fs: Cleanup Golang errors to be called 'e' and probe to be called as 'err'

- Replace the ACL checks back, remove them when bucket
  policy is implemented.
- Move FTW (File Tree Walk) into ioutils package.

pkg/ioutils/filepath.go

@@ -0,0 +1,150 @@
+/*
+ * Minio Cloud Storage, (C) 2015 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package ioutils
+
+import (
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+	"sort"
+)
+
+// IsDirEmpty Check if a directory is empty
+func IsDirEmpty(dirname string) (bool, error) {
+	names, err := ReadDirNamesN(dirname, 1)
+	if err != nil && err != io.EOF {
+		return false, err
+	}
+	if len(names) > 0 {
+		return false, nil
+	}
+	return true, nil
+}
+
+// FTW walks the file tree rooted at root, calling walkFn for each file or
+// directory in the tree, including root.
+func FTW(root string, walkFn FTWFunc) error {
+	info, err := os.Lstat(root)
+	if err != nil {
+		return walkFn(root, nil, err)
+	}
+	return walk(root, info, walkFn)
+}
+
+// getRealName - gets the proper filename for sorting purposes
+// Readdir() filters out directory names without separators, add
+// them back for proper sorting results.
+func getRealName(info os.FileInfo) string {
+	if info.IsDir() {
+		// Make sure directory has its end separator.
+		return info.Name() + string(os.PathSeparator)
+	}
+	return info.Name()
+}
+
+// readDirNames reads the directory named by dirname and returns
+// a sorted list of directory entries.
+func readDirNames(dirname string) ([]string, error) {
+	names, err := readDirUnsortedNames(dirname)
+	if err != nil {
+		return nil, err
+	}
+	sort.Strings(names)
+	return names, nil
+}
+
+func readDirUnsortedNames(dirname string) ([]string, error) {
+	f, err := os.Open(dirname)
+	if err != nil {
+		return nil, err
+	}
+	nameInfos, err := f.Readdir(-1)
+	if err != nil {
+		return nil, err
+	}
+	if err = f.Close(); err != nil {
+		return nil, err
+	}
+	var names []string
+	for _, nameInfo := range nameInfos {
+		names = append(names, getRealName(nameInfo))
+	}
+	return names, nil
+}
+
+// FTWFunc is the type of the function called for each file or directory
+// visited by Walk. The path argument contains the argument to Walk as a
+// prefix; that is, if Walk is called with "dir", which is a directory
+// containing the file "a", the walk function will be called with argument
+// "dir/a". The info argument is the os.FileInfo for the named path.
+type FTWFunc func(path string, info os.FileInfo, err error) error
+
+// ErrSkipDir is used as a return value from WalkFuncs to indicate that
+// the directory named in the call is to be skipped. It is not returned
+// as an error by any function.
+var ErrSkipDir = errors.New("skip this directory")
+
+// ErrSkipFile is used as a return value from WalkFuncs to indicate that
+// the file named in the call is to be skipped. It is not returned
+// as an error by any function.
+var ErrSkipFile = errors.New("skip this file")
+
+// ErrDirNotEmpty is used to throw error on directories which have atleast one regular
+// file or a symlink left
+var ErrDirNotEmpty = errors.New("directory not empty")
+
+// walk recursively descends path, calling walkFn.
+func walk(path string, info os.FileInfo, walkFn FTWFunc) error {
+	err := walkFn(path, info, nil)
+	if err != nil {
+		if info.Mode().IsDir() && err == ErrSkipDir {
+			return nil
+		}
+		if info.Mode().IsRegular() && err == ErrSkipFile {
+			return nil
+		}
+		return err
+	}
+
+	if !info.IsDir() {
+		return nil
+	}
+
+	names, err := readDirNames(path)
+	if err != nil {
+		return walkFn(path, info, err)
+	}
+	for _, name := range names {
+		filename := filepath.Join(path, name)
+		fileInfo, err := os.Lstat(filename)
+		if err != nil {
+			if err := walkFn(filename, fileInfo, err); err != nil && err != ErrSkipDir && err != ErrSkipFile {
+				return err
+			}
+		} else {
+			err = walk(filename, fileInfo, walkFn)
+			if err != nil {
+				if err == ErrSkipDir || err == ErrSkipFile {
+					return nil
+				}
+				return err
+			}
+		}
+	}
+	return nil
+}