Add MIME type detection to download (at least for images).

RFE#2937494

libraries/mime.lib.php

@@ -0,0 +1,27 @@
+<?php
+/* vim: set expandtab sw=4 ts=4 sts=4: */
+/**
+ * MIME detection code.
+ *
+ * @version $Id$
+ * @package phpMyAdmin
+ * @todo Maybe we could try to use fileinfo module if loaded
+ */
+
+/**
+ * Tries to detect MIME type of content.
+ */
+function PMA_detectMIME(&$test) {
+    $len = strlen($test);
+    if ($len >= 2 && $test[0] == chr(0xff) && $test[1] == chr(0xd8)) {
+        return 'image/jpeg';
+    }
+    if ($len >= 3 && substr($test, 0, 3) == 'GIF') {
+        return 'image/gif';
+    }
+    if ($len >= 4 && substr($test, 0, 4) == "\x89PNG") {
+        return 'image/png';
+    }
+    return 'application/octet-stream';
+}
+?>

tbl_get_field.php

@@ -10,6 +10,7 @@
  * Common functions.
  */
 require_once './libraries/common.inc.php';
+require_once './libraries/mime.lib.php';
 
 /* Check parameters */
 PMA_checkParameters(array('db', 'table', 'where_clause', 'transform_key'));
@@ -37,7 +38,7 @@ if ($result === false) {
 /* Avoid corrupting data */
 @ini_set('url_rewriter.tags','');
 
-header('Content-Type: application/octet-stream');
+header('Content-Type: ' . PMA_detectMIME($result));
 header('Expires: ' . gmdate('D, d M Y H:i:s') . ' GMT');
 header('Content-Disposition: attachment; filename="' . $table . '-' .  $transform_key . '.bin"');
 if (PMA_USR_BROWSER_AGENT == 'IE') {