misc/mntent_r.c

   1 /* Utilities for reading/writing fstab, mtab, etc.
   2    Copyright (C) 1995-2000, 2001, 2002, 2003 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 Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <alloca.h>
  21 #include <mntent.h>
  22 #include <stdio.h>
  23 #include <stdio_ext.h>
  24 #include <string.h>
  25 #include <sys/types.h>
  26
  27 #ifdef USE_IN_LIBIO
  28 # define flockfile(s) _IO_flockfile (s)
  29 # define funlockfile(s) _IO_funlockfile (s)
  30 #endif
  31
  32 #undef __setmntent
  33 #undef __endmntent
  34 #undef __getmntent_r
  35
  36 /* Prepare to begin reading and/or writing mount table entries from the
  37    beginning of FILE.  MODE is as for `fopen'.  */
  38 FILE *
  39 __setmntent (const char *file, const char *mode)
  40 {
  41   /* Extend the mode parameter with "c" to disable cancellation in the
  42      I/O functions.  */
  43   size_t modelen = strlen (mode);
  44   char newmode[modelen + 2];
  45   memcpy (mempcpy (newmode, mode, modelen), "c", 2);
  46   FILE *result = fopen (file, newmode);
  47
  48   if (result != NULL)
  49     /* We do the locking ourselves.  */
  50     __fsetlocking (result, FSETLOCKING_BYCALLER);
  51
  52   return result;
  53 }
  54 INTDEF(__setmntent)
  55 weak_alias (__setmntent, setmntent)
  56
  57
  58 /* Close a stream opened with `setmntent'.  */
  59 int
  60 __endmntent (FILE *stream)
  61 {
  62   if (stream)           /* SunOS 4.x allows for NULL stream */
  63     fclose (stream);
  64   return 1;             /* SunOS 4.x says to always return 1 */
  65 }
  66 INTDEF(__endmntent)
  67 weak_alias (__endmntent, endmntent)
  68
  69
  70 /* Since the values in a line are separated by spaces, a name cannot
  71    contain a space.  Therefore some programs encode spaces in names
  72    by the strings "\040".  We undo the encoding when reading an entry.
  73    The decoding happens in place.  */
  74 static char *
  75 decode_name (char *buf)
  76 {
  77   char *rp = buf;
  78   char *wp = buf;
  79
  80   do
  81     if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '4' && rp[3] == '0')
  82       {
  83         /* \040 is a SPACE.  */
  84         *wp++ = ' ';
  85         rp += 3;
  86       }
  87     else if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '1' && rp[3] == '1')
  88       {
  89         /* \011 is a TAB.  */
  90         *wp++ = '\t';
  91         rp += 3;
  92       }
  93     else if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '1' && rp[3] == '2')
  94       {
  95         /* \012 is a NEWLINE.  */
  96         *wp++ = '\n';
  97         rp += 3;
  98       }
  99     else if (rp[0] == '\\' && rp[1] == '\\')
 100       {
 101         /* We have to escape \\ to be able to represent all characters.  */
 102         *wp++ = '\\';
 103         rp += 1;
 104       }
 105     else if (rp[0] == '\\' && rp[1] == '1' && rp[2] == '3' && rp[3] == '4')
 106       {
 107         /* \134 is also \\.  */
 108         *wp++ = '\\';
 109         rp += 3;
 110       }
 111     else
 112       *wp++ = *rp;
 113   while (*rp++ != '\0');
 114
 115   return buf;
 116 }
 117
 118
 119 /* Read one mount table entry from STREAM.  Returns a pointer to storage
 120    reused on the next call, or null for EOF or error (use feof/ferror to
 121    check).  */
 122 struct mntent *
 123 __getmntent_r (FILE *stream, struct mntent *mp, char *buffer, int bufsiz)
 124 {
 125   char *cp;
 126   char *head;
 127
 128   flockfile (stream);
 129   do
 130     {
 131       char *end_ptr;
 132
 133       if (fgets_unlocked (buffer, bufsiz, stream) == NULL)
 134         {
 135           funlockfile (stream);
 136           return NULL;
 137         }
 138
 139       end_ptr = strchr (buffer, '\n');
 140       if (end_ptr != NULL)      /* chop newline */
 141         *end_ptr = '\0';
 142       else
 143         {
 144           /* Not the whole line was read.  Do it now but forget it.  */
 145           char tmp[1024];
 146           while (fgets_unlocked (tmp, sizeof tmp, stream) != NULL)
 147             if (strchr (tmp, '\n') != NULL)
 148               break;
 149         }
 150
 151       head = buffer + strspn (buffer, " \t");
 152       /* skip empty lines and comment lines:  */
 153     }
 154   while (head[0] == '\0' || head[0] == '#');
 155
 156   cp = __strsep (&head, " \t");
 157   mp->mnt_fsname = cp != NULL ? decode_name (cp) : (char *) "";
 158   if (head)
 159     head += strspn (head, " \t");
 160   cp = __strsep (&head, " \t");
 161   mp->mnt_dir = cp != NULL ? decode_name (cp) : (char *) "";
 162   if (head)
 163     head += strspn (head, " \t");
 164   cp = __strsep (&head, " \t");
 165   mp->mnt_type = cp != NULL ? decode_name (cp) : (char *) "";
 166   if (head)
 167     head += strspn (head, " \t");
 168   cp = __strsep (&head, " \t");
 169   mp->mnt_opts = cp != NULL ? decode_name (cp) : (char *) "";
 170   switch (head ? sscanf (head, " %d %d ", &mp->mnt_freq, &mp->mnt_passno) : 0)
 171     {
 172     case 0:
 173       mp->mnt_freq = 0;
 174     case 1:
 175       mp->mnt_passno = 0;
 176     case 2:
 177       break;
 178     }
 179   funlockfile (stream);
 180
 181   return mp;
 182 }
 183 INTDEF(__getmntent_r)
 184 weak_alias (__getmntent_r, getmntent_r)
 185
 186
 187 /* We have to use an encoding for names if they contain spaces or tabs.
 188    To be able to represent all characters we also have to escape the
 189    backslash itself.  This "function" must be a macro since we use
 190    `alloca'.  */
 191 #define encode_name(name) \
 192   do {                                                                        \
 193     const char *rp = name;                                                    \
 194                                                                               \
 195     while (*rp != '\0')                                                       \
 196       if (*rp == ' ' || *rp == '\t' || *rp == '\\')                           \
 197         break;                                                                \
 198       else                                                                    \
 199         ++rp;                                                                 \
 200                                                                               \
 201     if (*rp != '\0')                                                          \
 202       {                                                                       \
 203         /* In the worst case the length of the string can increase to         \
 204            founr times the current length.  */                                \
 205         char *wp;                                                             \
 206                                                                               \
 207         rp = name;                                                            \
 208         name = wp = (char *) alloca (strlen (name) * 4 + 1);                  \
 209                                                                               \
 210         do                                                                    \
 211           if (*rp == ' ')                                                     \
 212             {                                                                 \
 213               *wp++ = '\\';                                                   \
 214               *wp++ = '0';                                                    \
 215               *wp++ = '4';                                                    \
 216               *wp++ = '0';                                                    \
 217             }                                                                 \
 218           else if (*rp == '\t')                                               \
 219             {                                                                 \
 220               *wp++ = '\\';                                                   \
 221               *wp++ = '0';                                                    \
 222               *wp++ = '1';                                                    \
 223               *wp++ = '1';                                                    \
 224             }                                                                 \
 225           else if (*rp == '\n')                                               \
 226             {                                                                 \
 227               *wp++ = '\\';                                                   \
 228               *wp++ = '0';                                                    \
 229               *wp++ = '1';                                                    \
 230               *wp++ = '2';                                                    \
 231             }                                                                 \
 232           else if (*rp == '\\')                                               \
 233             {                                                                 \
 234               *wp++ = '\\';                                                   \
 235               *wp++ = '\\';                                                   \
 236             }                                                                 \
 237           else                                                                \
 238             *wp++ = *rp;                                                      \
 239         while (*rp++ != '\0');                                                \
 240       }                                                                       \
 241   } while (0)
 242
 243
 244 /* Write the mount table entry described by MNT to STREAM.
 245    Return zero on success, nonzero on failure.  */
 246 int
 247 __addmntent (FILE *stream, const struct mntent *mnt)
 248 {
 249   struct mntent mntcopy = *mnt;
 250   if (fseek (stream, 0, SEEK_END))
 251     return 1;
 252
 253   /* Encode spaces and tabs in the names.  */
 254   encode_name (mntcopy.mnt_fsname);
 255   encode_name (mntcopy.mnt_dir);
 256   encode_name (mntcopy.mnt_type);
 257   encode_name (mntcopy.mnt_opts);
 258
 259   return (fprintf (stream, "%s %s %s %s %d %d\n",
 260                    mntcopy.mnt_fsname,
 261                    mntcopy.mnt_dir,
 262                    mntcopy.mnt_type,
 263                    mntcopy.mnt_opts,
 264                    mntcopy.mnt_freq,
 265                    mntcopy.mnt_passno)
 266           < 0 ? 1 : 0);
 267 }
 268 weak_alias (__addmntent, addmntent)
 269
 270
 271 /* Search MNT->mnt_opts for an option matching OPT.
 272    Returns the address of the substring, or null if none found.  */
 273 char *
 274 __hasmntopt (const struct mntent *mnt, const char *opt)
 275 {
 276   const size_t optlen = strlen (opt);
 277   char *rest = mnt->mnt_opts, *p;
 278
 279   while ((p = strstr (rest, opt)) != NULL)
 280     {
 281       if (p == rest
 282           || (p[-1] == ','
 283               && (p[optlen] == '\0' ||
 284                   p[optlen] == '='  ||
 285                   p[optlen] == ',')))
 286         return p;
 287
 288       rest = strchr (rest, ',');
 289       if (rest == NULL)
 290         break;
 291       ++rest;
 292     }
 293
 294   return NULL;
 295 }
 296 weak_alias (__hasmntopt, hasmntopt)