commit 9d3499d9f33f98776fe06479a43da5eafaea2e7f
from: Stephen J Day <stephen.day@docker.com>
date: Fri Oct 30 04:35:49 2015 UTC

fs/p9p/new: fix cat command in 9pr

Signed-off-by: Stephen J Day <stephen.day@docker.com>

commit - 25c156598b90f01e3b80c2b1ddb8ab8c913d1139
commit + 9d3499d9f33f98776fe06479a43da5eafaea2e7f
blob - c3dc81061964b298f379e9139ccf77ae9781000f
blob + 25b2080e9f954172c4073e32232291a5f7030dbb
--- cmd/9pr/main.go
+++ cmd/9pr/main.go
@@ -305,13 +305,18 @@ func (c *fsCommander) cmdcat(ctx context.Context, args
 	}
 	defer c.session.Clunk(ctx, c.pwdfid)
 
-	_, msize, err := c.session.Open(ctx, targetfid, p9pnew.OREAD)
+	_, iounit, err := c.session.Open(ctx, targetfid, p9pnew.OREAD)
 	if err != nil {
 		return err
 	}
 
-	b := make([]byte, msize)
+	if iounit < 1 {
+		msize, _ := c.session.Version()
+		iounit = msize - 24 // size of message max minus fcall io header (Rread)
+	}
 
+	b := make([]byte, iounit)
+
 	n, err := c.session.Read(ctx, targetfid, b, 0)
 	if err != nil {
 		return err