os: avoid a string concat in readdir

R=golang-dev, crawshaw
CC=golang-dev
https://golang.org/cl/37690045

diff --git a/src/pkg/os/file_unix.go b/src/pkg/os/file_unix.go
index d49c70c5461adac5e2f3ffeab84f78f2211e1896..37677e2174056df6d378aa4823e39b36f4cb36ff 100644 (file)
--- a/src/pkg/os/file_unix.go
+++ b/src/pkg/os/file_unix.go
@@ -160,11 +160,10 @@ func (f *File) readdir(n int) (fi []FileInfo, err error) {
        if dirname == "" {
                dirname = "."
        }
-       dirname += "/"
        names, err := f.Readdirnames(n)
        fi = make([]FileInfo, 0, len(names))
        for _, filename := range names {
-               fip, lerr := lstat(dirname + filename)
+               fip, lerr := lstat(dirname + "/" + filename)
                if IsNotExist(lerr) {
                        // File disappeared between readdir + stat.
                        // Just treat it as if it didn't exist.