/*      $NetBSD: icfs.c,v 1.12 2025/05/04 20:18:26 andvar 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.
 */

/*
 * icfs: layer everything in lowercase
 * (unfinished, as is probably fairly easy to tell)
 *
 * Now, this "layered" file system demonstrates a nice gotcha with
 * mangling readdir entries.  In case we can't unmangle the name
 * (cf. rot13fs), we need to map the mangled name back to the real
 * name in lookup and store the actual lower layer name instead of
 * the mangled name.
 *
 * This is mounted without namecache.  Otherwise we might have
 * two different nodes for e.g. FoO and foo.  It might be possible
 * support name cache by having all namespace-altering operations
 * flush the directory namecache ...
 */

#include <sys/types.h>

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

PUFFSOP_PROTOS(ic)

static void usage(void);

static void
usage()
{

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

static void
dotolower(char *buf, size_t buflen)
{

        while (buflen--) {
                *buf = tolower((unsigned char)*buf);
                buf++;
        }
}

static int
icpathcmp(struct puffs_usermount *pu, struct puffs_pathobj *c1,
        struct puffs_pathobj *c2, size_t clen, int checkprefix)
{
        struct puffs_pathobj *po_root;
        char *cp1, *cp2;
        size_t rplen;

        po_root = puffs_getrootpathobj(pu);
        rplen = po_root->po_len;

        assert(clen >= rplen);

        cp1 = c1->po_path;
        cp2 = c2->po_path;

        if (strncasecmp(cp1 + rplen, cp2 + rplen, clen - rplen) != 0)
                return 1;

        if (checkprefix == 0)
                return 0;

        if (c1->po_len < c2->po_len)
                return 1;

        if (*(cp1 + clen) != '/')
                return 1;

        return 0;
}

static int
icpathxform(struct puffs_usermount *pu, const struct puffs_pathobj *po_base,
        const struct puffs_cn *pcn, struct puffs_pathobj *po_new)
{
        struct dirent entry, *result;
        char *src;
        size_t srclen;
        DIR *dp;

        dp = opendir(po_base->po_path);
        if (dp == NULL)
                return errno;

        src = pcn->pcn_name;
        srclen = pcn->pcn_namelen;
        for (;;) {
                if (readdir_r(dp, &entry, &result) != 0)
                        break;
                if (!result)
                        break;
                if (strcasecmp(result->d_name, pcn->pcn_name) == 0) {
                        src = result->d_name;
                        srclen = strlen(result->d_name);
                        break;
                }
        }

        po_new->po_path = strdup(src);
        po_new->po_len = srclen;
        closedir(dp);

        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, dpres;
        int ch;

        setprogname(argv[0]);

        if (argc < 3)
                usage();

        pflags = mntflags = dpres = 0;
        detach = 1;
        while ((ch = getopt(argc, argv, "o:sp")) != -1) {
                switch (ch) {
                case 'o':
                        mp = getmntopts(optarg, puffsmopts, &mntflags, &pflags);
                        if (mp == NULL)
                                err(1, "getmntopts");
                        freemntopts(mp);
                        break;
                case 'p':
                        dpres = 1;
                        break;
                case 's':
                        detach = 0;
                        break;
                }
        }
        pflags |= PUFFS_FLAG_BUILDPATH;
        pflags |= PUFFS_KFLAG_NOCACHE_NAME;
        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);

        if (dpres == 0)
                PUFFSOP_SET(pops, ic, node, readdir);

        if ((pu = puffs_init(pops, argv[0], "ic", 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_pathcmp(pu, icpathcmp);
        puffs_set_pathtransform(pu, icpathxform);

        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
ic_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) {
                dotolower(dp->d_name, dp->d_namlen);
                rl -= _DIRENT_SIZE(dp);
                dp = _DIRENT_NEXT(dp);
        }

        return 0;
}