/*      $NetBSD: paths.c,v 1.8 2008/08/12 19:44:39 pooka 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.
 */

#include <sys/cdefs.h>
#if !defined(lint)
__RCSID("$NetBSD: paths.c,v 1.8 2008/08/12 19:44:39 pooka Exp $");
#endif /* !lint */

#include <sys/hash.h>

#include <assert.h>
#include <errno.h>
#include <puffs.h>
#include <stdlib.h>

#include "puffs_priv.h"

/*
 * Generic routines for pathbuilding code
 */

int
puffs_path_pcnbuild(struct puffs_usermount *pu, struct puffs_cn *pcn,
        puffs_cookie_t parent)
{
        struct puffs_node *pn_parent = PU_CMAP(pu, parent);
        struct puffs_cn pcn_orig;
        struct puffs_pathobj po;
        int rv;

        assert(pn_parent->pn_po.po_path != NULL);
        assert(pu->pu_flags & PUFFS_FLAG_BUILDPATH);

        if (pu->pu_pathtransform) {
                rv = pu->pu_pathtransform(pu, &pn_parent->pn_po, pcn, &po);
                if (rv)
                        return rv;
        } else {
                po.po_path = pcn->pcn_name;
                po.po_len = pcn->pcn_namelen;
        }

        if (pu->pu_namemod) {
                /* XXX: gcc complains if I do assignment */
                memcpy(&pcn_orig, pcn, sizeof(pcn_orig));
                rv = pu->pu_namemod(pu, &pn_parent->pn_po, pcn);
                if (rv)
                        return rv;
        }

        rv = pu->pu_pathbuild(pu, &pn_parent->pn_po, &po, 0,
            &pcn->pcn_po_full);
        puffs_path_buildhash(pu, &pcn->pcn_po_full);

        if (pu->pu_pathtransform)
                pu->pu_pathfree(pu, &po);

        if (pu->pu_namemod && rv)
                *pcn = pcn_orig;

        return rv;
}

/*
 * substitute all (child) patch prefixes.  called from nodewalk, which
 * in turn is called from rename
 */
void *
puffs_path_prefixadj(struct puffs_usermount *pu, struct puffs_node *pn,
        void *arg)
{
        struct puffs_pathinfo *pi = arg;
        struct puffs_pathobj localpo;
        struct puffs_pathobj oldpo;
        int rv;

        /* can't be a path prefix */
        if (pn->pn_po.po_len < pi->pi_old->po_len)
                return NULL;

        if (pu->pu_pathcmp(pu, &pn->pn_po, pi->pi_old, pi->pi_old->po_len, 1))
                return NULL;

        /* otherwise we'd have two nodes with an equal path */
        assert(pn->pn_po.po_len > pi->pi_old->po_len);

        /* found a matching prefix */
        rv = pu->pu_pathbuild(pu, pi->pi_new, &pn->pn_po,
            pi->pi_old->po_len, &localpo);
        /*
         * XXX: technically we shouldn't fail, but this is the only
         * sensible thing to do here.  If the buildpath routine fails,
         * we will have paths in an inconsistent state.  Should fix this,
         * either by having two separate passes or by doing other tricks
         * to make an invalid path with BUILDPATHS acceptable.
         */
        if (rv != 0)
                abort();

        /* adjust hash sum */
        puffs_path_buildhash(pu, &localpo);

        /* out with the old and in with the new */
        oldpo = pn->pn_po;
        pn->pn_po = localpo;
        pu->pu_pathfree(pu, &oldpo);

        /* continue the walk */
        return NULL;
}

/*
 * called from nodewalk, checks for exact match
 */
void *
puffs_path_walkcmp(struct puffs_usermount *pu, struct puffs_node *pn, void *arg)
{
        struct puffs_pathobj *po = arg;
        struct puffs_pathobj po2;

        if (po->po_len != PNPLEN(pn))
                return NULL;

        /*
         * If hashing and the hash doesn't match, we know this is
         * definitely not a match.  Otherwise check for collisions.
         */
        if (pu->pu_flags & PUFFS_FLAG_HASHPATH)
                if (pn->pn_po.po_hash != po->po_hash)
                        return NULL;

        po2.po_path = PNPATH(pn);
        po2.po_len = PNPLEN(pn);

        if (pu->pu_pathcmp(pu, po, &po2, PNPLEN(pn), 0) == 0)
                return pn;
        return NULL;
}

/*
 * Hash sum building routine.  Use string hash if the buildpath routine
 * is the standard one, otherwise use binary hashes.  A bit whimsical
 * way to choose the routine, but the binary works for strings also,
 * so don't sweat it.
 */
void
puffs_path_buildhash(struct puffs_usermount *pu, struct puffs_pathobj *po)
{

        if ((pu->pu_flags & PUFFS_FLAG_HASHPATH) == 0)
                return;

        if (pu->pu_pathbuild == puffs_stdpath_buildpath)
                po->po_hash = hash32_strn(po->po_path, po->po_len,
                    HASH32_STR_INIT);
        else
                po->po_hash = hash32_buf(po->po_path, po->po_len,
                    HASH32_BUF_INIT);
}

/*
 * Routines provided to file systems which consider a path a tuple of
 * strings and / the component separator.
 */

/*ARGSUSED*/
int
puffs_stdpath_cmppath(struct puffs_usermount *pu, struct puffs_pathobj *c1,
        struct puffs_pathobj *c2, size_t clen, int checkprefix)
{
        char *p;
        int rv;

        rv = strncmp(c1->po_path, c2->po_path, clen);
        if (rv)
                return 1;

        if (checkprefix == 0)
                return 0;

        /* sanity for next step */
        if (!(c1->po_len > c2->po_len))
                return 1;

        /* check if it's really a complete path prefix */
        p = c1->po_path;
        if ((*(p + clen)) != '/')
                return 1;

        return 0;
}

/*ARGSUSED*/
int
puffs_stdpath_buildpath(struct puffs_usermount *pu,
        const struct puffs_pathobj *po_pre, const struct puffs_pathobj *po_comp,
        size_t offset, struct puffs_pathobj *newpath)
{
        char *path, *pcomp;
        size_t plen, complen;
        size_t prelen;
        int isdotdot;

        complen = po_comp->po_len - offset;

        /* seek to correct place & remove all leading '/' from component */
        pcomp = po_comp->po_path;
        pcomp += offset;
        while (*pcomp == '/') {
                pcomp++;
                complen--;
        }

        /* todotdot or nottodotdot */
        if (complen == 2 && strcmp(pcomp, "..") == 0)
                isdotdot = 1;
        else
                isdotdot = 0;

        /*
         * Strip trailing components from the preceending component.
         * This is an issue only for the root node, which we might want
         * to be at path "/" for some file systems.
         */
        prelen = po_pre->po_len;
        while (prelen > 0 && *((char *)po_pre->po_path + (prelen-1)) == '/') {
                assert(isdotdot == 0);
                prelen--;
        }

        if (isdotdot) {
                char *slash; /* sweet char of mine */
                
                slash = strrchr(po_pre->po_path, '/');
                assert(slash != NULL);

                plen = slash - (char *)po_pre->po_path;

                /*
                 * As the converse to not stripping the initial "/" above,
                 * don't nuke it here either.
                 */
                if (plen == 0)
                        plen++;

                path = malloc(plen + 1);
                if (path == NULL)
                        return errno;

                strlcpy(path, po_pre->po_path, plen+1);
        } else {
                /* + '/' + '\0' */
                plen = prelen + 1 + complen;
                path = malloc(plen + 1);
                if (path == NULL)
                        return errno;

                strlcpy(path, po_pre->po_path, prelen+1);
                strcat(path, "/");
                strncat(path, pcomp, complen);
        }

        newpath->po_path = path;
        newpath->po_len = plen;

        return 0;
}

/*ARGSUSED*/
void
puffs_stdpath_freepath(struct puffs_usermount *pu, struct puffs_pathobj *po)
{

        free(po->po_path);
}