package/aufs2-util/src/mount.aufs.c

   1 /*
   2  * Copyright (C) 2005-2009 Junjiro Okajima
   3  *
   4  * This program, aufs is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18
  19 /*
  20  * The main purpose of this script is updating /etc/mtab and calling auplilnk.
  21  * This behaviour is highly depending on mount(8) in util-linux package.
  22  */
  23
  24 #define _XOPEN_SOURCE   500     /* getsubopt */
  25 #define _BSD_SOURCE             /* dirfd */
  26
  27 #include <sys/types.h>
  28 #include <dirent.h>
  29 #include <mntent.h>
  30 #include <regex.h>
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <string.h>
  34 #include <unistd.h>
  35 #include <wait.h>
  36
  37 #include <linux/aufs_type.h>
  38 #include "au_util.h"
  39
  40 enum { Remount, Bind, Fake, Update, Verbose, AuFlush, LastOpt };
  41 static void test_opts(char opts[], unsigned char flags[])
  42 {
  43         int c;
  44         char *p, *o, *val, *pat[] = {
  45                 [Remount]       = "remount",
  46                 [Bind]          = "bind",
  47                 NULL
  48         };
  49
  50         o = strdup(opts);
  51         if (!o)
  52                 AuFin("stdup");
  53
  54         p = o;
  55         while (*p) {
  56                 c = getsubopt(&p, pat, &val);
  57                 switch (c) {
  58                 case Remount:
  59                         flags[Remount] = 1;
  60                         break;
  61                 case Bind:
  62                         flags[Bind] = 1;
  63                         break;
  64                 }
  65         }
  66         free(o);
  67 }
  68
  69 static int test_flush(char opts[])
  70 {
  71         int err, i;
  72         regex_t preg;
  73         char *p, *o;
  74         const char *pat = "^((add|ins|append|prepend|del)[:=]"
  75                 "|(mod|imod)[:=][^,]*=ro"
  76                 "|(noplink|ro)$)";
  77
  78
  79         o = strdup(opts);
  80         if (!o)
  81                 AuFin("stdup");
  82
  83         p = o;
  84         i = 1;
  85         while ((p = strchr(p, ','))) {
  86                 i++;
  87                 *p++ = 0;
  88         }
  89
  90         /* todo: try getsubopt(3)? */
  91         err = regcomp(&preg, pat, REG_EXTENDED | REG_NOSUB);
  92         if (err)
  93                 AuFin("regcomp");
  94
  95         p = o;
  96         while (i--) {
  97                 if (!regexec(&preg, p, 0, NULL, 0)) {
  98                         err = 1;
  99                         break;
 100                 } else
 101                         p += strlen(p) + 1;
 102         }
 103         regfree(&preg);
 104         free(o);
 105
 106         return err;
 107 }
 108
 109 static void do_mount(char *dev, char *mntpnt, int argc, char *argv[],
 110                      unsigned char flags[])
 111 {
 112         int i;
 113         const int ac = argc + 6;
 114         char *av[ac], **a;
 115
 116         /* todo: eliminate the duplicated options */
 117         a = av;
 118         *a++ = "mount";
 119         *a++ = "-i";
 120         if (flags[Fake])
 121                 *a++ = "-f";
 122         if (!flags[Bind] || !flags[Update])
 123                 *a++ = "-n";
 124         if (flags[Bind] && flags[Verbose])
 125                 *a++ = "-v";
 126         *a++ = "-t";
 127         *a++ = AUFS_NAME;
 128
 129         for (i = 3; i < argc; i++)
 130                 if (strcmp(argv[i], "-v") && strcmp(argv[i], "-n"))
 131                         *a++ = argv[i];
 132         *a++ = dev;
 133         *a++ = mntpnt;
 134         *a++ = NULL;
 135
 136 #ifdef DEBUG
 137         for (i = 0; av[i] && i < ac; i++)
 138                 puts(av[i]);
 139         exit(0);
 140 #endif
 141         execvp("mount", av);
 142         AuFin("mount");
 143 }
 144
 145 /* ---------------------------------------------------------------------- */
 146
 147 int main(int argc, char *argv[])
 148 {
 149         int err, c, status;
 150         pid_t pid;
 151         unsigned char flags[LastOpt];
 152         struct mntent ent;
 153         char *dev, *mntpnt, *opts, *cwd;
 154         DIR *cur;
 155
 156         if (argc < 3) {
 157                 errno = EINVAL;
 158                 AuFin(NULL);
 159         }
 160
 161         memset(flags, 0, sizeof(flags));
 162         flags[Update] = 1;
 163         opts = NULL;
 164
 165         /* mount(8) always passes the arguments in this order */
 166         dev = argv[1];
 167         mntpnt = argv[2];
 168         while ((c = getopt(argc - 2, argv + 2, "fnvo:")) != -1) {
 169                 switch (c) {
 170                 case 'f':
 171                         flags[Fake] = 1;
 172                         break;
 173                 case 'n':
 174                         flags[Update] = 0;
 175                         break;
 176                 case 'v':
 177                         flags[Verbose] = 1;
 178                         break;
 179                 case 'o':
 180                         opts = optarg;
 181                         break;
 182                 case '?':
 183                 case ':':
 184                         errno = EINVAL;
 185                         AuFin("internal error");
 186                 }
 187         }
 188
 189         cur = opendir(".");
 190         if (!cur)
 191                 AuFin(".");
 192         err = chdir(mntpnt);
 193         if (err)
 194                 AuFin("%s", mntpnt);
 195         cwd = getcwd(NULL, 0); /* glibc */
 196         if (!cwd)
 197                 AuFin("getcwd");
 198         err = fchdir(dirfd(cur));
 199         if (err)
 200                 AuFin("fchdir");
 201         closedir(cur); /* ignore */
 202
 203         if (opts)
 204                 test_opts(opts, flags);
 205
 206         if (!flags[Bind] && flags[Update]) {
 207                 err = access(MTab, R_OK | W_OK);
 208                 if (err)
 209                         AuFin(MTab);
 210         }
 211
 212         if (flags[Remount]) {
 213                 errno = EINVAL;
 214                 if (flags[Bind])
 215                         AuFin("both of remount and bind are specified");
 216                 flags[AuFlush] = test_flush(opts);
 217                 if (flags[AuFlush] /* && !flags[Fake] */) {
 218                         err = au_plink(cwd, AuPlink_FLUSH, 1, 1);
 219                         if (err)
 220                                 AuFin(NULL);
 221                 }
 222         }
 223
 224         pid = fork();
 225         if (!pid) {
 226                 /* actual mount operation */
 227                 do_mount(dev, mntpnt, argc, argv, flags);
 228                 return 0;
 229         } else if (pid < 0)
 230                 AuFin("fork");
 231
 232         err = waitpid(pid, &status, 0);
 233         if (err < 0)
 234                 AuFin("child process");
 235
 236         err = !WIFEXITED(status);
 237         if (!err)
 238                 err = WEXITSTATUS(status);
 239
 240         if (!err && !flags[Bind]) {
 241                 if (flags[Update])
 242                         err = au_update_mtab(cwd, flags[Remount],
 243                                              flags[Verbose]);
 244                 else if (flags[Verbose]) {
 245                         /* withoug blocking plink */
 246                         err = au_proc_getmntent(cwd, &ent);
 247                         if (!err)
 248                                 au_print_ent(&ent);
 249                         else
 250                                 AuFin("internal error");
 251                 }
 252         }
 253
 254         return err;
 255 }