Add os.Rename.

R=rsc
https://golang.org/cl/166058

src/pkg/os/file.go

@@ -370,7 +370,7 @@ func Remove(name string) Error {
 	return &PathError{"remove", name, Errno(e)};
 }
 
-// LinkError records an error during a link or symlink
+// LinkError records an error during a link or symlink or rename
 // system call and the paths that caused it.
 type LinkError struct {
 	Op	string;
@@ -418,6 +418,15 @@ func Readlink(name string) (string, Error) {
 	return "", nil;
 }
 
+// Rename renames a file.
+func Rename(oldname, newname string) Error {
+	e := syscall.Rename(oldname, newname);
+	if e != 0 {
+		return &LinkError{"rename", oldname, newname, Errno(e)}
+	}
+	return nil;
+}
+
 // Chmod changes the mode of the named file to mode.
 // If the file is a symbolic link, it changes the uid and gid of the link's target.
 func Chmod(name string, mode int) Error {

src/pkg/os/os_test.go

@@ -315,6 +315,27 @@ func TestLongSymlink(t *testing.T) {
 	}
 }
 
+func TestRename(t *testing.T) {
+	from, to := "renamefrom", "renameto";
+	Remove(to);	// Just in case.
+	file, err := Open(from, O_CREAT|O_WRONLY, 0666);
+	if err != nil {
+		t.Fatalf("open %q failed: %v", to, err)
+	}
+	if err = file.Close(); err != nil {
+		t.Errorf("close %q failed: %v", to, err)
+	}
+	err = Rename(from, to);
+	if err != nil {
+		t.Fatalf("rename %q, %q failed: %v", to, from, err)
+	}
+	defer Remove(to);
+	_, err = Stat(to);
+	if err != nil {
+		t.Errorf("stat %q failed: %v", to, err)
+	}
+}
+
 func TestForkExec(t *testing.T) {
 	r, w, err := Pipe();
 	if err != nil {