MDL-44828 filelib: Fix open error for force-downloaded files in mobile

Allow guessing of file's MIME type by default. Fallback to
application/octet-stream if MIME type cannot be determined.

diff --git a/lib/filelib.php b/lib/filelib.php
index 6375faf..4da13f2 100644 (file)
--- a/lib/filelib.php
+++ b/lib/filelib.php
@@ -1390,6 +1390,29 @@ function &get_mimetypes_array() {
     return core_filetypes::get_types();
 }
 
+/**
+ * Determine a file's MIME type based on the given filename using the function mimeinfo.
+ *
+ * This function retrieves a file's MIME type for a file that will be sent to the user.
+ * This should only be used for file-sending purposes just like in send_stored_file, send_file, and send_temp_file.
+ * Should the file's MIME type cannot be determined by mimeinfo, it will return 'application/octet-stream' as a default
+ * MIME type which should tell the browser "I don't know what type of file this is, so just download it.".
+ *
+ * @param string $filename The file's filename.
+ * @return string The file's MIME type or 'application/octet-stream' if it cannot be determined.
+ */
+function get_mimetype_for_sending($filename = '') {
+    // Guess the file's MIME type using mimeinfo.
+    $mimetype = mimeinfo('type', $filename);
+
+    // Use octet-stream as fallback if MIME type cannot be determined by mimeinfo.
+    if (!$mimetype || $mimetype === 'document/unknown') {
+        $mimetype = 'application/octet-stream';
+    }
+
+    return $mimetype;
+}
+
 /**
  * Obtains information about a filetype based on its extension. Will
  * use a default if no information is present about that particular
@@ -1988,12 +2011,8 @@ function readstring_accel($string, $mimetype, $accelerate) {
 function send_temp_file($path, $filename, $pathisstring=false) {
     global $CFG;
 
-    if (core_useragent::is_firefox()) {
-        // only FF is known to correctly save to disk before opening...
-        $mimetype = mimeinfo('type', $filename);
-    } else {
-        $mimetype = 'application/x-forcedownload';
-    }
+    // Guess the file's MIME type.
+    $mimetype = get_mimetype_for_sending($filename);
 
     // close session - not needed anymore
     \core\session\manager::write_close();
@@ -2076,12 +2095,10 @@ function send_file($path, $filename, $lifetime = null , $filter=0, $pathisstring
 
     \core\session\manager::write_close(); // Unlock session during file serving.
 
-    // Use given MIME type if specified, otherwise guess it using mimeinfo.
-    // IE, Konqueror and Opera open html file directly in browser from web even when directed to save it to disk :-O
-    // only Firefox saves all files locally before opening when content-disposition: attachment stated
-    $isFF         = core_useragent::is_firefox(); // only FF properly tested
-    $mimetype     = ($forcedownload and !$isFF) ? 'application/x-forcedownload' :
-                         ($mimetype ? $mimetype : mimeinfo('type', $filename));
+    // Use given MIME type if specified, otherwise guess it.
+    if (!$mimetype || $mimetype === 'document/unknown') {
+        $mimetype = get_mimetype_for_sending($filename);
+    }
 
     // if user is using IE, urlencode the filename so that multibyte file name will show up correctly on popup
     if (core_useragent::is_ie()) {
@@ -2254,13 +2271,15 @@ function send_stored_file($stored_file, $lifetime=null, $filter=0, $forcedownloa
 
     \core\session\manager::write_close(); // Unlock session during file serving.
 
-    // Use given MIME type if specified, otherwise guess it using mimeinfo.
-    // IE, Konqueror and Opera open html file directly in browser from web even when directed to save it to disk :-O
-    // only Firefox saves all files locally before opening when content-disposition: attachment stated
     $filename     = is_null($filename) ? $stored_file->get_filename() : $filename;
-    $isFF         = core_useragent::is_firefox(); // only FF properly tested
-    $mimetype     = ($forcedownload and !$isFF) ? 'application/x-forcedownload' :
-                         ($stored_file->get_mimetype() ? $stored_file->get_mimetype() : mimeinfo('type', $filename));
+
+    // Use given MIME type if specified.
+    $mimetype = $stored_file->get_mimetype();
+
+    // Otherwise guess it.
+    if (!$mimetype || $mimetype === 'document/unknown') {
+        $mimetype = get_mimetype_for_sending($filename);
+    }
 
     // if user is using IE, urlencode the filename so that multibyte file name will show up correctly on popup
     if (core_useragent::is_ie()) {

diff --git a/lib/tests/filelib_test.php b/lib/tests/filelib_test.php
index b32c328..555a45c 100644 (file)
--- a/lib/tests/filelib_test.php
+++ b/lib/tests/filelib_test.php
@@ -879,6 +879,30 @@ EOF;
         $this->assertEquals(true, $mimeinfo['txt']['defaulticon']);
     }
 
+    /**
+     * Tests for get_mimetype_for_sending function.
+     */
+    public function test_get_mimetype_for_sending() {
+        // Without argument.
+        $this->assertEquals('application/octet-stream', get_mimetype_for_sending());
+
+        // Argument is null.
+        $this->assertEquals('application/octet-stream', get_mimetype_for_sending(null));
+
+        // Filename having no extension.
+        $this->assertEquals('application/octet-stream', get_mimetype_for_sending('filenamewithoutextension'));
+
+        // Test using the extensions listed from the get_mimetypes_array function.
+        $mimetypes = get_mimetypes_array();
+        foreach ($mimetypes as $ext => $info) {
+            if ($ext === 'xxx') {
+                $this->assertEquals('application/octet-stream', get_mimetype_for_sending('SampleFile.' . $ext));
+            } else {
+                $this->assertEquals($info['type'], get_mimetype_for_sending('SampleFile.' . $ext));
+            }
+        }
+    }
+
     /**
      * Test curl agent settings.
      */