Added function for calculating md5 hash from Data. (#17762)

* Added function for calculating md5 hash from Data.

getFileMD5Hash now use getDataMD5Hash.

For example, AssetsManagerEx VerifyCallback.
Get Data from file, check equal size, if equal to get md5 hash.

* Data::isNull check size equal 0

* Build on linux and android.

Author: perminovVS

cocos/base/ccUtils.cpp

@@ -410,18 +410,28 @@ Node* findChild(Node* levelRoot, int tag)
 }
 
 std::string getFileMD5Hash(const std::string &filename)
+{
+    Data data;
+    FileUtils::getInstance()->getContents(filename, &data);
+
+    return getDataMD5Hash(data);
+}
+
+std::string getDataMD5Hash(const Data &data)
 {
     static const unsigned int MD5_DIGEST_LENGTH = 16;
 
-    Data d;
-    FileUtils::getInstance()->getContents(filename, &d);
+    if (data.isNull())
+    {
+        return std::string();
+    }
 
     md5_state_t state;
     md5_byte_t digest[MD5_DIGEST_LENGTH];
-    char hexOutput[(MD5_DIGEST_LENGTH << 1) + 1] = {0};
+    char hexOutput[(MD5_DIGEST_LENGTH << 1) + 1] = { 0 };
 
     md5_init(&state);
-    md5_append(&state, (const md5_byte_t *)d.getBytes(), (int)d.getSize());
+    md5_append(&state, (const md5_byte_t *)data.getBytes(), (int)data.getSize());
     md5_finish(&state, digest);
 
     for (int di = 0; di < 16; ++di)

cocos/base/ccUtils.h

@@ -29,6 +29,7 @@ THE SOFTWARE.
 #include <string>
 #include "2d/CCNode.h"
 #include "base/ccMacros.h"
+#include "base/CCData.h"
 
 /** @file ccUtils.h
 Misc free functions
@@ -170,6 +171,14 @@ namespace utils
      *  @return The md5 hash for the file
      */
     CC_DLL std::string getFileMD5Hash(const std::string &filename);
+
+
+    /**
+    *  Gets the md5 hash for the given buffer.
+    *  @param data The buffer to calculate md5 hash.
+    *  @return The md5 hash for the data
+    */
+    CC_DLL std::string getDataMD5Hash(const Data &data);
 }
 
 NS_CC_END