#include <fcall.h>

#include <u.h>
#include <libc.h>
#include <fcall.h>
#include "compat.h"
#include "error.h"

extern ulong kerndate;

void
mkqid(Qid *q, vlong path, ulong vers, int type)
{
q->type = type;
q->vers = vers;
q->path = path;
}

int
devno(int c, int user)
{
int i;

for(i = 0; devtab[i] != nil; i++){
if(devtab[i]->dc == c)
return i;
}
if(user == 0)
panic("devno %C 0x%ux", c, c);

return -1;
}

void
devdir(Chan *c, Qid qid, char *n, vlong length, char *user, long perm, Dir *db)
{
db->name = n;
db->qid = qid;
db->type = devtab[c->type]->dc;
db->dev = c->dev;
db->mode = (qid.type << 24) | perm;
db->atime = seconds();
db->mtime = kerndate;
db->length = length;
db->uid = user;
db->gid = eve;
db->muid = user;
}

/*
* the zeroth element of the table MUST be the directory itself for ..
*/
int
devgen(Chan *c, Dirtab *tab, int ntab, int i, Dir *dp)
{
if(tab == 0)
return -1;
if(i != DEVDOTDOT){
i++; /* skip first element for . itself */
if(i >= ntab)
return -1;
tab += i;
}
devdir(c, tab->qid, tab->name, tab->length, eve, tab->perm, dp);
return 1;
}

void
devreset(void)
{
}

void
devinit(void)
{
}

Chan*
devattach(int tc, char *spec)
{
Chan *c;
char *buf;

c = newchan();
mkqid(&c->qid, 0, 0, QTDIR);
c->type = devno(tc, 0);
if(spec == nil)
spec = "";
buf = smalloc(4+strlen(spec)+1);
sprint(buf, "#%C%s", tc, spec);
c->name = newcname(buf);
free(buf);
return c;
}

Chan*
devclone(Chan *c)
{
Chan *nc;

if(c->flag & COPEN)
panic("clone of open file type %C\n", devtab[c->type]->dc);

nc = newchan();

nc->type = c->type;
nc->dev = c->dev;
nc->mode = c->mode;
nc->qid = c->qid;
nc->offset = c->offset;
nc->aux = c->aux;
return nc;
}

Walkqid*
devwalk(Chan *c, Chan *nc, char **name, int nname, Dirtab *tab, int ntab, Devgen *gen)
{
int i, j, alloc;
Walkqid *wq;
char *n;
Dir dir;

isdir(c);

alloc = 0;
wq = smalloc(sizeof(Walkqid)+(nname-1)*sizeof(Qid));
if(waserror()){
if(alloc && wq->clone!=nil)
cclose(wq->clone);
free(wq);
return nil;
}
if(nc == nil){
nc = devclone(c);
nc->type = 0; /* device doesn't know about this channel yet */
alloc = 1;
}
wq->clone = nc;

for(j=0; j<nname; j++){
isdir(nc);
n = name[j];
if(strcmp(n, ".") == 0){
Accept:
wq->qid[wq->nqid++] = nc->qid;
continue;
}
if(strcmp(n, "..") == 0){
(*gen)(nc, tab, ntab, DEVDOTDOT, &dir);
nc->qid = dir.qid;
goto Accept;
}
for(i=0;; i++){
switch((*gen)(nc, tab, ntab, i, &dir)){
case -1:
if(j == 0)
error(Enonexist);
strncpy(up->error, Enonexist, ERRMAX);
goto Done;
case 0:
continue;
case 1:
if(strcmp(n, dir.name) == 0){
nc->qid = dir.qid;
goto Accept;
}
continue;
}
}
}
/*
* We processed at least one name, so will return some data.
* If we didn't process all nname entries succesfully, we drop
* the cloned channel and return just the Qids of the walks.
*/
Done:
poperror();
if(wq->nqid < nname){
if(alloc)
cclose(wq->clone);
wq->clone = nil;
}else if(wq->clone){
/* attach cloned channel to same device */
wq->clone->type = c->type;
}
return wq;
}

int
devstat(Chan *c, uchar *db, int n, Dirtab *tab, int ntab, Devgen *gen)
{
int i;
Dir dir;
char *p, *elem;

for(i=0;; i++)
switch((*gen)(c, tab, ntab, i, &dir)){
case -1:
if(c->qid.type & QTDIR){
if(c->name == nil)
elem = "???";
else if(strcmp(c->name->s, "/") == 0)
elem = "/";
else
for(elem=p=c->name->s; *p; p++)
if(*p == '/')
elem = p+1;
devdir(c, c->qid, elem, 0, eve, DMDIR|0555, &dir);
return convD2M(&dir, db, n);
}

error(Enonexist);
case 0:
break;
case 1:
if(c->qid.path == dir.qid.path){
return convD2M(&dir, db, n);
}
break;
}
}

long
devdirread(Chan *c, char *d, long n, Dirtab *tab, int ntab, Devgen *gen)
{
long k, m, dsz;
struct{
Dir;
char slop[100];
}dir;

k = c->offset;
for(m=0; m<n; k++){
switch((*gen)(c, tab, ntab, k, &dir)){
case -1:
return m;

case 0:
c->offset++; /* BUG??? (was DIRLEN: skip entry) */
break;

case 1:
dsz = convD2M(&dir, (uchar*)d, n-m);
if(dsz <= BIT16SZ){ /* <= not < because this isn't stat; read is stuck */
if(m == 0)
return -1;
return m;
}
m += dsz;
d += dsz;
break;
}
}

return m;
}

/*
* error(Eperm) if open permission not granted for up->user.
*/
void
devpermcheck(char *fileuid, ulong perm, int omode)
{
ulong t;
static int access[] = { 0400, 0200, 0600, 0100 };

if(strcmp(up->user, fileuid) == 0)
perm <<= 0;
else
if(strcmp(up->user, eve) == 0)
perm <<= 3;
else
perm <<= 6;

t = access[omode&3];
if((t&perm) != t)
error(Eperm);
}

Chan*
devopen(Chan *c, int omode, Dirtab *tab, int ntab, Devgen *gen)
{
int i;
Dir dir;

for(i=0;; i++){
switch((*gen)(c, tab, ntab, i, &dir)){
case -1:
goto Return;
case 0:
break;
case 1:
if(c->qid.path == dir.qid.path){
devpermcheck(dir.uid, dir.mode, omode);
goto Return;
}
break;
}
}
Return:
c->offset = 0;
if((c->qid.type&QTDIR) && omode!=OREAD)
error(Eperm);
c->mode = openmode(omode);
c->flag |= COPEN;
return c;
}

void
devcreate(Chan*, char*, int, ulong)
{
error(Eperm);
}

Block*
devbread(Chan *, long, ulong)
{
panic("no block read");
return nil;
}

long
devbwrite(Chan *, Block *, ulong)
{
panic("no block write");
return 0;
}

void
devremove(Chan*)
{
error(Eperm);
}

int
devwstat(Chan*, uchar*, int)
{
error(Eperm);
return 0;
}