Added FileHash utility class

Author: cmaglie

arduino-core/src/cc/arduino/utils/FileHash.java

@@ -0,0 +1,75 @@
+/*
+ * This file is part of Arduino.
+ *
+ * Copyright 2014 Arduino LLC (http://www.arduino.cc/)
+ *
+ * Arduino is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction.  Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License.  This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ */
+package cc.arduino.utils;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+public class FileHash {
+
+  /**
+   * Calculate a message digest of a file using the algorithm specified. The
+   * result is a string containing the algorithm name followed by ":" and by the
+   * resulting hash in hex.
+   * 
+   * @param file
+   * @param algorithm
+   *          For example "SHA-256"
+   * @return The algorithm followed by ":" and the hash, for example:<br />
+   *         "SHA-256:ee6796513086080cca078cbb383f543c5e508b647a71c9d6f39b7bca41071883"
+   * @throws IOException
+   * @throws NoSuchAlgorithmException
+   */
+  public static String hash(File file, String algorithm) throws IOException,
+      NoSuchAlgorithmException {
+    FileInputStream in = new FileInputStream(file);
+    try {
+      byte buff[] = new byte[10240];
+      MessageDigest digest = MessageDigest.getInstance(algorithm);
+      while (in.available() > 0) {
+        int read = in.read(buff);
+        digest.update(buff, 0, read);
+      }
+      byte[] hash = digest.digest();
+      String res = "";
+      for (byte b : hash) {
+        int c = b & 0xFF;
+        if (c < 0x10)
+          res += "0";
+        res += Integer.toHexString(c);
+      }
+      return algorithm + ":" + res;
+    } finally {
+      in.close();
+    }
+  }
+}