posix: Support UNC paths on windows. (#1887)

This allows us to now use 32K paths names on windows.

Fixes #1620

posix-utils_nix.go

@@ -0,0 +1,65 @@
+// +build linux darwin dragonfly freebsd netbsd openbsd
+
+/*
+ * Minio Cloud Storage, (C) 2016 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 main
+
+import (
+	"os"
+	"strings"
+	"unicode/utf8"
+)
+
+const pathMax = 4096 // 4k limit on all unixes.
+
+// isValidPath verifies if a path name is in accordance with FS limitations.
+func isValidPath(path string) bool {
+	if len(path) > pathMax || len(path) == 0 {
+		return false
+	}
+	if !utf8.ValidString(path) {
+		return false
+	}
+	return true
+}
+
+// isValidVolname verifies a volname name in accordance with object
+// layer requirements.
+func isValidVolname(volname string) bool {
+	if len(volname) < 3 || len(volname) > 63 {
+		return false
+	}
+	// Volname shouldn't have '/' in it.
+	return !strings.ContainsAny(volname, "/")
+}
+
+// mkdirAll creates a directory named path,
+// along with any necessary parents, and returns nil,
+// or else returns an error. The permission bits perm are used
+// for all directories that mkdirAll creates. If path is already
+// a directory, mkdirAll does nothing and returns nil.
+func mkdirAll(path string, perm os.FileMode) error {
+	return os.MkdirAll(path, perm)
+}
+
+// removeAll removes path and any children it contains.
+// It removes everything it can but returns the first error
+// it encounters.  If the path does not exist, RemoveAll
+// returns nil (no error).
+func removeAll(path string) error {
+	return os.RemoveAll(path)
+}