src/include/lxcmntent.c

   1 /* Utilities for reading/writing fstab, mtab, etc.
   2    Copyright (C) 1995-2000, 2001, 2002, 2003, 2006
   3    Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with this library; if not, write to the Free Software
  18    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  19  */
  20
  21 #include <alloca.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <mntent.h>
  25
  26 /* Since the values in a line are separated by spaces, a name cannot
  27  contain a space. Therefore some programs encode spaces in names
  28  by the strings "\040". We undo the encoding when reading an entry.
  29  The decoding happens in place. */
  30 static char *
  31 decode_name (char *buf)
  32 {
  33     char *rp = buf;
  34     char *wp = buf;
  35
  36     do
  37     if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '4' && rp[3] == '0')
  38     {
  39         /* \040 is a SPACE. */
  40         *wp++ = ' ';
  41         rp += 3;
  42     }
  43     else if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '1' && rp[3] == '1')
  44     {
  45         /* \011 is a TAB. */
  46         *wp++ = '\t';
  47         rp += 3;
  48     }
  49     else if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '1' && rp[3] == '2')
  50     {
  51         /* \012 is a NEWLINE. */
  52         *wp++ = '\n';
  53         rp += 3;
  54     }
  55     else if (rp[0] == '\\' && rp[1] == '\\')
  56     {
  57         /* We have to escape \\ to be able to represent all characters. */
  58         *wp++ = '\\';
  59         rp += 1;
  60     }
  61     else if (rp[0] == '\\' && rp[1] == '1' && rp[2] == '3' && rp[3] == '4')
  62     {
  63         /* \134 is also \\. */
  64         *wp++ = '\\';
  65         rp += 3;
  66     }
  67     else
  68         *wp++ = *rp;
  69     while (*rp++ != '\0');
  70
  71     return buf;
  72 }
  73
  74 /* Read one mount table entry from STREAM. Returns a pointer to storage
  75  reused on the next call, or null for EOF or error (use feof/ferror to
  76  check). */
  77 struct mntent *getmntent_r (FILE *stream, struct mntent *mp, char *buffer, int bufsiz)
  78 {
  79     char *cp;
  80     char *head;
  81
  82     do
  83     {
  84         char *end_ptr;
  85
  86         if (fgets (buffer, bufsiz, stream) == NULL)
  87         {
  88             return NULL;
  89         }
  90
  91         end_ptr = strchr (buffer, '\n');
  92         if (end_ptr != NULL) /* chop newline */
  93             *end_ptr = '\0';
  94         else
  95         {
  96             /* Not the whole line was read. Do it now but forget it. */
  97             char tmp[1024];
  98             while (fgets (tmp, sizeof tmp, stream) != NULL)
  99                 if (strchr (tmp, '\n') != NULL)
 100                     break;
 101         }
 102
 103         head = buffer + strspn (buffer, " \t");
 104         /* skip empty lines and comment lines: */
 105     }
 106     while (head[0] == '\0' || head[0] == '#');
 107
 108     cp = strsep (&head, " \t");
 109     mp->mnt_fsname = cp != NULL ? decode_name (cp) : (char *) "";
 110     if (head)
 111         head += strspn (head, " \t");
 112     cp = strsep (&head, " \t");
 113     mp->mnt_dir = cp != NULL ? decode_name (cp) : (char *) "";
 114     if (head)
 115         head += strspn (head, " \t");
 116     cp = strsep (&head, " \t");
 117     mp->mnt_type = cp != NULL ? decode_name (cp) : (char *) "";
 118     if (head)
 119         head += strspn (head, " \t");
 120     cp = strsep (&head, " \t");
 121     mp->mnt_opts = cp != NULL ? decode_name (cp) : (char *) "";
 122     switch (head ? sscanf (head, " %d %d ", &mp->mnt_freq, &mp->mnt_passno) : 0)
 123     {
 124         case 0:
 125             mp->mnt_freq = 0;
 126         case 1:
 127             mp->mnt_passno = 0;
 128         case 2:
 129             break;
 130     }
 131
 132     return mp;
 133 }
 134
 135 struct mntent *getmntent (FILE *stream)
 136 {
 137     static struct mntent m;
 138     static char *getmntent_buffer;
 139
 140     #define BUFFER_SIZE 4096
 141     if (getmntent_buffer == NULL) {
 142         getmntent_buffer = (char *) malloc (BUFFER_SIZE);
 143     }
 144
 145     return getmntent_r (stream, &m, getmntent_buffer, BUFFER_SIZE);
 146     #undef BUFFER_SIZE
 147 }
 148
 149
 150 /* Prepare to begin reading and/or writing mount table entries from the
 151  beginning of FILE. MODE is as for `fopen'. */
 152 FILE *setmntent (const char *file, const char *mode)
 153 {
 154     /* Extend the mode parameter with "c" to disable cancellation in the
 155     I/O functions and "e" to set FD_CLOEXEC. */
 156     size_t modelen = strlen (mode);
 157     char *newmode;
 158
 159     newmode = alloca(modelen + 3);
 160
 161     memcpy (newmode, mode, modelen);
 162     memcpy (newmode + modelen, "ce", 3);
 163     FILE *result = fopen (file, newmode);
 164
 165     return result;
 166 }
 167
 168
 169 /* Close a stream opened with `setmntent'. */
 170 int endmntent (FILE *stream)
 171 {
 172     if (stream) /* SunOS 4.x allows for NULL stream */
 173     fclose (stream);
 174     return 1; /* SunOS 4.x says to always return 1 */
 175 }
 176
 177 /* Search MNT->mnt_opts for an option matching OPT.
 178  Returns the address of the substring, or null if none found. */
 179 char *hasmntopt (const struct mntent *mnt, const char *opt)
 180 {
 181     const size_t optlen = strlen (opt);
 182     char *rest = mnt->mnt_opts, *p;
 183
 184     while ((p = strstr (rest, opt)) != NULL)
 185     {
 186         if ((p == rest || p[-1] == ',')
 187             && (p[optlen] == '\0' || p[optlen] == '=' || p[optlen] == ','))
 188             return p;
 189
 190         rest = strchr (p, ',');
 191         if (rest == NULL)
 192             break;
 193         ++rest;
 194     }
 195
 196     return NULL;
 197 }