From: Akshat Kumar <seed@mail.nanosouffle.net>
Date: Sun, 23 Sep 2012 22:30:28 +0000 (+1000)
Subject: pkg/go/ast: Avoid doing zero-length writes to the fd.
X-Git-Tag: go1.1rc2~2365
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=659d1df1bcd44ec6bb92f9592a8c92670d862d3c;p=gostls13.git

pkg/go/ast: Avoid doing zero-length writes to the fd.

After each line, ast.Print would do a zero-length write,
which would hit the boundary condition on Plan 9 when
reading over pipes (since message boundaries are
preserved). This change makes sure we only do positive-
length writes.

R=rsc, rminnich, dave, r
CC=golang-dev
https://golang.org/cl/6558046
---

diff --git a/src/pkg/go/ast/print.go b/src/pkg/go/ast/print.go
index 2de9af299e..4a1ce480f4 100644
--- a/src/pkg/go/ast/print.go
+++ b/src/pkg/go/ast/print.go
@@ -108,8 +108,10 @@ func (p *printer) Write(data []byte) (n int, err error) {
 		}
 		p.last = b
 	}
-	m, err = p.output.Write(data[n:])
-	n += m
+	if len(data) > n {
+		m, err = p.output.Write(data[n:])
+		n += m
+	}
 	return
 }