MDL-22955 output: Fixed bug by ensuring we generate an SVG candidate …

…even for regular format requests

theme/image.php

@@ -131,11 +131,38 @@
 require("$CFG->dirroot/lib/setup.php");
 
 $theme = theme_config::load($themename);
-$imagefile = $theme->resolve_image_location($image, $component, $usesvg);
-
 $rev = theme_get_revision();
 $etag = sha1("$themename/$component/$rev/$image");
 
+// We're not using SVG and there is no cached version of this file (in any format).
+// As we're going to be caching a format other than svg, and because svg use is conditional we need to ensure that at the same
+// time we cache a version of the SVG if it exists. If we don't do this other users who ask for SVG would not ever get it as
+// there is a cached image already of another format.
+// Remember this only gets run once before any candidate exists, and only if we want a cached revision.
+if (!$usesvg && $rev > -1) {
+    $imagefile = $theme->resolve_image_location($image, $component, true);
+    if (!empty($imagefile) && is_readable($imagefile)) {
+        $cacheimage = cache_image($image, $imagefile, $candidatelocation);
+        $pathinfo = pathinfo($imagefile);
+        // There is no SVG equivilant, we've just successfully cached an image of another format.
+        if ($pathinfo['extension'] !== 'svg') {
+            // Serve the file as we would in a normal request.
+            if (connection_aborted()) {
+                die;
+            }
+            // make sure nothing failed
+            clearstatcache();
+            if (file_exists($cacheimage)) {
+                send_cached_image($cacheimage, $etag);
+            }
+            send_uncached_image($imagefile);
+            exit;
+        }
+    }
+}
+
+// Either SVG was requested or we've cached a SVG version and are ready to serve a regular format.
+$imagefile = $theme->resolve_image_location($image, $component, $usesvg);
 if (empty($imagefile) or !is_readable($imagefile)) {
     if ($rev > -1) {
         if (!file_exists($candidatelocation)) {
@@ -150,23 +177,7 @@
 }
 
 if ($rev > -1) {
-    $pathinfo = pathinfo($imagefile);
-    $cacheimage = "$candidatelocation/$image.".$pathinfo['extension'];
-
-    clearstatcache();
-    if (!file_exists(dirname($cacheimage))) {
-        @mkdir(dirname($cacheimage), $CFG->directorypermissions, true);
-    }
-
-    // Prevent serving of incomplete file from concurrent request,
-    // the rename() should be more atomic than copy().
-    ignore_user_abort(true);
-    if (@copy($imagefile, $cacheimage.'.tmp')) {
-        rename($cacheimage.'.tmp', $cacheimage);
-        @chmod($cacheimage, $CFG->filepermissions);
-        @unlink($cacheimage.'.tmp'); // just in case anything fails
-    }
-    ignore_user_abort(false);
+    $cacheimage = cache_image($image, $imagefile, $candidatelocation);
     if (connection_aborted()) {
         die;
     }
@@ -253,4 +264,33 @@ function get_contenttype_from_ext($ext) {
             return 'image/vnd.microsoft.icon';
     }
     return 'document/unknown';
+}
+
+/**
+ * Caches a given image file.
+ *
+ * @param string $image The name of the image that was requested.
+ * @param string $imagefile The location of the image file we want to cache.
+ * @param string $candidatelocation The location to cache it in.
+ * @return string The path to the cached image.
+ */
+function cache_image($image, $imagefile, $candidatelocation) {
+    global $CFG;
+    $pathinfo = pathinfo($imagefile);
+    $cacheimage = "$candidatelocation/$image.".$pathinfo['extension'];
+
+    clearstatcache();
+    if (!file_exists(dirname($cacheimage))) {
+        @mkdir(dirname($cacheimage), $CFG->directorypermissions, true);
+    }
+
+    // Prevent serving of incomplete file from concurrent request,
+    // the rename() should be more atomic than copy().
+    ignore_user_abort(true);
+    if (@copy($imagefile, $cacheimage.'.tmp')) {
+        rename($cacheimage.'.tmp', $cacheimage);
+        @chmod($cacheimage, $CFG->filepermissions);
+        @unlink($cacheimage.'.tmp'); // just in case anything fails
+    }
+    return $cacheimage;
 }