libmount/src/optmap.c

   1 /*
   2  * Copyright (C) 2010 Karel Zak <kzak@redhat.com>
   3  *
   4  * This file may be redistributed under the terms of the
   5  * GNU Lesser General Public License.
   6  */
   7
   8 /**
   9  * SECTION: optmap
  10  * @title: Option maps
  11  * @short_description: description for mount options
  12  *
  13  * The mount(2) linux syscall uses two arguments for mount options:
  14  *
  15  *      @mountflags: (see MS_* macros in linux/fs.h)
  16  *
  17  *      @mountdata: (usully a comma separated string of options)
  18  *
  19  * The libmount uses options-map(s) to describe mount options.
  20  *
  21  * The option description (map entry) includes:
  22  *
  23  *      @name: and argument name
  24  *
  25  *      @id: (in the map unique identifier or a mountflags, e.g MS_RDONLY)
  26  *
  27  *      @mask: (MNT_INVERT, MNT_NOMTAB)
  28  *
  29  * The option argument value is defined by:
  30  *
  31  *      "="   -- required argument, e.g "comment="
  32  *
  33  *      "[=]" -- optional argument, e.g. "loop[=]"
  34  *
  35  * Example:
  36  *
  37  * <informalexample>
  38  *   <programlisting>
  39  *     #define MY_MS_FOO   (1 << 1)
  40  *     #define MY_MS_BAR   (1 << 2)
  41  *
  42  *     libmnt_optmap myoptions[] = {
  43  *       { "foo",   MY_MS_FOO },
  44  *       { "nofoo", MY_MS_FOO | MNT_INVERT },
  45  *       { "bar=",  MY_MS_BAR },
  46  *       { NULL }
  47  *     };
  48  *   </programlisting>
  49  * </informalexample>
  50  *
  51  * The libmount defines two basic built-in options maps:
  52  *
  53  *      @MNT_LINUX_MAP: fs-independent kernel mount options (usually MS_* flags)
  54  *
  55  *      @MNT_USERSPACE_MAP: userspace specific mount options (e.g. "user", "loop")
  56  *
  57  * For more details about option map struct see "struct mnt_optmap" in
  58  * mount/mount.h.
  59  */
  60 #include "mountP.h"
  61 #include "strutils.h"
  62
  63 /*
  64  * fs-independent mount flags (built-in MNT_LINUX_MAP)
  65  */
  66 static const struct libmnt_optmap linux_flags_map[] =
  67 {
  68    { "ro",       MS_RDONLY },                 /* read-only */
  69    { "rw",       MS_RDONLY, MNT_INVERT },     /* read-write */
  70    { "exec",     MS_NOEXEC, MNT_INVERT },     /* permit execution of binaries */
  71    { "noexec",   MS_NOEXEC },                 /* don't execute binaries */
  72    { "suid",     MS_NOSUID, MNT_INVERT },     /* honor suid executables */
  73    { "nosuid",   MS_NOSUID },                 /* don't honor suid executables */
  74    { "dev",      MS_NODEV, MNT_INVERT },      /* interpret device files  */
  75    { "nodev",    MS_NODEV },                  /* don't interpret devices */
  76
  77    { "sync",     MS_SYNCHRONOUS },            /* synchronous I/O */
  78    { "async",    MS_SYNCHRONOUS, MNT_INVERT },/* asynchronous I/O */
  79
  80    { "dirsync",  MS_DIRSYNC },                /* synchronous directory modifications */
  81    { "remount",  MS_REMOUNT, MNT_NOMTAB },    /* alter flags of mounted FS */
  82    { "bind",     MS_BIND },                   /* Remount part of the tree elsewhere */
  83    { "rbind",    MS_BIND | MS_REC },          /* Idem, plus mounted subtrees */
  84 #ifdef MS_NOSUB
  85    { "sub",      MS_NOSUB, MNT_INVERT },      /* allow submounts */
  86    { "nosub",    MS_NOSUB },                  /* don't allow submounts */
  87 #endif
  88 #ifdef MS_SILENT
  89    { "silent",   MS_SILENT },                 /* be quiet  */
  90    { "loud",     MS_SILENT, MNT_INVERT },     /* print out messages. */
  91 #endif
  92 #ifdef MS_MANDLOCK
  93    { "mand",     MS_MANDLOCK },               /* Allow mandatory locks on this FS */
  94    { "nomand",   MS_MANDLOCK, MNT_INVERT },   /* Forbid mandatory locks on this FS */
  95 #endif
  96 #ifdef MS_NOATIME
  97    { "atime",    MS_NOATIME, MNT_INVERT },    /* Update access time */
  98    { "noatime",  MS_NOATIME },                /* Do not update access time */
  99 #endif
 100 #ifdef MS_I_VERSION
 101    { "iversion", MS_I_VERSION },              /* Update inode I_version time */
 102    { "noiversion", MS_I_VERSION,  MNT_INVERT},/* Don't update inode I_version time */
 103 #endif
 104 #ifdef MS_NODIRATIME
 105    { "diratime", MS_NODIRATIME, MNT_INVERT }, /* Update dir access times */
 106    { "nodiratime", MS_NODIRATIME },           /* Do not update dir access times */
 107 #endif
 108 #ifdef MS_RELATIME
 109    { "relatime", MS_RELATIME },               /* Update access times relative to mtime/ctime */
 110    { "norelatime", MS_RELATIME, MNT_INVERT }, /* Update access time without regard to mtime/ctime */
 111 #endif
 112 #ifdef MS_STRICTATIME
 113    { "strictatime", MS_STRICTATIME },         /* Strict atime semantics */
 114    { "nostrictatime", MS_STRICTATIME, MNT_INVERT }, /* kernel default atime */
 115 #endif
 116 #ifdef MS_LAZYTIME
 117    { "lazytime", MS_LAZYTIME },               /* Update {a,m,c}time on the in-memory inode only */
 118    { "nolazytime", MS_LAZYTIME, MNT_INVERT },
 119 #endif
 120 #ifdef MS_PROPAGATION
 121    { "unbindable",  MS_UNBINDABLE,          MNT_NOHLPS | MNT_NOMTAB }, /* Unbindable */
 122    { "runbindable", MS_UNBINDABLE | MS_REC, MNT_NOHLPS | MNT_NOMTAB },
 123    { "private",     MS_PRIVATE,             MNT_NOHLPS | MNT_NOMTAB }, /* Private */
 124    { "rprivate",    MS_PRIVATE | MS_REC,    MNT_NOHLPS | MNT_NOMTAB },
 125    { "slave",       MS_SLAVE,               MNT_NOHLPS | MNT_NOMTAB }, /* Slave */
 126    { "rslave",      MS_SLAVE | MS_REC,      MNT_NOHLPS | MNT_NOMTAB },
 127    { "shared",      MS_SHARED,              MNT_NOHLPS | MNT_NOMTAB }, /* Shared */
 128    { "rshared",     MS_SHARED | MS_REC,     MNT_NOHLPS | MNT_NOMTAB },
 129 #endif
 130    { NULL, 0, 0 }
 131 };
 132
 133 /*
 134  * userspace mount option (built-in MNT_USERSPACE_MAP)
 135  */
 136 static const struct libmnt_optmap userspace_opts_map[] =
 137 {
 138    { "defaults", 0, 0 },               /* default options */
 139
 140    { "auto",    MNT_MS_NOAUTO, MNT_NOHLPS | MNT_INVERT | MNT_NOMTAB },  /* Can be mounted using -a */
 141    { "noauto",  MNT_MS_NOAUTO, MNT_NOHLPS | MNT_NOMTAB },  /* Can only be mounted explicitly */
 142
 143    { "user[=]", MNT_MS_USER },                             /* Allow ordinary user to mount (mtab) */
 144    { "nouser",  MNT_MS_USER, MNT_INVERT | MNT_NOMTAB },    /* Forbid ordinary user to mount */
 145
 146    { "users",   MNT_MS_USERS, MNT_NOMTAB },                /* Allow ordinary users to mount */
 147    { "nousers", MNT_MS_USERS, MNT_INVERT | MNT_NOMTAB },   /* Forbid ordinary users to mount */
 148
 149    { "owner",   MNT_MS_OWNER, MNT_NOMTAB },                /* Let the owner of the device mount */
 150    { "noowner", MNT_MS_OWNER, MNT_INVERT | MNT_NOMTAB },   /* Device owner has no special privs */
 151
 152    { "group",   MNT_MS_GROUP, MNT_NOMTAB },                /* Let the group of the device mount */
 153    { "nogroup", MNT_MS_GROUP, MNT_INVERT | MNT_NOMTAB },   /* Device group has no special privs */
 154
 155    /*
 156     * Note that traditional init scripts assume the _netdev option in /etc/mtab to
 157     * umount network block devices on shutdown.
 158     */
 159    { "_netdev", MNT_MS_NETDEV },                           /* Device requires network */
 160
 161    { "comment=", MNT_MS_COMMENT, MNT_NOHLPS | MNT_NOMTAB },/* fstab comment only */
 162    { "x-",      MNT_MS_XCOMMENT, MNT_NOHLPS | MNT_NOMTAB | MNT_PREFIX }, /* x- options */
 163
 164    { "loop[=]", MNT_MS_LOOP, MNT_NOHLPS },                             /* use the loop device */
 165    { "offset=", MNT_MS_OFFSET, MNT_NOHLPS | MNT_NOMTAB },                  /* loop device offset */
 166    { "sizelimit=", MNT_MS_SIZELIMIT, MNT_NOHLPS | MNT_NOMTAB },    /* loop device size limit */
 167    { "encryption=", MNT_MS_ENCRYPTION, MNT_NOHLPS | MNT_NOMTAB },          /* loop device encryption */
 168
 169    { "nofail",  MNT_MS_NOFAIL, MNT_NOMTAB },               /* Do not fail if ENOENT on dev */
 170
 171    { "uhelper=", MNT_MS_UHELPER },                         /* /sbin/umount.<helper> */
 172
 173    { "helper=", MNT_MS_HELPER },                           /* /sbin/mount.<helper> */
 174
 175    { NULL, 0, 0 }
 176 };
 177
 178 /**
 179  * mnt_get_builtin_map:
 180  * @id: map id -- MNT_LINUX_MAP or MNT_USERSPACE_MAP
 181  *
 182  * MNT_LINUX_MAP - Linux kernel fs-independent mount options
 183  *                 (usually MS_* flags, see linux/fs.h)
 184  *
 185  * MNT_USERSPACE_MAP - userpace mount(8) specific mount options
 186  *                     (e.g user=, _netdev, ...)
 187  *
 188  * Returns: static built-in libmount map.
 189  */
 190 const struct libmnt_optmap *mnt_get_builtin_optmap(int id)
 191 {
 192         assert(id);
 193
 194         if (id == MNT_LINUX_MAP)
 195                 return linux_flags_map;
 196         else if (id == MNT_USERSPACE_MAP)
 197                 return userspace_opts_map;
 198         return NULL;
 199 }
 200
 201 /*
 202  * Looks up the @name in @maps and returns a map and in @mapent
 203  * returns the map entry
 204  */
 205 const struct libmnt_optmap *mnt_optmap_get_entry(
 206                                 struct libmnt_optmap const **maps,
 207                                 int nmaps,
 208                                 const char *name,
 209                                 size_t namelen,
 210                                 const struct libmnt_optmap **mapent)
 211 {
 212         int i;
 213
 214         assert(maps);
 215         assert(nmaps);
 216         assert(name);
 217         assert(namelen);
 218
 219         if (mapent)
 220                 *mapent = NULL;
 221
 222         for (i = 0; i < nmaps; i++) {
 223                 const struct libmnt_optmap *map = maps[i];
 224                 const struct libmnt_optmap *ent;
 225                 const char *p;
 226
 227                 for (ent = map; ent && ent->name; ent++) {
 228                         if (ent->mask & MNT_PREFIX) {
 229                                 if (startswith(name, ent->name)) {
 230                                         if (mapent)
 231                                                 *mapent = ent;
 232                                         return map;
 233                                 }
 234                                 continue;
 235                         }
 236                         if (strncmp(ent->name, name, namelen))
 237                                 continue;
 238                         p = ent->name + namelen;
 239                         if (*p == '\0' || *p == '=' || *p == '[') {
 240                                 if (mapent)
 241                                         *mapent = ent;
 242                                 return map;
 243                         }
 244                 }
 245         }
 246         return NULL;
 247 }
 248