/*      $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);
}