- implemented utility functions for directory reading/traversal

- added tests

R=rsc
DELTA=62  (61 added, 1 deleted, 0 changed)
OCL=35788
CL=35802

src/pkg/io/utils.go

@@ -9,6 +9,7 @@ package io
 import (
 	"bytes";
 	"os";
+	"sort";
 )
 
 // ReadAll reads from r until an error or EOF and returns the data it read.
@@ -37,9 +38,36 @@ func WriteFile(filename string, data []byte, perm int) os.Error {
 		return err;
 	}
 	n, err := f.Write(data);
+	f.Close();
 	if err == nil && n < len(data) {
 		err = ErrShortWrite;
 	}
-	f.Close();
 	return err;
 }
+
+// A dirList implements sort.Interface.
+type dirList []*os.Dir
+
+func (d dirList) Len() int { return len(d); }
+func (d dirList) Less(i, j int) bool { return d[i].Name < d[j].Name; }
+func (d dirList) Swap(i, j int) { d[i], d[j] = d[j], d[i]; }
+
+// ReadDir reads the directory named by dirname and returns
+// a list of sorted directory entries.
+func ReadDir(dirname string) ([]*os.Dir, os.Error) {
+	f, err := os.Open(dirname, os.O_RDONLY, 0);
+	if err != nil {
+		return nil, err;
+	}
+	list, err := f.Readdir(-1);
+	f.Close();
+	if err != nil {
+		return nil, err;
+	}
+	dirs := make(dirList, len(list));
+	for i := range list {
+		dirs[i] = &list[i];
+	}
+	sort.Sort(dirs);
+	return dirs, nil;
+}

src/pkg/io/utils_test.go

@@ -59,3 +59,35 @@ func TestWriteFile(t *testing.T) {
 	// cleanup
 	os.Remove(filename);	// ignore error
 }
+
+
+func TestReadDir(t *testing.T) {
+	dirname := "rumpelstilzchen";
+	_, err := ReadDir(dirname);
+	if err == nil {
+		t.Fatalf("ReadDir %s: error expected, none found", dirname);
+	}
+
+	dirname = ".";
+	list, err := ReadDir(dirname);
+	if err != nil {
+		t.Fatalf("ReadDir %s: %v", dirname, err);
+	}
+
+	foundTest := false;
+	foundObj := false;
+	for _, dir := range list {
+		switch {
+		case dir.IsRegular() && dir.Name == "utils_test.go":
+			foundTest = true;
+		case dir.IsDirectory() && dir.Name == "_obj":
+			foundObj = true;
+		}
+	}
+	if !foundTest {
+		t.Fatalf("ReadDir %s: test file not found", dirname);
+	}
+	if !foundObj {
+		t.Fatalf("ReadDir %s: _obj directory not found", dirname);
+	}
+}