issue #777, make photo cache time configurable, read the comments.

1 files changed, 15 insertions, 3 deletions

diff --git a/mod/photo.php b/mod/photo.php
index 8cb82e8ff..66280cb76 100644
--- a/mod/photo.php
+++ b/mod/photo.php
@@ -224,9 +224,21 @@ function photo_init(&$a) {
 
 	}
 	else {
-
-	 	header("Expires: " . gmdate("D, d M Y H:i:s", time() + (3600*24)) . " GMT");
-		header("Cache-Control: max-age=" . (3600*24));
+		// The photo cache default is 1 day to provide a privacy trade-off,
+		// as somebody reducing photo permissions on a photo that is already 
+		// "in the wild" won't be able to stop the photo from being viewed
+		// for this amount amount of time once it is in the browser cache.
+		// The privacy expectations of your site members and their perception 
+		// of privacy where it affects the entire project may be affected.
+		// This has performance considerations but we highly recommend you 
+		// leave it alone. 
+
+		$cache = get_config('system','photo_cache_time');
+		if(! $cache)
+			$cache = (3600 * 24); // 1 day
+
+	 	header("Expires: " . gmdate("D, d M Y H:i:s", time() + $cache) . " GMT");
+		header("Cache-Control: max-age=" . $cache);
 
 	}
 	echo $data;