JosephLenton#9 remains silent if returning non-HTML

Sometimes people request JS and CSS through PHP scripts,
in a non-ajaxy way. For example linking to a PHP script in a script tag.

This change will make PHP Error be silent if it believes it is on one of
those occasions.

It also changes the 'getResponseHeaders' method, to merge the apache
and non-apache headers together. It seems one can contain info the other
does not.

Author: joseph lenton

src/php_error.php

@@ -520,6 +520,47 @@ class ErrorHandler
                     'is_subclass_of'
             );
 
+            /**
+             * When returning values, if a mime type is set,
+             * then PHP Error should only output if the mime type
+             * is one of these.
+             */
+            private static $ALLOWED_RETURN_MIME_TYPES = array(
+                    'text/html',
+                    'application/xhtml+xml'
+            );
+            
+            /**
+             * This attempts to state if this is *not* a PHP request,
+             * but it cannot say if it *is* a PHP request. It achieves
+             * this by looking for a mime type.
+             *
+             * For example if the mime type is JavaScript, then we
+             * know it's not PHP. However there is no "yes, this is
+             * definitely a normal HTML response" flag we can check.
+             */
+            private static function isNonPHPRequest() {
+                /*
+                 * Check if we are a mime type that isn't allowed.
+                 *
+                 * Anything other than 'text/html' or similar will cause
+                 * this to turn off.
+                 */
+                $response = ErrorHandler::getResponseHeaders();
+
+                foreach ( $response as $key => $value ) {
+                    if ( strtolower($key) === 'content-type' ) {
+                        if ( ! in_array($value, ErrorHandler::$ALLOWED_RETURN_MIME_TYPES) ) {
+                            return true;
+                        }
+
+                        break;
+                    }
+                }
+
+                return false;
+            }
+
             /**
              * Looks up a description for the symbol given,
              * and if found, it is returned.
@@ -979,22 +1020,26 @@ private static function getRequestHeaders() {
             }
 
             private static function getResponseHeaders() {
-                if ( function_exists('apache_response_headers') ) {
-                    return apache_response_headers();
-                } else {
-                    $headers = array();
+                $headers = function_exists('apache_response_headers') ?
+                        apache_response_headers() :
+                        array() ;
 
-                    if ( function_exists('headers_list') ) {
-                        $hList = headers_list();
+                /*
+                 * Merge the headers_list into apache_response_headers.
+                 * 
+                 * This is because sometimes things are in one, which are
+                 * not present in the other.
+                 */
+                if ( function_exists('headers_list') ) {
+                    $hList = headers_list();
 
-                        foreach ($hList as $header) {
-                            $header = explode(":", $header);
-                            $headers[ array_shift($header) ] = trim( implode(":", $header) );
-                        }
+                    foreach ($hList as $header) {
+                        $header = explode(":", $header);
+                        $headers[ array_shift($header) ] = trim( implode(":", $header) );
                     }
-
-                    return $headers;
                 }
+
+                return $headers;
             }
 
             public static function identifyTypeHTML( $arg, $recurseLevels=1 ) {
@@ -1370,7 +1415,11 @@ private function endBuffer() {
                 global $_php_error_is_ini_enabled;
 
                 if ( $_php_error_is_ini_enabled ) {
-                    if ( !$this->isAjax && $this->catchAjaxErrors ) {
+                    if ( 
+                            !$this->isAjax &&
+                             $this->catchAjaxErrors &&
+                            !ErrorHandler::isNonPHPRequest()
+                    ) {
                         $content  = ob_get_contents();
                         $handlers = ob_list_handlers();
 
@@ -2219,8 +2268,20 @@ public function reportError( $code, $message, $errLine, $errFile, $ex=null ) {
 
                 $this->logError( $message, $errFile, $errLine, $ex );
 
+                /**
+                 * It runs if:
+                 *  - it is globally enabled
+                 *  - this error handler is enabled
+                 *  - we believe it is a regular html request, or ajax
+                 */
                 global $_php_error_is_ini_enabled;
-                if ( $_php_error_is_ini_enabled ) {
+                if (
+                        $_php_error_is_ini_enabled &&
+                        $this->isOn() && (
+                                $this->isAjax ||
+                                !ErrorHandler::isNonPHPRequest()
+                        )
+                ) {
                     $root = $this->applicationRoot;
 
                     list( $ex, $stackTrace, $code, $errFile, $errLine ) =