp == '\\')                           \
 165         break;                                                                \
 166       else                                                                    \
 167         ++rp;                                                                 \
 168                                                                               \
 169     if (*rp != '\0')                                                          \
 170       {                                                                       \
 171         /* In the worst case the length of the string can increase to         \
 172            founr times the current length.  */                                \
 173         char *wp;                                                             \
 174                                                                               \
 175         rp = name;                                                            \
 176         name = wp = (char *) alloca (strlen (name) * 4 + 1);                  \
 177                                                                               \
 178         do                                                                    \
 179           if (*rp == ' ')                                                     \
 180             {                                                                 \
 181               *wp++ = '\\';                                                   \
 182               *wp++ = '0';                                                    \
 183               *wp++ = '4';                                                    \
 184               *wp++ = '0';                                                    \
 185             }                                                                 \
 186           else if (*rp == '\t')                                               \
 187             {                                                                 \
 188               *wp++ = '\\';                                                   \
 189               *wp++ = '0';                                                    \
 190               *wp++ = '1';                                                    \
 191               *wp++ = '2';                                                    \
 192             }                                                                 \
 193           else if (*rp == '\\')                                               \
 194             {                                                                 \
 195               *wp++ = '\\';                                                   \
 196               *wp++ = '\\';                                                   \
 197             }                                                                 \
 198           else                                                                \
 199             *wp++ = *rp;                                                      \
 200         while (*rp++ != '\0');                                                \
 201       }                                                                       \
 202   } while (0)
 203
 204
 205 /* Write the mount table entry described by MNT to STREAM.
 206    Return zero on success, nonzero on failure.  */
 207 int
 208 __addmntent (FILE *stream, const struct mntent *mnt)
 209 {
 210   struct mntent mntcopy = *mnt;
 211   if (fseek (stream, 0, SEEK_END))
 212     return 1;
 213
 214   /* Encode spaces and tabs in the names.  */
 215   encode_name (mntcopy.mnt_fsname);
 216   encode_name (mntcopy.mnt_dir);
 217   encode_name (mntcopy.mnt_type);
 218   encode_name (mntcopy.mnt_opts);
 219
 220   return (fprintf (stream, "%s %s %s %s %d %d\n",
 221                    mntcopy.mnt_fsname,
 222                    mntcopy.mnt_dir,
 223                    mntcopy.mnt_type,
 224                    mntcopy.mnt_opts,
 225                    mntcopy.mnt_freq,
 226                    mntcopy.mnt_passno)
 227           < 0 ? 1 : 0);
 228 }
 229 weak_alias (__addmntent, addmntent)
 230
 231
 232 /* Search MNT->mnt_opts for an option matching OPT.
 233    Returns the address of the substring, or null if none found.  */
 234 char *
 235 __hasmntopt (const struct mntent *mnt, const char *opt)
 236 {
 237   const size_t optlen = strlen (opt);
 238   char *rest = mnt->mnt_opts, *p;
 239
 240   while ((p = strstr (rest, opt)) != NULL)
 241     {
 242       if (p == rest
 243           || (p[-1] == ','
 244               && (p[optlen] == '\0' ||
 245                   p[optlen] == '='  ||
 246                   p[optlen] == ',')))
 247         return p;
 248
 249       rest = strchr (rest, ',');
 250       if (rest == NULL)
 251         break;
 252       ++rest;
 253     }
 254
 255   return NULL;
 256 }
 257 weak_alias (__hasmntopt, hasmntopt)