bug #58181 [HttpFoundation] Update links for X-Accel-Redirect and f…

…ail properly when `X-Accel-Mapping` is missing (nicolas-grekas)

This PR was merged into the 5.4 branch.

Discussion
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[HttpFoundation] Update links for `X-Accel-Redirect` and fail properly when `X-Accel-Mapping` is missing

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        | -
| License       | MIT

The current link is dead and the failure is currently a notice. Let's make this fail properly instead. /cc `@dunglas` ;)

Commits
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bfc490d7d8 [HttpFoundation] Update links for X-Accel-Redirect and fail properly when X-Accel-Mapping is missing

BinaryFileResponse.php

@@ -244,8 +244,12 @@ public function prepare(Request $request)
             }
             if ('x-accel-redirect' === strtolower($type)) {
                 // Do X-Accel-Mapping substitutions.
-                // @link https://www.nginx.com/resources/wiki/start/topics/examples/x-accel/#x-accel-redirect
-                $parts = HeaderUtils::split($request->headers->get('X-Accel-Mapping', ''), ',=');
+                // @link https://github.com/rack/rack/blob/main/lib/rack/sendfile.rb
+                // @link https://mattbrictson.com/blog/accelerated-rails-downloads
+                if (!$request->headers->has('X-Accel-Mapping')) {
+                    throw new \LogicException('The "X-Accel-Mapping" header must be set when "X-Sendfile-Type" is set to "X-Accel-Redirect".');
+                }
+                $parts = HeaderUtils::split($request->headers->get('X-Accel-Mapping'), ',=');
                 foreach ($parts as $part) {
                     [$pathPrefix, $location] = $part;
                     if (substr($path, 0, \strlen($pathPrefix)) === $pathPrefix) {