net: handle single-line non-\n-terminated files correctly in readLine

Fixes #6646.

R=rsc, bradfitz
CC=golang-dev
https://golang.org/cl/15960047

src/pkg/net/hosts_test.go

@@ -53,6 +53,19 @@ func TestLookupStaticHost(t *testing.T) {
 	hostsPath = p
 }
 
+// https://code.google.com/p/go/issues/detail?id=6646
+func TestSingleLineHostsFile(t *testing.T) {
+	p := hostsPath
+	hostsPath = "testdata/hosts_singleline"
+
+	ips := lookupStaticHost("odin")
+	if len(ips) != 1 || ips[0] != "127.0.0.2" {
+		t.Errorf("lookupStaticHost = %v, want %v", ips, []string{"127.0.0.2"})
+	}
+
+	hostsPath = p
+}
+
 func TestLookupHost(t *testing.T) {
 	// Can't depend on this to return anything in particular,
 	// but if it does return something, make sure it doesn't

src/pkg/net/parse.go

@@ -54,7 +54,7 @@ func (f *file) readLine() (s string, ok bool) {
 		if n >= 0 {
 			f.data = f.data[0 : ln+n]
 		}
-		if err == io.EOF {
+		if err == io.EOF || err == io.ErrUnexpectedEOF {
 			f.atEOF = true
 		}
 	}

src/pkg/net/testdata/hosts_singleline

@@ -0,0 +1 @@
+127.0.0.2	odin