thumb: error image also on unexpected exceptions

Output is expected to be an image so avoid HTML responses.
Replace 501 placeholder by a common 500.png on any resize error.
Preserve message in X-Error header for debugging.

diff --git a/thumb/index.php b/thumb/index.php
index 66de10673a1dc4235f96f70a4b11b3769b70fbdd..e8b3bcb0e5b18cfc782f6278f08ffb829016e412 100644 (file)
--- a/thumb/index.php
+++ b/thumb/index.php
@@ -5,14 +5,6 @@ list ($height, $imgpath) = explode('/', ltrim($Args, '/'), 2);
 $width= 1000;
 $imgpath = preg_replace('{^(?=[0-9]+/)}', 'data/', $imgpath, 1);
 
-if (!function_exists('popen')) {
-       http_response_code(501);
-       $target = '501.png';
-       header('Content-type: '.mime_content_type($target));
-       readfile($target);
-       exit;
-}
-
 if (!file_exists($imgpath)) {
        http_response_code(404);
        exit;
@@ -24,7 +16,14 @@ if (!file_exists($target)) {
                mkthumb($imgpath, $target, $width, $height);
        }
        catch (Exception $e) {
-               http_response_code(500);
+               http_response_code($e->getCode() ?: 500);
+               $target = '500.png';
+               if (file_exists($target)) {
+                       header("X-Error: ".$e->getMessage());
+                       header('Content-type: '.mime_content_type($target));
+                       readfile($target);
+                       exit;
+               }
                trigger_error("thumbnail creation failed: ".$e->getMessage(), E_USER_WARNING);
                exit;
        }
@@ -42,6 +41,9 @@ function mkthumb($source, $target, $width, $height)
 
 function mkthumb_exec($source, $target, $width, $height)
 {
+       if (!function_exists('popen')) {
+               throw new Exception("exec disallowed on this server", 501);
+       }
        $cmd = implode(' ', array_map('escapeshellarg', [
                'convert',
                '-trim',