commit a6036d0f379802f758a29f876bfade2bd53a3c40
from: Omar Polo <op@omarpolo.com>
date: Tue Dec 21 17:04:57 2021 UTC

ensure that a walk with zero paths don't replies with a qid

A walk of zero paths is used to duplicate a fid.  it doesn't make sense
to reply with a body containing the qid relative to the file, because
it's not a real walk, it's just a duplication.  Furthermore, it would
break the expectations that the number of qid returned is less or equal
to the walked components.

commit - a72c4af60ba6e38d8025562a9f073fd95d163197
commit + a6036d0f379802f758a29f876bfade2bd53a3c40
blob - 5dee77d3c2edb602fb3b668eb6f88ed3472d854f
blob + 4241d5adf869284cced71791e2faa7645639ba54
--- client.c
+++ client.c
@@ -1040,7 +1040,7 @@ twalk(struct np_msg_header *hdr, const uint8_t *data, 
 		if (nf == NULL && (nf = new_fid(f->qid, newfid)) == NULL)
 			fatal("new_fid duplication");
 
-		np_walk(hdr->tag, 1, f->qid);
+		np_walk(hdr->tag, 0, NULL);
 		return;
 	}
 
blob - b916ec1968612dd7186765cffe9e0844c068c637
blob + 382139a46e99c9528b458d83d64e222316f8809d
--- regress/walk-suite.9ps
+++ regress/walk-suite.9ps
@@ -52,3 +52,13 @@ testing "walk with an invalid component" dir "./root" 
 	walk(0, 1, "/non-exists")
 	expect-error()
 }
+
+testing "zero-path walk don't reply with a qid" dir "./root" {
+	mount(0, "/")
+	walk(0, 1)
+	m = recv()
+	assert (
+		m.type == Rwalk
+		m.nwqid == 0
+	)
+}