a

kern/dev.c

@@ -0,0 +1,468 @@
+#include	"u.h"
+#include	"lib.h"
+#include	"dat.h"
+#include	"fns.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;
+	if(c->flag&CMSG)
+		qid.type |= QTMOUNT;
+	db->qid = qid;
+	db->type = devtab[c->type]->dc;
+	db->dev = c->dev;
+	db->mode = perm;
+	db->mode |= qid.type << 24;
+	db->atime = seconds();
+	db->mtime = kerndate;
+	db->length = length;
+	db->uid = user;
+	db->gid = eve;
+	db->muid = user;
+}
+
+/*
+ * (here, Devgen is the prototype; devgen is the function in dev.c.)
+ * 
+ * a 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 Devgen is expected to list its children
+ * as you iterate s.
+ * 
+ * (ii) whether or not c is a directory, a 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 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 Devgen in question follows (i)
+ * for this particular c, devstat will not find the necessary info.
+ * with our particular Devgen functions, this happens only for
+ * directories, so devstat makes something up, assuming
+ * c->name, c->qid, eve, DMDIR|0555.
+ * 
+ * devdirread assumes (i).  the callers have to make sure
+ * that the Devgen satisfies (i) for the chan being read.
+ */
+/*
+ * the zeroth element of the table MUST be the directory itself for ..
+*/
+int
+devgen(Chan *c, char *name, Dirtab *tab, int ntab, int i, 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)
+{
+}
+
+void
+devinit(void)
+{
+}
+
+void
+devshutdown(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->umh = nil;
+	nc->mountid = c->mountid;
+	nc->aux = c->aux;
+	nc->pgrpid = c->pgrpid;
+	nc->mid = c->mid;
+	nc->mqid = c->mqid;
+	nc->mcp = c->mcp;
+	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;
+
+	if(nname > 0)
+		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++){
+		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){
+			if((*gen)(nc, nil, tab, ntab, DEVDOTDOT, &dir) != 1){
+				print("devgen walk .. in dev%s %llux broken\n",
+					devtab[nc->type]->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. 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;
+		for(i=0;; i++) {
+			switch((*gen)(nc, n, tab, ntab, i, &dir)){
+			case -1:
+			Notfound:
+				if(j == 0)
+					error(Enonexist);
+				kstrcpy(up->errstr, 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, nil, 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);
+				n = convD2M(&dir, db, n);
+				if(n == 0)
+					error(Ebadarg);
+				return n;
+			}
+			print("devstat %C %llux\n", devtab[c->type]->dc, c->qid.path);
+
+			error(Enonexist);
+		case 0:
+			break;
+		case 1:
+			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;
+		}
+	error(Egreg);	/* not reached? */
+	return -1;
+}
+
+long
+devdirread(Chan *c, char *d, long n, Dirtab *tab, int ntab, Devgen *gen)
+{
+	long m, dsz;
+	struct{
+		Dir d;
+		char slop[100];
+	}dir;
+
+	for(m=0; m<n; c->dri++) {
+		switch((*gen)(c, nil, tab, ntab, c->dri, &dir.d)){
+		case -1:
+			return m;
+
+		case 0:
+			break;
+
+		case 1:
+			dsz = convD2M(&dir.d, (uchar*)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, 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, nil, 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 *c, char *name, int mode, ulong perm)
+{
+	USED(c);
+	USED(name);
+	USED(mode);
+	USED(perm);
+
+	error(Eperm);
+}
+
+Block*
+devbread(Chan *c, long n, ulong offset)
+{
+	Block *bp;
+
+	bp = allocb(n);
+	if(bp == 0)
+		error(Enomem);
+	if(waserror()) {
+		freeb(bp);
+		nexterror();
+	}
+	bp->wp += devtab[c->type]->read(c, bp->wp, n, offset);
+	poperror();
+	return bp;
+}
+
+long
+devbwrite(Chan *c, Block *bp, ulong offset)
+{
+	long n;
+
+	if(waserror()) {
+		freeb(bp);
+		nexterror();
+	}
+	n = devtab[c->type]->write(c, bp->rp, BLEN(bp), offset);
+	poperror();
+	freeb(bp);
+
+	return n;
+}
+
+void
+devremove(Chan *c)
+{
+	USED(c);
+	error(Eperm);
+}
+
+int
+devwstat(Chan *c, uchar *a, int n)
+{
+	USED(c);
+	USED(a);
+	USED(n);
+
+	error(Eperm);
+	return 0;
+}
+
+void
+devpower(int a)
+{
+	USED(a);
+	error(Eperm);
+}
+
+int
+devconfig(int a, char *b, DevConf *c)
+{
+	USED(a);
+	USED(b);
+	USED(c);
+	error(Eperm);
+	return 0;
+}