#include	"u.h"
#include	"../port/lib.h"
#include	"mem.h"
#include	"dat.h"
#include	"fns.h"
#include	"../port/error.h"
#include	"kexec.h"

enum
{
	Maxkexecsize = 16300,
};

int kxdbg = 0;
#define KXDBG if(!kxdbg) {} else print



static Kexecgrp	*kexecgrp(Chan *c);
static int	kexecwriteable(Chan *c);


static Kexecgrp	kgrp;	/* global kexec group containing the kernel configuration */

static Kvalue*
kexeclookup(Kexecgrp *kg, uintptr addr, ulong qidpath)
{
	Kvalue *e;
	int i;

	for(i=0; i<kg->nent; i++){
		e = kg->ent[i];
		if(e->qid.path == qidpath || e->addr==addr)
			return e;
	}
	return nil;
}

static int
kexecgen(Chan *c, char *name, Dirtab*, int, int s, Dir *dp)
{
	Kexecgrp *kg;
	Kvalue *e;
	uintptr addr;

	print("starting gen name %s\n", name);

	if(s == DEVDOTDOT){
		devdir(c, c->qid, "#§", 0, eve, DMDIR|0775, dp);
		return 1;
	}
	print("getting kg name %s\n", name);
	
	kg = kexecgrp(c);
	rlock(kg);
	e = 0;
	if(name) {
		addr = strtoull(name, nil, 0);
		print("got addr %p\n", addr);

		e = kexeclookup(kg, addr, -1);
	}else if(s < kg->nent)
		e = kg->ent[s];

	if(e == 0) {
		runlock(kg);
		return -1;
	}

	/* make sure name string continues to exist after we release lock */
	// how will we free this?
	snprint(up->genbuf, sizeof up->genbuf, "0x%p", addr);
	print("up->genbuf %s e 0x%p\n", up->genbuf, e);
	print("e qid %d e->addr 0x%p size %ld len %ld\n", e->qid, e->addr, e->size, e->len);

	devdir(c, e->qid, up->genbuf, e->len, eve, 0666, dp);
	runlock(kg);
	print("finished gen\n");
	
	return 1;
}

#define QPATH(p,d,t)    ((p)<<16 | (d)<<8 | (t)<<0)

static Chan*
kexecattach(char *spec)
{
	Chan *c;
//	Kexecgrp *kgrp = nil;
        Qid qid;
	

	c = devattach(L'§', spec);
	c->aux = &kgrp;
	return c;
}

static Walkqid*
kexecwalk(Chan *c, Chan *nc, char **name, int nname)
{
	return devwalk(c, nc, name, nname, 0, 0, kexecgen);
}


static long
kexecstat(Chan *c, uchar *db, long n)
{
	long nn;

	if(c->qid.type & QTDIR)
		c->qid.vers = kexecgrp(c)->vers;
	nn = devstat(c, db, n, 0, 0, kexecgen);

	return nn;
}

static Chan*
kexecopen(Chan *c, int omode)
{
	Kexecgrp *kg;
	Kvalue *e;
	int trunc;

	kg = kexecgrp(c);
	if(c->qid.type & QTDIR) {
		if(omode != OREAD)
			error(Eperm);
	}else {
		trunc = omode & OTRUNC;
		if(omode != OREAD && !kexecwriteable(c))
			error(Eperm);
		if(trunc)
			wlock(kg);
		else
			rlock(kg);
		e = kexeclookup(kg, 0, c->qid.path);
		if(e == 0) {
			if(trunc)
				wunlock(kg);
			else
				runlock(kg);
			error(Enonexist);
		}
		if(trunc && e->size) { // better validity check?
			e->qid.vers++;
			e->size = 0;
			e->len = 0;
		}
		if(trunc)
			wunlock(kg);
		else
			runlock(kg);
	}
	c->mode = openmode(omode);
	c->flag |= COPEN;
	c->offset = 0;
	return c;
}

static void
kexeccreate(Chan *c, char *name, int omode, int)
{
	Kexecgrp *kg;
	Kvalue *e;
	Kvalue **ent;
	uintptr addr;

	addr = strtoull(name, nil, 0);

	if(c->qid.type != QTDIR)
		error(Eperm);

	omode = openmode(omode);
	kg = kexecgrp(c);

	wlock(kg);
	if(waserror()) {
		wunlock(kg);
		nexterror();
	}

	if(kexeclookup(kg, addr, -1))
		error(Eexist);

	e = smalloc(sizeof(Kvalue));
	e->addr = addr;

	if(kg->nent == kg->ment){
		kg->ment += 32;
		ent = smalloc(sizeof(kg->ent[0])*kg->ment);
		if(kg->nent)
			memmove(ent, kg->ent, sizeof(kg->ent[0])*kg->nent);
		free(kg->ent);
		kg->ent = ent;
	}
	e->qid.path = ++kg->path;
	e->qid.vers = 0;
	kg->vers++;
	kg->ent[kg->nent++] = e;
	c->qid = e->qid;

	wunlock(kg);
	poperror();

	c->offset = 0;
	c->mode = omode;
	c->flag |= COPEN;
}

static void
kexecremove(Chan *c)
{
	int i;
	Kexecgrp *kg;
	Kvalue *e;

	if(c->qid.type & QTDIR)
		error(Eperm);

	kg = kexecgrp(c);
	wlock(kg);
	e = 0;
	for(i=0; i<kg->nent; i++){
		if(kg->ent[i]->qid.path == c->qid.path){
			e = kg->ent[i];
			kg->nent--;
			kg->ent[i] = kg->ent[kg->nent];
			kg->vers++;
			break;
		}
	}
	wunlock(kg);
	if(e == 0)
		error(Enonexist);
	free(e);
}

static void
kexecclose(Chan *c)
{
	/*
	 * cclose can't fail, so errors from remove will be ignored.
	 * since permissions aren't checked,
	 * kexecremove can't not remove it if its there.
	 */
	if(c->flag & CRCLOSE)
		kexecremove(c);
}

static long
kexecread(Chan *c, void *a, long n, vlong off)
{
	Kexecgrp *kg;
	Kvalue *e;
	long offset;

	if(c->qid.type & QTDIR)
		return devdirread(c, a, n, 0, 0, kexecgen);

	kg = kexecgrp(c);
	rlock(kg);
	e = kexeclookup(kg, 0, c->qid.path);
	if(e == 0) {
		runlock(kg);
		error(Enonexist);
	}

	offset = off;
	if(offset > e->len)	/* protects against overflow converting vlong to long */
		n = 0;
	else if(offset + n > e->len)
		n = e->len - offset;
	if(n <= 0)
		n = 0;
//	else
//		memmove(a, e->value+offset, n);
	runlock(kg);
	return n;
}

/*

need to make slots. the slots themselves can be set somewhere else.

need make the writes 

open will handle the parsing of the hex numbers.

no, do it the other way around. just define the slots. 
can work on the interface later. 

kmap the space where the values need to stay safe. 

then when that is correct you can do it the other. 

kmap address range
put it in 


write is going to be significantly different. 

the first thing to do is to make this just work. 
	add to the kernel cfg.

*/

static long
kexecwrite(Chan *c, void *a, long n, vlong off)
{
	Kexecgrp *kg;
	Kvalue *e;
	long offset;

	if(n <= 0)
		return 0;
	offset = off;
	if(offset > Maxkexecsize || n > (Maxkexecsize - offset))
		error(Etoobig);
	print("a: %s\n", a);
	kg = kexecgrp(c);
	wlock(kg);
	e = kexeclookup(kg, 0, c->qid.path);
	if(e == 0) {
		wunlock(kg);
		error(Enonexist);
	}

	// XXX: what to do with what is written?

	e->qid.vers++;
	kg->vers++;
	wunlock(kg);
	return n;
}

Dev kexecdevtab = {
	L'§',
	"kexec",

	devreset,
	devinit,
	devshutdown,
	kexecattach,
	kexecwalk,
	kexecstat,
	kexecopen,
	kexeccreate,
	kexecclose,
	kexecread,
	devbread,
	kexecwrite,
	devbwrite,
	kexecremove,
	devwstat,
};

void
kexeccpy(Kexecgrp *to, Kexecgrp *from)
{
	int i;
	Kvalue *ne, *e;

	rlock(from);
	to->ment = (from->nent+31)&~31;
	to->ent = smalloc(to->ment*sizeof(to->ent[0]));
	for(i=0; i<from->nent; i++){
		e = from->ent[i];
		ne = smalloc(sizeof(Kvalue));
		ne->addr = e->addr;
		ne->size = e->size;
		ne->qid.path = ++to->path;
		to->ent[i] = ne;
	}
	to->nent = from->nent;
	runlock(from);
}

void
closekgrp(Kexecgrp *kg)
{
	int i;
	Kvalue *e;

	if(decref(kg) == 0){
		for(i=0; i<kg->nent; i++){
			e = kg->ent[i];
			free(e);
		}
		free(kg->ent);
		free(kg);
	}
}

static Kexecgrp*
kexecgrp(Chan *c)
{
	if(c->aux == nil)
		return &kgrp;
	return c->aux;
}

static int
kexecwriteable(Chan *c)
{
	return iseve() || c->aux == nil;
}