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#include        "all.h"

#define MSIZE   (MAXDAT+128)

static void
seterror(Fcall *ou, int err)
{

        if(0 <= err && err < MAXERR)
                ou->ename = errstring[err];
        else
                ou->ename = "unknown error";
}

static int
fsversion(Chan* chan, Fcall* f, Fcall* r)
{
        if(f->msize < MSIZE)
                r->msize = f->msize;
        else
                r->msize = MSIZE;
        /*
         * Should check the '.' stuff here.
         * What happens if Tversion has already been seen?
         */
        if(strcmp(f->version, VERSION9P) == 0){
                r->version = VERSION9P;
                chan->msize = r->msize;
        }else
                r->version = "unknown";

        fileinit(chan);
        return 0;
}

char *keyspec = "proto=p9any role=server";

static int
fsauth(Chan *chan, Fcall *f, Fcall *r)
{
        int err, fd;
        char *aname;
        File *file;
        int afd;
        AuthRpc *rpc;

        err = 0;
        if(chan == cons.srvchan)
                return Eauthmsg;
        file = filep(chan, f->afid, 1);
        if(file == nil)
                return Efidinuse;

        /* forget any previous authentication */
        file->cuid = 0;

        if(access("/mnt/factotum", 0) < 0)
                if((fd = open("/srv/factotum", ORDWR)) >= 0)
                        mount(fd, -1, "/mnt", MBEFORE, "");

        afd = open("/mnt/factotum/rpc", ORDWR);
        if(afd < 0){
                err = Esystem;
                goto out;
        }
        rpc = auth_allocrpc(afd);
        if(rpc == nil){
                close(afd);
                err = Esystem;
                goto out;
        }
        file->rpc = rpc;
        if(auth_rpc(rpc, "start", keyspec, strlen(keyspec)) != ARok){
                err = Esystem;
                goto out;
        }

        aname = f->aname;
        if(!aname[0])
                aname = "main";
        file->fs = fsstr(aname);
        if(file->fs == nil){
                err = Ebadspc;
                goto out;
        }
        file->uid = strtouid(f->uname);
        if(file->uid < 0){
                err = Ebadu;
                goto out;
        }
        file->qid.path = 0;
        file->qid.vers = 0;
        file->qid.type = QTAUTH;
        r->qid = file->qid;

out:
        if(file != nil){
                qunlock(file);
                if(err != 0)
                        freefp(file);
        }
        return err;
}

int
authread(File *file, uchar *data, int count)
{
        AuthInfo *ai;
        AuthRpc *rpc;
        int rv;

        rpc = file->rpc;
        if(rpc == nil)
                return -1;

        rv = auth_rpc(rpc, "read", nil, 0);
        switch(rv){
        case ARdone:
                ai = auth_getinfo(rpc);
                if(ai == nil)
                        return -1;
                if(chat)
                        print("authread identifies user as %s\n", ai->cuid);
                file->cuid = strtouid(ai->cuid);
                auth_freeAI(ai);
                if(file->cuid == 0)
                        return -1;
                if(chat)
                        print("%s is a known user\n", ai->cuid);
                return 0;
        case ARok:
                if(count < rpc->narg)
                        return -1;
                memmove(data, rpc->arg, rpc->narg);
                return rpc->narg;
        case ARphase:
                return -1;
        default:
                return -1;
        }
}

int
authwrite(File *file, uchar *data, int count)
{
        int ret;

        ret = auth_rpc(file->rpc, "write", data, count);
        if(ret != ARok)
                return -1;
        return count;
}

void
mkqid9p1(Qid9p1* qid9p1, Qid* qid)
{
        if(qid->path & 0xFFFFFFFF00000000LL)
                panic("mkqid9p1: path %lluX\n", qid->path);
        qid9p1->path = qid->path & 0xFFFFFFFF;
        if(qid->type & QTDIR)
                qid9p1->path |= QPDIR;
        qid9p1->version = qid->vers;
}

void
authfree(File *fp)
{
        if(fp->rpc != nil){
                close(fp->rpc->afd);
                free(fp->rpc);
                fp->rpc = nil;
        }
}

void
mkqid9p2(Qid* qid, Qid9p1* qid9p1, int mode)
{
        qid->path = (ulong)(qid9p1->path & ~QPDIR);
        qid->vers = qid9p1->version;
        qid->type = 0;
        if(mode & DDIR)
                qid->type |= QTDIR;
        if(mode & DAPND)
                qid->type |= QTAPPEND;
        if(mode & DLOCK)
                qid->type |= QTEXCL;
}

static int
checkattach(Chan *chan, File *afile, File *file, Filsys *fs)
{
        uchar buf[1];

        if(chan == cons.srvchan || chan == cons.chan)
                return 0;

        /* if no afile, this had better be none */
        if(afile == nil){
                if(file->uid == 0){
                        if(!allownone && !chan->authed)
                                return Eauth;
                        return 0;
                }
                return Eauth;
        }

        /* otherwise, we'ld better have a usable cuid */
        if(!(afile->qid.type&QTAUTH))
                return Eauth;
        if(afile->uid != file->uid || afile->fs != fs)
                return Eauth;
        if(afile->cuid <= 0){
                if(authread(afile, buf, 0) != 0)
                        return Eauth;
                if(afile->cuid <= 0)
                        return Eauth;
        }
        file->uid = afile->cuid;

        /* once someone has authenticated on the channel, others can become none */
        chan->authed = 1;

        return 0;
}               

static int
fsattach(Chan* chan, Fcall* f, Fcall* r)
{
        char *aname;
        Iobuf *p;
        Dentry *d;
        File *file;
        File *afile;
        Filsys *fs;
        long raddr;
        int error, u;

        aname = f->aname;
        if(!aname[0])   /* default */
                aname = "main";
        p = nil;
        afile = filep(chan, f->afid, 0);
        file = filep(chan, f->fid, 1);
        if(file == nil){
                error = Efidinuse;
                goto out;
        }

        u = -1;
        if(chan != cons.chan){
                if(strcmp(f->uname, "adm") == 0){
                        error = Eauth;
                        goto out;
                }
                u = strtouid(f->uname);
                if(u < 0){
                        error = Ebadu;
                        goto out;
                }
        }
        file->uid = u;

        fs = fsstr(aname);
        if(fs == nil){
                error = Ebadspc;
                goto out;
        }

        if(error = checkattach(chan, afile, file, fs))
                goto out;

        raddr = getraddr(fs->dev);
        p = getbuf(fs->dev, raddr, Bread);
        d = getdir(p, 0);
        if(d == nil || checktag(p, Tdir, QPROOT) || !(d->mode & DALLOC)){
                error = Ealloc;
                goto out;
        }
        if(iaccess(file, d, DEXEC)){
                error = Eaccess;
                goto out;
        }
        if(file->uid == 0 && isro(fs->dev)) {
                /*
                 * 'none' not allowed on dump
                 */
                error = Eaccess;
                goto out;
        }
        accessdir(p, d, FREAD);
        mkqid(&file->qid, d, 1);
        file->fs = fs;
        file->addr = raddr;
        file->slot = 0;
        file->open = 0;
        freewp(file->wpath);
        file->wpath = 0;

        r->qid = file->qid;

//      if(cons.flags & attachflag)
//              print("9p2: attach %s %T to \"%s\" C%d\n",
//                      chan->whoname, chan->whotime, fs->name, chan->chan);

out:
//      if((cons.flags & attachflag) && error)
//              print("9p2: attach %s %T SUCK EGGS --- %s\n",
//                      f->uname, time(), errstr[error]);
        if(p != nil)
                putbuf(p);
        if(afile != nil)
                qunlock(afile);
        if(file != nil){
                qunlock(file);
                if(error)
                        freefp(file);
        }

        return error;
}

static int
fsflush(Chan* chan, Fcall*, Fcall*)
{
        runlock(&chan->reflock);
        wlock(&chan->reflock);
        wunlock(&chan->reflock);
        rlock(&chan->reflock);

        return 0;
}

static void
clone(File* nfile, File* file)
{
        Wpath *wpath;

        nfile->qid = file->qid;

        lock(&wpathlock);
        nfile->wpath = file->wpath;
        for(wpath = nfile->wpath; wpath != nil; wpath = wpath->up)
                wpath->refs++;
        unlock(&wpathlock);

        nfile->fs = file->fs;
        nfile->addr = file->addr;
        nfile->slot = file->slot;
        nfile->uid = file->uid;
        nfile->cuid = 0;
        nfile->open = file->open & ~FREMOV;
}

static int
walkname(File* file, char* wname, Qid* wqid)
{
        Wpath *w;
        Iobuf *p, *p1;
        Dentry *d, *d1;
        int error, slot;
        long addr, qpath;

        p = p1 = nil;

        /*
         * File must not have been opened for I/O by an open
         * or create message and must represent a directory.
         */
        if(file->open != 0){
                error = Emode;
                goto out;
        }

        p = getbuf(file->fs->dev, file->addr, Bread);
        if(p == nil || checktag(p, Tdir, QPNONE)){
                error = Edir1;
                goto out;
        }
        if((d = getdir(p, file->slot)) == nil || !(d->mode & DALLOC)){
                error = Ealloc;
                goto out;
        }
        if(!(d->mode & DDIR)){
                error = Edir1;
                goto out;
        }
        if(error = mkqidcmp(&file->qid, d))
                goto out;

        /*
         * For walked elements the implied user must
         * have permission to search the directory.
         */
        if(file->cp != cons.chan && iaccess(file, d, DEXEC)){
                error = Eaccess;
                goto out;
        }
        accessdir(p, d, FREAD);

        if(strcmp(wname, ".") == 0){
setdot:
                if(wqid != nil)
                        *wqid = file->qid;
                goto out;
        }
        if(strcmp(wname, "..") == 0){
                if(file->wpath == 0)
                        goto setdot;
                putbuf(p);
                p = nil;
                addr = file->wpath->addr;
                slot = file->wpath->slot;
                p1 = getbuf(file->fs->dev, addr, Bread);
                if(p1 == nil || checktag(p1, Tdir, QPNONE)){
                        error = Edir1;
                        goto out;
                }
                if((d1 = getdir(p1, slot)) == nil || !(d1->mode & DALLOC)){
                        error = Ephase;
                        goto out;
                }
                lock(&wpathlock);
                file->wpath->refs--;
                file->wpath = file->wpath->up;
                unlock(&wpathlock);
                goto found;
        }

        for(addr = 0; ; addr++){
                if(p == nil){
                        p = getbuf(file->fs->dev, file->addr, Bread);
                        if(p == nil || checktag(p, Tdir, QPNONE)){
                                error = Ealloc;
                                goto out;
                        }
                        d = getdir(p, file->slot);
                        if(d == nil ||  !(d->mode & DALLOC)){
                                error = Ealloc;
                                goto out;
                        }
                }
                qpath = d->qid.path;
                p1 = dnodebuf1(p, d, addr, 0);
                p = nil;
                if(p1 == nil || checktag(p1, Tdir, qpath)){
                        error = Eentry;
                        goto out;
                }
                for(slot = 0; slot < DIRPERBUF; slot++){
                        d1 = getdir(p1, slot);
                        if(!(d1->mode & DALLOC))
                                continue;
                        if(strncmp(wname, d1->name, NAMELEN) != 0)
                                continue;
                        /*
                         * update walk path
                         */
                        if((w = newwp()) == nil){
                                error = Ewalk;
                                goto out;
                        }
                        w->addr = file->addr;
                        w->slot = file->slot;
                        w->up = file->wpath;
                        file->wpath = w;
                        slot += DIRPERBUF*addr;
                        goto found;
                }
                putbuf(p1);
                p1 = nil;
        }

found:
        file->addr = p1->addr;
        mkqid(&file->qid, d1, 1);
        putbuf(p1);
        p1 = nil;
        file->slot = slot;
        if(wqid != nil)
                *wqid = file->qid;

out:
        if(p1 != nil)
                putbuf(p1);
        if(p != nil)
                putbuf(p);

        return error;
}

static int
fswalk(Chan* chan, Fcall* f, Fcall* r)
{
        int error, nwname;
        File *file, *nfile, tfile;

        /*
         * The file identified by f->fid must be valid in the
         * current session and must not have been opened for I/O
         * by an open or create message.
         */
        if((file = filep(chan, f->fid, 0)) == nil)
                return Efid;
        if(file->open != 0){
                qunlock(file);
                return Emode;
        }

        /*
         * If newfid is not the same as fid, allocate a new file;
         * a side effect is checking newfid is not already in use (error);
         * if there are no names to walk this will be equivalent to a
         * simple 'clone' operation.
         * Otherwise, fid and newfid are the same and if there are names
         * to walk make a copy of 'file' to be used during the walk as
         * 'file' must only be updated on success.
         * Finally, it's a no-op if newfid is the same as fid and f->nwname
         * is 0.
         */
        r->nwqid = 0;
        if(f->newfid != f->fid){
                if((nfile = filep(chan, f->newfid, 1)) == nil){
                        qunlock(file);
                        return Efidinuse;
                }
        }
        else if(f->nwname != 0){
                nfile = &tfile;
                memset(nfile, 0, sizeof(File));
                nfile->cp = chan;
                nfile->fid = ~0;
        }
        else{
                qunlock(file);
                return 0;
        }
        clone(nfile, file);

        /*
         * Should check name is not too long.
         */
        error = 0;
        for(nwname = 0; nwname < f->nwname; nwname++){
                error = walkname(nfile, f->wname[nwname], &r->wqid[r->nwqid]);
                if(error != 0 || ++r->nwqid >= MAXDAT/sizeof(Qid))
                        break;
        }

        if(f->nwname == 0){
                /*
                 * Newfid must be different to fid (see above)
                 * so this is a simple 'clone' operation - there's
                 * nothing to do except unlock unless there's
                 * an error.
                 */
                if(error){
                        freewp(nfile->wpath);
                        qunlock(nfile);
                        freefp(nfile);
                }
                else
                        qunlock(nfile);
        }
        else if(r->nwqid < f->nwname){
                /*
                 * Didn't walk all elements, 'clunk' nfile
                 * and leave 'file' alone.
                 * Clear error if some of the elements were
                 * walked OK.
                 */
                freewp(nfile->wpath);
                if(nfile != &tfile){
                        qunlock(nfile);
                        freefp(nfile);
                }
                if(r->nwqid != 0)
                        error = 0;
        }
        else{
                /*
                 * Walked all elements. If newfid is the same
                 * as fid must update 'file' from the temporary
                 * copy used during the walk.
                 * Otherwise just unlock (when using tfile there's
                 * no need to unlock as it's a local).
                 */
                if(nfile == &tfile){
                        file->qid = nfile->qid;
                        freewp(file->wpath);
                        file->wpath = nfile->wpath;
                        file->addr = nfile->addr;
                        file->slot = nfile->slot;
                }
                else
                        qunlock(nfile);
        }
        qunlock(file);

        return error;
}

static int
fsopen(Chan* chan, Fcall* f, Fcall* r)
{
        Iobuf *p;
        Dentry *d;
        File *file;
        Tlock *t;
        Qid qid;
        int error, ro, fmod, wok;

        wok = 0;
        p = nil;

        if(chan == cons.chan || writeallow)
                wok = 1;

        if((file = filep(chan, f->fid, 0)) == nil){
                error = Efid;
                goto out;
        }

        /*
         * if remove on close, check access here
         */
        ro = isro(file->fs->dev) || (writegroup && !ingroup(file->uid, writegroup));
        if(f->mode & ORCLOSE){
                if(ro){
                        error = Eronly;
                        goto out;
                }
                /*
                 * check on parent directory of file to be deleted
                 */
                if(file->wpath == 0 || file->wpath->addr == file->addr){
                        error = Ephase;
                        goto out;
                }
                p = getbuf(file->fs->dev, file->wpath->addr, Bread);
                if(p == nil || checktag(p, Tdir, QPNONE)){
                        error = Ephase;
                        goto out;
                }
                if((d = getdir(p, file->wpath->slot)) == nil || !(d->mode & DALLOC)){
                        error = Ephase;
                        goto out;
                }
                if(iaccess(file, d, DWRITE)){
                        error = Eaccess;
                        goto out;
                }
                putbuf(p);
        }
        p = getbuf(file->fs->dev, file->addr, Bread);
        if(p == nil || checktag(p, Tdir, QPNONE)){
                error = Ealloc;
                goto out;
        }
        if((d = getdir(p, file->slot)) == nil || !(d->mode & DALLOC)){
                error = Ealloc;
                goto out;
        }
        if(error = mkqidcmp(&file->qid, d))
                goto out;
        mkqid(&qid, d, 1);
        switch(f->mode & 7){

        case OREAD:
                if(iaccess(file, d, DREAD) && !wok)
                        goto badaccess;
                fmod = FREAD;
                break;

        case OWRITE:
                if((d->mode & DDIR) || (iaccess(file, d, DWRITE) && !wok))
                        goto badaccess;
                if(ro){
                        error = Eronly;
                        goto out;
                }
                fmod = FWRITE;
                break;

        case ORDWR:
                if((d->mode & DDIR)
                || (iaccess(file, d, DREAD) && !wok)
                || (iaccess(file, d, DWRITE) && !wok))
                        goto badaccess;
                if(ro){
                        error = Eronly;
                        goto out;
                }
                fmod = FREAD+FWRITE;
                break;

        case OEXEC:
                if((d->mode & DDIR) || (iaccess(file, d, DEXEC) && !wok))
                        goto badaccess;
                fmod = FREAD;
                break;

        default:
                error = Emode;
                goto out;
        }
        if(f->mode & OTRUNC){
                if((d->mode & DDIR) || (iaccess(file, d, DWRITE) && !wok))
                        goto badaccess;
                if(ro){
                        error = Eronly;
                        goto out;
                }
        }
        t = 0;
        if(d->mode & DLOCK){
                if((t = tlocked(p, d)) == nil){
                        error = Elocked;
                        goto out;
                }
        }
        if(f->mode & ORCLOSE)
                fmod |= FREMOV;
        file->open = fmod;
        if((f->mode & OTRUNC) && !(d->mode & DAPND)){
                dtrunc(p, d);
                qid.vers = d->qid.version;
        }
        r->qid = qid;
        file->tlock = t;
        if(t != nil)
                t->file = file;
        file->lastra = 1;
        goto out;

badaccess:
        error = Eaccess;
        file->open = 0;

out:
        if(p != nil)
                putbuf(p);
        if(file != nil)
                qunlock(file);

        r->iounit = chan->msize-IOHDRSZ;

        return error;
}

static int
dir9p2(Dir* dir, Dentry* dentry, void* strs)
{
        char *op, *p;

        memset(dir, 0, sizeof(Dir));
        mkqid(&dir->qid, dentry, 1);
        dir->mode = (dir->qid.type<<24)|(dentry->mode & 0777);
        dir->atime = dentry->atime;
        dir->mtime = dentry->mtime;
        dir->length = dentry->size;

        op = p = strs;
        dir->name = p;
        p += sprint(p, "%s", dentry->name)+1;

        dir->uid = p;
        uidtostr(p, dentry->uid);
        p += strlen(p)+1;

        dir->gid = p;
        uidtostr(p, dentry->gid);
        p += strlen(p)+1;

        dir->muid = p;
        strcpy(p, "");
        p += strlen(p)+1;

        return p-op;
}

static int
checkname9p2(char* name)
{
        char *p;

        /*
         * Return length of string if valid, 0 if not.
         */
        if(name == nil)
                return 0;

        for(p = name; *p != 0; p++){
                if((*p & 0xFF) <= 040)
                        return 0;
        }

        return p-name;
}

static int
fscreate(Chan* chan, Fcall* f, Fcall* r)
{
        Iobuf *p, *p1;
        Dentry *d, *d1;
        File *file;
        int error, slot, slot1, fmod, wok, l;
        long addr, addr1, path;
        Tlock *t;
        Wpath *w;

        wok = 0;
        p = nil;

        if(chan == cons.chan || writeallow)
                wok = 1;

        if((file = filep(chan, f->fid, 0)) == nil){
                error = Efid;
                goto out;
        }
        if(isro(file->fs->dev) || (writegroup && !ingroup(file->uid, writegroup))){
                error = Eronly;
                goto out;
        }

        p = getbuf(file->fs->dev, file->addr, Bread);
        if(p == nil || checktag(p, Tdir, QPNONE)){
                error = Ealloc;
                goto out;
        }
        if((d = getdir(p, file->slot)) == nil || !(d->mode & DALLOC)){
                error = Ealloc;
                goto out;
        }
        if(error = mkqidcmp(&file->qid, d))
                goto out;
        if(!(d->mode & DDIR)){
                error = Edir2;
                goto out;
        }
        if(iaccess(file, d, DWRITE) && !wok) {
                error = Eaccess;
                goto out;
        }
        accessdir(p, d, FREAD);

        /*
         * Check the name is valid and will fit in an old
         * directory entry.
         */
        if((l = checkname9p2(f->name)) == 0){
                error = Ename;
                goto out;
        }
        if(l+1 > NAMELEN){
                error = Etoolong;
                goto out;
        }
        if(strcmp(f->name, ".") == 0 || strcmp(f->name, "..") == 0){
                error = Edot;
                goto out;
        }

        addr1 = 0;
        slot1 = 0;      /* set */
        for(addr = 0; ; addr++){
                if((p1 = dnodebuf(p, d, addr, 0)) == nil){
                        if(addr1 != 0)
                                break;
                        p1 = dnodebuf(p, d, addr, Tdir);
                }
                if(p1 == nil){
                        error = Efull;
                        goto out;
                }
                if(checktag(p1, Tdir, d->qid.path)){
                        putbuf(p1);
                        goto phase;
                }
                for(slot = 0; slot < DIRPERBUF; slot++){
                        d1 = getdir(p1, slot);
                        if(!(d1->mode & DALLOC)){
                                if(addr1 == 0){
                                        addr1 = p1->addr;
                                        slot1 = slot + addr*DIRPERBUF;
                                }
                                continue;
                        }
                        if(strncmp(f->name, d1->name, sizeof(d1->name)) == 0){
                                putbuf(p1);
                                error = Eexist;
                                goto out;
                        }
                }
                putbuf(p1);
        }

        switch(f->mode & 7){
        case OEXEC:
        case OREAD:             /* seems only useful to make directories */
                fmod = FREAD;
                break;

        case OWRITE:
                fmod = FWRITE;
                break;

        case ORDWR:
                fmod = FREAD+FWRITE;
                break;

        default:
                error = Emode;
                goto out;
        }
        if(f->perm & PDIR)
                if((f->mode & OTRUNC) || (f->perm & PAPND) || (fmod & FWRITE))
                        goto badaccess;
        /*
         * do it
         */
        path = qidpathgen(&file->fs->dev);
        if((p1 = getbuf(file->fs->dev, addr1, Bread|Bimm|Bmod)) == nil)
                goto phase;
        d1 = getdir(p1, slot1);
        if(d1 == nil || checktag(p1, Tdir, d->qid.path)) {
                putbuf(p1);
                goto phase;
        }
        if(d1->mode & DALLOC){
                putbuf(p1);
                goto phase;
        }

        strncpy(d1->name, f->name, sizeof(d1->name));
        if(chan == cons.chan){
                d1->uid = cons.uid;
                d1->gid = cons.gid;
        }
        else{
                d1->uid = file->uid;
                d1->gid = d->gid;
                f->perm &= d->mode | ~0666;
                if(f->perm & PDIR)
                        f->perm &= d->mode | ~0777;
        }
        d1->qid.path = path;
        d1->qid.version = 0;
        d1->mode = DALLOC | (f->perm & 0777);
        if(f->perm & PDIR) {
                d1->mode |= DDIR;
                d1->qid.path |= QPDIR;
        }
        if(f->perm & PAPND)
                d1->mode |= DAPND;
        t = nil;
        if(f->perm & PLOCK){
                d1->mode |= DLOCK;
                t = tlocked(p1, d1);
                /* if nil, out of tlock structures */
        }
        accessdir(p1, d1, FWRITE);
        mkqid(&r->qid, d1, 0);
        putbuf(p1);
        accessdir(p, d, FWRITE);

        /*
         * do a walk to new directory entry
         */
        if((w = newwp()) == nil){
                error = Ewalk;
                goto out;
        }
        w->addr = file->addr;
        w->slot = file->slot;
        w->up = file->wpath;
        file->wpath = w;
        file->qid = r->qid;
        file->tlock = t;
        if(t != nil)
                t->file = file;
        file->lastra = 1;
        if(f->mode & ORCLOSE)
                fmod |= FREMOV;
        file->open = fmod;
        file->addr = addr1;
        file->slot = slot1;
        goto out;

badaccess:
        error = Eaccess;
        goto out;

phase:
        error = Ephase;

out:
        if(p != nil)
                putbuf(p);
        if(file != nil)
                qunlock(file);

        r->iounit = chan->msize-IOHDRSZ;

        return error;
}

static int
fsread(Chan* chan, Fcall* f, Fcall* r)
{
        uchar *data;
        Iobuf *p, *p1;
        File *file;
        Dentry *d, *d1;
        Tlock *t;
        long addr, offset, start, tim;
        int error, iounit, nread, count, n, o, slot;
        Dir dir;
        char strdata[28*10];

        p = nil;
        data = (uchar*)r->data;
        count = f->count;
        offset = f->offset;
        nread = 0;
        if((file = filep(chan, f->fid, 0)) == nil){
                error = Efid;
                goto out;
        }
        if(file->qid.type & QTAUTH){
                nread = authread(file, data, count);
                if(nread < 0)
                        error = Esystem;
                else
                        error = 0;
                goto out;
        }
        if(!(file->open & FREAD)){
                error = Eopen;
                goto out;
        }
        iounit = chan->msize-IOHDRSZ;
        if(count < 0 || count > iounit){
                error = Ecount;
                goto out;
        }
        if(offset < 0){
                error = Eoffset;
                goto out;
        }
        p = getbuf(file->fs->dev, file->addr, Bread);
        if(p == nil || checktag(p, Tdir, QPNONE)){
                error = Ealloc;
                goto out;
        }
        if((d = getdir(p, file->slot)) == nil || !(d->mode & DALLOC)){
                error = Ealloc;
                goto out;
        }
        if(error = mkqidcmp(&file->qid, d))
                goto out;
        if(t = file->tlock){
                tim = time(0);
                if(t->time < tim || t->file != file){
                        error = Ebroken;
                        goto out;
                }
                /* renew the lock */
                t->time = tim + TLOCK;
        }
        accessdir(p, d, FREAD);
        if(d->mode & DDIR)
                goto dread;
        if(offset+count > d->size)
                count = d->size - offset;
        while(count > 0){
                if(p == nil){
                        p = getbuf(file->fs->dev, file->addr, Bread);
                        if(p == nil || checktag(p, Tdir, QPNONE)){
                                error = Ealloc;
                                goto out;
                        }
                        if((d = getdir(p, file->slot)) == nil || !(d->mode & DALLOC)){
                                error = Ealloc;
                                goto out;
                        }
                }
                addr = offset / BUFSIZE;
                o = offset % BUFSIZE;
                n = BUFSIZE - o;
                if(n > count)
                        n = count;
                p1 = dnodebuf1(p, d, addr, 0);
                p = nil;
                if(p1 != nil){
                        if(checktag(p1, Tfile, QPNONE)){
                                error = Ephase;
                                putbuf(p1);
                                goto out;
                        }
                        memmove(data+nread, p1->iobuf+o, n);
                        putbuf(p1);
                }
                else
                        memset(data+nread, 0, n);
                count -= n;
                nread += n;
                offset += n;
        }
        goto out;

dread:
        /*
         * Pick up where we left off last time if nothing has changed,
         * otherwise must scan from the beginning.
         */
        if(offset == file->doffset /*&& file->qid.vers == file->dvers*/){
                addr = file->dslot/DIRPERBUF;
                slot = file->dslot%DIRPERBUF;
                start = offset;
        }
        else{
                addr = 0;
                slot = 0;
                start = 0;
        }

dread1:
        if(p == nil){
                /*
                 * This is just a check to ensure the entry hasn't
                 * gone away during the read of each directory block.
                 */
                p = getbuf(file->fs->dev, file->addr, Bread);
                if(p == nil || checktag(p, Tdir, QPNONE)){
                        error = Ealloc;
                        goto out1;
                }
                if((d = getdir(p, file->slot)) == nil || !(d->mode & DALLOC)){
                        error = Ealloc;
                        goto out1;
                }
        }
        p1 = dnodebuf1(p, d, addr, 0);
        p = nil;
        if(p1 == nil)
                goto out1;
        if(checktag(p1, Tdir, QPNONE)){
                error = Ephase;
                putbuf(p1);
                goto out1;
        }

        for(; slot < DIRPERBUF; slot++){
                d1 = getdir(p1, slot);
                if(!(d1->mode & DALLOC))
                        continue;
                dir9p2(&dir, d1, strdata);
                if((n = convD2M(&dir, data+nread, iounit - nread)) <= BIT16SZ){
                        putbuf(p1);
                        goto out1;
                }
                start += n;
                if(start < offset)
                        continue;
                if(count < n){
                        putbuf(p1);
                        goto out1;
                }
                count -= n;
                nread += n;
                offset += n;
        }
        putbuf(p1);
        slot = 0;
        addr++;
        goto dread1;

out1:
        if(error == 0){
                file->doffset = offset;
                file->dvers = file->qid.vers;
                file->dslot = slot+DIRPERBUF*addr;
        }

out:
        /*
         * Do we need this any more?
        count = f->count - nread;
        if(count > 0)
                memset(data+nread, 0, count);
         */
        if(p != nil)
                putbuf(p);
        if(file != nil)
                qunlock(file);
        r->count = nread;
        r->data = (char*)data;

        return error;
}

static int
fswrite(Chan* chan, Fcall* f, Fcall* r)
{
        Iobuf *p, *p1;
        Dentry *d;
        File *file;
        Tlock *t;
        long offset, addr, tim, qpath;
        int count, error, nwrite, o, n;

        offset = f->offset;
        count = f->count;

        nwrite = 0;
        p = nil;

        if((file = filep(chan, f->fid, 0)) == nil){
                error = Efid;
                goto out;
        }
        if(file->qid.type & QTAUTH){
                nwrite = authwrite(file, (uchar*)f->data, count);
                if(nwrite < 0)
                        error = Esystem;
                else
                        error = 0;
                goto out;
        }
        if(!(file->open & FWRITE)){
                error = Eopen;
                goto out;
        }
        if(isro(file->fs->dev) || (writegroup && !ingroup(file->uid, writegroup))){
                error = Eronly;
                goto out;
        }
        if(count < 0 || count > chan->msize-IOHDRSZ){
                error = Ecount;
                goto out;
        }
        if(offset < 0) {
                error = Eoffset;
                goto out;
        }
        if((p = getbuf(file->fs->dev, file->addr, Bread|Bmod)) == nil){
                error = Ealloc;
                goto out;
        }
        if((d = getdir(p, file->slot)) == nil || !(d->mode & DALLOC)){
                error = Ealloc;
                goto out;
        }
        if(error = mkqidcmp(&file->qid, d))
                goto out;
        if(t = file->tlock) {
                tim = time(0);
                if(t->time < tim || t->file != file){
                        error = Ebroken;
                        goto out;
                }
                /* renew the lock */
                t->time = tim + TLOCK;
        }
        accessdir(p, d, FWRITE);
        if(d->mode & DAPND)
                offset = d->size;
        if(offset+count > d->size)
                d->size = offset+count;
        while(count > 0){
                if(p == nil){
                        p = getbuf(file->fs->dev, file->addr, Bread|Bmod);
                        if((d = getdir(p, file->slot)) == nil || !(d->mode & DALLOC)){
                                error = Ealloc;
                                goto out;
                        }
                }
                addr = offset / BUFSIZE;
                o = offset % BUFSIZE;
                n = BUFSIZE - o;
                if(n > count)
                        n = count;
                qpath = d->qid.path;
                p1 = dnodebuf1(p, d, addr, Tfile);
                p = nil;
                if(p1 == nil) {
                        error = Efull;
                        goto out;
                }
                if(checktag(p1, Tfile, qpath)){
                        putbuf(p1);
                        error = Ephase;
                        goto out;
                }
                memmove(p1->iobuf+o, f->data+nwrite, n);
                p1->flags |= Bmod;
                putbuf(p1);
                count -= n;
                nwrite += n;
                offset += n;
        }

out:
        if(p != nil)
                putbuf(p);
        if(file != nil)
                qunlock(file);
        r->count = nwrite;

        return error;
}

static int
_clunk(File* file, int remove, int wok)
{
        Tlock *t;
        int error;

        error = 0;
        if(t = file->tlock){
                if(t->file == file)
                        t->time = 0;            /* free the lock */
                file->tlock = 0;
        }
        if(remove)
                error = doremove(file, wok);
        file->open = 0;
        freewp(file->wpath);
        freefp(file);
        qunlock(file);

        return error;
}

static int
fsclunk(Chan* chan, Fcall* f, Fcall*)
{
        File *file;

        if((file = filep(chan, f->fid, 0)) == nil)
                return Efid;

        _clunk(file, file->open & FREMOV, 0);
        return 0;
}

static int
fsremove(Chan* chan, Fcall* f, Fcall*)
{
        File *file;

        if((file = filep(chan, f->fid, 0)) == nil)
                return Efid;

        return _clunk(file, 1, chan == cons.chan);
}

static int
fsstat(Chan* chan, Fcall* f, Fcall* r, uchar* data)
{
        Dir dir;
        Iobuf *p;
        Dentry *d;
        File *file;
        int error, len;

        if((file = filep(chan, f->fid, 0)) == nil)
                return Efid;

        p = getbuf(file->fs->dev, file->addr, Bread);
        if(p == nil || checktag(p, Tdir, QPNONE)){
                error = Edir1;
                goto out;
        }
        if((d = getdir(p, file->slot)) == nil || !(d->mode & DALLOC)){
                error = Ealloc;
                goto out;
        }
        if(error = mkqidcmp(&file->qid, d))
                goto out;

        if(d->qid.path == QPROOT)       /* stat of root gives time */
                d->atime = time(0);

        len = dir9p2(&dir, d, data);
        data += len;
        if((r->nstat = convD2M(&dir, data, chan->msize - len)) == 0)
                error = Ersc;
        else
                r->stat = data;

out:
        if(p != nil)
                putbuf(p);
        if(file != nil)
                qunlock(file);

        return error;
}

static int
fswstat(Chan* chan, Fcall* f, Fcall*, char *strs)
{
        Iobuf *p, *p1;
        Dentry *d, *d1, xd;
        File *file;
        int error, slot, uid, gid, l;
        long addr;
        Dir dir;
        ulong mode;

        p = p1 = nil;
        d1 = nil;

        if((file = filep(chan, f->fid, 0)) == nil){
                error = Efid;
                goto out;
        }

        /*
         * if user none,
         * can't do anything
         * unless allow.
         */
        if(file->uid == 0 && !wstatallow){
                error = Eaccess;
                goto out;
        }

        if(isro(file->fs->dev) || (writegroup && !ingroup(file->uid, writegroup))){
                error = Eronly;
                goto out;
        }

        /*
         * first get parent
         */
        if(file->wpath){
                p1 = getbuf(file->fs->dev, file->wpath->addr, Bread);
                if(p1 == nil){
                        error = Ephase;
                        goto out;
                }
                d1 = getdir(p1, file->wpath->slot);
                if(d1 == nil || checktag(p1, Tdir, QPNONE) || !(d1->mode & DALLOC)){
                        error = Ephase;
                        goto out;
                }
        }

        if((p = getbuf(file->fs->dev, file->addr, Bread)) == nil){
                error = Ealloc;
                goto out;
        }
        d = getdir(p, file->slot);
        if(d == nil || checktag(p, Tdir, QPNONE) || !(d->mode & DALLOC)){
                error = Ealloc;
                goto out;
        }
        if(error = mkqidcmp(&file->qid, d))
                goto out;

        /*
         * Convert the message and fix up
         * fields not to be changed.
         */
        if(convM2D(f->stat, f->nstat, &dir, strs) == 0){
                print("9p2: convM2D returns 0\n");
                error = Econvert;
                goto out;
        }
        if(dir.uid == nil || strlen(dir.uid) == 0)
                uid = d->uid;
        else
                uid = strtouid(dir.uid);
        if(dir.gid == nil || strlen(dir.gid) == 0)
                gid = d->gid;
        else
                gid = strtouid(dir.gid);
        if(dir.name == nil || strlen(dir.name) == 0)
                dir.name = d->name;
        else{
                if((l = checkname9p2(dir.name)) == 0){
                        error = Ename;
                        goto out;
                }
                if(l > NAMELEN){
                        error = Etoolong;
                        goto out;
                }
        }

        /*
         * Before doing sanity checks, find out what the
         * new 'mode' should be:
         * if 'type' and 'mode' are both defaults, take the
         * new mode from the old directory entry;
         * else if 'type' is the default, use the new mode entry;
         * else if 'mode' is the default, create the new mode from
         * 'type' or'ed with the old directory mode;
         * else neither are defaults, use the new mode but check
         * it agrees with 'type'.
         */
        if(dir.qid.type == 0xFF && dir.mode == ~0){
                dir.mode = d->mode & 0777;
                if(d->mode & DLOCK)
                        dir.mode |= DMEXCL;
                if(d->mode & DAPND)
                        dir.mode |= DMAPPEND;
                if(d->mode & DDIR)
                        dir.mode |= DMDIR;
        }
        else if(dir.qid.type == 0xFF){
                /* nothing to do */
        }
        else if(dir.mode == ~0)
                dir.mode = (dir.qid.type<<24)|(d->mode & 0777);
        else if(dir.qid.type != ((dir.mode>>24) & 0xFF)){
                error = Eqidmode;
                goto out;
        }

        /*
         * Check for unknown type/mode bits
         * and an attempt to change the directory bit.
         */
        if(dir.mode & ~(DMDIR|DMAPPEND|DMEXCL|0777)){
                error = Enotm;
                goto out;
        }
        if(d->mode & DDIR)
                mode = DMDIR;
        else
                mode = 0;
        if((dir.mode^mode) & DMDIR){
                error = Enotd;
                goto out;
        }

        if(dir.mtime == ~0)
                dir.mtime = d->mtime;
        if(dir.length == ~0)
                dir.length = d->size;

        /*
         * Currently, can't change length.
         */
        if(dir.length != d->size){
                error = Enotl;
                goto out;
        }

        /*
         * if chown,
         * must be god
         * wstatallow set to allow chown during boot
         */
        if(uid != d->uid && !wstatallow) {
                error = Enotu;
                goto out;
        }

        /*
         * if chgroup,
         * must be either
         *      a) owner and in new group
         *      b) leader of both groups
         * wstatallow and writeallow are set to allow chgrp during boot
         */
        while(gid != d->gid) {
                if(wstatallow || writeallow)
                        break;
                if(d->uid == file->uid && ingroup(file->uid, gid))
                        break;
                if(leadgroup(file->uid, gid))
                        if(leadgroup(file->uid, d->gid))
                                break;
                error = Enotg;
                goto out;
        }

        /*
         * if rename,
         * must have write permission in parent
         */
        while(strncmp(d->name, dir.name, sizeof(d->name)) != 0) {
                if(checkname(dir.name) || d1 == nil) {
                        error = Ename;
                        goto out;
                }
                if(strcmp(dir.name, ".") == 0 || strcmp(xd.name, "..") == 0) {
                        error = Ename;
                        goto out;
                }

                /*
                 * drop entry to prevent lock, then
                 * check that destination name is unique,
                 */
                putbuf(p);
                for(addr = 0; ; addr++) {
                        if((p = dnodebuf(p1, d1, addr, 0)) == nil)
                                break;
                        if(checktag(p, Tdir, d1->qid.path)) {
                                putbuf(p);
                                continue;
                        }
                        for(slot = 0; slot < DIRPERBUF; slot++) {
                                d = getdir(p, slot);
                                if(!(d->mode & DALLOC))
                                        continue;
                                if(strncmp(dir.name, d->name, sizeof(d->name)) == 0) {
                                        error = Eexist;
                                        goto out;
                                }
                        }
                        putbuf(p);
                }

                /*
                 * reacquire entry
                 */
                if((p = getbuf(file->fs->dev, file->addr, Bread)) == nil){
                        error = Ephase;
                        goto out;
                }
                d = getdir(p, file->slot);
                if(d == nil || checktag(p, Tdir, QPNONE) || !(d->mode & DALLOC)) {
                        error = Ephase;
                        goto out;
                }

                if(wstatallow || writeallow) /* set to allow rename during boot */
                        break;
                if(d1 == nil || iaccess(file, d1, DWRITE)) {
                        error = Eaccess;
                        goto out;
                }
                break;
        }

        /*
         * if mode/time, either
         *      a) owner
         *      b) leader of either group
         */
        mode = dir.mode & 0777;
        if(dir.mode & DMAPPEND)
                mode |= DAPND;
        if(dir.mode & DMEXCL)
                mode |= DLOCK;
        while(d->mtime != dir.mtime || ((d->mode^mode) & (DAPND|DLOCK|0777))) {
                if(wstatallow)                  /* set to allow chmod during boot */
                        break;
                if(d->uid == file->uid)
                        break;
                if(leadgroup(file->uid, gid))
                        break;
                if(leadgroup(file->uid, d->gid))
                        break;
                error = Enotu;
                goto out;
        }
        d->mtime = dir.mtime;
        d->uid = uid;
        d->gid = gid;
        d->mode = (mode & (DAPND|DLOCK|0777)) | (d->mode & (DALLOC|DDIR));

        strncpy(d->name, dir.name, sizeof(d->name));
        accessdir(p, d, FWSTAT);

out:
        if(p != nil)
                putbuf(p);
        if(p1 != nil)
                putbuf(p1);
        if(file != nil)
                qunlock(file);

        return error;
}

static int
recv(Chan *c, uchar *buf, int n)
{
        int fd, m, len;

        fd = c->chan;
        /* read count */
        qlock(&c->rlock);
        m = readn(fd, buf, BIT32SZ);
        if(m != BIT32SZ){
                qunlock(&c->rlock);
                if(m < 0){
                        print("readn(BIT32SZ) fails: %r\n");
                        return -1;
                }
                print("readn(BIT32SZ) returns %d: %r\n", m);
                return 0;
        }

        len = GBIT32(buf);
        if(len <= BIT32SZ || len > n){
                print("recv bad length %d\n", len);
                werrstr("bad length in 9P2000 message header");
                qunlock(&c->rlock);
                return -1;
        }
        len -= BIT32SZ;
        m = readn(fd, buf+BIT32SZ, len);
        qunlock(&c->rlock);
        if(m < len){
                print("recv wanted %d got %d\n", len, m);
                return 0;
        }
        return BIT32SZ+m;
}

static void
send(Chan *c, uchar *buf, int n)
{
        int fd, m;

        fd = c->chan;
        qlock(&c->wlock);
        m = write(fd, buf, n);
        qunlock(&c->wlock);
        if(m == n)
                return;
        panic("write failed");
}

void
serve9p2(Chan *chan, uchar *ib, int nib)
{
        uchar inbuf[MSIZE+IOHDRSZ], outbuf[MSIZE+IOHDRSZ];
        Fcall f, r;
        char ename[64];
        int error, n, type;

        chan->msize = MSIZE;
        fmtinstall('F', fcallfmt);

        for(;;){
                if(nib){
                        memmove(inbuf, ib, nib);
                        n = nib;
                        nib = 0;
                }else
                        n = recv(chan, inbuf, sizeof inbuf);
                if(chat){
                        print("read msg %d (fd %d)\n", n, chan->chan);
                        if(n <= 0)
                                print("\terr: %r\n");
                }
                if(n == 0 && (chan == cons.srvchan || chan == cons.chan))
                        continue;
                if(n <= 0)
                        break;
                if(convM2S(inbuf, n, &f) != n){
                        print("9p2: cannot decode\n");
                        continue;
                }

                type = f.type;
                if(type < Tversion || type >= Tmax || (type&1) || type == Terror){
                        print("9p2: bad message type %d\n", type);
                        continue;
                }

                if(CHAT(chan))
                        print("9p2: f %F\n", &f);

                r.type = type+1;
                r.tag = f.tag;
                error = 0;

                rlock(&mainlock);
                rlock(&chan->reflock);
                switch(type){
                default:
                        r.type = Rerror;
                        snprint(ename, sizeof ename, "unknown message: %F", &f);
                        r.ename = ename;
                        break;
                case Tversion:
                        error = fsversion(chan, &f, &r);
                        break;
                case Tauth:
                        error = fsauth(chan, &f, &r);
                        break;
                case Tattach:
                        error = fsattach(chan, &f, &r);
                        break;
                case Tflush:
                        error = fsflush(chan, &f, &r);
                        break;
                case Twalk:
                        error = fswalk(chan, &f, &r);
                        break;
                case Topen:
                        error = fsopen(chan, &f, &r);
                        break;
                case Tcreate:
                        error = fscreate(chan, &f, &r);
                        break;
                case Tread:
                        r.data = (char*)inbuf;
                        error = fsread(chan, &f, &r);
                        break;
                case Twrite:
                        error = fswrite(chan, &f, &r);
                        break;
                case Tclunk:
                        error = fsclunk(chan, &f, &r);
                        break;
                case Tremove:
                        error = fsremove(chan, &f, &r);
                        break;
                case Tstat:
                        error = fsstat(chan, &f, &r, inbuf);
                        break;
                case Twstat:
                        error = fswstat(chan, &f, &r, (char*)outbuf);
                        break;
                }
                runlock(&chan->reflock);
                runlock(&mainlock);

                if(error != 0){
                        r.type = Rerror;
                        if(error >= MAXERR){
                                snprint(ename, sizeof(ename), "error %d", error);
                                r.ename = ename;
                        }
                        else
                                r.ename = errstring[error];
                }
                if(CHAT(chan))
                        print("9p2: r %F\n", &r);
        
                n = convS2M(&r, outbuf, sizeof outbuf);
                if(n == 0){
                        type = r.type;
                        r.type = Rerror;
                        snprint(ename, sizeof(ename), "9p2: convS2M: type %d", type);
                        r.ename = ename;
                        print(ename);
                        n = convS2M(&r, outbuf, sizeof outbuf);
                        if(n == 0){
                                /*
                                 * What to do here, the failure notification failed?
                                 */
                                panic("can't write anything at all");
                        }
                }
                send(chan, outbuf, n);
        }
        fileinit(chan);
        close(chan->chan);
        if(chan == cons.srvchan || chan == cons.chan)
                print("console chan read error");
}