nginx - php header <!-- Core Error --> and file currupted -

i'm having issue since update php version 5.4.41.

i'm running on nginx server php 5.4.41.

i've made php code allow me retrieve file , download it. since updated php code file i'm trying download corrupted. upload txt file , see happening.

ex: if upload text file test inside after download it, become

<!--core error-->test 

here complete code

<?php  require_once("include.php"); if(!xml2php("customer")) { $smarty->assign('error_msg',"error in language file"); }  //grab key url $key = $var['key'];  if ($var['escape'] == 1) {  if (isset($key)) {  $q = "select * ".prfx."table_customer_backup     customer_backup_key=".$db->qstr($key);  if(!$rs = $db->execute($q)) {     force_page('core', 'error&error_msg=mysql error: '.$db-    >errormsg().'&menu=1&type=database');     exit;     } else {      $customer_backup_filename = $rs->fields['customer_backup_filename'];     $customer_backup_ext = $rs->fields['customer_backup_ext'];     $customer_backup_file_link = $rs->fields['customer_backup_file_link'];     $customer_backup_filetype = $rs->fields['customer_backup_filetype'];      }         if(empty($customer_backup_file_link)){          force_page('core', 'error&error_msg=this key not valid');         exit;         }  } else {     force_page('core', 'error&error_msg=this key not valid');     exit;     }  $fakefilename= $customer_backup_filename.".".$customer_backup_ext;  $file = $customer_backup_file_link;    if (isset($customer_backup_file_link, $customer_backup_ext,      $customer_backup_filename, $customer_backup_filetype) &&      file_exists($customer_backup_file_link)){      ignore_user_abort(true);     set_time_limit(0); // disable time limit script      header("cache-control: public");     header("content-description: file transfer");     header("content-type: ".$customer_backup_filetype);     header("content-disposition: attachment; filename=".$fakefilename);     header("content-length: ".filesize($file));     header("content-transfer-encoding: binary");      readfile($file);  } else {     force_page('core', 'error&error_msg=there problem downloading  file. please contact administrator.');     exit; }  } else {  force_page('core', 'error&error_msg=there problem downloading   file. please contact administrator.'); exit; }  $smarty->display('customer'.sep.'download.tpl');  //exit;  ?> 

i discover if put // in front of

header("content-type: ".$customer_backup_filetype); header("content-disposition: attachment; filename=".$fakefilename); 

to ignore file display browser without issue

i need i've been working on issue 2 days , haven't found nothing.

update :

i discover if try escape smarty template engine not work same issue. if load smarty template engine text display without error.

http://www.exemple.com/index.php?page=customer:download&key=1414830421&escape=1 //escaping smarty template engine

the <!--core error--> has originate place before:

readfile($file); 

since line content 'test' written, displays after it.

my guesses be, source either 1 of:

• include.php
• xml2php()
• $db->execute()

maybe add additional output code, narrow down line, <!--core error--> gets written.