misc/mntent_r.c

   1 /* Utilities for reading/writing fstab, mtab, etc.
   2    Copyright (C) 1995,1996,1997,1998,1999,2000 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       break;
 148     }
 149   funlockfile (stream);
 150
 151   return mp;
 152 }
 153 weak_alias (__getmntent_r, getmntent_r)
 154
 155
 156 /* We have to use an encoding for names if they contain spaces or tabs.
 157    To be able to represent all characters we also have to escape the
 158    backslash itself.  This "function" must be a macro since we use
 159    `alloca'.  */
 160 #define encode_name(name) \
 161   do {                                                                        \
 162     const char *rp = name;                                                    \
 163                                                                               \
 164     while (*rp != '\0')                                                       \
 165       if (*rp == ' ' || *rp == '\t' || *rp == '\\')                           \
 166         break;                                                                \
 167       else                                                                    \
 168         ++rp;                                                                 \
 169                                                                               \
 170     if (*rp != '\0')                                                          \
 171       {                                                                       \
 172         /* In the worst case the length of the string can increase to         \
 173            founr times the current length.  */                                \
 174         char *wp;                                                             \
 175                                                                               \
 176         rp = name;                                                            \
 177         name = wp = (char *) alloca (strlen (name) * 4 + 1);                  \
 178                                                                               \
 179         do                                                                    \
 180           if (*rp == ' ')                                                     \
 181             {                                                                 \
 182               *wp++ = '\\';                                                   \
 183               *wp++ = '0';                                                    \
 184               *wp++ = '4';                                                    \
 185               *wp++ = '0';                                                    \
 186             }                                                                 \
 187           else if (*rp == '\t')                                               \
 188             {                                                                 \
 189               *wp++ = '\\';                                                   \
 190               *wp++ = '0';                                                    \
 191               *wp++ = '1';                                                    \
 192               *wp++ = '2';                                                    \
 193             }                                                                 \
 194           else if (*rp == '\\')                                               \
 195             {                                                                 \
 196               *wp++ = '\\';                                                   \
 197               *wp++ = '\\';                                                   \
 198             }                                                                 \
 199           else                                                                \
 200             *wp++ = *rp;                                                      \
 201         while (*rp++ != '\0');                                                \
 202       }                                                                       \
 203   } while (0)
 204
 205
 206 /* Write the mount table entry described by MNT to STREAM.
 207    Return zero on success, nonzero on failure.  */
 208 int
 209 __addmntent (FILE *stream, const struct mntent *mnt)
 210 {
 211   struct mntent mntcopy = *mnt;
 212   if (fseek (stream, 0, SEEK_END))
 213     return 1;
 214
 215   /* Encode spaces and tabs in the names.  */
 216   encode_name (mntcopy.mnt_fsname);
 217   encode_name (mntcopy.mnt_dir);
 218   encode_name (mntcopy.mnt_type);
 219   encode_name (mntcopy.mnt_opts);
 220
 221   return (fprintf (stream, "%s %s %s %s %d %d\n",
 222                    mntcopy.mnt_fsname,
 223                    mntcopy.mnt_dir,
 224                    mntcopy.mnt_type,
 225                    mntcopy.mnt_opts,
 226                    mntcopy.mnt_freq,
 227                    mntcopy.mnt_passno)
 228           < 0 ? 1 : 0);
 229 }
 230 weak_alias (__addmntent, addmntent)
 231
 232
 233 /* Search MNT->mnt_opts for an option matching OPT.
 234    Returns the address of the substring, or null if none found.  */
 235 char *
 236 __hasmntopt (const struct mntent *mnt, const char *opt)
 237 {
 238   const size_t optlen = strlen (opt);
 239   char *rest = mnt->mnt_opts, *p;
 240
 241   while ((p = strstr (rest, opt)) != NULL)
 242     {
 243       if (p == rest
 244           || (p[-1] == ','
 245               && (p[optlen] == '\0' ||
 246                   p[optlen] == '='  ||
 247                   p[optlen] == ',')))
 248         return p;
 249
 250       rest = strchr (rest, ',');
 251       if (rest == NULL)
 252         break;
 253       ++rest;
 254     }
 255
 256   return NULL;
 257 }
 258 weak_alias (__hasmntopt, hasmntopt)