text: /* mount.c - mount filesystems
   *
   * Copyright 2014 Rob Landley <rob@landley.net>
   *
   * See http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/mount.html
   *
   * Note: -hV is bad spec, haven't implemented -FsLU yet
   * no mtab (/proc/mounts does it) so -n is NOP.
   * TODO mount -o loop,autoclear (linux git 96c5865559ce)
  
  USE_MOUNT(NEWTOY(mount, "?O:afnrvwt:o*[-rw]", TOYFLAG_BIN|TOYFLAG_STAYROOT))
  //USE_NFSMOUNT(NEWTOY(nfsmount, "?<2>2", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_STAYROOT))
  
  config MOUNT
    bool "mount"
    default y
    help
      usage: mount [-afFrsvw] [-t TYPE] [-o OPTION,] [[DEVICE] DIR]
  
      Mount new filesystem(s) on directories. With no arguments, display existing
      mounts.
  
      -a	Mount all entries in /etc/fstab (with -t, only entries of that TYPE)
      -O	Only mount -a entries that have this option
      -f	Fake it (don't actually mount)
      -r	Read only (same as -o ro)
      -w	Read/write (default, same as -o rw)
      -t	Specify filesystem type
      -v	Verbose
  
      OPTIONS is a comma separated list of options, which can also be supplied
      as --longopts.
  
      Autodetects loopback mounts (a file on a directory) and bind mounts (file
      on file, directory on directory), so you don't need to say --bind or --loop.
      You can also "mount -a /path" to mount everything in /etc/fstab under /path,
      even if it's noauto. DEVICE starting with UUID= is identified by blkid -U.
  
  #config SMBMOUNT
  #  bool "smbmount"
  #  default n
  #  helo
  #    usage: smbmount SHARE DIR
  #
  #    Mount smb share with user/pasword prompt as necessary.
  #
  #config NFSMOUNT
  #  bool "nfsmount"
  #  default n
  #  help
  #    usage: nfsmount SHARE DIR
  #
  #    Invoke an eldrich horror from the dawn of time.
  */
  
  #define FOR_mount
  #include "toys.h"
  
  GLOBALS(
    struct arg_list *optlist;
    char *type;
    char *bigO;
  
    unsigned long flags;
    char *opts;
    int okuser;
  )
  
  // mount.tests should check for all of this:
  // TODO detect existing identical mount (procfs with different dev name?)
  // TODO user, users, owner, group, nofail
  // TODO -p (passfd)
  // TODO -a -t notype,type2
  // TODO --subtree
  // TODO --rbind, -R
  // TODO make "mount --bind,ro old new" work (implicit -o remount)
  // TODO mount -a
  // TODO mount -o remount
  // TODO fstab: lookup default options for mount
  // TODO implement -v
  // TODO "mount -a -o remount,ro" should detect overmounts
  // TODO work out how that differs from "mount -ar"
  // TODO what if you --bind mount a block device somewhere (file, dir, dev)
  // TODO "touch servername; mount -t cifs servername path"
  // TODO mount -o remount a user mount
  // TODO mount image.img sub (auto-loopback) then umount image.img
  // TODO mount UUID=blah
  
  // Strip flags out of comma separated list of options, return flags,.
  static long flag_opts(char *new, long flags, char **more)
  {
    struct {
      char *name;
      long flags;
    } opts[] = {
      // NOPs (we autodetect --loop and --bind)
      {"loop", 0}, {"bind", 0}, {"defaults", 0}, {"quiet", 0},
      {"user", 0}, {"nouser", 0}, // checked in fstab, ignored in -o
      {"ro", MS_RDONLY}, {"rw", ~MS_RDONLY},
      {"nosuid", MS_NOSUID}, {"suid", ~MS_NOSUID},
      {"nodev", MS_NODEV}, {"dev", ~MS_NODEV},
      {"noexec", MS_NOEXEC}, {"exec", ~MS_NOEXEC},
      {"sync", MS_SYNCHRONOUS}, {"async", ~MS_SYNCHRONOUS},
      {"noatime", MS_NOATIME}, {"atime", ~MS_NOATIME},
      {"norelatime", ~MS_RELATIME}, {"relatime", MS_RELATIME},
      {"nodiratime", MS_NODIRATIME}, {"diratime", ~MS_NODIRATIME},
      {"loud", ~MS_SILENT},
      {"shared", MS_SHARED}, {"rshared", MS_SHARED|MS_REC},
      {"slave", MS_SLAVE}, {"rslave", MS_SLAVE|MS_REC},
      {"private", MS_PRIVATE}, {"rprivate", MS_SLAVE|MS_REC},
      {"unbindable", MS_UNBINDABLE}, {"runbindable", MS_UNBINDABLE|MS_REC},
      {"remount", MS_REMOUNT}, {"move", MS_MOVE},
      // mand dirsync rec iversion strictatime
    };
  
    if (new) for (;;) {
      char *comma = strchr(new, ',');
      int i;
  
      if (comma) *comma = 0;
  
      // If we recognize an option, apply flags
      for (i = 0; i < ARRAY_LEN(opts); i++) if (!strcasecmp(opts[i].name, new)) {
        long ll = opts[i].flags;
  
        if (ll < 0) flags &= ll;
        else flags |= ll;
  
        break;
      }
  
      // If we didn't recognize it, keep string version
      if (more && i == ARRAY_LEN(opts)) {
        i = *more ? strlen(*more) : 0;
        *more = xrealloc(*more, i + strlen(new) + 2);
        if (i) (*more)[i++] = ',';
        strcpy(i+*more, new);
      }
  
      if (!comma) break;
      *comma = ',';
      new = comma + 1;
    }
  
    return flags;
  }
  
  // Shell out to a program, returning the output string or NULL on error
  static char *tortoise(int loud, char **cmd)
  {
    int rc, pipe, len;
    pid_t pid;
  
    pid = xpopen(cmd, &pipe, 1);
    len = readall(pipe, toybuf, sizeof(toybuf)-1);
    rc = xpclose(pid, pipe);
    if (!rc && len > 1) {
      if (toybuf[len-1] == '\n') --len;
      toybuf[len] = 0;
      return toybuf;
    }
    if (loud) error_msg("%s failed %d", *cmd, rc);
  
    return 0;
  }
  
  static void mount_filesystem(char *dev, char *dir, char *type,
    unsigned long flags, char *opts)
  {
    FILE *fp = 0;
    int rc = EINVAL;
    char *buf = 0;
  
    if (FLAG(f)) return;
  
    if (getuid()) {
      if (TT.okuser) TT.okuser = 0;
      else {
        error_msg("'%s' not user mountable in fstab", dev);
  
        return;
      }
    }
  
    if (strstart(&dev, "UUID=")) {
      char *s = tortoise(0, (char *[]){"blkid", "-U", dev, 0});
  
      if (!s) return error_msg("No uuid %s", dev);
      dev = s;
    }
  
    // Autodetect bind mount or filesystem type
  
    if (type && !strcmp(type, "auto")) type = 0;
    if (flags & MS_MOVE) {
      if (type) error_exit("--move with -t");
    } else if (!type) {
      struct stat stdev, stdir;
  
      // file on file or dir on dir is a --bind mount.
      if (!stat(dev, &stdev) && !stat(dir, &stdir)
          && ((S_ISREG(stdev.st_mode) && S_ISREG(stdir.st_mode))
              || (S_ISDIR(stdev.st_mode) && S_ISDIR(stdir.st_mode))))
      {
        flags |= MS_BIND;
      } else fp = xfopen("/proc/filesystems", "r");
    } else if (!strcmp(type, "ignore")) return;
    else if (!strcmp(type, "swap"))
      toys.exitval |= xrun((char *[]){"swapon", "--", dev, 0});
  
    for (;;) {
      int fd = -1, ro = 0;
  
      // If type wasn't specified, try all of them in order.
      if (fp && !buf) {
        size_t i;
  
        if (getline(&buf, &i, fp)<0) {
          error_msg("%s: need -t", dev);
          break;
        }
        type = buf;
        // skip nodev devices
        if (!isspace(*type)) {
          free(buf);
          buf = 0;
  
          continue;
        }
        // trim whitespace
        while (isspace(*type)) type++;
        i = strlen(type);
        if (i) type[i-1] = 0;
      }
      if (FLAG(v))
        printf("try '%s' type '%s' on '%s'\n", dev, type, dir);
      for (;;) {
        rc = mount(dev, dir, type, flags, opts);
        // Did we succeed, fail unrecoverably, or already try read-only?
        if (!rc || (errno != EACCES && errno != EROFS) || (flags&MS_RDONLY))
          break;
        // If we haven't already tried it, use the BLKROSET ioctl to ensure
        // that the underlying device isn't read-only.
        if (fd == -1) {
          if (FLAG(v))
            printf("trying BLKROSET ioctl on '%s'\n", dev);
          if (-1 != (fd = open(dev, O_RDONLY))) {
            rc = ioctl(fd, BLKROSET, &ro);
            close(fd);
            if (!rc) continue;
          }
        }
        fprintf(stderr, "'%s' is read-only\n", dev);
        flags |= MS_RDONLY;
      }
  
      // Trying to autodetect loop mounts like bind mounts above (file on dir)
      // isn't good enough because "mount -t ext2 fs.img dir" is valid, but if
      // you _do_ accept loop mounts with -t how do you tell "-t cifs" isn't
      // looking for a block device if it's not in /proc/filesystems yet
      // because the fs module won't be loaded until you try the mount, and
      // if you can't then DEVICE existing as a file would cause a false
      // positive loopback mount (so "touch servername" becomes a potential
      // denial of service attack...)
      //
      // Solution: try the mount, let the kernel tell us it wanted a block
      // device, then do the loopback setup and retry the mount.
  
      if (rc && errno == ENOTBLK) {
        dev = tortoise(1, (char *[]){"losetup",
          (flags&MS_RDONLY) ? "-fsr" : "-fs", dev, 0});
        if (!dev) break;
        continue;
      }
  
      free(buf);
      buf = 0;
      if (!rc) break;
      if (fp && (errno == EINVAL || errno == EBUSY)) continue;
  
      perror_msg("'%s'->'%s'", dev, dir);
  
      break;
    }
    if (fp) fclose(fp);
  }
  
  void mount_main(void)
  {
    char *opts = 0, *dev = 0, *dir = 0, **ss;
    long flags = MS_SILENT;
    struct arg_list *o;
    struct mtab_list *mtl, *mtl2 = 0, *mm, *remount;
  
  // TODO
  // remount
  //   - overmounts
  // shared subtree
  // -o parsed after fstab options
  // test if mountpoint already exists (-o noremount?)
  
    // First pass; just accumulate string, don't parse flags yet. (This is so
    // we can modify fstab entries with -a, or mtab with remount.)
    for (o = TT.optlist; o; o = o->next) comma_collate(&opts, o->arg);
    if (FLAG(r)) comma_collate(&opts, "ro");
    if (FLAG(w)) comma_collate(&opts, "rw");
  
    // Treat each --option as -o option
    for (ss = toys.optargs; *ss; ss++) {
      char *sss = *ss;
  
      // If you realy, really want to mount a file named "--", we support it.
      if (sss[0]=='-' && sss[1]=='-' && sss[2]) comma_collate(&opts, sss+2);
      else if (!dev) dev = sss;
      else if (!dir) dir = sss;
      // same message as lib/args.c ">2" which we can't use because --opts count
      else error_exit("Max 2 arguments\n");
    }
  
    if (FLAG(a) && dir) error_exit("-a with >1 arg");
  
    // For remount we need _last_ match (in case of overmounts), so traverse
    // in reverse order. (Yes I'm using remount as a boolean for a bit here,
    // the double cast is to get gcc to shut up about it.)
    remount = (void *)(long)comma_scan(opts, "remount", 0);
    if ((FLAG(a) && !access("/proc/mounts", R_OK)) || remount) {
      mm = dlist_terminate(mtl = mtl2 = xgetmountlist(0));
      if (remount) remount = mm;
    }
  
    // Do we need to do an /etc/fstab trawl?
    // This covers -a, -o remount, one argument, all user mounts
    if (FLAG(a) || (dev && (!dir || getuid() || remount))) {
      if (!remount) dlist_terminate(mtl = xgetmountlist("/etc/fstab"));
  
      for (mm = remount ? remount : mtl; mm; mm = (remount ? mm->prev : mm->next))
      {
        struct mtab_list *mmm = 0;
        int aflags, noauto, len;
  
        // Check for noauto and get it out of the option list. (Unknown options
        // that make it to the kernel give filesystem drivers indigestion.)
        noauto = comma_scan(mm->opts, "noauto", 1);
  
        if (FLAG(a)) {
          // "mount -a /path" to mount all entries under /path
          if (dev) {
             len = strlen(dev);
             if (strncmp(dev, mm->dir, len)
                 || (mm->dir[len] && mm->dir[len] != '/')) continue;
          } else if (noauto) continue; // never present in the remount case
          if (!mountlist_istype(mm,TT.type) || !comma_scanall(mm->opts,TT.bigO))
            continue;
        } else {
          if (dir && strcmp(dir, mm->dir)) continue;
          if (dev && strcmp(dev, mm->device) && (dir || strcmp(dev, mm->dir)))
            continue;
        }
  
        // Don't overmount the same dev on the same directory
        // (Unless root explicitly says to in non -a mode.)
        if (mtl2 && !remount)
          for (mmm = mtl2; mmm; mmm = mmm->next)
            if (!strcmp(mm->dir, mmm->dir) && !strcmp(mm->device, mmm->device))
              break;
   
        // user only counts from fstab, not opts.
        if (!mmm) {
          char *aopts = 0;
          TT.okuser = comma_scan(mm->opts, "user", 1);
          aflags = flag_opts(mm->opts, flags, &aopts);
          aflags = flag_opts(opts, aflags, &aopts);
          if (remount) {
              // clear type and opts for remount
              aflags |= MS_REMOUNT;
              strcpy(mm->type, "none");
              aopts = NULL;
          }
          mount_filesystem(mm->device, mm->dir, mm->type, aflags, aopts);
          free(aopts);
          if (!remount && errno == EINVAL) continue;
        } // TODO else if (getuid()) error_msg("already there") ?
  
        if (!FLAG(a)) break;
      }
      if (CFG_TOYBOX_FREE) {
        llist_traverse(mtl, free);
        llist_traverse(mtl2, free);
      }
      if (!mm && !FLAG(a))
        error_exit("'%s' not in %s", dir ? dir : dev,
                   remount ? "/proc/mounts" : "fstab");
  
    // show mounts from /proc/mounts
    } else if (!dev) {
      for (mtl = xgetmountlist(0); mtl && (mm = dlist_pop(&mtl)); free(mm)) {
        char *s = 0;
  
        if (TT.type && strcmp(TT.type, mm->type)) continue;
        if (*mm->device == '/') s = xabspath(mm->device, 0);
        xprintf("%s on %s type %s (%s)\n",
                s ? s : mm->device, mm->dir, mm->type, mm->opts);
        free(s);
      }
  
    // two arguments
    } else {
      char *more = 0;
  
      flags = flag_opts(opts, flags, &more);
      mount_filesystem(dev, dir, TT.type, flags, more);
      if (CFG_TOYBOX_FREE) free(more);
    }
  }
  