Track backup and restore progress

Track backup and restore progress based on the sizes of the files
as they are being added to the tar backup file. Update the
progress bar based on the sizes of the files.

Change-Id: Idf649efa1db3e91830b4b2add86203a3f30042ff

twrp-functions.cpp

@@ -299,6 +299,30 @@ std::string TWFunc::Remove_Trailing_Slashes(const std::string& path, bool leaveL
 	return res;
 }
 
+vector<string> TWFunc::split_string(const string &in, char del, bool skip_empty) {
+	vector<string> res;
+
+	if (in.empty() || del == '\0')
+		return res;
+
+	string field;
+	istringstream f(in);
+	if (del == '\n') {
+		while(getline(f, field)) {
+			if (field.empty() && skip_empty)
+				continue;
+		res.push_back(field);
+		}
+	} else {
+		while(getline(f, field, del)) {
+			if (field.empty() && skip_empty)
+				continue;
+			res.push_back(field);
+		}
+	}
+	return res;
+}
+
 #ifndef BUILD_TWRPTAR_MAIN
 
 // Returns "/path" from a full /path/to/file.name