Added execute.php

backend/execute.php

+<?php
+
+$postData = file_get_contents("php://input");
+
+$uid = $postData['id'];
+$filename = $postData['filename'];
+$language = $postData['language'];
+$input_data = $postData['input_data'];
+
+$ret_stat = 0;
+
+$template = $uid . strval(rand(1, 1000000));
+$in_fname = "temp_in" . $template;
+
+$file = fopen($in_fname, 'w');
+file_put_contents($in_fname, $input_data);
+fclose($file);
+
+$out_fname = "temp_out" . $template;
+
+if(strcmp($language, "cpp") == 0)
+{
+    $base = basename($filename, ".cpp");
+    system("./" . $uid . "/" . $base . " < " . $in_fname . " > " . $out_fname, $ret_stat);
+}
+
+else if(strcmp($language, "java") == 0)
+{
+    $base = basename($filename, ".java");
+    system("java -cp " . $uid . "/ " . $base . " < " . $in_fname . " > " . $out_fname, $ret_stat);
+}
+
+else if(strcmp($language, "python") == 0)
+{
+    system("python3 " . $uid . "/" . $filename . " < " . $in_fname . " > " . $out_fname, $ret_stat);
+}
+
+if($ret_stat != 0)
+{
+    echo "Runtime Error!!";
+}
+
+else
+{
+    $file = fopen($out_fname, 'r');
+    echo fread($file, filesize($out_fname));
+    fclose($file);
+}
+
+unlink($in_fname);
+unlink($out_fname);
+
+?>
\ No newline at end of file