Related to issue

http://bitbucket.org/rsc/plan9port/issue/38/

This patch tries to make 9pserve work again with
9P2000 clients, in case the server handled by 9pserve
expects 9P2000.u.

(Since changeset
http://bitbucket.org/rsc/plan9port/changeset/d9843471f0bc/
servers using srv() stop communicating after they
received a 9P2000 msg that has a different .u
definition.)

Tattach, Tauth and Tcreate 9P2000 messages will
be translated now, if neccessary, to 9P2000.u by
growing them to the new size, and providing the
missing (default) values.

The code of the first two message types has been
tested with drawterm on linux (dialing factotum),
and mounts from within 9vx to plan9port's factotum
and dossrv.

The code for Tcreate couldn't be tested due to lack
of file servers both speaking 9P2000.u and allowing file
creation.

R=rsc_swtch, rsc
CC=codebot
http://codereview.appspot.com/151052

1 files changed, 53 insertions, 0 deletions

diff --git a/src/cmd/9pserve.c b/src/cmd/9pserve.c
index 8e03843a..264b34b6 100644
--- a/src/cmd/9pserve.c
+++ b/src/cmd/9pserve.c
@@ -132,6 +132,8 @@ int timefmt(Fmt*);
 void dorootstat(void);
 int stripudirread(Msg*);
 int cvtustat(Fcall*, uchar**, int);
+void cvtuauthattach(Fcall*, uchar**);
+void cvtucreate(Fcall*, uchar**);
 
 void
 usage(void)
@@ -439,6 +441,8 @@ connthread(void *arg)
 				m->tx.uname = getuser();	/* what srv.c used */
 				repack(&m->tx, &m->tpkt, c->dotu);
 			}
+			if(dotu && !c->dotu)
+				cvtuauthattach(&m->tx, &m->tpkt);
 			break;
 		case Twalk:
 			if((m->fid = gethash(c->fid, m->tx.fid)) == nil){
@@ -473,12 +477,16 @@ connthread(void *arg)
 				continue;
 			}
 			m->afid->ref++;
+			if(dotu && !c->dotu)
+				cvtuauthattach(&m->tx, &m->tpkt);
 			break;
 		case Tcreate:
 			if(dotu && !c->dotu && (m->tx.perm&(DMSYMLINK|DMDEVICE|DMNAMEDPIPE|DMSOCKET))){
 				err(m, "unsupported file type");
 				continue;
 			}
+			if(dotu && !c->dotu)
+				cvtucreate(&m->tx, &m->tpkt);
 			goto caseTopen;
 		case Topenfd:
 			if(m->tx.mode&~(OTRUNC|3)){
@@ -1532,3 +1540,48 @@ stripudirread(Msg* msg)
 	return 0;
 }
 
+void*
+updateptr(uchar *p0, uchar *p0old, void *p)
+{
+	return p0 + ((uchar*)p - p0old);
+}
+
+uchar*
+growpkt(uchar **ppkt, int sz)
+{
+	int n;
+	uchar *ap, *pkt;
+
+	pkt = *ppkt;
+	n = GBIT32(pkt);
+	pkt = erealloc(pkt, n+sz);
+	PBIT32(pkt, n+sz);
+	ap = &pkt[n];
+	memset(ap, 0, sz);
+	*ppkt = pkt;
+	return ap;	
+}
+void
+cvtuauthattach(Fcall *f, uchar **ppkt)
+{
+	uchar *opkt, *ap;
+	
+	opkt = *ppkt;
+	ap = growpkt(ppkt, BIT32SZ);
+	PBIT32(ap, NOUID);
+
+	if(*ppkt != opkt){
+		f->uname = updateptr(*ppkt, opkt, f->uname);
+		f->aname = updateptr(*ppkt, opkt, f->aname);
+	}
+}
+void
+cvtucreate(Fcall *f, uchar **ppkt)
+{
+	uchar *opkt;
+
+	opkt = *ppkt;
+	growpkt(ppkt, BIT16SZ);	/* add an empty `extension' */
+	if(*ppkt != opkt)
+		f->name = updateptr(*ppkt, opkt, f->name);
+}