/*      $NetBSD: rot13fs.c,v 1.17 2008/09/12 14:40:47 christos Exp $    */

/*
* Copyright (c) 2007  Antti Kantee.  All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

/*
* rot13fs: puffs layering experiment
* (unfinished, as is probably fairly easy to tell)
*
* This also demonstrates how namemod can be easily set to any
* function which reverses itself (argument -f provides a case-flipping
* file system).
*/

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <puffs.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

PUFFSOP_PROTOS(rot13)

static void usage(void);

static void
usage()
{

       errx(1, "usage: %s [-s] [-o mntopts] rot13path mountpath",
           getprogname());
}

static void (*flipflop)(void *, size_t);

static uint8_t tbl[256];

static void
dorot13(void *buf, size_t buflen)
{
       uint8_t *b = buf;

       while (buflen--) {
               *b = tbl[*b];
               b++;
       }
}

static void
docase(void *buf, size_t buflen)
{
       unsigned char *b = buf;

       while (buflen--) {
               if (isalpha(*b))
                       *b ^= 0x20;
               b++;
       }
}

static int
rot13path(struct puffs_usermount *pu, struct puffs_pathobj *base,
       struct puffs_cn *pcn)
{

       flipflop(pcn->pcn_name, pcn->pcn_namelen);

       return 0;
}

int
main(int argc, char *argv[])
{
       struct puffs_usermount *pu;
       struct puffs_ops *pops;
       struct puffs_pathobj *po_root;
       struct puffs_node *pn_root;
       struct stat sb;
       mntoptparse_t mp;
       int mntflags, pflags;
       int detach;
       int ch;
       int i;

       setprogname(argv[0]);

       if (argc < 3)
               usage();

       flipflop = dorot13;
       pflags = mntflags = 0;
       detach = 1;
       while ((ch = getopt(argc, argv, "fo:s")) != -1) {
               switch (ch) {
               case 'f':
                       flipflop = docase;
                       break;
               case 'o':
                       mp = getmntopts(optarg, puffsmopts, &mntflags, &pflags);
                       if (mp == NULL)
                               err(1, "getmntopts");
                       freemntopts(mp);
                       break;
               case 's':
                       detach = 0;
                       break;
               }
       }
       pflags |= PUFFS_FLAG_BUILDPATH;
       argv += optind;
       argc -= optind;

       if (pflags & PUFFS_FLAG_OPDUMP)
               detach = 0;

       if (argc != 2)
               usage();

       if (lstat(argv[0], &sb) == -1)
               err(1, "stat %s", argv[0]);
       if ((sb.st_mode & S_IFDIR) == 0)
               errx(1, "%s is not a directory", argv[0]);

       PUFFSOP_INIT(pops);
       puffs_null_setops(pops);

       PUFFSOP_SET(pops, rot13, node, readdir);
       PUFFSOP_SET(pops, rot13, node, read);
       PUFFSOP_SET(pops, rot13, node, write);

       if ((pu = puffs_init(pops, argv[0], "rot13", NULL, pflags)) == NULL)
               err(1, "mount");

       pn_root = puffs_pn_new(pu, NULL);
       if (pn_root == NULL)
               err(1, "puffs_pn_new");
       puffs_setroot(pu, pn_root);

       po_root = puffs_getrootpathobj(pu);
       if (po_root == NULL)
               err(1, "getrootpathobj");
       po_root->po_path = argv[0];
       po_root->po_len = strlen(argv[0]);
       puffs_stat2vattr(&pn_root->pn_va, &sb);

       puffs_set_namemod(pu, rot13path);

       /* initialize rot13 tables */
       for (i = 0; i < 256; i++)
               tbl[i] = (uint8_t)i;
       for (i = 0; i <= 26; i++)
               tbl[i + 'a'] = 'a' + ((i + 13) % 26);
       for (i = 0; i < 26; i++)
               tbl[i + 'A'] = 'A' + ((i + 13) % 26);

       if (detach)
               if (puffs_daemon(pu, 1, 1) == -1)
                       err(1, "puffs_daemon");

       if (puffs_mount(pu, argv[1], mntflags, pn_root) == -1)
               err(1, "puffs_mount");
       if (puffs_mainloop(pu) == -1)
               err(1, "mainloop");

       return 0;
}

int
rot13_node_readdir(struct puffs_usermount *pu, void *opc, struct dirent *dent,
       off_t *readoff, size_t *reslen, const struct puffs_cred *pcr,
       int *eofflag, off_t *cookies, size_t *ncookies)
{
       struct dirent *dp;
       size_t rl;
       int rv;

       dp = dent;
       rl = *reslen;

       rv = puffs_null_node_readdir(pu, opc, dent, readoff, reslen, pcr,
           eofflag, cookies, ncookies);
       if (rv)
               return rv;

       while (rl > *reslen) {
               flipflop((uint8_t *)dp->d_name, dp->d_namlen);
               rl -= _DIRENT_SIZE(dp);
               dp = _DIRENT_NEXT(dp);
       }

       return 0;
}

int
rot13_node_read(struct puffs_usermount *pu, void *opc,
       uint8_t *buf, off_t offset, size_t *resid,
       const struct puffs_cred *pcr, int ioflag)
{
       uint8_t *prebuf = buf;
       size_t preres = *resid;
       int rv;

       rv = puffs_null_node_read(pu, opc, buf, offset, resid, pcr, ioflag);
       if (rv)
               return rv;

       flipflop(prebuf, preres - *resid);

       return rv;
}

int
rot13_node_write(struct puffs_usermount *pu, void *opc,
       uint8_t *buf, off_t offset, size_t *resid,
       const struct puffs_cred *pcr, int ioflag)
{

       flipflop(buf, *resid);
       return puffs_null_node_write(pu, opc, buf, offset, resid, pcr, ioflag);
}

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