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

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

Fixes #1620

posix-utils_common.go

@@ -0,0 +1,37 @@
+/*
+ * 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 "strings"
+
+// List of reserved words for files, includes old and new ones.
+var posixReservedPrefix = []string{
+	"$tmpfile",
+	// Add new reserved words if any used in future.
+}
+
+// hasPosixReservedPrefix - has reserved prefix.
+func hasPosixReservedPrefix(name string) (isReserved bool) {
+	for _, reservedKey := range posixReservedPrefix {
+		if strings.HasPrefix(name, reservedKey) {
+			isReserved = true
+			break
+		}
+		isReserved = false
+	}
+	return isReserved
+}