kern/src/ns/dev.c

#include <vfs.h>
#include <kfs.h>
#include <slab.h>
#include <kmalloc.h>
#include <kref.h>
#include <string.h>
#include <stdio.h>
#include <assert.h>
#include <error.h>
#include <cpio.h>
#include <pmap.h>
#include <smp.h>
#include <fcall.h>

//extern uint32_t   kerndate;
uint32_t kerndate = 0;

void
mkqid(struct qid *q, int64_t path, uint32_t vers, int type)
{
	q->type = type;
	q->vers = vers;
	q->path = path;
}

void
devdir(struct chan *c, struct qid qid, char *n, int64_t length, char *user,
	   long perm, struct dir *db)
{
	db->name = n;
	if (c->flag & CMSG)
		qid.type |= QTMOUNT;
	db->qid = qid;
	/*
	 * When called via devwalk c->dev is NULL
	 * until the walk succeeds.
	 */
	if (c->dev != NULL)
		db->type = c->dev->dc;
	else
		db->type = -1;
	db->dev = c->devno;
	db->mode = perm;
	db->mode |= qid.type << 24;
	db->atime = 0;	//seconds
	db->mtime = kerndate;
	db->length = length;
	db->uid = user;
	db->gid = eve;
	db->muid = user;
}

/*
 * (here, struct devgen is the prototype; devgen is the function in dev.c.)
 *
 * a struct devgen is expected to return the directory entry for ".."
 * if you pass it s==DEVDOTDOT (-1).  otherwise...
 *
 * there are two contradictory rules.
 *
 * (i) if c is a directory, a struct devgen is expected to list its children
 * as you iterate s.
 *
 * (ii) whether or not c is a directory, a struct devgen is expected to list
 * its siblings as you iterate s.
 *
 * devgen always returns the list of children in the root
 * directory.  thus it follows (i) when c is the root and (ii) otherwise.
 * many other struct devgens follow (i) when c is a directory and (ii) otherwise.
 *
 * devwalk assumes (i).  it knows that devgen breaks (i)
 * for children that are themselves directories, and explicitly catches them.
 *
 * devstat assumes (ii).  if the struct devgen in question follows (i)
 * for this particular c, devstat will not find the necessary info.
 * with our particular struct devgen functions, this happens only for
 * directories, so devstat makes something assuming
 * c->name, c->qid, eve, DMDIR|0555.
 *
 * devdirread assumes (i).  the callers have to make sure
 * that the struct devgen satisfies (i) for the chan being read.
 */
/*
 * the zeroth element of the table MUST be the directory itself for ..
*/
int
devgen(struct chan *c, char *name, struct dirtab *tab, int ntab, int i,
	   struct dir *dp)
{
	if (tab == 0)
		return -1;
	if (i == DEVDOTDOT) {
		/* nothing */
	} else if (name) {
		for (i = 1; i < ntab; i++)
			if (strcmp(tab[i].name, name) == 0)
				break;
		if (i == ntab)
			return -1;
		tab += i;
	} else {
		/* skip over the first element, that for . itself */
		i++;
		if (i >= ntab)
			return -1;
		tab += i;
	}
	devdir(c, tab->qid, tab->name, tab->length, eve, tab->perm, dp);
	return 1;
}

void devreset()
{
}

void devinit()
{
}

void devshutdown()
{
}

struct chan *devattach(int dc, char *spec)
{
	struct chan *c;
	char *buf;
	int len = strlen(spec) + 2 + 1;	/* 2 for #c, 1 for \0 */
	/*
	 * There are no error checks here because
	 * this can only be called from the driver of dc
	 * which pretty much guarantees devtabget will
	 * succeed.
	 */
	c = newchan();
	mkqid(&c->qid, 0, 0, QTDIR);
	c->dev = devtabget(dc, 0);
	if (spec == NULL)
		spec = "";
	buf = kzmalloc(len, KMALLOC_WAIT);
	snprintf(buf, len, "#%c%s", dc, spec);
	c->path = newpath(buf);
	kfree(buf);
	return c;
}

struct chan *devclone(struct chan *c)
{
	struct chan *nc;

	if (c->flag & COPEN) {
		panic("devclone: file of type %c already open\n",
			  c->dev != NULL ? c->dev->dc : -1);
	}

	nc = newchan();

	/*
	 * The caller fills dev in if and when necessary.
	 nc->dev = NULL;                    //XDYNXX
	 */
	nc->devno = c->devno;
	nc->mode = c->mode;
	nc->qid = c->qid;
	nc->offset = c->offset;
	nc->umh = NULL;
	nc->aux = c->aux;
	nc->mqid = c->mqid;
	nc->mc = c->mc;
	return nc;
}

struct walkqid *devwalk(struct chan *c, struct chan *nc, char **name, int nname,
						struct dirtab *tab, int ntab, devgen_t * gen)
{
	ERRSTACK(2);
	int i, j;
	volatile int alloc;	/* to keep waserror from optimizing this out */
	struct walkqid *wq;
	char *n;
	struct dir dir;

	if (nname > 0)
		isdir(c);
	alloc = 0;
	wq = kzmalloc(sizeof(struct walkqid) + (nname) * sizeof(struct qid),
				  KMALLOC_WAIT);
	if (waserror()) {
		if (alloc && wq->clone != NULL)
			cclose(wq->clone);
		kfree(wq);
		poperror();
		return NULL;
	}
	if (nc == NULL) {
		nc = devclone(c);
		/*
		 * nc->dev remains NULL for now.        //XDYNX
		 */
		alloc = 1;
	}
	wq->clone = nc;
	dir.qid.path = 0;
	for (j = 0; j < nname; j++) {
		if (!(nc->qid.type & QTDIR)) {
			if (j == 0)
				error(Enotdir);
			goto Done;
		}
		n = name[j];
		if (strcmp(n, ".") == 0) {
Accept:
			wq->qid[wq->nqid++] = nc->qid;
			continue;
		}
		if (strcmp(n, "..") == 0) {
			/*
			 * Use c->dev->name in the error because
			 * nc->dev should be NULL here.
			 */
			if ((*gen) (nc, NULL, tab, ntab, DEVDOTDOT, &dir) != 1) {
				printk("devgen walk .. in dev%s %#llux broken\n",
					   c->dev->name, nc->qid.path);
				error("broken devgen");
			}
			nc->qid = dir.qid;
			goto Accept;
		}
		/*
		 * Ugly problem: If we're using devgen, make sure we're
		 * walking the directory itself, represented by the first
		 * entry in the table, and not trying to step into a sub-
		 * directory of the table, e.g. /net/net. struct devgen itself
		 * should take care of the problem, but it doesn't have
		 * the necessary information (that we're doing a walk).
		 */
		if (gen == devgen && nc->qid.path != tab[0].qid.path)
			goto Notfound;
		dir.qid.path = 0;
		for (i = 0;; i++) {
			switch ((*gen) (nc, n, tab, ntab, i, &dir)) {
				case -1:
Notfound:
					if (j == 0)
						error(Enonexist);
					set_errstr(Enonexist);
					goto Done;
				case 0:
					continue;
				case 1:
					printd("DEVWALK looking for %s, found %s, path %p", n,
					       dir.name, dir.qid.path);
					if (strcmp(n, dir.name) == 0) {
						printd(" MATCH!\n");
						nc->qid = dir.qid;
						goto Accept;
					}
					printd("\n");
					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 struct qids of the walks.
	 */
Done:
	poperror();
	if (wq->nqid < nname) {
		if (alloc)
			cclose(wq->clone);
		wq->clone = NULL;
	} else if (wq->clone) {
		/* attach cloned channel to same device */
//what goes here:                   //XDYNX
// ->dev must be NULL because can't walk an open chan, right?
// what about ref count on dev?
		wq->clone->dev = c->dev;
		//if(wq->clone->dev)            //XDYNX
		//  devtabincr(wq->clone->dev);
	}
	return wq;
}

long
devstat(struct chan *c, uint8_t * db, long n, struct dirtab *tab, int ntab,
		devgen_t * gen)
{
	int i;
	struct dir dir;
	char *p, *elem;

	printd("\nFresh Devstat, chan path %p\n", c->qid.path);
	dir.qid.path = 0;
	for (i = 0;; i++) {
		switch ((*gen) (c, NULL, tab, ntab, i, &dir)) {
			case -1:
				if (c->qid.type & QTDIR) {
					if (c->path == NULL)
						elem = "???";
					else if (strcmp(c->path->s, "/") == 0)
						elem = "/";
					else
						for (elem = p = c->path->s; *p; p++)
							if (*p == '/')
								elem = p + 1;
					devdir(c, c->qid, elem, 0, eve, DMDIR | 0555, &dir);
					n = convD2M(&dir, db, n);
					if (n == 0)
						error(Ebadarg);
					return n;
				}
				error(Enonexist);
			case 0:
				printd("DEVSTAT got 0\n");
				break;
			case 1:
				printd("DEVSTAT gen returns path %p name %s, want path %p\n", 
				       dir.qid.path, dir.name, c->qid.path);
				if (c->qid.path == dir.qid.path) {
					if (c->flag & CMSG)
						dir.mode |= DMMOUNT;
					n = convD2M(&dir, db, n);
					if (n == 0)
						error(Ebadarg);
					return n;
				}
				break;
		}
	}
}

long
devdirread(struct chan *c, char *d, long n, struct dirtab *tab, int ntab,
		   devgen_t * gen)
{
	long m, dsz;
	struct dir dir;

	dir.qid.path = 0;
	for (m = 0; m < n; c->dri++) {
		switch ((*gen) (c, NULL, tab, ntab, c->dri, &dir)) {
			case -1:
				return m;

			case 0:
				break;

			case 1:
				dsz = convD2M(&dir, (uint8_t *) d, n - m);
				if (dsz <= BIT16SZ) {	/* <= not < because this isn't stat; read is stuck */
					if (m == 0)
						error(Eshort);
					return m;
				}
				m += dsz;
				d += dsz;
				break;
		}
	}

	return m;
}

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

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

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

struct chan *devopen(struct chan *c, int omode, struct dirtab *tab, int ntab,
					 devgen_t * gen)
{
	int i;
	struct dir dir;

	dir.qid.path = 0;
	for (i = 0;; i++) {
		switch ((*gen) (c, NULL, 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(struct chan *a, char *b, int c, int d)
{
	error(Eperm);
}

/* no analog in akaros yet. */

struct block *devbread(struct chan *c, long n, int64_t offset)
{
	ERRSTACK(2);
	struct block *bp;

	bp = allocb(n);
	if (bp == 0)
		error(Enomem);
	if (waserror()) {
		freeb(bp);
		nexterror();
	}
	bp->wp += c->dev->read(c, bp->wp, n, offset);
	poperror();
	return bp;
}

long
devbwrite(struct chan *c, struct block *bp, int64_t offset)
{
	ERRSTACK(2);
	long n;

	if (waserror()) {
		freeb(bp);
		nexterror();
	}
	n = c->dev->write(c, bp->rp, BLEN(bp), offset);
	poperror();
	freeb(bp);

	return n;
}

void devremove(struct chan *c)
{
	error(Eperm);
}

long devwstat(struct chan *c, uint8_t * a, long b)
{
	error(Eperm);
	return 0;
}

void devpower(int onoff)
{
	error(Eperm);
}

int devconfig(int a, char *b, void *v)
{
	error(Eperm);
	return 0;
}

char *devchaninfo(struct chan *chan, char *ret, size_t ret_l)
{
	snprintf(ret, ret_l, "qid.path: %p, qid.type: %02x\n", chan->qid.path,
	         chan->qid.type);
	return ret;
}