net: avoid nil dereference if /etc/services can't be opened

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4081041

diff --git a/src/pkg/net/port.go b/src/pkg/net/port.go
index cd18d2b42aa6ac582efde7a6f14f286192e6e0a3..7d25058b29cd7e6572be7573156ab8d62eb6b198 100644 (file)
--- a/src/pkg/net/port.go
+++ b/src/pkg/net/port.go
@@ -18,7 +18,9 @@ var onceReadServices sync.Once
 func readServices() {
        services = make(map[string]map[string]int)
        var file *file
-       file, servicesError = open("/etc/services")
+       if file, servicesError = open("/etc/services"); servicesError != nil {
+               return
+       }
        for line, ok := file.readLine(); ok; line, ok = file.readLine() {
                // "http 80/tcp www www-http # World Wide Web HTTP"
                if i := byteIndex(line, '#'); i >= 0 {