net: don't return io.EOF from zero byte reads on Plan 9

Updates #15735.
Fixes #15741.

Change-Id: Ic4ad7e948e8c3ab5feffef89d7a37417f82722a1
Reviewed-on: https://go-review.googlesource.com/23199
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/net/fd_plan9.go b/src/net/fd_plan9.go
index 8e272b1eb85e53b3cfc2abc8a14a5c465133a841..7533232dc9b5eb27c3b74b584f2b4efcf1779220 100644 (file)
--- a/src/net/fd_plan9.go
+++ b/src/net/fd_plan9.go
@@ -76,6 +76,9 @@ func (fd *netFD) Read(b []byte) (n int, err error) {
                return 0, err
        }
        defer fd.readUnlock()
+       if len(b) == 0 {
+               return 0, nil
+       }
        n, err = fd.data.Read(b)
        if isHangup(err) {
                err = io.EOF