Added character validation

common/utilities/file_hash.cpp

@@ -0,0 +1,60 @@
+/* Copyright: (c) Kayne Ruse 2016
+ * 
+ * This software is provided 'as-is', without any express or implied
+ * warranty. In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ * 
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ * 
+ * 1. The origin of this software must not be misrepresented; you must not
+ * claim that you wrote the original software. If you use this software
+ * in a product, an acknowledgment in the product documentation would be
+ * appreciated but is not required.
+ * 
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ * misrepresented as being the original software.
+ * 
+ * 3. This notice may not be removed or altered from any source
+ * distribution.
+*/
+#include "file_hash.hpp"
+
+#include <fstream>
+
+//hash a byte array into a 32-bit integer
+unsigned fnv_hash_1a_32(void *key, int len) {
+	unsigned char *p = static_cast<unsigned char*>(key);
+	unsigned h = 0x811c9dc5;
+	for (int i = 0; i < len; i++) {
+		h = ( h ^ p[i] ) * 0x01000193;
+	}
+	return h;
+}
+
+int getFileHash(std::string fname) {
+	std::ifstream is(fname, std::ios::in | std::ios::binary);
+
+	//if the file doesn't exist, return a hash of -1
+	if (!is.is_open()) {
+		return -1;
+	}
+
+	//get the file size
+	is.seekg(0, std::ios_base::end);
+	int size = is.tellg();
+	is.seekg(0);
+
+	//create a buffer of that size
+	char buffer[size];
+
+	//load the data
+	is.read(buffer, size);
+
+	//cleanup
+	is.close();
+
+	//finally, return the hash value
+	return fnv_hash_1a_32(buffer, size);
+}